<table><caption>**Table 1.** Influence of metabolizable energy, level and duration of feed restriction on performance of broilers</caption><thead><tr><th rowspan="2">variable</th><th colspan="4">FCR</th><th colspan="4">BW (g)</th></tr><tr><th>1-7 d</th><th>8-21d</th><th>22-42d</th><th>1-42d</th><th>1-7 d</th><th>8-21d</th><th>22-42d</th><th>1-42d</th></tr></thead><tbody><tr><td>ME (kcal/kg)</td><td>*</td><td>**</td><td>NS</td><td>**</td><td>*</td><td>**</td><td>NS</td><td>**</td></tr><tr><td></td><td></td><td>1.53±</td><td></td><td></td><td></td><td>565.4±</td><td></td><td></td></tr><tr><td>Norm</td><td>1.03±0.05<sup>b</sup></td><td>0.04<sup>a</sup></td><td>1.85±0.05</td><td>1.73±0.04<sup>a</sup></td><td>145.4±7.1<sup>a</sup></td><td>24.0<sup>b</sup></td><td>1797.4±66.1</td><td>2508.3±75.3<sup>b</sup></td></tr><tr><td>High</td><td>1.07±0.05<sup>a</sup></td><td>1.40±0.04<sup>b</sup></td><td>1.82±0.08</td><td>1.68±0.06<sup>b</sup></td><td>141.0±6.1<sup>b</sup></td><td>618.7±26.5<sup>a</sup></td><td>1827.1±103.4</td><td>2586.2±119.0<sup>a</sup></td></tr><tr><td>Level of FR (%)</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>**</td></tr><tr><td>90</td><td>1.05±0.05</td><td>1.46±0.07</td><td>1.84±0.08</td><td>1.70±0.06</td><td>143.9±7.5</td><td>611.8±30.7</td><td>1826.6±91.1</td><td>2582.3±106.1<sup>a</sup></td></tr><tr><td>85</td><td>1.06±0.05</td><td>1.47±0.08</td><td>1.83±0.06</td><td>1.70±0.05</td><td>142.5±6.3</td><td>571.7±30.7</td><td>1797.9±82.5</td><td>2512.1±95.9<sup>b</sup></td></tr><tr><td>Duration of FR (age)</td><td>NS</td><td>NS</td><td>*</td><td>*</td><td>NS</td><td>NS</td><td>**</td><td>**</td></tr><tr><td>8-21</td><td>1.04±0.03</td><td>1.46±0.07</td><td>1.80±0.07<sup>b</sup></td><td>1.68±0.05<sup>b</sup></td><td>143.9±4.6</td><td>592.7±35.6</td><td>1862.7±67.6<sup>a</sup></td><td>2599.3±84.8<sup>a</sup></td></tr><tr><td>8-28</td><td>1.05±0.05</td><td>1.46±0.08</td><td>1.84±0.08<sup>ab</sup></td><td>1.71±0.07<sup>ab</sup></td><td>142.6±6.6</td><td>595.4±39.4</td><td>1837.3±89.0<sup>a</sup></td><td>2575.3±114.6<sup>a</sup></td></tr><tr><td>8-35</td><td>1.05±0.07</td><td>1.48±0.08</td><td>1.86±0.05<sup>a</sup></td><td>1.72±0.04<sup>a</sup></td><td>143.1±9.2</td><td>587.2±36.5</td><td>1736.8±43.0<sup>b</sup></td><td>2467.1±66.1<sup>b</sup></td></tr><tr><td>SEM</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.10</td><td>5.3</td><td>12.6</td><td>15.3</td></tr></tbody></table>

<sup>a-b</sup> Means within columns with different superscripts are significantly different (P < 0.05).

No interaction were observed for BW and FCR. *significant at P ≤0.05. **significant at P ≤0.01. NS: not significant.

Table 2 presents mean glucoce (GLU), triglyceride (TG) and triidothyronine (T₃) concentrations in serum of broilers. Results showed that no significant difference was detected for the concentration of T₃ and TG between treatments at 21, 28 and 35d of age and also, concentration of T3 and GLU at 42d of age. Serum concentrations of TG was significantly higher in norm-ME group rather than high-ME group at 42d of age (P<0.01). Also, interaction between level of FR and duration of FR were observed for TG content at 42d of age (P<0.05). Content of TG in birds that received 90% FR was more than 85% FR at 14 and 28d of FR, but at 21d of FR was least in 90% FR. In total, TG content in birds that received FR regimens with 85% for 28 days was lower content. GLU concentration at 28d of age was higher in treatments with high-ME value (P<0.01). As shown in Table 3, interaction between ME of diet and level of FR were observed for GLU content at 21d and 35d of age (P<0.01). Increasing of ME in treatments with 90% FR decreased GLU content at 21d of age. In contrast at 35d of age, increase in ME enhanced GLU content in broilers with 85% or 90% FR (Table 4). In this experiment, elevating ME level increased TG content at 42d of age while did not influenced GLU and T₃ content. Also, in treatments with 14 and 28d of FR duration, GLU content was increased with increase in IFR (85%). Presumably, increase in ME enhanced growth rate and decreased adiponectine hormone secretion, stimulation of fatty acids oxidation, reduction content of TG and improved GLU metabolism (Zhu et al., 2004; Maddineni et al., 2005).

## Conclusions

According to the results, elevating energy content in the first week of age, reduced BW, while improved BW and FCR during 2 to 6 w of age. It seems, higher ME content and applying feed restriction in 90% of ross recommendation during 8-28 days (3 week) provide better productivity of birds fed pellet diet. It is recommended that in future trials, measured the occurrence of metabolic disorders that common in pellet diet especially in areas with high altitude.
<table><caption>**Table 2.** Effect of dietary metabolizable energy, level and duration of feed restriction on serum metabolites in broiler chickens</caption><thead><tr><th rowspan="2">Variable</th><th colspan="3">D 21</th><th colspan="3">D 28</th><th colspan="3">D 35</th><th colspan="3">D 42</th></tr><tr><th>TG (mg/dl)</th><th>GLU (mg/dl)</th><th>T<sub>3</sub> (ng/ml)</th><th>TG (mg/dl)</th><th>GLU (mg/dl)</th><th>T<sub>3</sub> (ng/ml)</th><th>TG (mg/dl)</th><th>GLU (mg/dl)</th><th>T<sub>3</sub> (ng/ml)</th><th>TG (mg/dl)</th><th>GLU (mg/dl)</th><th>T<sub>3</sub> (ng/ml)</th></tr></thead><tbody><tr><td>ME (kcal/kg)</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>**</td><td>NS</td><td>NS</td><td>**</td><td>NS</td><td>**</td><td>NS</td><td>NS</td></tr><tr><td rowspan="3">Norm</td><td>124.2±</td><td>226.1±2</td><td>1.55±0</td><td>220.2±</td><td>201.1±4</td><td>1.57±0</td><td>187.0±</td><td>212.5±3</td><td>1.52±0</td><td>209.1±6</td><td>226.2±3</td><td>1.51±0</td></tr><tr><td>43.6</td><td>7.0</td><td>.05</td><td>59.9</td><td>5.1<sup>b</sup></td><td>.15</td><td>99.1</td><td>2.1</td><td>.10</td><td>1.7<sup>a</sup></td><td>7/5</td><td>.06</td></tr><tr><td>131.5±</td><td>220.6±3</td><td>1.52±0</td><td>182.1±</td><td>250.2±1</td><td>1.54±0</td><td>165.1±</td><td>263.2±1</td><td>1.55±0</td><td>137.7±6</td><td>236.8±2</td><td>1.54±0</td></tr><tr><td>High</td><td>89.8</td><td>0.0</td><td>.15</td><td>13.7</td><td>8.6<sup>a</sup></td><td>.08</td><td>18.0</td><td>3.9</td><td>.11</td><td>2.6<sup>b</sup></td><td>2.8</td><td>.09</td></tr><tr><td>Level of FR (%)</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>**</td><td>NS</td><td>*</td><td>NS</td><td>NS</td></tr><tr><td rowspan="3">90</td><td>145.4±</td><td>220.5±3</td><td>1.55±0</td><td>242.4±</td><td>212.3±3</td><td>1.58±0</td><td>132.3±</td><td>254.8±1</td><td>1.52±0</td><td>152.3±6</td><td>227.7±3</td><td>1.51±0</td></tr><tr><td>87.2</td><td>0.0</td><td>.05</td><td>24.5</td><td>7.1</td><td>.15</td><td>49.4</td><td>7.2</td><td>.11</td><td>6.9</td><td>4.5</td><td>.08</td></tr><tr><td>107.2±</td><td>226.1±2</td><td>1.52±0</td><td>258.0±</td><td>239.1±4</td><td>1.53±0</td><td>107.2±</td><td>226.1±2</td><td>1.48±0</td><td>192.2±7</td><td>235.4±2</td><td>1.53±0</td></tr><tr><td>85</td><td>47.7</td><td>7.0</td><td>.15</td><td>6.8</td><td>4.3</td><td>.08</td><td>47.7</td><td>7.0</td><td>.06</td><td>1.2</td><td>7.6</td><td>.07</td></tr><tr><td>Duration of FR (age)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>8-21</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>163.6±8</td><td>227.4±2</td><td>1.55±0</td></tr><tr><td>8-28</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>1.3</td><td>9.6</td><td>.09</td></tr><tr><td>8-35</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>162.9±7</td><td>238.2±2</td><td>1.51±0</td></tr><tr><td>SEM</td><td>17.1738</td><td>6.923</td><td>0.0311</td><td>23.2465</td><td>10.4656</td><td>0.033</td><td>17.6419</td><td>8.853</td><td>0.0302</td><td>5.6</td><td>6.4</td><td>.08</td></tr><tr><td>P-Values</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>192.8±5</td><td>229.3±3</td><td>1.51±0</td></tr><tr><td>E×I</td><td>NS</td><td>**</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>**</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>E×D</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>I×D</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>*</td><td>NS</td><td>NS</td></tr><tr><td>E×I×D</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>NS</td><td>NS</td><td>NS</td></tr></tbody></table>

a–b Means within columns with different superscripts are significantly different (P < 0.05).

* significant at P ≤0.05. ** significant at P ≤0.01. NS: not significant.

<table><caption>**Table 3.** Interaction of ME, level and duration of FR on TG content (mg/dl) at 42d of age</caption><thead><tr><th rowspan="2">Level of FR (%)</th><th colspan="3">Duration (age)</th></tr><tr><th>8-21d</th><th>8-28d</th><th>8-35</th></tr></thead><tbody><tr><td>90</td><td>210.1±69.8<sup>a</sup></td><td>162.5±75.1<sup>ab</sup></td><td>182.5±64.7<sup>a</sup></td></tr><tr><td>85</td><td>164.7±92.4<sup>ab</sup></td><td>201.7±43.8<sup>a</sup></td><td>115.6±47.9<sup>b</sup></td></tr></tbody></table>

a–b Means within rows and columns with different superscripts are significantly different (P < 0.05).

<table><caption>**Table 4.** Interaction of ME and level of FR on GLU content (mg/dl) at 21d and 35d of age</caption><thead><tr><th rowspan="2">ME (Kcal/kg)</th><th colspan="2">D 21</th><th colspan="2">D 35</th></tr><tr><th>90</th><th>85</th><th>90</th><th>85</th></tr></thead><tbody><tr><td>Norm</td><td>241.1±1.7<sup>a</sup></td><td>211.0±33.0<sup>ab</sup></td><td>240.3±6.7<sup>b</sup></td><td>184.8±17.7<sup>c</sup></td></tr><tr><td>High</td><td>199.9±31.0<sup>b</sup></td><td>241.2±1.6<sup>a</sup></td><td>269.4±8.8<sup>a</sup></td><td>256.9±16.3<sup>ab</sup></td></tr></tbody></table>

a–c Means within rows and columns with different superscripts are significantly different (P < 0.05).

## Literature

MADDINENI, S., S. METZGER, O. OCON, I. I. I. HENDRICKS, R. RAMACHANDRAN, 2005: Adiponectin gene is expressed in multiple tissues in the chicken: Food deprivation influences adiponectin messenger ribonucleic acid expression. Endocrinol. 146, 4250-4256.

ZHU, M., J. MIURA, L. X. LU, M. BERNIER, R. DECABO, M. A. LANE, G. S. ROTH, D. K. INGRAM, 2004, Circulating adiponectin levels increase in rats on caloric restriction: The potential for insulin sensitization. Exp. Gerontol. 39, 1049-1059.

URDANETA-RINCON, M., S. LEESON, 2002: Quantitative and qualitative feed restriction on growth characteristics of male broiler chickens. Poult. Sci. 81(5), 679-688.
# SIMULATION AND EXPERIMENTAL VALIDATION TO PREDICT FEED INTAKE IN PRE-LAYING PHASE

H. C. P. Bendezu<fnref n="1" />, N. K. Sakomura<fnref n="1" />*, E. B. Malheiros<fnref n="1" />, R. M. Gous<fnref n="2" />

**Corresponding author:** sakomura@fcav.unesp.br

## Abstract

The objective of this study was to make a simulation using mathematical model to predict feed intake (FI) taking into account the growth of reproductive organs in pre-laying phase and evaluate the models. The FI was calculated based on the deposition of protein and lipid into three compartments (body, feathers, reproductive organs and liver). Two trials were conducted. Ninety-six Isa Brown pullets from 16 to 28 weeks were used in the first trial. Twice a week four of these birds were slaughtered. The weight of the birds, liver, ovary and oviduct were measured and samples were taken to analyze dry matter, gross energy and crude protein. Seventy-six Isa Brown pullets from 16 to 24 weeks were used in the second trial. The FI was measured every day for each hen until the first egg was laid. Gompertz function was fitted to the data of the first trial and the parameters were used to estimate protein (DP) and lipid deposition (DL). The energy for maintenance (MH) was calculated based on actual protein content and protein weight at maturity. The model of effective energy requirement is $EER=MH+50DP+56DL$. FI was calculated by dividing the EER and effective energy content in the feed. The output of the simulation of feed intake for Isa-Brown and Hy-Line were evaluated by regressing residual value with the predicted value centered. The simulation of feed intake overall overestimated 0.41g/day and 2.65 g/day for Hy-Line and Isa-brown, respectively. On the other hand, significant linear bias was observed for Hy-Line ($P<0.001$), in contrast Isa-Brown ($P>0.05$). The assessment of the result indicates the simulation models for predict feed intake was more accurate and less precision for Hy-Line than Isa-Brown.

**Keywords:** evaluation, pullets, nutrition model

## Introduction

In poultry production, feed intake is largely influenced by environment, genetic potential and economic circumstances leading poultry nutritionists to develop an optimum feeding strategy under these conditions. Considering these circumstances in poultry production is essential for accurately predicting feed intake, which could lead to a reduction of feed costs. In this context, models seem to be a strategic tool for poultry industry and, despite the fact that several models to predict and simulate feed intake for poultry have been used.

The accuracy of model for predicting feed intake depends on successful description of the bird's growth potential. In this context, Silva (2014) developed a model to predict daily amino acid intake prior the birds reach the sexual maturity taking into account the development of the reproductive organs (ovary and oviduct). However, the effect of the development of the reproductive organs and liver on the feed intake has not been described and experimental evaluation is necessary to compare the simulated data with the real data to determine the accuracy and the precision of the models. Thus, the objective of this study was to make a simulation using a mathematical model to predict feed intake taking into account the growth of reproductive organs in pre-laying phase and evaluate the result of the simulation model.

## Material and Methods

Two experiments were conducted at the Laboratory of Poultry Science, Faculty of Agriculture and Veterinary Sciences (FCAV), Universidade Estadual Paulista (UNESP), Jaboticabal, São Paulo, Brazil. The first experiment was conducted to describe the growth of the reproductive organs and estimate the protein and lipid deposition into three compartments (body, reproductive organs and liver), based on that predict desire feed intake in pre-laying phase. The second experiment was conducted to evaluate the output of simulation model (desire feed intake).

Ninety six Isa-Brown pullets were slaughter from 15 to 28 weeks in the first experiment. Twice a week four birds were slaughtered. The birds selected for slaughter were kept in a fasting period for 24 hours and then slaughter by CO₂ asphyxiation. The feathers, body free of feathers, liver, ovary and oviduct were weight. These samples were taken and identified to analyze dry matter, gross energy, crude protein (N × 6.25) and ash.

<footnote n="1">¹Dept. of Animal Science, University of São Paulo State, Jaboticabal-São Paulo, Brazil</footnote>

<footnote n="2">²Animal and Poultry Science, University KwaZulu-Natal, Scottsville 3209, South Africa</footnote>
The protein content of each compartment (liver, ovary and oviduct) was fitted by Gompertz equation to estimate the parameter. The derivative of the Gompertz function described by Emmans (1997) was used to estimate the deposition of protein (DP, g/day) by the following equation $DP = b \times P_t \times \ln(\frac{P_m}{P_t})$ and the deposition of lipid (DL, g/day) was estimated $DL = DP \times LP_m \times b_1 \times (Pt/Pm)^{b1-1}$, where $b_1$ value is estimated by $b_1 = 1.46 \times LP_m^{0.23}$. The effective energy requirement (EER, KJ/day) of the birds was calculated by the following equation: $EER = EEM + 50(\frac{DP}{1000}) + 56(\frac{DL}{1000})$, where EEM is the effective energy for maintenance (KJ/day) and is calculated as $EEM = M_E \times P_t \times (P_m)^{-0.27}/1000$ and $M_E$ is 1.63 MJ per maintenance. The value of energy for maintenance requirement only considered the energy requirement for maintenance of the body. For these reason, energy for maintenance was calculated based on protein body deposition and protein maturity of body. The parameters to describe the body protein for Isa-Brown and Hy-Line were obtained from Silva (2014). Who calculated the Gompertz parameter of different strains of pullets. Desired food intake (DFI, g) is estimated as follows equation: $DFI = EER/EEC$, where EEC is the effective energy content in the feed (KJ/g) and this value estimated by $EEF = 1.17ME - 4.29CP - 2.44$ and ME is the metabolizable energy content in the feed is expressed as KJ/g and crude protein content (CP) in the feed is expressed as g/g.

The models described above were integrated in the Vensim simulation software (Ventana Systems, 2003). The simulation was defined from 105 to 137 days of age, as a result of the development of each compartment during this period. In order to evaluate the simulation model, the results of DFI from two different pullets strain were compared with the data compiled from the second experiment. Seventy six of Isa-Brown and seventy six of Hy-Line pullets, from 15 to 24 weeks of age, were used. All the birds were allocated in individual cage. The feed intake was measured every day and was registered the day, which the first egg was laid. This arrangement allowed to monitor the change of feed intake before and after 14 days from the first egg for each. The predicted result of feed intake (DFI) by the model was compared with the observed value of feed intake fourteen days before the first egg in the experiment. The output of the simulation model of feed intake was evaluated by regressing residual (observed minus predicted) values with the predicted values centered (DFI-mean of DFI) using PROC GLM procedure of the statistical software SAS (Statistical Analysis System, version 9.0).

## Results

The weight of body, liver, ovary and oviduct increased in function of the age but a different rate. The liver, ovary and oviduct have greater development in pre-laying phase which is in agreement with the literature (Bowmaker and Gous, 1989). The Gompertz equation was used to describe the growth of the reproductive organs and liver. Oviduct reaches maturity earlier than the other organs because presented higher $W_m$ (44.2 g) and b (0.11/d) values than liver ($W_m$=35.6 g, b = 0.06/d) and ovary ($W_m$=33.6 g, b = 0.07/d). Predicted value of protein weight in the liver ($W_m$=5.58 g, b=0.09/d) increased slightly in the experimental period (105 to 137 days of age) because the maximal growth rate for liver happened at 93 days thus the daily deposition of protein decreased over the pre-laying phase. However, the predicted values of protein weight in the ovary ($W_m$=4.81 g, b = 0.18/d) and oviduct ($W_m$=6.96 g, b = 0.12/d) had a higher gain over this period because the daily deposition of protein increased in pre-laying phase. Additionally, the values obtained for maturity rate of protein in the ovary was higher than oviduct, for this reason protein in ovary reaches maturity earlier than the oviduct. In contrast, the lipid deposition was estimated as desired lipid growth to quantify the relationship between protein and lipid (Emmans, 1981). This concept has the advantage of controlling the lipid growth based on the voluntary feed intake. Predicted value of lipid weight in the liver ($W_m$=1.04 g, b = 0.06/d) increased in this period in contrast to protein growth. Growth of liver in this period is mainly due to the fat stored in this compartment, probably to support yolk output throughout the laying period (Bowmaker and Gous, 1989). The predicted value of lipid weight in the ovary ($W_m$=6.68 g, b = 0.34/d) also increased and was probably due to the follicle development. Similarly, lipid weight in the oviduct ($W_m$=0.81 g, b = 0.09/d) increased but in a lower rate than in the ovary.

The effective energy requirement was calculated take into account all the parameters to explain above. Additionally, the effective energy content in the feed was 10.74 KJ/g. The maximum predicted value of feed intake in this period was 69.64 and 79.5 g/day for Isa-Brown and Hy-Line, respectively. This value is 0.5 grams less than that suggested by the Isa Brown guidelines at 17 weeks of age and 7 grams more than that suggested by the Hy-Line guidelines at the same age (Isa Brown, 2011; Hy-Line, 2013). Considering the nutritional specification for pre-laying diets from the guidelines, the effective energy content was 10.27 KJ/g (EM = 2750 kcal/kg; CP=17%) and the EER calculated by the simulation model, the desire feed intake was 79.39 g/day, which is in agreement with Isa-Brown guidelines (Isa Brown, 2011) at 17 week of age. In the same way, the effective energy content was 11.09 KJ/g (EM = 2911 kcal/kg; CP=17%) and the EER
calculated by the simulation model, the desire feed intake was 63.57 g/day, which is in agreement with Hy-Line guide-
lines (Hy-Line, 2011) at 17 week of age. This result indicates that the difference between the predicted feed intake by
simulation and the feed intake suggested by guidelines due to the energy feed content value.

Conclusions

The simulation of feed intake overall overestimated 0.41(P>0.05) and 2.65 g/day (P<0.001) for Hy-Line and Isa-brown, respectively. On the other hand, significant linear bias was observed for Hy-Line (P<0.001), in contrast Isa-Brown (P>0.05). The assessment of the result indicates the simulation models for predict feed intake was more accurate and less precision for Hy-Line than Isa-Brown.

Literature

EMMANS G.C. 1997: A method to predict the food intake of domestic animals from birth to maturity as a function of time. Journal of Theoretical Biology **186**, 189-200.

SILVA E.P., SAKOMURA N.K., HAUSCHILD, L. and GOUS R.M. 2014: Model to estimate the amino acid requirements for growth and sexual development in laying pullets. In *Nutritional Modelling in Pig and Pultry Production* (eds N.K. Sakomura, R.M. Gous, I. Kyriazakis and L. Hauschild), pp. 223-233.CABI, Oxiforshire, State/UK.

VENTANA SYSTEM 2003. Vensim simulation software. Available <http://www.vensim.com>
# THE DEVELOPMENT OF LACTOBACILLI IN THE BROILER GASTROINTESTINAL TRACT

Samir Ranjitkar<fnref n="1" />, Blair Lawley<fnref n="2" />, Gerald Tannock<fnref n="2" />, Ricarda M. Engberg<fnref n="1" />

**Corresponding author:** samir.ranjitkar@anis.au.dk

## Abstract

A feeding trial with maize based feed (MBF) and maize based feed supplemented with 30% crimped kernel maize silage (CKMS) was conducted to investigate the age-related microbial community compositions in the gastrointestinal (GI) tract of broilers. Contents from crop, gizzard, ileum and ceca were collected on day 8, 15, 22, 25, 29 and 36. Microbial diversity was analysed by 454 pyrosequencing of the 16S rRNA gene. Since no significant difference was observed between MBF and CKMS, the data from both treatments were pooled. In all segments and at all ages, the majority of the sequences belonged to the phylum Firmicutes. Of these, the Lactobacillaceae were most abundant in all segments except in the ceca. Within the genus *Lactobacillus*, the abundance of *L. johnsonii* was generally highest in all intestinal segments and at all bird ages. From day 15 to day 22, a remarkable increase of *L. salivarius* was observed in the contents of crop (7%-33%), gizzard (4%-12% and ileum (1%-26%). The abundance of *L. salivarius* remained high throughout the entire growth period. The *L. salivarius* de-conjugates bile acids and is suspected to depress broiler growth via decreased fat digestion. Decreased numbers of *L. salivarius* have been observed earlier when antibiotic growth promoters were used. Problems related to reduced broiler growth and GI disorders occurred in the growth period between days 21-28 after the withdrawal of these compounds, which might be associated with the steep increase of *L. salivarius* at this time point.

**Keywords:** broiler, maize silage, fermented feed, gut microflora, Lactobacilli, dysbacteriosis

## Introduction

Antibiotic growth promoters (AGPs) were successfully used as a feed additive to modulate the gastrointestinal (GI) microflora for maintaining gut health and improved broiler growth. After the discontinuation of AGPs in broilers, gastrointestinal (GI) health problems related to dysbacteriosis have increased in the European Union (EU). Dysbacteriosis is typically observed between 20 to 30 days of age resulting in wet litter, non-specific enteritis, decreased nutrient digestibility, and poor broiler performance (TEIRLYNCK et al., 2011). Thus, among other dietary interventions to address these GI problems, fermented feed has gained increasing attention in animal nutrition. Fermented feed has a low pH (3.5-4.5) and contains numerous lactic acid bacteria (10⁸-10⁹ cfu/g feed) and has been shown to improve the gut health and performance (CANIBE et al., 2007). Considering the lactobacilli as a dominant bacterial population in GI tract, the study of the succession of *Lactobacillus* species might be relevant to understand these GI disorders in broilers. In this respect, age-related development of lactobacilli was studied in the upper and lower GI tract of broilers fed with either a maize based diet or a diet supplemented with crimped kernel maize silage (CKMS).

## Material and Methods

The CKMS was prepared by crimping and ensiling maize kernels for approximately 8 weeks with the addition of a commercial organic acids mixture (Kemira AIV Pro®, Kemira, Finland). A total of 240 day-old male broiler chicks (Ross 308) were divided into 2 dietary groups with 4 replicates, and distributed randomly into 8 pens (30 birds/pen). A starter feed containing 22.5% crude protein and 11.4 MJ metabolizable energy per kg was provided from 1-7 days, and was the same for both groups. From day 8 onwards, Group 1 received a grower diet containing 58% maize (maize based feed, MBF), and Group 2 received a maize based grower feed supplemented with 30% CKMS (CKMS-30), replacing maize on dry matter basis. Additionally, 10% whole wheat was added in both diets to increase the gizzard function. Both diets were formulated as iso-caloric (11.58 MJ/kg) and iso-nitrogenous (CP 19.78%) without addition of enzymes and coccidiostat. Feed and water were provided ad libitum during the feeding trial (1-36 days). Lactic acid bacteria (LAB) in the feed were counted on MRS agar.

<footnote n="1">¹Department of Animal Science, Aarhus University, Tjele, Denmark</footnote>

<footnote n="2">²Department of Microbiology and Immunology, University of Otago, New Zealand</footnote>
Four birds were randomly selected from each pen and killed by cervical dislocation at six time points (8, 15, 22, 25, 29 and 36 days). The contents from crop, gizzard, ileum and ceca were rapidly collected and stored at -80°C until analysis. DNA was extracted using QIAGEN DNA Stool Mini Kit. Sequencing of the samples was carried through pyrosequencing of the 16S rRNA gene using Roche 454 FLX sequencing method. Analysis of the sequencing results were carried out using QIIME and UPARSE pyrosequencing pipeline packages with default settings. Statistical analysis on the relative abundance of lactobacilli was done using the GLM procedure of SAS® with following general model: Yᵢⱼ = μ + αᵢ + βⱼ + (αβ)ᵢⱼ + εᵢⱼ, where Yᵢⱼ was the observed dependent variable, μ was the overall mean, αᵢ was the effect of treatments (MBF and CKMS-30), βⱼ was the effect of days, (αβ)ᵢⱼ was the interaction, and εᵢⱼ was the random error. Results are given as least square means (LSM) with a pooled standard error (SE). Probability values <0.05 were considered as significant.

## Results

The LAB count was higher in CKMS-30 (6.89 log cfu/g) compared to MBF (3.60 log cfu/g). Pyrosequencing data analysis showed Firmicutes to be the most dominant phylum in all age groups representing up to 98% of the total sequences. The family Lactobacillaceae represented most of the Firmicutes in all intestinal segments (58-98%) except in the ceca where Lachnospiraceae (20-39%) were dominant. Since no significant difference was observed in the relative abundance of microbiota between the two dietary treatments in any of the segments, a pooled data set was used in the further data analysis. The genus *Lactobacillus* represented 99-100% of Lactobacillaceae in all four GI segments. Apart from the ceca, the relative abundance of *Lactobacillus* was highest and quite stable in the crop (94-98%), gizzard (58-86%) and ileum (61-73%) during the entire broiler production period (Table 1). In the ceca, *Lactobacillus* started to decrease from 17.5% to 7.8% at day 15, and remained low (2-3%) during the remaining growth period (P<0.001). Variations in *Lactobacillus* species were determined in all intestinal segments as broilers grew older. Among the four dominant species of *Lactobacillus*, *L. johnsonii* was abundant in all age groups (Table 1). The relative abundance of *L. reuteri* and *L. crispatus* was higher during the early growth period (up to d 15), but *L. salivarius* dominated in the final growth phase (from d 22) in all GI segments. From d 15 to d 22, a remarkable increase of *L. salivarius* was observed in the contents of crop (7%-33%, P<0.001), gizzard (4%-12%, P=0.003) and ileum (1%-26%, P<0.001).

## Conclusions

There was no influence of the diets on the lactobacilli population although the CKMS-30 diet showed high lactobacilli counts (6.89 log cfu/g) compared to MBF (3.60 log cfu/g). Keeping the high numbers of lactobacilli in crop contents (10⁹ cfu/g) in mind, the contribution of CKMS containing about 10⁷ cfu/g diet (primarily *L. plantarum*) added at dietary levels of 30% was below 1% in crop content. Therefore, the modulatory action of *Lactobacillus* provided as probiotic feed additives or fermented feed will possibly be more effective if used in higher concentration exceeding 10⁹ cfu/g. A clear temporal variation in the relative abundance of *Lactobacillus* species was observed in all GI segments. The *L. salivarius* is known to de-conjugation bile acids, leading to poor lipid digestion and depressed broiler growth (GUBAN et al., 2006; RAMASAMY et al., 2010). The rise in the abundance of *L. salivarius* coincides within the period between 20-30 days where typically GI problems occurred in broilers related to dysbacteriosis. A significant decrease of *L. salivarius* was reported in the GI tract of broilers receiving feed supplemented with antimicrobials (salinomycin, bacitracin, monensin) compared to the broilers fed a non-supplemented control diet (ENGBERG et al., 2000; GUBAN et al., 2006). Therefore, the substantial increase in the abundance of *L. salivarius* in the ileum after d 15 could be a possible factor contributing to the increased frequency of GI problems related to dysbacteriosis in broilers after the discontinuation of AGPs.
<table><caption>**Table 1:** Relative abundance of *Lactobacillus* in crop, gizzard, ileum and ceca on different time points</caption><thead><tr><th rowspan="2">Segment</th><th rowspan="2">Item</th><th colspan="6">Days</th><th rowspan="2">SE</th><th rowspan="2">P-value</th></tr><tr><th>8</th><th>15</th><th>22</th><th>25</th><th>29</th><th>36</th></tr></thead><tbody><tr><td rowspan="5">Crop</td><td><i>Lactobacillus</i></td><td>97.43</td><td>96.74</td><td>96.10</td><td>97.58</td><td>96.30</td><td>94.21</td><td>1.17</td><td>0.399</td></tr><tr><td><i>L. johnsonii</i></td><td>47.66</td><td>56.39</td><td>51.57</td><td>46.32</td><td>50.47</td><td>40.42</td><td>6.89</td><td>0.692</td></tr><tr><td><i>L. reuteri</i></td><td>19.79<sup>a</sup></td><td>23.81<sup>a</sup></td><td>8.67<sup>b</sup></td><td>16.95<sup>ab</sup></td><td>8.34<sup>b</sup></td><td>10.94<sup>b</sup></td><td>3.29</td><td>0.007</td></tr><tr><td><i>L. crispatus</i></td><td>23.27<sup>a</sup></td><td>4.19<sup>b</sup></td><td>1.81<sup>b</sup></td><td>0.52<sup>b</sup></td><td>1.48<sup>b</sup></td><td>2.78<sup>b</sup></td><td>5.39</td><td>0.041</td></tr><tr><td><i>L. salivarius</i></td><td>2.19<sup>b</sup></td><td>6.99<sup>b</sup></td><td>32.59<sup>a</sup></td><td>32.74<sup>a</sup></td><td>33.56<sup>a</sup></td><td>37.9<sup>a</sup></td><td>5.62</td><td>&lt;0.001</td></tr><tr><td rowspan="5">Gizzard</td><td><i>Lactobacillus</i></td><td>64.17</td><td>86.49</td><td>63.75</td><td>62.27</td><td>60.94</td><td>58.42</td><td>6.94</td><td>0.075</td></tr><tr><td><i>L. johnsonii</i></td><td>36.01<sup>b</sup></td><td>55.44<sup>a</sup></td><td>33.05<sup>b</sup></td><td>31.06<sup>b</sup></td><td>32.36<sup>b</sup></td><td>32.91<sup>b</sup></td><td>6.06</td><td>0.058</td></tr><tr><td><i>L. reuteri</i></td><td>6.95<sup>ab</sup></td><td>11.77<sup>a</sup></td><td>4.11<sup>b</sup></td><td>6.20<sup>b</sup></td><td>3.22<sup>b</sup></td><td>5.95<sup>b</sup></td><td>1.96</td><td>0.059</td></tr><tr><td><i>L. crispatus</i></td><td>6.49</td><td>3.60</td><td>1.65</td><td>0.90</td><td>1.59</td><td>3.21</td><td>1.71</td><td>0.239</td></tr><tr><td><i>L. salivarius</i></td><td>0.26<sup>c</sup></td><td>3.74<sup>b</sup></td><td>12.25<sup>a</sup></td><td>14.50<sup>a</sup></td><td>10.70<sup>ab</sup></td><td>6.81<sup>bc</sup></td><td>2.61</td><td>0.003</td></tr><tr><td rowspan="5">Ileum</td><td><i>Lactobacillus</i></td><td>60.30</td><td>65.93</td><td>72.64</td><td>73.29</td><td>67.34</td><td>67.69</td><td>7.19</td><td>0.856</td></tr><tr><td><i>L. johnsonii</i></td><td>34.77</td><td>45.06</td><td>39.57</td><td>48.82</td><td>34.62</td><td>26.46</td><td>6.09</td><td>0.145</td></tr><tr><td><i>L. reuteri</i></td><td>9.96<sup>a</sup></td><td>9.96<sup>a</sup></td><td>3.57<sup>b</sup></td><td>4.97<sup>b</sup></td><td>3.15<sup>b</sup></td><td>1.57<sup>b</sup></td><td>1.34</td><td>&lt;0.001</td></tr><tr><td><i>L. crispatus</i></td><td>15.59</td><td>7.15</td><td>2.97</td><td>2.24</td><td>2.19</td><td>3.71</td><td>3.55</td><td>0.079</td></tr><tr><td><i>L. salivarius</i></td><td>0.94<sup>c</sup></td><td>0.87<sup>c</sup></td><td>26.45<sup>ab</sup></td><td>17.14<sup>b</sup></td><td>27.31<sup>ab</sup></td><td>35.81<sup>a</sup></td><td>4.68</td><td>&lt;0.001</td></tr><tr><td rowspan="5">Ceca</td><td><i>Lactobacillus</i></td><td>17.47<sup>a</sup></td><td>7.79<sup>b</sup></td><td>3.14<sup>bc</sup></td><td>3.05<sup>bc</sup></td><td>2.18<sup>c</sup></td><td>3.27<sup>bc</sup></td><td>1.25</td><td>&lt;0.001</td></tr><tr><td><i>L. johnsonii</i></td><td>7.04<sup>a</sup></td><td>4.04<sup>b</sup></td><td>1.74<sup>c</sup></td><td>1.41<sup>c</sup></td><td>0.77<sup>c</sup></td><td>1.09<sup>c</sup></td><td>0.71</td><td>&lt;0.001</td></tr><tr><td><i>L. reuteri</i></td><td>6.72<sup>a</sup></td><td>2.61<sup>b</sup></td><td>0.17<sup>c</sup></td><td>0.10<sup>c</sup></td><td>0.15<sup>c</sup></td><td>0.26<sup>c</sup></td><td>0.790</td><td>&lt;0.001</td></tr><tr><td><i>L. crispatus</i></td><td>3.58<sup>a</sup></td><td>0.81<sup>b</sup></td><td>0.06<sup>b</sup></td><td>0.01<sup>b</sup></td><td>0.00<sup>b</sup></td><td>0.10<sup>b</sup></td><td>0.58</td><td>&lt;0.001</td></tr><tr><td><i>L. salivarius</i></td><td>0.11<sup>b</sup></td><td>0.31<sup>b</sup></td><td>1.17<sup>a</sup></td><td>1.49<sup>a</sup></td><td>1.25<sup>a</sup></td><td>1.82<sup>a</sup></td><td>0.27</td><td>&lt;0.001</td></tr></tbody></table>

## Literature

CANIBE, N., O. HØJBERG, J. H. BADSBERG, B. B. JENSEN, 2007: Effect of feeding fermented liquid feed and fermented grain on gastrointestinal ecology and growth performance in piglets. J Anim Sci. **85**, 2959-2971.

ENGBERG, R. M., M. S. HEDEMANN, T. D. LESER, B. B. JENSEN, 2000: Effect of zinc bacitracin and salinomycin on intestinal microflora and performance of broilers. Poult Sci. **79**, 1311-1319.

TEIRLYNCK, E., M. GUSSEM, J. DEWULF, F. HAESEBROUCK, R. DUCATELLE, F. V. IMMERSEEL, 2011: Morphometric evaluation of dysbacteriosis in broilers. Avian Pathol. **40**, 139-144.

GUBAN, J., D. KORVER, G. ALLISON, G. TANNOCK, 2006: Relationship of dietary antimicrobial drug administration with broiler performance, decreased population levels of *Lactobacillus salivarius*, and reduced bile salt deconjugation in the ileum of broiler chickens. Poult Sci. **85**, 2186-2194.

RAMASAMY, K., ABDULLAH, N., WONG, M.C., KARUTHAN, C., HO, Y.W., 2010: Bile salt deconjugation and cholesterol removal from media by *Lactobacillus* strains used as probiotics in chickens. J. Sci. Food Agr. **90**, 65-69.

<footnote>a-c LSMEANS within the same row with different superscripts differ significantly (P < 0.05)</footnote>
# HISTOMORPHOMETRIC MEASURES OF INTESTINAL SEGMENTS AND BIOMETRY OF THE DIGESTIVE SYSTEM AND IMMUNE SYSTEM OF BROILER CHICKS HATCHED FROM DIFFERENT EGG WEIGHTS AND BREEDER AGES

J. S. Santos<fnref n="1" />,*, E. M. Oliveira<fnref n="1" />; A. L. M. Carneiro<fnref n="1" />; M. A. Andrade<fnref n="2" />; M. B. Cafe<fnref n="1" />,<fnref n="3" />; J. H. Stringhini<fnref n="1" />,<fnref n="3" />,*

## Abstract

The purpose of this study was to evaluate the intestinal development of embryos and of broiler chicks supplemented with different levels of digestible lysine in pre-starter diet. A total of 740 eggs from breeders at 36 weeks of age and different egg weights (ranging from 56 to 65g and from 66 to 72g) were weighed, identified and incubated. After 18 days of incubation, 4 eggs per treatment were broken, the embryo removed and fragments of the duodenum and jejunum were collected. Fragments were fixed in 10% formalin for preparation of histological slides, and stained by HE method. Images were digitized, and histomorphometric measures were recorded by Image J software in a Carl Zeiss microscope. The same procedures were performed at hatch, and at 7 and 14 days of age. Statistical analyses were performed using Anova and Tukey test (5%) to compare averages. Chicks from heavy eggs presented higher values of villus height of jejunum at hatch, which could result in an increased nutrient absorption. However, at 7 and 14 days of age this difference was not observed, showing the use of increasing levels of digestible lysine in pre-starter diets did not result in any significant effect. Pre-starter diets supplemented with digestible lysine did not show the same efficacy to accelerate intestinal cells development as they do to muscle tissues.

## Introduction

The high productivity observed in poultry production depends, among several factors, on the nutrients obtainment by the body. Therefore, specific diets for each life period, genetic line or environmental conditions have been researched and employed. However, the intestinal mucosa must present adequate structural morphological and physiological characteristics to properly digest and absorb such diets (MAIORKA, 2004).

The small intestine mucosa is a functional element that can be characterized as a permeable layer for nutrients absorption and a barrier against pernicious compounds (VAN LEEUWEN, 2002).

At hatch, broiler's gastrointestinal tract is anatomically complete, but its functional capacity for digestion is not completely mature. The gastrointestinal tract needs morphological and physiological adaptations, which are stimulated by the presence of the feed, justifying the importance of quality and composition of the diet in the first week of life of broiler chicks (MAIORKA et al., 2000b).

In this experiment, we aimed to evaluate the development of intestines, digestive and immune organs of broiler chicks hatched from different egg weights and breeder ages supplemented with different levels of digestible lysine in pre-starter diets.

## Material and Methods

We used 740 eggs of heavy Cobb 500 genetic line breeders at 36 weeks of age and two different egg weight range (56 to 65 grams and 66 to 72 grams). Of these, 40 eggs were separated, identified and weighed (20 light eggs, 56-65g, and 20 heavy eggs, 66 a 72g) for physical evaluation.

Eggs separated for physical evaluation were immersed in saline solution to determine specific gravity. Eggs were then dried and cracked to measure yolk and albumen height and diameter with a digital caliper. Yolk and albumen were individually weighed in a 0.01 grams precision scale and pH was measured with a potentiometer. Eggshells were washed and maintained in a forced air movement oven at 65 °C during 72 hours. Eggshell thickness were determined with digital caliper.

<footnote n="1">¹Departamento de Produção Animal, Universidade Federal de Goiás, GOIANIA, Brazil</footnote>

<footnote n="2">²Departamento de Medicina Veterinária, Universidade Federal de Goiás, GOIANIA, Brazil</footnote>

<footnote n="3">³CNPq researcher</footnote>

<footnote>*Corresponding authors: jenuvet@hotmail.com and jhstring@uol.com.br</footnote>

<footnote>**Keywords:** amino acid, crypt, diet, nutrition, villus</footnote>
The remaining eggs were individually identified, weighed and allotted uniformly in the incubators. At the beginning of the hatching period, temperature and moisture were maintained constant at 37.8 °C and between 60 and 65%, respectively. At the final period, temperature was reduced to 37.5 °C and moisture increased to 70%. After 14 days of hatching period, candling was carried out in 24 eggs from each incubator in order to verify egg fertility. At 18 days of the incubation period, eggs were individually involved in air-permeable tissue according to each treatment.

On the 18th day of incubation, four eggs of each incubator, two from each experimental treatment (light or heavy eggs), totaling 12 eggs, were removed from the incubator and cooled for 6 hours. After that, each egg was identified and broken in a Petri's plate. The intestines were weighed and fragments of duodenum and jejunum were collected to prepare the histological slides.

At hatch, all chicks were weighed and sexed by the wings, and 60 of them were randomly distributed into groups according to the digestible lysine level in four heated batteries. At birth, seven and fourteen days of age, one chick per replicate was euthanized and fragments of duodenum and jejunum were collected to prepare the histological slides. The slides received pigments according to the methodology of Luna (1968) using Hematoxilin-Eosin method, fixed in a formalin 10% solution. Slides images were digitized in a light field optical microscope to the computer and captured by Image J program. Statistical analysis was performed by the procedure ANOVA of SAEG and Tukey test (5% probability) was applied for average comparison.

## Results and Discussion

The results of villus height and crypt depth of duodenum and jejunum for 18-day old embryos, and for chicks at birth, seven and fourteen days of life, from egg with different weights at the beginning of incubation, are displayed in Tables 1 and 2. No statistical difference was observed for villus height in duodenum and crypt depth in duodenum and jejunum for the egg weights analyzed. Different results were observed by Ferreira (2010), who verified difference for villus height and crypt depth for duodenum and jejunum but did not verify any effect of the digestible sulfur amino acids analyzed for chicks hatched from different egg weights before incubation. In our experiment, digestible lysine levels did not affect the results.

These results allowed us to conclude the increment of digestible lysine levels in pre-starter diet did not act effectively to improve the development of intestinal structures cells as it does in muscle tissue growing. Basic function of lysine is an intense participation in body protein deposition (Bertechini, 2012) and this amino acid tends to affect poultry body growing, specially muscles (Tesseraud et al., 1999).

It is possible to conclude that in this experiment egg weight and digestible lysine supplementation did not affect intestinal organ development of chicks.

## Literature

* BERTECHINI, A.G. Nutrição de monogástricos. Lavras: UFLA, 2006. 301p.

* FERREIRA, L.L. Desenvolvimento de embriões e pintos de corte provenientes de ovos de diferentes pesos e idades de matriz e níveis de aminoácidos sulfurados na fase pós-eclosão. 2010, Dissertação (Mestrado em Medicina Veterinária), Escola de Veterinária e Zootecnia. Universidade Federal de Goiás, Goiânia, 2010.

* LUNA, L. G. Manual of histologic staining methods of the armed forces institute of pathology. 3 ed. New York: McGraw-hill, 258p., 1968.

* MAIORKA, A.; SANTIN, E.; FISCHER DA SILVA, A.V., BRUNO, L.D.G.; BOLELI, I.C.; MACARI, M. Desenvolvimento do trato gastrointestinal de embriões oriundos de matrizes pesadas de 30 e 60 semanas de idade. Braz.J.Poult.Sci., v.2, p.141-148, 2000 b.

* MAIORKA, A.; SANTIN, E.; SILVA, A.V.F.; ROUTMAN, K.S.; PIZAURO JR., J.M.; MACARI, M. Effect of broiler breeder age on pancreas enzymes activity and digestive tract weight of embryos and chicks. Revista Brasileira de Ciência Avícola, Campinas, v.6, p.19-22, 2004.

* TESSERAUD, S.; BIHAN-DUVAL, E. Le.; PERESSON, R.; MICHEL, J. CHAGNEAU, A.M. Response of chicks lines selected on carcass quality to dietary lysine supply: live performance and muscle development. Poult. Sci., v.78, n.1, p.80-84, 1999.

* VAN LEEUWEN, P. Significance of combined nutritional and morphological precaecal parameters for feed evaluation in nonruminants. 2002, 153f. Tese (Doutorado em Medicina Veterinária), Wageningen University, Holanda, 2002.
<table><caption>**Table 01.** Vilus height (µm) and crypt depth (µm) of broiler embryos at 18 days of incubation and neonatal chicks hatched from eggs with different weights</caption><thead><tr><th rowspan="2"></th><th rowspan="2"></th><th colspan="2">Villus height (µm)</th><th colspan="2">Crypt depth (µm)</th></tr><tr><th>Duodenum</th><th>Jejunum</th><th>Duodenum</th><th>Jejunum</th></tr></thead><tbody><tr><td colspan="6">Broiler embryos at 18 days of incubation</td></tr><tr><td></td><td>56-65g</td><td>276.66</td><td>170.44 b</td><td>96.37</td><td>74.81</td></tr><tr><td rowspan="2">Egg weight</td><td>66-72g</td><td>299.56</td><td>175.02 a</td><td>85.74</td><td>81.24</td></tr><tr><td>P</td><td>ns</td><td>0.022</td><td>Ns</td><td>ns</td></tr><tr><td></td><td>CV (%)</td><td>13.04</td><td>13.87</td><td>16.59</td><td>21.27</td></tr><tr><td colspan="6">Neonatal chicks</td></tr><tr><td></td><td>56-65g</td><td>601.98</td><td>435.09 a</td><td>131.61</td><td>106.62</td></tr><tr><td rowspan="2">Egg weight</td><td>66-72g</td><td>690.72</td><td>353.59 b</td><td>134.91</td><td>123.21</td></tr><tr><td>P</td><td>ns</td><td>0.030</td><td>ns</td><td>ns</td></tr><tr><td></td><td>CV (%)</td><td>25.60</td><td>19.62</td><td>17.56</td><td>40.16</td></tr></tbody></table>

<table><caption>**Table 02.** Vilus height (µm) and crypt depth (µm) of broiler at 7 and 14 days of age hatched from eggs with different weights, supplemented with increasing levels of digestible lysine</caption><thead><tr><th rowspan="2"></th><th colspan="2">Villus height (µm)</th><th colspan="2">Crypt depth (µm)</th><th colspan="2">Villus height (µm)</th><th colspan="2">Crypt depth (µm)</th></tr><tr><th>Duodenum</th><th>Jejunum</th><th>Duodenum</th><th>Jejunum</th><th>Duodenum</th><th>Jejunum</th><th>Duodenum</th><th>Jejunum</th></tr></thead><tbody><tr><td colspan="9">7 days</td></tr><tr><td colspan="9">14 days</td></tr><tr><td colspan="9">Egg weight</td></tr><tr><td>56-65g</td><td>1178</td><td>695</td><td>427</td><td>290</td><td>1177.0</td><td>687</td><td>687</td><td>304</td></tr><tr><td>66-72g</td><td>1160</td><td>559</td><td>345</td><td>284</td><td>1246.9</td><td>698</td><td>698</td><td>269</td></tr><tr><td colspan="9">Digestible Lysine Levels (%)</td></tr><tr><td>1.1</td><td>1173</td><td>523</td><td>411</td><td>365</td><td>1246</td><td>567</td><td>392</td><td>274</td></tr><tr><td>1.2</td><td>1168</td><td>553</td><td>327</td><td>220</td><td>1148</td><td>623</td><td>372</td><td>240</td></tr><tr><td>1.3</td><td>1125</td><td>551</td><td>449</td><td>298</td><td>1098</td><td>799</td><td>374</td><td>390</td></tr><tr><td>1.4</td><td>1214</td><td>578</td><td>368</td><td>276</td><td>1354</td><td>761</td><td>338</td><td>260</td></tr><tr><td colspan="9">P</td></tr><tr><td>Age</td><td>Ns</td><td>ns</td><td>ns</td><td>ns</td><td>Ns</td><td>ns</td><td>Ns</td><td>Ns</td></tr><tr><td>Lysine</td><td>Ns</td><td>ns</td><td>ns</td><td>ns</td><td>Ns</td><td>ns</td><td>Ns</td><td>Ns</td></tr><tr><td>Age* Lys</td><td>Ns</td><td>ns</td><td>ns</td><td>ns</td><td>Ns</td><td>ns</td><td>Ns</td><td>Ns</td></tr><tr><td>CV (%)</td><td>13.2</td><td>41.2</td><td>13.7</td><td>28.4</td><td>14.5</td><td>16.8</td><td>11.3</td><td>30.8</td></tr></tbody></table>

<footnote>a,b Averages followed by distinct letters in the same column differs by Tukey test (P<0,05); ns = non-significant, CV = coefficient of variation</footnote>

<footnote>a,b Averages followed by distinct letters in the same column differ by Tukey test (P<0,05); ns = non-significant, CV = coefficient of variation</footnote>
P-261 (ID 88)

# EFFECTS OF SLAUGHTER WEIGHT AND SEX ON CARCASS YIELD, FAT AND FATTY ACID COMPOSITION OF MEAT IN BROILERS

A. Sozcu, U. Sahan

Dept. of Animal Science, Uludag University, Turkey

Corresponding author: ardasozcu@uludag.edu.tr

## Abstract

The aim of this research was to investigate the effects of slaughter weight and sex on carcass yield, fat and fatty acid composition of broiler meat. A total of 360 broilers were grown separately as female and male. At age of 42 day, broilers were classified by live weight as light and heavy. For measurements, a total of 30 broilers each group (slaughter weight/sex) were slaughtered. Meat samples of breast and thigh were analysed for fat and fatty acids. Slaughter weight was found to be highest as 3214.6 g in heavy-male broilers. Carcass yield was higher in light broilers than heavy broilers, whereas it was higher in females than males. Significant interactions were observed for breast and thigh meat, were highest as 808.3 g and 907.2 g, respectively in heavy-males. Fat content of breast was affected by both slaughter weight and sex, whereas fat content of thigh was affected by only slaughter weight. Saturated fatty acid content of breast was higher in males (33.8%) than females (33.4%). The highest content of MUFA and PUFA was observed in female-light broilers (31.6% and 33.5%, respectively). The highest MUFA content of 27.5% was found in female-light broilers, whereas PUFA content was found to be higher in light-males (34.5%) and heavy-females (34.5%). These results shows that slaughter weight at the same age and also sex affected carcass yield and also fat and fatty acid contents of breast and thigh meat in broilers.

**Keywords:** broiler, slaughter weight, sex, fat, fatty acid

## Introduction

Nowadays, consumers and the broiler industry have shown a demand for desirable carcass conformation scores, sensory characteristics and nutritional value, besides high slaughter yield (Holchman et al., 2003). Poultry meat quality is affected by some factors like slaughter age, sex, handling and slaughter conditions. Breast and thigh muscles of chicken represent the highest proportion of whole carcass and differ in their chemical composition and sensory quality (Oluyemi ve Robert, 2000). So the aim of the current study was to determine the effects of slaughter weight and sex on carcass yield, fat and fatty acid composition of breast and thigh of broiler carcass.

## Material and Methods

A total of 360 chicks (180 males/females) were obtained from a commercial Ross 308 broiler breeder flock at 52 weeks of age. The chicks were placed in 12 floor pens (n=3 pens per treatment group). The chicks were weighed using a balance at ±0.1 g precision on the 1st day of the growing period and received a starter diet (22.5% CP and ME 12.8 MJ/kg; days 1-14), a grower diet (22.0% CP and ME 13.3 MJ/kg; 15-28), and a finisher diet (21.0% CP and ME 13.5 MJ/kg; days 29-42. Feed and water were offered ad libitum during the growing period.

On slaughter day, broilers were classified as light and heavy. Before slaughter, feed was withdrawn 12 h before slaughter at 42 d of age. A total of 30 broilers from each group were individually weighed to determine slaughter weight and then were slaughtered. The carcass yield was calculated as a percentage of slaughter weight. Then the carcasses were divided into pieces as wing, breast, neck and back, thigh and drumstick (Raseta and Dakic, 1984). During slaughter process, samples of breast and thigh pieces were collected and stored at -20°C for further fatty acid analysis. Fatty acid analyses were performed with method described by Cherian et al. (2002). The fatty acid contents of the breast and thigh meat were given as percentages of total fatty acids.

A factorial arrangement of treatments was used in the study. Data were subjected to analysis of one-way variance analyses (SAS, 1989), by ANOVA procedures. Analyses for percentage data were conducted after a square root of arc sine transformation of the data. Significant differences among treatment means were determined by the Tukey's test.
## Results

The effects of slaughter weight and sex on slaughter yield are presented in Table 1. Slaughter and carcass weight was found as the highest in heavy male broilers (P<0.05). On the other hand, the carcass yield was similar between the treatment groups.

<table><caption>**Table 1:** The effects of slaughter weight and sex on slaughter yield</caption><thead><tr><th rowspan="2">Groups</th><th colspan="3">Slaughter yield</th></tr><tr><th>Slaughter weight</th><th>Carcass weight</th><th>Carcass yield</th></tr></thead><tbody><tr><td colspan="4" style="text-align: center; font-weight: bold;">Slaughter weight (SW)</td></tr><tr><td>Light (L)</td><td>2598.3 ± 59.9 <sup>b</sup></td><td>1961.9 ± 42.8 <sup>b</sup></td><td>75.6 ± 0.72 <sup>a</sup></td></tr><tr><td>Heavy (H)</td><td>2948.3 ± 59.9 <sup>a</sup></td><td>2132.0 ± 42.8 <sup>a</sup></td><td>72.3 ± 0.72 <sup>b</sup></td></tr><tr><td colspan="4" style="text-align: center; font-weight: bold;">Sex (S)</td></tr><tr><td>Female (F)</td><td>2576.5 ± 59.9 <sup>b</sup></td><td>1922.8 ± 42.8 <sup>b</sup></td><td>74.7 ± 0.72 <sup>a</sup></td></tr><tr><td>Male (M)</td><td>2970.0 ± 59.9 <sup>a</sup></td><td>2171.3 ± 42.8 <sup>a</sup></td><td>73.2 ± 0.72 <sup>b</sup></td></tr><tr><td colspan="4" style="text-align: center; font-weight: bold;">Slaughter weight x Sex (SW x S)</td></tr><tr><td>L x F</td><td>2471.1 ± 84.7 <sup>b</sup></td><td>1898.8 ± 60.5 <sup>b</sup></td><td>76.9 ± 1.01</td></tr><tr><td>L x M</td><td>2725.4 ± 84.7 <sup>c</sup></td><td>2025.1 ± 60.5 <sup>b</sup></td><td>74.3 ± 1.01</td></tr><tr><td>H x F</td><td>2681.9 ± 84.7 <sup>bc</sup></td><td>1946.7 ± 60.5 <sup>b</sup></td><td>72.6 ± 1.01</td></tr><tr><td>H x M</td><td>3214.6 ± 84.7 <sup>a</sup></td><td>2317.4 ± 60.5 <sup>a</sup></td><td>72.1 ± 1.01</td></tr><tr><td colspan="4" style="text-align: center; font-weight: bold;">P-Values</td></tr><tr><td>SW</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>Sex</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.044</td></tr><tr><td>SW x S</td><td>0.024</td><td>0.006</td><td>NS</td></tr></tbody></table>

a,b Means ±SEM in column that possess diferent superscripts differ significantly (P<0.01;P < 0.05). NS: P > 0.05

<table><caption>**Table 2.** The effects of slaughter weight and sex on carcass pieces weight</caption><thead><tr><th rowspan="2">Groups</th><th colspan="4">Carcass pieces</th></tr><tr><th>Wing (g)</th><th>Breast (g)</th><th>Thigh + Drumstick (g)</th><th>Neck + Back (g)</th></tr></thead><tbody><tr><td colspan="5" style="text-align: center; font-weight: bold;">Slaughter weight (SW)</td></tr><tr><td>Light</td><td>198.1 ± 3.97 <sup>b</sup></td><td>685.1 ± 18.8 <sup>b</sup></td><td>771.9 ± 18.78 <sup>b</sup></td><td>306.8 ± 7.37 <sup>b</sup></td></tr><tr><td>Heavy</td><td>215.8 ± 3.97 <sup>a</sup></td><td>763.4 ± 18.8 <sup>a</sup></td><td>823.8 ± 18.78 <sup>a</sup></td><td>329.0 ± 7.37 <sup>a</sup></td></tr><tr><td colspan="5" style="text-align: center; font-weight: bold;">Sex (S)</td></tr><tr><td>Female</td><td>191.7 ± 3.97 <sup>b</sup></td><td>701.3 ± 18.8 <sup>b</sup></td><td>736.2 ± 18.78 <sup>b</sup></td><td>293.5 ± 7.37 <sup>b</sup></td></tr><tr><td>Male</td><td>222.2 ± 3.97 <sup>a</sup></td><td>747.3 ± 18.8 <sup>a</sup></td><td>859.4 ± 18.78 <sup>a</sup></td><td>342.4 ± 7.37 <sup>a</sup></td></tr><tr><td colspan="5" style="text-align: center; font-weight: bold;">SW x S</td></tr><tr><td>L x F</td><td>189.8 ± 5.62 <sup>c</sup></td><td>684.0 ± 26.5 <sup>b</sup></td><td>732.1 ± 26.56 <sup>c</sup></td><td>292.9 ± 10.43 <sup>c</sup></td></tr><tr><td>L x M</td><td>206.5 ± 5.62 <sup>b</sup></td><td>686.3 ± 26.5 <sup>b</sup></td><td>811.6 ± 26.56 <sup>b</sup></td><td>320.8 ± 10.43 <sup>b</sup></td></tr><tr><td>H x F</td><td>193.7 ± 5.62 <sup>bc</sup></td><td>718.5 ± 26.5 <sup>b</sup></td><td>740.3 ± 26.56 <sup>c</sup></td><td>294.1 ± 10.43 <sup>bc</sup></td></tr><tr><td>H x M</td><td>238.0 ± 5.62 <sup>a</sup></td><td>808.3 ± 26.5 <sup>a</sup></td><td>907.2 ± 26.56 <sup>a</sup></td><td>363.9 ± 10.43 <sup>a</sup></td></tr><tr><td colspan="5" style="text-align: center; font-weight: bold;">P-Values</td></tr><tr><td>SW</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.008</td><td>0.004</td></tr><tr><td>Sex</td><td>&lt;0.01</td><td>0.017</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>SW x S</td><td>0.001</td><td>0.023</td><td>0.024</td><td>0.006</td></tr></tbody></table>

a,b Means ±SEM in column that possess diferent superscripts differ significantly (P<0.01;P < 0.05). NS: P > 0.05

The weight of carcass pieces by slaughter weight and sex are presented in Table 2. The weights of carcass pieces including wing, breast, thigh and drumstick were found higher in heavy male broilers (P<0.05).

The effects of chick weight and sex on saturated and unsaturated fatty acid content of breast and thigh are presented in Table 3. Whereas the fat content of breast were higher in light broilers and female broilers, it was higher in only heavy broilers. Saturated fatty acids of thigh were higher by 35.6% and 35.4%, respectively in light broilers and also in male broilers. The highest contents of MUFA and PUFA were observed in light female broilers. Whereas, MUFA content of thigh was the highest in light female, PUFA content was higher in light male and heavy female broilers (P<0.01).
<table><caption>Table 3. The effects of chick weight and sex on saturated and unsaturated fatty acid content of breast and thigh (%)</caption><thead><tr><th rowspan="2">Groups</th><th colspan="4">Breast</th><th colspan="3">Thigh</th></tr><tr><th>Fat content</th><th>Saturated</th><th>MUFA</th><th>PUFA</th><th>Fat content</th><th>Saturated</th><th>MUFA</th><th>PUFA</th></tr></thead><tbody><tr><td colspan="9" style="text-align: center; font-weight: bold;">Slaughter Weight (SW)</td></tr><tr><td>Light</td><td>1.17 ±<br>0.08 <sup>a</sup></td><td>33.6 ±<br>0.16</td><td>28.8 ±<br>0.27 <sup>a</sup></td><td>32.9 ± 0.17 <sup>a</sup></td><td>1.36 ±<br>0.10 <sup>b</sup></td><td>35.6 ± 0.32 <sup>a</sup></td><td>25.6 ±<br>0.26 <sup>a</sup></td><td>33.0 ± 1.18</td></tr><tr><td>Heavy</td><td>0.95 ±<br>0.08 <sup>b</sup></td><td>33.7 ±<br>0.16</td><td>26.8 ±<br>0.27 <sup>b</sup></td><td>31.7 ± 0.17 <sup>b</sup></td><td>1.66 ±<br>0.10 <sup>a</sup></td><td>34.1 ± 0.32 <sup>b</sup></td><td>23.0 ±<br>0.26 <sup>b</sup></td><td>31.8 ± 1.18</td></tr><tr><td colspan="9" style="text-align: center; font-weight: bold;">Sex (S)</td></tr><tr><td>Female<br>(F)</td><td>1.35 ±<br>0.08 <sup>a</sup></td><td>33.4 ±<br>0.16 <sup>b</sup></td><td>29.8 ±<br>0.27 <sup>a</sup></td><td>32.5 ± 0.17 <sup>a</sup></td><td>1.43 ±<br>0.10</td><td>34.3 ± 0.32 <sup>b</sup></td><td>25.3 ±<br>0.26 <sup>a</sup></td><td>33.5 ± 1.18</td></tr><tr><td>Male (M)</td><td>0.77 ±<br>0.08 <sup>b</sup></td><td>33.8 ±<br>0.16 <sup>a</sup></td><td>25.9 ±<br>0.27 <sup>b</sup></td><td>32.1 ± 0.17 <sup>b</sup></td><td>1.59 ±<br>0.10</td><td>35.4 ± 0.32 <sup>a</sup></td><td>23.3 ±<br>0.26 <sup>b</sup></td><td>31.3 ± 1.18</td></tr><tr><td colspan="9" style="text-align: center; font-weight: bold;">SW x S</td></tr><tr><td>L x F</td><td>1.52 ±<br>0.11</td><td>33.3 ±<br>0.22</td><td>31.6 ±<br>0.39 <sup>a</sup></td><td>33.5 ± 0.22 <sup>a</sup></td><td>1.44 ±<br>0.15 <sup>b</sup></td><td>33.4 ± 0.46</td><td>27.5 ±0.37<br><sup>a</sup></td><td>31.5 ± 1.67<br><sup>ab</sup></td></tr><tr><td>L x M</td><td>0.81 ±<br>0.11</td><td>33.8 ±<br>0.22</td><td>26.1 ±<br>0.39 <sup>c</sup></td><td>32.3 ± 0.22 <sup>b</sup></td><td>1.28 ±<br>0.15 <sup>b</sup></td><td>34.9 ± 0.46</td><td>23.6 ±0.37<br><sup>b</sup></td><td>34.5 ± 1.67 <sup>a</sup></td></tr><tr><td>H x F</td><td>1.17 ±<br>0.11</td><td>33.5 ±<br>0.22</td><td>28.0 ±<br>0.39 <sup>b</sup></td><td>31.5 ± 0.22 <sup>c</sup></td><td>1.41 ±<br>0.15 <sup>b</sup></td><td>35.3 ± 0.46</td><td>23.1 ±0.37<br><sup>b</sup></td><td>34.5 ± 1.67 <sup>a</sup></td></tr><tr><td>H x M</td><td>0.72 ±<br>0.11</td><td>33.8 ±<br>0.22</td><td>25.7 ±<br>0.39 <sup>c</sup></td><td>31.9 ± 0.22<br><sup>bc</sup></td><td>1.91 ±<br>0.15 <sup>a</sup></td><td>36.0 ± 0.46</td><td>22.9 ±0.37<br><sup>b</sup></td><td>28.1 ± 1.67 <sup>b</sup></td></tr><tr><td colspan="9" style="text-align: center; font-weight: bold;">P- Values</td></tr><tr><td>SW</td><td>0.011</td><td>NS</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.006</td><td>&lt;0.01</td><td>&lt;0.01</td><td>NS</td></tr><tr><td>S</td><td>&lt;0.01</td><td>0.015</td><td>&lt;0.01</td><td>0.019</td><td>NS</td><td>0.002</td><td>&lt;0.01</td><td>NS</td></tr><tr><td>SW x S</td><td>NS</td><td>NS</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.003</td><td>NS</td><td>&lt;0.01</td><td>&lt;0.01</td></tr></tbody></table>

a,b Means ±SEM in column that possess diferent superscripts differ significantly (P<0.01;P < 0.05). NS: P > 0.05

## Conclusions

In conclusion, slaughter weight and sex affected carcass yield, fat and fatty acid composition of breast and thigh. Consumers prefer to buy whole carcass or carcass pieces due to nutritional value, especially fat and fatty acid content and also sensory quality. At this point, determining the effecting factors of chemical composition of broiler meat could be beneficial to manipulate broiler feeding practices.

## Literature

CHERIAN, G., CAMPBELL, A., T. PARKER, 2009: Egg quality and lipid composition of eggs from hens fed Camelina sativa. J. Appl. Poult. Res. 18, 143–150.

HOLCMAN, A., VADNJAL, R., ŽLENDER, B., V. STIBILJ, 2003: Chemical composition of chicken meat from free range and extensive indoor rearing. Arch. Geflügelk, 67, 120–124.

OLUYEMI, J.A., F.A. ROBERT, 2000. Poultry Production in Warm Wet Climate, Macmillian Press Ltd., pp: 78-168.

RASETA J., DAKIĆ M. (1984): Higijena mesa (Higijena mesa živine i jaja). Veterinarski fakultet Beograd.

SAS Institute Inc. 1989. A user's guide to SAS. SAS Institute, Inc. Cary, NC.
P-262 (ID 82)

ELEVATED HATCHER TEMPERATURE AFFECTS ONE DAY OLD CHICK QUALITY AND GROWTH PERFORMANCE DURING EARLY POST-HATCH PERIOD

A. Sozcu, A. Ipek

Dept. of Animal Science, Uludag University, Turkey

Corresponding author: ardasozcu@uludag.edu.tr

**Abstract**

The aim of the study was to determine the effects of elevated hatcher temperature on one day old chick quality and broiler growth performance during early post-hatch period. The hatcher temperatures were applied as follows: control (36.8-37.0°C) and elevated hatcher temperature (38.8-39.0°C) during hatching period. One day old chick quality was measured by different scoring systems including Tona score, Pasgar score, chick body weight, yolk free body weight and chick length. The quality of chicks from control group was found to be higher with Tona and Pasgar scores (P<0.01). One day old chick weight and yolk free body weight were found to be higher in chicks as compared to control group as 44.3 g and 40.7 g, respectively (P<0.01). Chick length was found to be similar between groups. During early post-hatch period, live weight was higher in chicks from control group than chicks from elevated hatcher temperature group (P<0.01). Relative growth was found to be higher by 373.0% in chicks from control group between days 1 and 7, whereas it was found higher with a value of 172.3% in chicks from elevated hatcher temperatures between days 7-14 (P<0.01). In conclusion, elevated hatcher temperature affected one-day old chick quality including chick weight and yolk free chick weight, and broiler growth performance during early term of post-hatch period.

**Keywords:** elevated hatcher temperature, chick quality, Tona, Pasgar, growth rate

**Introduction**

The one-day old chick quality is an important issue for hatchery success and also profitability of broiler producers (Decuypere and Bruggemen 2007). Some various quality scoring systems have been developed considering different quantitative and qualitative parameters such as Tona score and Pasgar score (Boerjan 2002, Tona et al. 2003). There are four quantitative methods for scoring chick quality; Tona or Pasgar score, the one-day old chick weight, yolk free chick weight and chick length (Meijerhof 2009).

Incubation temperature is one of the most important factors to assure optimum chick quality and also for post-hatch broiler performance (Lourens 2003, Willemsen et al. 2008, Ipek et al. 2014). Fluctuations in setter or hatcher temperatures have negative impacts on chick quality and it causes major economic losses because of the negative effects on post-hatch performance and slaughter yield (Wilson 1991, Shafey 2004). So the aim of the current study was to determine the effects of elevated hatcher temperatures on one day old chick quality and growth performance during early post-hatch period.

**Material and Methods**

The total of 1800 eggs was obtained from a commercial Ross 308 broiler breeder parent stock at 42 weeks of age. All eggs were weighed (55-65 g) and then incubated in same incubator at 37.5°C and a 55-60% RH during the first 18 days of incubation. On 18th day of incubation, the eggs placed into hatching baskets (560 eggs per treatment group) and then the eggs were transferred to two hatcher cabinets (640 capacity egg hatcher) for these temperature: control (36.8-37.0 °C), and elevated hatcher temperature (38.8-39.0 °C).

After completing hatching process, the chick quality was measured with Tona score, Pasgar score, chick hatching weight, yolk free chick weight and chick length. A total of 90 chicks per group were randomly chosen for Tona and Pasgar methods (Boerjan, 2002; Tona et al., 2003). Then these chicks were measured for chick weight and length (Hill 2001). A total of 40 chicks were randomly killed by cervical dislocation to determine yolk free chick weight.

A total of 50 chicks each two groups were placed rearing pens. Feed and water were offered ad libitum during the rearing period. The live weight values were monitored on a weekly basis and relative growth was calculated with formula reported by Willemsen et al. (2008).
The effects of different hatcher temperatures on chick quality and growth performance were analyzed by 1-way ANOVA using the general linear model procedure (SAS). Analyses for percentage data were conducted after square root of arc sine transformation of the data. Significant differences among means were determined by a Duncan's multiple range test.

## Results

The effects of different hatcher temperatures on chick quality are presented in Table 1. Tona and Pasgar scores were higher by 90.4 and 8.9, respectively in the control group (P<0.01). Similarly, the chick weight and yolk free chick weight were higher in the control group (P<0.01). The chick length was similar between the treatment groups.

<table><caption>**Table 1.** Chick quality scores with different scoring methods</caption><thead><tr><th rowspan="2">Groups</th><th colspan="5">Scoring Methods</th></tr><tr><th>Tona Score<sup>1</sup></th><th>Pasgar Score<sup>1</sup></th><th>CW<sup>1</sup></th><th>YFC<sup>2</sup></th><th>Chick Length<sup>1</sup></th></tr></thead><tbody><tr><td></td><td>n= 90</td><td>n=90</td><td>n=90</td><td>n=40</td><td>n=90</td></tr><tr><td>Control</td><td>90.4 ± 6.03</td><td>8.9 ± 1.05</td><td>44.3 ± 2.78</td><td>39.3 ± 2.27</td><td>20.0 ± 0.58</td></tr><tr><td>Elevated</td><td>68.9 ± 16.66</td><td>8.3 ± 1.10</td><td>40.7 ± 1.48</td><td>35.3 ± 1.00</td><td>20.1 ± 0.65</td></tr><tr><td>Probabilities</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.356</td></tr></tbody></table>

The live weights of chicks from different hatcher temperatures during the growing period are presented in Table 2. On 1st day of growing period, live weights of chicks were higher in the control group than other (P<0.01). From 1st day to 14th day of the growing period, the chicks of the control group was consistently heavier by 208.5 and 543.8 on day 7 and 14, respectively, compared to the chicks of the elevated hatcher temperature group (P<0.01).

<table><caption>**Table 2.** Live weight of chicks from different hatcher temperatures during the growing period</caption><thead><tr><th rowspan="2">Groups</th><th colspan="3">Live weight (g)</th></tr><tr><th>1.day</th><th>7.day</th><th>14.day</th></tr></thead><tbody><tr><td>Control</td><td>44.2 ± 0.44</td><td>208.5 ± 8.80</td><td>543.8 ± 70.34</td></tr><tr><td>Elevated</td><td>40.5 ± 0.24</td><td>165.6 ± 4.69</td><td>449.6 ± 11.43</td></tr><tr><td>Probabilities</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td></tr></tbody></table>

The relative growth of the chicks from different hatcher temperatures during the growing period are presented in Table 3. Between day 1 and 7 of growing period, the relative growth was the highest in the control group by 373.0%, compared to elevated hatcher temperature group by 307.9%, respectively (P<0.01). Between day 7 and 14, the higher relative growth rate was found in elevated hatcher temperature group by 172.3% than the control (P<0.01).

<table><caption>**Table 3.** Relative growth (%) of chicks from different hatcher temperatures with during the growing period (n=50 chicks)</caption><thead><tr><th rowspan="2">Groups</th><th colspan="2">Relative growth (%)</th></tr><tr><th>1-7</th><th>7-14</th></tr></thead><tbody><tr><td>Control</td><td>373.0 ± 32.8</td><td>160.9 ± 34.4</td></tr><tr><td>Elevated</td><td>307.9 ± 26.3</td><td>172.3 ± 17.54</td></tr><tr><td>Probabilities</td><td>&lt;0.01</td><td>&lt;0.01</td></tr></tbody></table>

<footnote n="1">¹: n=90 chicks/treatment ²: n=40 chicks/treatment CW: Chick weight YFCW: Yolk free chick weight</footnote>

<footnote>n=50 chicks/treatment</footnote>
Conclusions

In conclusion, the one-day old chick quality can be measured by different scoring methods to predict broiler perform-
ance. The first term of profitability in broiler production depends on hatchery management and good quality chick pro-
duction. During incubation, especially incubation temperature affects seriously embryonic development during incuba-
tion, chick quality at hatch and post-hatch broiler performance. In large scale broiler production, growth rate, feed con-
version rate, total mortality and slaughter yield are too important parameters. Because of first week broiler growth per-
formance and mortality are related with chick quality, determining the chick quality with a high accuracy and objectivity
is very important issue. At this point, the effects of incubation conditions on chick quality could be known well and con-
sidered in scoring of chick quality.

Literature

BOERJAN, M. 2002: Programs for single stage incubationand chick quality. Poult Avian Biol Rev. 13, 237-238.

DECUYPERE, E., V. BRUGGEMAN, 2007: The endocrine interface of environmental and egg factors affecting chick quality. Poult Sci. 86, 1037-1042.

HILL, D. 2001: Chick length uniformity profiles as a field measurement of chick quality. Poult Avian Biol Rev. 12: 188 (Abstr).

IPEK, A, U. SAHAN, S.C. BAYCAN, A. SOZCU, 2014: The effects of different eggshell temperatures on embryonic development, hatchability, chick quality and first week broiler performance. Poult. Sci. 93, 464-472.

LOURENS, S. 2003: Residual yolk and egg weight loss during incubation under controlled eggshell temperatures. Poult Avian Biol Rev. 14, 209:211.

MEIJERHOF, R. 2009: The influence of incubation on chick quality and broiler performance. In Proccedings Of 20th Annual Australian Poultry Science Symposium, 9-11 February 2009, Sidney, Australia, pp. 167-170.

SAS Institute Inc. 1989. A user's guide to SAS. SAS Institute, Inc. Cary, NC.

SHAFEY, T.M. 2004: Effect of lighted incubation on embryonic growth and hatchability performance of two strains of layer breeder eggs. Br Poult Sci. 45, 223-229.

TONA, K., F. BAMELIS, B. DE KETELAERE, V. BRUGGEMAN, V.M.B. MORAES, J. BUYSE, O. ONAGBESAN, E. DECUYPERE, 2003: Effects of egg storage time on spread of hatch, chick quality and chick juvenile growth. Poult Sci. 82, 736-741.

WILLEMSEN, H, N. EVERAERT, A. WITTERS, L. DE DMIT, M. DEBONNE, F. VERSCHUERE, P. GARAIN, D. BERCKMANS, E. DECUYPERE, V. BRUGGEMAN, 2008: Critical assesment of chick quality measurements as an indicator of posthatch performance. Poult Sci. 87, 2358-2366.

WILSON, H.R. 1991: Interrelationship of egg size, chick size, posthatching growth and hatchability. World's Poult Sci J. 47, 5-19.
P-263 (ID 240)

COCCIDIOSIS PREVENTION STRATEGIES AND PRACTICES IN THE AMERICAS

V. Stanev<fnref n="1" />, R. Vargas<fnref n="2" />, M. Quiroz<fnref n="2" />, D. Vancraeynest<fnref n="1" />

**Abstract**

The study objective was to evaluate the most commonly used strategies and practices in coccidiosis control in the Americas. Seventy five interviews with participants from Argentina, Brazil, Canada, Colombia, Mexico and Peru were carried out in the period March-April 2014. Nearly half of all broiler production in the region was represented.

In respect to the number of rotations, 84% of the respondents have used two or more different anticoccidial programs in the last 12 months, and only 16% have not rotated at all. The study indicated considerable understanding and agreement with the basic coccidiosis prevention postulates: (i) not to use a certain drug for too long (77% strongly agree); (ii) to give products sufficient rest after each period of use (69% strongly agree); (iii) to rotate between products of different classes (67% strongly agree) and (iv) to use a synthetic drug in a clean-up program at least once per year (63% strongly agree). The majority of respondents agreed that to avoid resistance development, the drugs should be rotated before having signs of inefficacy, demonstrating a high level of judicious drug use.

Only 9.4% of the respondents were not satisfied by the current control of coccidiosis in their respective operations, while 48% were “completely satisfied” and 42.7% “somewhat satisfied”. In countries with low rotation rate, satisfaction of coccidiosis control was the least, indicating correlation between the use of rotation and efficacy of prevention.

**Introduction**

Coccidiosis is one of the greatest threats to flock health and profitability of the poultry industry, costing an estimated $3 billion globally each year (Lillehoj, 2006). The disease can manifest itself in a clinical or a subclinical form. While the clinical form is relatively easy to diagnose and most of the time efficaciously treated, subclinical disease often remains hidden. Nevertheless, subclinical coccidiosis comprises up to 80% of the costs related to coccidiosis (Williams, 1998). To combat this costly disease, poultry producers and veterinarians have long reached for in-feed anticoccidial drugs and, more recently, vaccines. In-feed anticoccidials are by far the most vastly used prevention tool for coccidiosis control in poultry, under modern production practices. In its commission report 233/2008, the European Commission recognizes their use as “essential”. Unfortunately if these products are used injudiciously, resistance of field *Eimeria* strains ultimately develops and anticoccidial efficacy declines (Mathis et al., 1984; Chapman, 1986; 1997 and 2007). Moreover, the latest anticoccidial drug came in commercial use in the 1990s and no new products are anticipated to enter this segment in the near term, making it critically important for producers and veterinarians to use products in a way that maximizes performance while preserving long term efficacy.

In this respect the basic postulates in anticoccidial prevention are (i) not to use same drug for too long, as it is generally acknowledged that overuse of anticoccidial products will eventually lead to the development of resistance (Mathis et al., 1984; Chapman, 1986; 1997 and 2007); (ii) to give a rest period to all products that share a similar resistance mechanism, so that the *Eimeria* population is not exposed to the same/similar drug, which is beneficial for restoration of sensitivity (Chapman and McFarland, 2003); (iii) to avoid the use of drugs with similar structure and mode of action avoiding cross-resistance (McDougald et al., 1987; Bedrnik et al., 1989; Chapman and Hacker, 1994; Chapman, 2007; Marien et al., 2007), by rotating between products of different classes; and lastly (iv) to use a synthetic drug at least once yearly to reduce infection pressure (DeGussem, 2005).

The objective of the study was to evaluate the most commonly used strategies and practices in coccidiosis control in the Americas. To gain a deeper understanding and insights regarding current use of anticoccidials and vaccines; to identify common programs used, including rotational practices; to explore the efficacy perceptions among users and evaluate the correlation between satisfaction level and the prevention strategies employed.

<footnote n="1">¹ Zoetis International Services, Paris, France</footnote>

<footnote n="2">² Zoetis Global Poultry, Durham, NC, USA</footnote>
## Materials and Methods

Poultry producers, nutritionists and veterinarians across North and South America were interviewed. Seventy five interviews with participants from Argentina, Brazil, Canada, Colombia, Mexico and Peru were carried out during the period of March and April, 2014. Nearly half of all broiler production in the region was represented by the study participants (Fig.1). The following areas where explored:

* Satisfaction with current control of coccidiosis

* Types of programs used to control coccidiosis

* Number of rotations in the past 12 months

* Industry stand on basic coccidiosis control strategy's postulates

* To change anticoccidial control tools to maximize program performance while preserving long term efficacy

* To rest the anticoccidial drugs after period of use to allow them restoring efficacy

* Rotation should be carried out among drugs of different classes in order to provide effective coccidiosis control

* Once a year synthetic anticoccidial should be used as a chemical clean-up in order to reduce the infection pressure on the farm

* Anticoccidial drugs should be rotated at given intervals even if they still seem to be working in order to avoid resistance development, thus increasing the level of subclinical coccidiosis or having clinical outbreaks, but most important to preserve the anticoccidial drugs viable for future use (avoid 'burning' the products).

* Significance of the coccidiosis challenge on the field.

<figure><img src="image_84.png" /><figcaption>Fig 1. Sample representativeness</figcaption></figure>

## Results

Only 9.4% of the respondents were not satisfied by the current control of coccidiosis in their respective operations, while 48.0% are “completely satisfied” and 42.7% “somewhat satisfied”. Significantly more respondents in Argentina and Mexico are “completely satisfied” with current control of coccidiosis, as compared to respondents in all other countries. Respondents in Colombia and Peru were least satisfied (Fig. 2).

<figure><img src="image_85.png" /><figcaption>Fig. 2 Satisfaction with current coccidiosis control program. Arrows for the different countries indicate higher than average, average or below average satisfaction level.</figcaption></figure>

22% of the protocols involved a synthetic product (either on its own or in combination product) during the whole grow-out cycle (Fig. 4).

In respect to the number of different programs used, 84% of the respondents replied they have used two or more different anticoccidial programs in the last 12 months, and only 16% have not rotated at all. Based on the number of broilers produced in a weekly basis, broiler operations used an average of 2.5 different protocols for coccidiosis over the past year. Incidence of rotation is highest in Argentina and Canada and lowest in Colombia and Peru (Fig. 3).

Nearly two-thirds of protocols (prevention programs) involve a combination product (ionophore + synthetic) or a synthetic coccidiostat in the starter feed followed by an ionophore in the grower/finisher feed, while
In respect to the basic coccidiosis control postulates, 77.3% of the respondents “strongly agree” with the need to rotate between different coccidiosis control products in order to maximize program performance while preserving long term efficacy. 66.7% are aware of the cross-resistance between products with similar chemical structure and mode of action, so agree that rotation should be carried out between products of different classes. 69.3% of the respondents “strongly agree” that “resting” the anticoccidial drugs is needed to allow them restoring their efficacy and 62.7% “strongly agree” with the importance of at least an annual chemical clean-up (Fig. 5).

<figure><img src="image_86.png" /><figcaption>**Fig. 3** Number of rotations in the last 12 months Arrows for the different countries indicate more than average, average or below average frequency of rotation.</figcaption></figure>

<figure><img src="image_87.png" /><figcaption>**Fig. 4** Types of coccidiosis prevention programs used in the last 12 months</figcaption></figure>

<figure><img src="image_88.png" /><figcaption>**Fig. 5** Agreement with the basic coccidiosis control postulates.</figcaption></figure>

## Discussion and Conclusions

The study data indicated that there was considerable understanding and agreement with the basic coccidiosis prevention postulates. The majority of respondents consented with the basic anticoccidial prevention postulates: (i) not to use same drug for too long, as it is generally acknowledged that overuse of anticoccidial products will eventually lead to the development of resistance (Mathis et al., 1984; Chapman, 1986; 1997 and 2007); (ii) to give a rest period to all products
that share a similar resistance mechanism, so that the *Eimeria* population is not exposed to the same/similar drug, which is beneficial for restoration of sensitivity (Chapman and McFarland, 2003); (iii) to avoid the use of drugs with similar structure and mode of action avoiding cross-resistance (McDougald *et al.*, 1987; Bedrnik *et al.*, 1989; Chapman and Hacker, 1994; Chapman, 2007; Marien *et al.*, 2007), by rotating between products of different classes; and lastly (iv) the use of a synthetic drug at least once yearly to reduce infection pressure (DeGussem, 2005). Moreover, the majority of respondents agreed that the drugs should be rotated before having signs of inefficacy in order to avoid resistance development. This demonstrates a high level of judicious drug use. Only 9.4% of the respondents were not satisfied by the current control of coccidiosis in their respective operations, while 48% were "completely satisfied" and 42.7% "someWHAT SATISFIED". In countries with low rotation rate, satisfaction of coccidiosis control was the least, indicating correlation between the use of rotation and efficacy of prevention

References

Bedrnik, P., Jurkovic, P., Kucera J., Firmanova, A. (1989). Cross-resistance to the ionophorous polyether anticoccidial drugs in Eimeria tenella isolates from Czechoslovakia. Poultry Science 68(1): 89-93.

Chapman, H.D., and Hacker, A.B. (1994). Sensitivity of field isolates of Eimeria from two broiler complexes to anticoccidial drugs in the chicken. Poultry Science, 73(9):1404-1408.

Chapman, H.D. (1997). Biochemical, genetic and applied aspects of drug resistance in Eimeria parasites of the fowl. Avian Pathology, 26: 221-244.

Chapman, 2007. Rotation programmes for coccidiosis control. International Poultry Production, 15: 7-9.

Commission of the European Union., 2008. REPORT FROM THE COMMISSION TO THE COUNCIL AND THE EUROPEAN PARLIAMENT ON THE USE OF COCCIDIOSTATS AND HISTOMONOSTATS AS FEED ADDITIVES. COM(2008)233 final.

De Gussem, M. (2005). Coccidiosis control in poultry: importance of the quality of anticoccidial premixes. Proceedings of the IXth International Coccidiosis Conference, Foz do Iguassu, September 19-23, 2005

Lillhoj H. Functional genomics approaches to study host pathogen interactions in mucosal pathogens, Proceedings of the Korean Society of Poultry Science Meeting, Nov. 10, 2006.

Marien, M., De Gussem, M., Vancraeynest, D., Fort, G. and Naciri, M. (2007). Indication of cross-resistance between different monovalent ionophores as determined by an anticoccidial sensitivity test (AST). Proceedings XVIth European Symposium on Poultry Nutrition, August 26-30 2007, Strasbourg, France.

Mathis, G.F., McDougald, L.R., McMurray, B. (1984). Drug sensitivity of coccidia from broiler breeder pullets and from broilers in the same integrated company. Avian Diseases, 28 (2): 453-459.

McDougald, L.R., Lamas Da Silva, J. M., Solis, J., Braga, M. (1987). A Survey of Sensitivity to Anticoccidial Drugs in 60 Isolates of Coccidia from Broiler Chickens in Brazil and Argentina. Avian Diseases, 31, (2): 287-292.

Williams, R.B. (1999). A compartmentalised model for the estimation of the cost of coccidiosis to the world's chicken production industry. *International Journal for Parasitology* 29, 1209-1229
P-264 (ID 149)

EFFECT OF DIFFERENT DIETARY LEVELS OF ENERGY AND PROTEIN ON PERFORMANCE OF JAPANESE QUAIL DURING GROWER PHASE

H.R. Taheri, and M. Abbasi

Dept. of Animal Science, University of Zanjan, Zanjan, 45371-38791, Iran

Corresponding author: taherihr@gmail.com

Abstract

This research was conducted to investigate the effect of different levels of metabolisable energy and crude protein on performance, carcass characteristics and blood parameters of Japanese quail during grower phase (14-28 d of age). Nine hundreds 14-d-old male birds were used to examine 3 levels of energy (2900, 3050 and 3200 Kcal of ME/Kg of the diet) and 3 levels of protein (21.6, 24 and 26.4% CP) by a 3*3 factorial arrangement in a completely randomized design with 5 replicates of 20 birds. Feed intake, weight gain and feed conversion ratio (FCR) were measured during whole period. At the end of the experiment, 2 birds from each replicate were selected to measure the blood parameters (TG, total cholesterol, LDL and uric acid) and carcass characteristics. Respectively, the lowest and highest levels of energy and protein enhanced (P<0.05) daily feed intake. Daily weight gain was not affected by the treatments (P>0.05), however, FCR was improved by the diets of 3050 and 3200 Kcal ME/Kg compared with that of 2900 Kcal ME/Kg. Energy and protein interaction was significant (P<0.05) for the relative weight of liver; the treatment with 3200 Kcal ME/Kg and 24% CP showed the highest value. Among blood parameters, uric acid was decreased (P<0.05) by the diets of 3050 and 3200 Kcal ME/Kg. Based on performance results, 3050 Kcal ME/Kg of the diet can be proposed for Japanese quail nutrition during the grower phase.

**Keywords:** crude protein, grower phase, Japanese quail, metabolisable energy, performance

Introduction

Energy and protein are primary nutritional requirements of all classes of animals and types of production, including growing quails. These requirements must be met before requirements for other nutrients are addressed. Although few works have been conducted to investigate the effect of metabolisable energy in Japanese quail nutrition (Kaur et al., 2008), there is a lack of information on energy levels more than 3100 Kcal/kg, alone or in combination with different levels of crude protein. In addition, the literature is silent on the effect of different levels of energy and protein in different phase of growth period, separately. Therefore, this research was conducted to investigate the effect of different levels of metabolisable energy and crude protein on growth performance, carcass characteristics and blood parameters of Japanese quail (*Coturnix coturnix Japonica*) during grower phase (14 to 28 d of age).

**Material and Methods**

Nine hundreds 14-d-old male birds were used to examine 3 levels of energy (2900, 3050 and 3200 Kcal of ME/Kg of the diet) and 3 levels of protein (21.6, 24 and 26.4% CP) by a 3*3 factorial arrangement in a completely randomized design with 5 replicates of 20 birds (table 1). All the groups were subjected to similar management practices (brooding, lighting, feeding and watering) throughout the experiment except the diets offered. Lighting cycle was 23L:1D and brooding temperature gradually decreased from 37°C during the initial 3 days to 22-24°C by 28 d of age. Water and experimental diets were supplied *ad libitum*. All the replicates had similar mean body weight (64±3 g) at d 14. All the birds received a regular diet (2900 Kcal/Kg ME and 24% CP) before the experiment (i. e. from 1 to 14 d of age). Daily feed intake, daily weight gain and feed conversion ratio (FCR) were measured during whole period. At the end of the experiment, 2 birds from each replicate were selected to measure the blood parameters (triglyceride, total cholesterol, LDL and uric acid) and relative weight of carcass and liver. All data were analyzed using GLM procedure of SAS. The treatment means were compared using Duncan test.
<table><caption>**Table 1.** Composition of experimental diets</caption><thead><tr><th></th><th colspan="9">Experimental diets</th></tr></thead><tbody><tr><td>ME levels (Kcal/Kg)</td><td>2900</td><td>2900</td><td>2900</td><td>3050</td><td>3050</td><td>3050</td><td>3200</td><td>3200</td><td>3200</td></tr><tr><td>Crude protein levels (%)</td><td>21.6</td><td>24</td><td>26.4</td><td>21.6</td><td>24</td><td>26.4</td><td>21.6</td><td>24</td><td>26.4</td></tr><tr><td>Diet ingredients (%)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Corn</td><td>53.9</td><td>49</td><td>24.95</td><td>51.9</td><td>47</td><td>42.61</td><td>50</td><td>44</td><td>39.5</td></tr><tr><td>Soybean meal (44% CP)</td><td>25</td><td>29.7</td><td>33</td><td>24.6</td><td>29.6</td><td>31.3</td><td>22.6</td><td>27</td><td>30</td></tr><tr><td>Corn gluten meal (60% CP)</td><td>7</td><td>8.5</td><td>11</td><td>7.7</td><td>9</td><td>12.5</td><td>9.6</td><td>11.2</td><td>13.7</td></tr><tr><td>Wheat bran</td><td>3.58</td><td>2.22</td><td>0.64</td><td>2.71</td><td>1.24</td><td>0.63</td><td>2.12</td><td>1.65</td><td>0.7</td></tr><tr><td>Wheat</td><td>5</td><td>5</td><td>5</td><td>5</td><td>5</td><td>5</td><td>5</td><td>5</td><td>5</td></tr><tr><td>Vegetable oil</td><td>0.8</td><td>1</td><td>0.9</td><td>3.3</td><td>3.5</td><td>3.3</td><td>5.7</td><td>6.3</td><td>6.3</td></tr><tr><td>Dicalcium phosphate</td><td>1.65</td><td>1.61</td><td>1.57</td><td>1.65</td><td>1.61</td><td>1.57</td><td>1.65</td><td>1.61</td><td>1.57</td></tr><tr><td>Calcium carbonate</td><td>1.05</td><td>1.05</td><td>1.12</td><td>1.05</td><td>1.05</td><td>1.12</td><td>1.05</td><td>1.05</td><td>1.12</td></tr><tr><td>Common salt</td><td>0.2</td><td>0.2</td><td>0.18</td><td>0.2</td><td>0.2</td><td>0.18</td><td>0.2</td><td>0.2</td><td>0.18</td></tr><tr><td>Sodium bicarbonate</td><td>0.42</td><td>0.43</td><td>0.46</td><td>0.42</td><td>0.43</td><td>0.46</td><td>0.42</td><td>0.43</td><td>0.46</td></tr><tr><td>Potassium bicarbonate</td><td>0.3</td><td>0.14</td><td>0</td><td>0.35</td><td>0.2</td><td>0.2</td><td>0.49</td><td>0.33</td><td>0.2</td></tr><tr><td>L-threonine</td><td>0.21</td><td>0.23</td><td>0.23</td><td>0.21</td><td>0.23</td><td>0.23</td><td>0.21</td><td>0.23</td><td>0.23</td></tr><tr><td>L-lysine hydrochloride</td><td>0.39</td><td>0.42</td><td>0.45</td><td>0.41</td><td>0.44</td><td>0.5</td><td>0.46</td><td>0.5</td><td>0.54</td></tr><tr><td>Mineral premix</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td></tr><tr><td>Vitamin premix<sup>1</sup></td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td></tr><tr><td>Calculated analysis</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>ME (Kcal/Kg)</td><td>2914</td><td>2911</td><td>2915</td><td>3054</td><td>3048</td><td>3048</td><td>3203</td><td>3204</td><td>3203</td></tr><tr><td>Crude protein (%)</td><td>21.62</td><td>24</td><td>26.4</td><td>21.6</td><td>23.97</td><td>26.42</td><td>21.65</td><td>24</td><td>26.35</td></tr><tr><td>Lysine (%)</td><td>1.23</td><td>1.37</td><td>1.49</td><td>1.23</td><td>1.38</td><td>1.49</td><td>1.23</td><td>1.37</td><td>1.5</td></tr><tr><td>Methionine+Cystine (%)</td><td>0.74</td><td>0.81</td><td>0.89</td><td>0.74</td><td>0.81</td><td>0.9</td><td>0.75</td><td>0.82</td><td>0.91</td></tr></tbody></table>

## Results

Respectively, the lowest and highest levels of energy and protein enhanced daily feed intake (table 2). In poultry, it has been shown that feed intake increase in response to low levels of energy and decrease due to high crude protein or amino acid imbalance of the diets. A higher feed intake with decrease in dietary energy concentration was to compensate energy intake. Daily weight gain was not affected by the treatments, however, FCR was improved by the diets of 3050 and 3200 Kcal ME/Kg compared with that of 2900 Kcal ME/Kg. The results of growth performance indicate Japanese quail may need more concentration of energy than that suggested by the National Research Council (2900 Kcal ME/Kg). There was no interaction between energy and protein for performance parameters. Energy and protein interaction was significant for the relative weight of liver; the treatment with 3200 Kcal ME/Kg and 24% CP showed the highest value. There was no significant difference among treatments for relative weight of carcass. Among blood parameters, uric acid was decreased by the diets of 3050 and 3200 Kcal ME/Kg. The reduction of blood uric acid may be due to the improved protein utilization at high levels of energy. This result can explain the better performance of Japanese quail given diets with 3050 or 3200 Kcal ME/Kg. Main effects and also the interaction of energy and protein were not significant.

<footnote n="1">¹Each Kg of vitamin premix contained; vitamin A, 3500000 IU (retinyl acetate); cholecalciferol, 1000000 IU; vitamin E, 9000 IU (dl-a-tocopheryl acetate); menadione, 1000 mg; thiamine, 900 mg; riboflavin, 3300 mg; niacin, 5000 mg; pantothenic acid, 15000 mg; pyridoxine, 150 mg; folic acid, 500 mg; vitamin B₁₂, 7.5 mg; choline, 500 mg; biotin, 50 mg. Each Kg of mineral premix contained; manganese, 50000 mg; zinc, 50000 mg; iron 25000 mg; copper 50000 mg; iodine, 500 mg; selenium, 100 mg; cobalt 90 mg.</footnote>
cant for other blood parameters and these results were contrary to our expectation, because high concentration of energy usually enhance the lipogenesis and increase the blood lipid parameters in animals.

<table><caption>**Table 2.** Effect of different levels of ME and CP on growth performance<fnref n="1" /> (14 to 28 d of age) carcass characteristics (g/100 g body weight, on d 28) and blood parameters (mg/dl, on d 28) of Japanese quail during grower phase</caption><thead><tr><th colspan="2">Treatments</th><th>DWG (g)</th><th>DFI (g)</th><th>FCR</th><th>Carcass</th><th>Liver</th><th>TG</th><th>TC</th><th>LDL</th><th>Uric acid</th></tr></thead><tbody><tr><td rowspan="3">ME (Kcal/Kg)</td><td>2900</td><td>6.29</td><td>18.07<sup>a</sup></td><td>2.88<sup>a</sup></td><td>57.88</td><td>2.14</td><td>94.46</td><td>187.80</td><td>82.13</td><td>2.80<sup>a</sup></td></tr><tr><td>3050</td><td>6.29</td><td>16.84<sup>b</sup></td><td>2.69<sup>b</sup></td><td>57.50</td><td>2.15</td><td>90.86</td><td>177.20</td><td>71.08</td><td>1.57<sup>b</sup></td></tr><tr><td>3200</td><td>6.17</td><td>15.80<sup>c</sup></td><td>2.58<sup>b</sup></td><td>56.77</td><td>2.14</td><td>89.86</td><td>179.33</td><td>69.54</td><td>1.26<sup>b</sup></td></tr><tr><td>SEM</td><td></td><td>0.144</td><td>0.225</td><td>0.059</td><td>0.439</td><td>0.059</td><td>4.862</td><td>8.649</td><td>4.567</td><td>0.222</td></tr><tr><td rowspan="3">CP (%)</td><td></td><td>21.6</td><td>6.18</td><td>16.45<sup>b</sup></td><td>2.68</td><td>57.95</td><td>2.06</td><td>87.93</td><td>195.67</td><td>81.41</td><td>1.58</td></tr><tr><td></td><td>24</td><td>6.11</td><td>16.98<sup>ab</sup></td><td>2.79</td><td>56.84</td><td>2.13</td><td>88.80</td><td>173.80</td><td>70.71</td><td>2.10</td></tr><tr><td></td><td>26.4</td><td>6.66</td><td>17.29<sup>a</sup></td><td>2.69</td><td>57.37</td><td>2.24</td><td>98.46</td><td>174.87</td><td>70.64</td><td>1.94</td></tr><tr><td>SEM</td><td></td><td>0.144</td><td>0.225</td><td>0.059</td><td>0.439</td><td>0.059</td><td>4.862</td><td>8.649</td><td>4.567</td><td>0.222</td></tr><tr><td rowspan="8">ME * CP</td><td>2900</td><td>21.6</td><td>6.41</td><td>18.23</td><td>2.58</td><td>58.18</td><td>1.93<sup>b</sup></td><td>87.60</td><td>208.60</td><td>94.36</td><td>2.54</td></tr><tr><td>2900</td><td>24</td><td>5.83</td><td>15.73</td><td>2.72</td><td>58.57</td><td>2.24<sup>ab</sup></td><td>85.80</td><td>188.00</td><td>75.86</td><td>1.36</td></tr><tr><td>2900</td><td>26.4</td><td>6.32</td><td>15.38</td><td>2.46</td><td>57.09</td><td>2.01<sup>ab</sup></td><td>90.40</td><td>190.40</td><td>74.02</td><td>0.86</td></tr><tr><td>3050</td><td>21.6</td><td>6.07</td><td>18.05</td><td>2.98</td><td>56.84</td><td>2.23<sup>ab</sup></td><td>88.60</td><td>167.40</td><td>72.24</td><td>3.42</td></tr><tr><td>3050</td><td>24</td><td>6.47</td><td>17.20</td><td>2.66</td><td>57.31</td><td>1.93<sup>b</sup></td><td>90.40</td><td>170.60</td><td>70.30</td><td>1.64</td></tr><tr><td>3050</td><td>26.4</td><td>5.80</td><td>15.67</td><td>2.72</td><td>56.36</td><td>2.17<sup>ab</sup></td><td>87.40</td><td>183.40</td><td>69.60</td><td>1.26</td></tr><tr><td>3200</td><td>21.6</td><td>6.41</td><td>17.94</td><td>2.82</td><td>58.62</td><td>2.24<sup>ab</sup></td><td>107.20</td><td>187.40</td><td>79.80</td><td>2.44</td></tr><tr><td>3200</td><td>24</td><td>6.59</td><td>17.59</td><td>2.68</td><td>56.63</td><td>2.29<sup>a</sup></td><td>96.40</td><td>173.00</td><td>67.10</td><td>1.72</td></tr><tr><td>3200</td><td>26.4</td><td>6.40</td><td>16.34</td><td>2.57</td><td>56.86</td><td>2.17<sup>ab</sup></td><td>91.80</td><td>164.20</td><td>65.02</td><td>1.68</td></tr><tr><td>SEM</td><td></td><td>0.250</td><td>0.389</td><td>0.102</td><td>0.760</td><td>0.103</td><td>8.421</td><td>14.981</td><td>7.911</td><td>0.385</td></tr></tbody></table><table><thead><tr><th colspan="10">P values</th></tr></thead><tbody><tr><td>ME</td><td></td><td>0.78</td><td>0.01</td><td>0.01</td><td>0.20</td><td>0.98</td><td>0.78</td><td>0.66</td><td>0.11</td><td>0.01</td></tr><tr><td>CP</td><td></td><td>0.19</td><td>0.03</td><td>0.36</td><td>0.21</td><td>0.12</td><td>0.24</td><td>0.14</td><td>0.17</td><td>0.25</td></tr><tr><td>ME * CP</td><td></td><td>0.18</td><td>0.08</td><td>0.60</td><td>0.03</td><td>0.47</td><td>0.82</td><td>0.70</td><td>0.80</td><td>0.44</td></tr></tbody></table>

Means within columns with no common superscript differ significantly (P<0.05).

## Conclusions

Based on performance results, 3050 Kcal ME/Kg of the diet can be proposed for Japanese quail nutrition during the grower phase. In addition, low level of crude protein did not affect the performance adversely and can be considered in formulation of quail diets.

## Literature

KAUR, S., A. B. MANDAL, K. B. SINGH, M. M. Kadam, 2008: The response of Japanese quails (heavy body weight line) to dietary energy levels and graded essential amino acid levels on growth performance and immuno-competence. Livest. Sci. **117**, 255-262.

<footnote n="1">¹Daily Weight Gain (DWG), Daily Feed Intake (DFI) and Feed Conversion Ratio (FCR).</footnote>
P-266 (ID 6)

STARCH AND PROTEIN INTESTINAL UPTAKES IN TANDEM INFLUENCE WEIGHT GAIN OF BROILER CHICKENS

Ha H Truong<fnref n="1" />,<fnref n="2" />, Rachael M Bold<fnref n="3" />, Sonia Yun Liu<fnref n="1" /> and Peter H Selle<fnref n="1" />

**Corresponding author:** htru7891@uni.sydney.edu.au

**Abstract**

Phosphorus-adequate, maize-based diets, without and with 500 FTU/kg *Buttiauxella* phytase, were offered to broilers to assess the effects of phytase on starch and amino acid digestive dynamics at 40 days post-hatch. Starch and protein (sum of 16 amino acids) disappearance rates from four small intestinal segments and starch:protein disappearance rate ratios were calculated. The multiple linear regression equation (r = 0.936; P < 0.001) indicated that increasing protein disappearance rates from the three anterior small intestinal segments advantages weight gains; whereas, increasing starch disappearance are disadvantageous. There was a negative, linear relationship (r = -0.766; P < 0.005) between starch:protein disappearance rate ratios at the proximal ileum with 40-day weight gains. Phytase supplementation effectively condensed starch:protein disappearance rates in the three distal small intestinal segments (P < 0.02 - < 0.001). The branched chained amino acids were the most indicative of the sixteen amino acids. Starch:isoleucine (r = -0.832; P < 0.001) starch:valine (r = -0.810, P < 0.001) and starch:leucine (r = -0.752, P < 0.005) disappearance rate ratios were negatively correlated to weight gains. It is evident from the present study that intestinal uptakes of starch and protein in tandem have a marked influence on weight gains that were favourably manipulated by phytase with the suggestion that branch-chained amino acids may play a pivotal role.

**Keywords:** digestive dynamics, branch-chain amino acids, phytase, extra-phosphoric effects

**Introduction**

The probability is that phytate has anti-nutritive properties in respect of energy utilisation in poultry and that phytase generates reciprocal 'extra-phosphoric' energy responses (RAVINDRAN and SELLE, 2010). As starch is the dominant energy source, it follows that phytase responses at least partially stem from improvements in starch utilisation. As ileal starch digestibility is inherently high, it may prove instructive to determine apparent starch digestibility coefficients in anterior small intestinal segments, where starch digestion is less complete, in order to detect responses to phytase and its effects on starch digestive dynamics. Similarly with amino acids, while the capacity of phytase to improve ileal amino acid digestibility is established which is not the case with amino acid digestive dynamics. Increasing evidence suggests that starch and protein utilisation should not be considered separately but in tandem (LIU and SELLE, 2015). Therefore this investigation considers the effects of phytase on both starch and protein digestion dynamics in relation to weight gains of broilers.

**Materials and Methods**

The feeding study consisted of P-adequate, maize-based diets without and with 500 FTU/kg *Buttiauxella* phytase; each dietary treatment was offered to eight replicate cages with six birds per cage. Diets were steam-pelleted at a conditioning temperature of 84°C and fed as crumbles. At day 40, all birds were weighed and euthanised to take digesta samples from four small intestinal segments [proximal jejunum (PJ), distal jejunum (DJ), proximal ileum (PI), distal ileum (DI)] which were pooled for each cage. Starch concentrations in diets and digesta were determined by a procedure based on dimethyl sulfoxide, α-amylase and amyloglucosidase (MAHASUKHONTHACHAT et al., 2010). Amino acid concentrations of diets and digesta samples were determined following 24 hour liquid hydrolysis at 110°C in 6M HCl and then 16 amino acids are analysed using the Walters AccQTag Ultra chemistry on a Waters Acquity UPLC. The apparent digestibility coefficients of starch and amino acids in four small intestinal sites were calculated from the following equation where acid insoluble ash (AIA) was the dietary marker:

$$ \text{Apparent digestibility coefficient} = \frac{[(\text{nutrient/AIA})_{\text{diet}} - (\text{nutrient/AIA})_{\text{digesta}}]}{(\text{nutrient/AIA})_{\text{diet}}} $$

<footnote n="1">¹Poultry Research Foundation within The University of Sydney, NSW, Australia</footnote>

<footnote n="2">²Poultry CRC, University of New England, Armidale NSW, Australia</footnote>

<footnote n="3">³DuPont Industrial Biosciences, Danisco (UK) Ltd, Marlborough, UK</footnote>
Starch and protein disappearance rates (g/bird/day) from four small intestinal segments were calculated from the following equation:

$$ \text{Disappearance rate} = \text{feed intake}_{\text{(g/bird/day)}} \times \text{dietary nutrient}_{\text{(g/kg)}} \times \text{digestibility coefficient.} $$

Protein concentrations in diets were based on the sum of the 16 amino acids assessed and digestibility coefficients were calculated from the average values of the 16 amino acids quantified. Experimental data was analysed as a one-way ANOVA of dietary treatments using the IBM® SPSS® Statistics 20 program (IBM Corporation. Somers, NY USA).

## Results

Inclusion of 500 FTU/kg *Buttiauxella* phytase in P-adequate, maize-based broiler diets increased weight gains by 11.8% (2937 versus 2627 g/bird; P < 0.001) at 40 days post-hatch. Starch to protein disappearance rate ratios in the distal jejunum, proximal ileum and distal ileum were significantly condensed following phytase supplementation as shown in Table 1. In these three segments the average ratio was narrowed by 7.36% from 2.99 to 2.77:1

<table><caption>**Table 1.** Effects of exogenous phytase on starch:protein disappearance rate ratios in four small intestinal segments in broilers offered maize-based diets at 40 days post-hatch.</caption><thead><tr><th rowspan="2">Treatment</th><th colspan="4">Starch:protein disappearance rate ratios</th></tr><tr><th>Proximal jejunum</th><th>Distal jejunum</th><th>Proximal ileum</th><th>Distal ileum</th></tr></thead><tbody><tr><td>0</td><td>2.93</td><td>3.22</td><td>2.90</td><td>2.85</td></tr><tr><td>500 FTU/kg</td><td>2.44</td><td>2.78</td><td>2.79</td><td>2.73</td></tr><tr><td>SEM</td><td>0.2090</td><td>0.1041</td><td>0.0129</td><td>0.0289</td></tr><tr><td>Significance (P =)</td><td>0.132</td><td>0.013</td><td>&lt; 0.001</td><td>0.015</td></tr></tbody></table>

The was a negative linear relationship (r = -0.766; P < 0.005) between starch:protein disappearance rate ratios at the proximal ileum with weight gains. Relationships between weight gain and starch:amino acid disappearance rate ratios were deduced where the branched chained amino acids were the most closely correlated. Starch:isoleucine (r = -0.832; P < 0.001) starch:valine (r = -0.810, P < 0.001) and starch:leucine (r = -0.752, P < 0.005) disappearance rate ratios were negatively correlated to weight gains as shown in Figure 1.

## Conclusions

The negative, linear relationship (r = -0.766; P < 0.005) between starch:protein disappearance rate ratios at the proximal ileum with 40-day weight gains is an important outcome as it demonstrates the interactive impact of glucose and amino acid intestinal uptakes on broiler performance. The multiple linear regression equation (r = 0.936; P < 0.001)

$$ y_{\text{weight gain (g/bird)}} = 857.53 + 109.12\*\text{protein}_{\text{(g/bird/day)}} - 13.34\*\text{starch}_{\text{(g/bird/day)}}. $$

clearly demonstrates that it is advantageous to accelerate protein digestion but retard starch digestion.

As phytase condensed starch:protein disappearance rate ratios to significant extents in the three caudal small intestinal segments it positively impacted on starch and protein digestion in tandem. In this respect the impact of phytase on branched-chain amino acids may be pivotal. The antagonism between branched-chain amino acids is recognised and this probably stems from their systemic catabolism in broilers (CALVERT et al., 1982). Also, it appears that among essential amino acids, branched-chain amino acids are especially susceptible to catabolism in the gut mucosa in pigs (CHEN et al., 2007). The effects of phytase on the digestive dynamics of branch-chained amino acids in respect of their catabolism in the gut mucosa appears to merit further attention. In conclusion, this study has demonstrated that phytase possesses 'extra-phosphoric' effects in respect of the digestive dynamics of starch/glucose and protein/amino acids via the manipulation of their disappearance rate ratios. Narrower starch:protein disappearance rate ratios benefit weight gains. It appears that the impact of phytase on intestinal uptakes of amino acids may be more pronounced than on glucose which would should favour narrower starch:protein disappearance rate ratios and benefit broiler performance.
<figure><img src="image_89.png" /><figcaption>**Figure 1.** Linear relationship between starch:isoleucine (r = -0.832; P < 0.001), starch:leucine (r = -0.752; P = 0.005) and starch:valine (r = -0.810; P < 0.001) disappearance rate ratios and weight gains at 40 days post-hatch.</figcaption></figure>

## Literature

CALVERT, C., KLASING, K., AUSTIC, R. 1982: Involvement of food intake and amino acid catabolism in the branched-chain amino acid antagonism in chicks. J Nutr. **112**, 627-635.

CHEN, L., Yin, Y.L., Jobgen, S.C., Knabe, D.A. 2007: In vitro oxidation of essential amino acids by jejunal mucosa cells of growing pigs. Livestock Sci. **109**, 19-23.

LIU, S.Y., SELLE, P.H., 2015: A consideration of starch and protein digestive dynamics in chicken-meat production. Worlds Poult. Sci. J (accepted for publication).

MAHASUKHONTHACHAT, K., SOPADE, P.A., GIDLEY, M.J., 2010: Kinetics of starch digestion and functional properties of twin-screw extruded sorghum. J Cereal Sci. **51**, 392-401.

RAVINDRAN, V., SELLE, P.H. 2010: Phytate: Anti-nutritive effects on energy and amino acid utilization. Proc. 46th Eastern Nutr. Conf. pp 1-12. Anim. Nutr. Assoc. Canada.
# THE EFFECT OF GENOTYPE, HOUSING SYSTEM AND CALCIUM ON OVIPOSITION TIME AND EGG SHELL QUALITY

Tůmová, E.<fnref n="1" />, V. Charvátová<fnref n="1" />, M. Englmaierová<fnref n="2" />

**Corresponding author:** tumova@af.czu.cz

## Abstract

The aim of the study was to evaluate the effect of housing system (cages vs. litter), genotype (commercial hybrid Lohmann White and pure breed Czech Hen) and calcium content in feed mixture (3.0 % vs. 3.5 %) on time of oviposition and egg shell quality. Oviposition time was evaluated during laying cycle at 6.00, 10.00 and 14.00 h. Eggs for quality assessment were collected in a four week interval, all eggs laid from each cage or litter pen at each collection time. The significant interaction of genotype, housing and Ca (P=0.044) was observed in oviposition time. The highest number of eggs was laid by Czech Hen on litter and 3.5 % Ca at 6.00 h (21.28 %) and the lowest (0.85 %) by the same genotype in cage on 3.0 % Ca at 10.00 h. Also egg weight was affected by the significant interaction of genotype, housing and Ca (P=0.001); however, there was not interaction of genotype, housing, Ca and oviposition in egg weight. The heaviest eggs were in Lohmann White in cages with 3.0 % Ca (62.1 g). Egg shell quality was affected by genotype and time of oviposition. The significant interaction of genotype, oviposition and Ca in egg shell strength (P=0.003) revealed the strongest shells in Lohmann White in cages with 3.5 % Ca at 6.00 h. Results of the study show of interactions of genotype, housing and Ca in oviposition time as well as in egg shell quality.

**Keywords:** laying hens, oviposition, strain, cage, litter, calcium, egg shell

## Introduction

Oviposition time plays a key role in determining egg shell quality because the amount of deposited shell is a linear function of the time spent in the shell gland. Eggs being normally laid between 7.30 and 16 h (Campo et al., 2007). Egg shell characteristics are better in the afternoon eggs (TŮMOVÁ et al., 2009, 2013). Time of oviposition and egg shell quality are affected by genotype (CAMPO et al., 2007, TŮMOVÁ et al., 2009, 2013), housing system (TŮMOVÁ et al., 2009, 2013). There are a few data of the effect of Ca on oviposition and egg shell quality (NOVO et al., 1997). The aim of the study was to evaluate the effect of housing system (cages vs. litter), genotype (commercial hybrid Lohmann White and pure breed Czech Hen) and calcium content in feed mixture (3.0 % vs. 3.5 %) on time of oviposition and egg shell quality.

## Material and methods

The experiment with 126 laying hens of Lohmann LSL (Lohmann) and pure breed Czech Hen (CH) were housed in conventional cages Eurovent (72 hens, 550 cm<fnref n="2" /> / hen, 3 hens in a cage, 12 cages for genotype) and in six littered pens (60 hens, 7 hens.m⁻<fnref n="2" />, 10 hens / pen and 3 pens for each genotype) was carried out from 20 to 60 weeks of age. Laying hens in both housing systems were fed commercial type of feed mixtures which differed only in Ca content, 3.5% respectively 3.0%. The daily photoperiod consisted of 15 h light and 9 h darkness. Oviposition was evaluated according to a collection time which was at 6.00, 10.00 and 14.00 during the whole experiment. Eggs for quality assessment were collected in a four week interval, two days in row, all eggs laid from each cage or litter and there were analysed in total 1496 eggs. Eggs were weighed, and the shell strength was determined by the shell-breaking method using a QC-SPA device (TSS York, UK). Egg shell thickness was evaluated by QCT shell thickness micrometer (TSS York, UK). Egg shell proportion was calculated from egg shell weight, which was determined after drying, and egg weight.

Time of oviposition and egg shell quality data were evaluated by four-way (oviposition, housing, genotype, and Ca level interaction) analysis of variance using the GLM procedure of SAS (SAS Institute Inc, Cary, Nc, 2003).

<footnote n="1">¹Department of Animal Husbandry, Czech University of Life Sciences Prague, 165 21 Prague 6 Suchdol, Czech Republic</footnote>

<footnote n="2">²Department of Nutrition Physiology and Animal Product Quality, Institute of Animal Science Prague - Uhřiněves, Přátelství 815, 104 00 Prague - Uhřiněves, Czech Republic</footnote>
## Results and discussion

The results of oviposition (Table 1) show the significant interaction of all factors evaluated in the present study (P=0.044). The highest number of eggs was laid by Czech Hen on litter and 3.5 % Ca at 6.00 h (21.28 %) and the lowest (0.85 %) by the same genotype in cage on 3.0 % Ca at 10.00 h. Results correspond with CAMPO et al. (2007), TŮMOVÁ et al. (2009, 2013) that different genotypes vary in their laying pattern, litter housing delayed oviposition time (TŮMOVÁ et al., 2009, 2013). Higher dietary calcium had a minor effect on oviposition in Lohmann hens which agrees with NOVO et al. (1997) but decreased a number of laid eggs at 14.00 h in Czech Hen.

Egg weight (P=0.001) and egg shell strength (P=0.036) were affected by the significant interaction of genotype, housing and Ca (Table 2). Results show that egg weight and egg shell strength can be affected by interaction of different factors which is in agreement with our previous data (TŮMOVÁ et al., 2009, 2013). Lohmann hens produced eggs with higher egg shell percentage (P=0.001) and thickness (P=0.001) which is a result of long-term selection for these characteristics, and corresponds with our previous results (TŮMOVÁ et al., 2013).

## Acknowledgement

The study was supported by Project NAAR No. QJ 1310002.

## Literature

CAMPO J.L., GIL M.G., DÁVILA S.G., 2007: Differences among white-, tinted-, and brown-egg laying hens for incidence of eggs laid on the floor and for oviposition time. Arch. Gefügelkde, **71**, 105-109.

NOVO R.P., GAMA L.T., SOARES M.C., 1997: Effects of oviposition time, hen age and extra dietary calcium on egg characteristics and hatchability. J. Appl. Poult. Res. **6**, 335-343.

TŮMOVÁ, E., CHARVÁTOVÁ, V., ENGLMAIEROVÁ, M., 2013: The effect of oviposition time and housing system on egg quality in Lohmann LSL and Czech Hen. XV European Symposium on the Quality of Eggs and Egg Products, Bergamo 15-19 September 2013, W.rld Poultry Sci. J., Volume **69**, Supplement, 6p.

TŮMOVÁ, E., SKŘIVAN, M., ENGLMAIEROVÁ, M., ZITA, L., 2009: The effect of genotype, housing system and egg collection time on egg quality in egg type hens. Czech Journal Anim. Sci., **54**, 17 – 23.

<table><caption>**Table 1** Mean number of eggs from two genotypes housed in cages and on litter and fed two Ca levels (%)</caption><thead><tr><th>Time of collection</th><th>Housing system</th><th>Dietary Ca level (%)</th><th>Lohmann</th><th>Czech Hen</th><th>Significance</th></tr></thead><tbody><tr><td rowspan="2">6.00</td><td rowspan="2">Cage</td><td>3.0</td><td>2.69</td><td>14.89</td><td rowspan="12">0.044</td></tr><tr><td>3.5</td><td>2.29</td><td>7.66</td></tr><tr><td rowspan="2">Litter</td><td>3.0</td><td>2.61</td><td>7.66</td></tr><tr><td>3.5</td><td>4.98</td><td>21.28</td></tr><tr><td rowspan="2">10.00</td><td rowspan="2">Cage</td><td>3.0</td><td>14.86</td><td>0.85</td></tr><tr><td>3.5</td><td>12.96</td><td>2.13</td></tr><tr><td rowspan="2">Litter</td><td>3.0</td><td>9.49</td><td>3.40</td></tr><tr><td>3.5</td><td>18.97</td><td>2.55</td></tr><tr><td rowspan="2">14.00</td><td rowspan="2">Cage</td><td>3.0</td><td>10.04</td><td>11.49</td></tr><tr><td>3.5</td><td>9.41</td><td>8.08</td></tr><tr><td rowspan="2">Litter</td><td>3.0</td><td>3.95</td><td>8.94</td></tr><tr><td>3.5</td><td>7.75</td><td>11.06</td></tr></tbody></table>
<table><caption>**Table 2** Mean egg weight and egg shell measurements of eggs collected at three times during a day from two genotypes housed in cages and on litter and fed two Ca levels</caption><thead><tr><th>Time of collection</th><th>Genotype</th><th>Housing system</th><th>Dietary Ca level (%)</th><th>Egg weight (g)</th><th>Egg shell percentage (%)</th><th>Egg shell thickness (mm)</th><th>Egg shell strength (g/cm²)</th></tr></thead><tbody><tr><td rowspan="6">6.00</td><td rowspan="2">Lohmann</td><td>Cage</td><td>3.0</td><td>61.3<sup>b</sup></td><td>11.9</td><td>0.34</td><td>3964</td></tr><tr><td>Litter</td><td>3.5</td><td>61.6<sup>b</sup></td><td>12.3</td><td>0.36</td><td>4603</td></tr><tr><td rowspan="2">CH</td><td>Cage</td><td>3.0</td><td>59.2<sup>d</sup></td><td>11.9</td><td>0.34</td><td>3944</td></tr><tr><td>Litter</td><td>3.5</td><td>62.0<sup>ab</sup></td><td>12.2</td><td>0.36</td><td>4259</td></tr><tr><td rowspan="2">Lohmann</td><td>Cage</td><td>3.0</td><td>47.4<sup>g</sup></td><td>11.4</td><td>0.32</td><td>4500</td></tr><tr><td>Litter</td><td>3.5</td><td>47.6<sup>g</sup></td><td>10.6</td><td>0.29</td><td>3620</td></tr><tr><td rowspan="6">10.00</td><td rowspan="2">Lohmann</td><td>Cage</td><td>3.0</td><td>49.9<sup>e</sup></td><td>12.0</td><td>0.35</td><td>4501</td></tr><tr><td>Litter</td><td>3.5</td><td>46.7<sup>g</sup></td><td>11.4</td><td>0.32</td><td>4053</td></tr><tr><td rowspan="2">CH</td><td>Cage</td><td>3.0</td><td>61.8<sup>b</sup></td><td>12.3</td><td>0.35</td><td>4526</td></tr><tr><td>Litter</td><td>3.5</td><td>60.2<sup>c</sup></td><td>12.6</td><td>0.36</td><td>4502</td></tr><tr><td rowspan="2">Lohmann</td><td>Cage</td><td>3.0</td><td>58.5<sup>d</sup></td><td>12.1</td><td>0.34</td><td>4294</td></tr><tr><td>Litter</td><td>3.5</td><td>60.8<sup>c</sup></td><td>12.3</td><td>0.36</td><td>4541</td></tr><tr><td rowspan="6">14.00</td><td rowspan="2">Lohmann</td><td>Cage</td><td>3.0</td><td>51.3<sup>e</sup></td><td>13.5</td><td>0.38</td><td>5432</td></tr><tr><td>Litter</td><td>3.5</td><td>57.1<sup>d</sup></td><td>11.6</td><td>0.33</td><td>3051</td></tr><tr><td rowspan="2">CH</td><td>Cage</td><td>3.0</td><td>48.2<sup>f</sup></td><td>11.8</td><td>0.33</td><td>4131</td></tr><tr><td>Litter</td><td>3.5</td><td>49.9<sup>e</sup></td><td>11.8</td><td>0.34</td><td>4347</td></tr><tr><td rowspan="2">Lohmann</td><td>Cage</td><td>3.0</td><td>62.1<sup>ab</sup></td><td>12.0</td><td>0.35</td><td>4169</td></tr><tr><td>Litter</td><td>3.5</td><td>60.6<sup>c</sup></td><td>12.3</td><td>0.35</td><td>4153</td></tr><tr><td rowspan="6">14.00</td><td rowspan="2">CH</td><td>Cage</td><td>3.0</td><td>57.8<sup>d</sup></td><td>12.0</td><td>0.35</td><td>4399</td></tr><tr><td>Litter</td><td>3.5</td><td>59.8<sup>d</sup></td><td>12.2</td><td>0.36</td><td>4330</td></tr><tr><td rowspan="2">CH</td><td>Cage</td><td>3.0</td><td>46.9<sup>g</sup></td><td>11.8</td><td>0.31</td><td>4385</td></tr><tr><td>Litter</td><td>3.5</td><td>54.0<sup>d</sup></td><td>10.9</td><td>0.30</td><td>3871</td></tr><tr><td rowspan="2">CH</td><td>Cage</td><td>3.0</td><td>52.8<sup>e</sup></td><td>11.8</td><td>0.32</td><td>4090</td></tr><tr><td>Litter</td><td>3.5</td><td>50.8<sup>f</sup></td><td>11.3</td><td>0.31</td><td>4281</td></tr><tr><td colspan="2">Significance: Genotype</td><td></td><td></td><td>0.001</td><td>0.001</td><td>0.001</td><td>0.002</td></tr><tr><td colspan="2">Housing</td><td></td><td></td><td>0.001</td><td>NS</td><td>0.002</td><td>NS</td></tr><tr><td colspan="2">Ca</td><td></td><td></td><td>NS</td><td>0.011</td><td>NS</td><td>NS</td></tr><tr><td colspan="2">Genotype*housing*Ca</td><td></td><td></td><td>0.001</td><td>NS</td><td>NS</td><td>0.036</td></tr></tbody></table>
P-268 (ID 118)

# THE EFFECT OF EARLY FEED RESTRICTION, GENOTYPE AND SEX ON PERFORMANCE AND CARCASS COMPOSITION OF BROILER CHICKENS

L. Uhlířová and E. Tůmová

Department of Animal Husbandry, Czech University of Life Sciences Prague, Kamýcká 129, Praha 6 – Suchdol, 165 21, Czech Republic

**Corresponding author:** uhliroval@af.czu.cz

## Abstract

The purpose of this study was to evaluate the effect of intensity of early feed restriction along with genotype and sex on performance and carcass composition in two genotypes and both sexes of broiler chicken. In three-factorial experiment (2x2x3) a total of 4860 one day old broiler chickens were divided into 12 groups (genotypes Ross 308 and Cobb 500; males and females; groups ADL, R1 and R2). ADL chickens were fed *ad libitum* over the whole experiment, whereas the R1 a R2 chickens had the feed restriction (R1 80% of ADL group, R2 65% of ADL group) between 8th and 14th day of age. Feed restriction reduced live weight at 35 days of age (P=0.001), feed intake (P=0.001) and mortality (P=0.021; 8.55 % Ross ♂ ADL and 2.25 % Cobb ♂ R2). Genotype affected live weight at 35 days of age (P=0.004) in favour of Cobb hybrid. Regarding the sex, higher live weight at 35 days of age (P=0.001) and feed intake (P=0.001) were found in males. There was a minor effect of evaluated factors on carcass composition. It can be concluded that feed restriction significantly decreased mortality without negative effect on growth, feed conversion ratio and carcass composition.

**Keywords:** chicken, feed restriction, genotype, performance, carcass composition

## Introduction

Modern genotypes of broiler chicken are due to genetic selection able to reach required slaughter weight in shorter period of time. On the other hand, this increased growth rate brings also several negative responses such as greater susceptibility to skeletal and metabolic disorders or increased fat deposition (LIPPENS et al., 2000).

One of the possibilities, how to avoid rapid growth rate and negatives associated with it, is an application of early feed restriction. Although early feed restriction reduces growth performance, compensatory growth in realimentation period allows to reach required live weight. Slower growth rate in early stages of life is beneficial in terms of feed efficiency and breeding cost (ZHAN et al., 2007). Regarding the fat deposition, results obtained from feed restriction programs to reduce the carcass fat content in broiler chickens have been inconsistent. Such inconsistency may relate to different feeding strategies applied, which may affect the bird's response to feed restriction (URDANETA-RINCON and LEESON, 2002). BENYI et al. (2009) reported that another factor that influences the reaction of broiler chickens to feed restriction is the genetic makeup of chickens. Genetic potencial not only affects the growth intensity and body composition of the bird because of its effects on nutrient requirement, but also affects compensatory growth of broilers subjected to feed restriction.

The aim of this study is to evaluate the effect of early feed restriction, genotype and sex on growth performance and carcass composition of broiler chickens.

## Material and Methods

A total of 4860 one day old broiler chickens were weighed and divided into 12 groups (405 chickens per group) according to genotype (Ross 308 and Cobb 500), sex and feeding regime (ADL, R1 and R2). ADL chickens were fed *ad libitum* over the entire experiment, whereas the R1 and R2 groups had the feed restriction between 8th and 14th day of age. The R1 group received 80 % of ADL group's feed intake, whereas the R2 received 65 % of ADL group's feed intake. Before and after the restriction period both restricted groups were fed *ad libitum* until the end of the experiment.

Chickens were housed in pens on litter (135 chickens per pen) and fed complete feed mixtures, BR1 (crude protein content 23.39 %) to 14 days of age, BR2 (crude protein content 20.89 %) to 28 days of age and BR3 (crude protein content 19.98 %) until the end of experiment which ran until 35 days of age. Weighing was conducted weekly and feed consumption was recorded daily. At the end of the fattening period 8 birds of each group were slaughtered on average weight of the group. After the slaughtering carcass composition was evaluated according to standard method.
The results were processed in SAS software (SAS Institute Inc., Cary, NC, 2003) by multiple analysis of variance with interaction of genotype, sex and group.

## Results and discussion

Results of growth performance are presented in Table 2. No significant interactions between genotype, sex and group were recorded. Feed restriction significantly reduced live weight at 35 days of age (P=0.001), weight gain (P=0.017), feed intake (P=0.001) and mortality (P=0.021). With increasing intensity of feed restriction measurements more decreased. Genotype affected significantly live weight at 35 days of age (P=0.004) as well in favour of Cobb hybrid. Regarding the sex, higher live weight at 35 days of age (P=0.004), weight gain (P=0.017) and feed intake (P=0.001) were in males. These results are in agreement with LIPPENS et al. (2000) and ZHAN et al. (2007).

<table><caption>**Table 2:** Growth performance</caption><thead><tr><th>Genotype</th><th>Sex</th><th>Group</th><th>LW 1 (g)</th><th>LW 35 (g)</th><th>WG 1 – 35 (g/d)</th><th>FI 1 – 35 (g/d)</th><th>FCR 1 – 35</th><th>Mortality 1 – 35 (%)</th></tr></thead><tbody><tr><td rowspan="9">Ross</td><td rowspan="3">♂</td><td>ADL</td><td>43.87</td><td>2098</td><td>58.32</td><td>105.63</td><td>1.96</td><td>8.55</td></tr><tr><td>R1</td><td>43.80</td><td>2026</td><td>56.67</td><td>99.09</td><td>1.87</td><td>6.30</td></tr><tr><td>R2</td><td>43.85</td><td>1965</td><td>54.76</td><td>97.04</td><td>1.88</td><td>4.95</td></tr><tr><td rowspan="3">♀</td><td>ADL</td><td>43.21</td><td>1920</td><td>53.44</td><td>90.98</td><td>1.81</td><td>5.85</td></tr><tr><td>R1</td><td>43.41</td><td>1855</td><td>51.75</td><td>88.48</td><td>1.82</td><td>7.20</td></tr><tr><td>R2</td><td>43.31</td><td>1836</td><td>51.14</td><td>89.25</td><td>1.84</td><td>2.70</td></tr><tr><td rowspan="9">Cobb</td><td rowspan="3">♂</td><td>ADL</td><td>46.72</td><td>2107</td><td>58.91</td><td>100.33</td><td>1.83</td><td>6.75</td></tr><tr><td>R1</td><td>46.17</td><td>2019</td><td>56.51</td><td>97.17</td><td>1.83</td><td>4.50</td></tr><tr><td>R2</td><td>46.22</td><td>1991</td><td>55.76</td><td>96.05</td><td>1.81</td><td>2.25</td></tr><tr><td rowspan="3">♀</td><td>ADL</td><td>46.07</td><td>1966</td><td>54.91</td><td>92.79</td><td>1.80</td><td>4.50</td></tr><tr><td>R1</td><td>45.87</td><td>1893</td><td>52.73</td><td>89.71</td><td>1.80</td><td>4.50</td></tr><tr><td>R2</td><td>45.97</td><td>1847</td><td>51.48</td><td>87.61</td><td>1.80</td><td>3.60</td></tr><tr><td>Genotype</td><td></td><td></td><td><strong>0.001</strong></td><td><strong>0.004</strong></td><td>0.405</td><td>0.175</td><td>0.271</td><td>0.073</td></tr><tr><td>Sex</td><td></td><td></td><td><strong>0.001</strong></td><td><strong>0.001</strong></td><td><strong>0.001</strong></td><td><strong>0.001</strong></td><td>0.322</td><td>0.335</td></tr><tr><td>Group</td><td></td><td></td><td>0.281</td><td><strong>0.001</strong></td><td><strong>0.017</strong></td><td><strong>0.001</strong></td><td>0.925</td><td><strong>0.021</strong></td></tr><tr><td>Genotype x Sex x Group</td><td></td><td></td><td>0.788</td><td>0.201</td><td>0.893</td><td>0.176</td><td>0.887</td><td>0.551</td></tr></tbody></table>

LW 1 – live weight at 1 day of age, LW 35 – live weight at 35 days of age, WG 1 – 35 – weight gain 1 – 35 days of age, FI 1 – 35 – feed intake 1 – 35 days of age, FCR 1 – 35 – feed conversion ratio 1 – 35 days of age

Table 3 shows results of selected carcass parameters. There were no significant interactions between genotype, sex and group as well as group and genotype did not affect evaluated parameters. Significant effect of sex was found in abdominal fat share from carcass (P=0.001) with higher values in females and thigh muscle share from carcass that was higher in males (P=0.022). Our results are similar to those of LIPPENS et al. (2000). On the contrary, ZHANG et al. (2007) reported significantly lower dressing percentage in restricted chickens.
<table><caption>**Table 3:** Selected carcass parameters</caption><thead><tr><th>Genotype</th><th>Sex</th><th>Group</th><th>Dressing percentage (%)</th><th>Abdominal fat / carcass (%)</th><th>Breast muscle / carcass (%)</th><th>Thigh muscle / carcass (%)</th><th>Meat / carcass (%)</th></tr></thead><tbody><tr><td rowspan="6">Ross</td><td rowspan="3">♂</td><td>ADL</td><td>71.13</td><td>1.83</td><td>25.02</td><td>21.31</td><td>46.33</td></tr><tr><td>R1</td><td>78.11</td><td>1.96</td><td>26.48</td><td>20.53</td><td>47.01</td></tr><tr><td>R2</td><td>72.29</td><td>2.02</td><td>25.26</td><td>21.35</td><td>46.62</td></tr><tr><td rowspan="3">♀</td><td>ADL</td><td>73.15</td><td>2.19</td><td>26.55</td><td>20.29</td><td>46.84</td></tr><tr><td>R1</td><td>73.55</td><td>2.13</td><td>24.73</td><td>19.01</td><td>43.74</td></tr><tr><td>R2</td><td>74.10</td><td>2.30</td><td>25.88</td><td>20.72</td><td>46.60</td></tr><tr><td rowspan="6">Cobb</td><td rowspan="3">♂</td><td>ADL</td><td>73.28</td><td>1.22</td><td>26.43</td><td>21.02</td><td>47.46</td></tr><tr><td>R1</td><td>73.18</td><td>1.53</td><td>25.94</td><td>22.33</td><td>48.28</td></tr><tr><td>R2</td><td>74.07</td><td>1.92</td><td>25.35</td><td>21.11</td><td>46.45</td></tr><tr><td rowspan="3">♀</td><td>ADL</td><td>74.08</td><td>2.15</td><td>27.07</td><td>20.74</td><td>47.82</td></tr><tr><td>R1</td><td>74.27</td><td>2.12</td><td>25.27</td><td>20.98</td><td>46.26</td></tr><tr><td>R2</td><td>74.83</td><td>2.35</td><td>27.88</td><td>20.08</td><td>47.96</td></tr><tr><td>Genotype</td><td></td><td></td><td>0.516</td><td>0.138</td><td>0.288</td><td>0.227</td><td>0.179</td></tr><tr><td>Sex</td><td></td><td></td><td>0.304</td><td><strong>0.001</strong></td><td>0.445</td><td><strong>0.022</strong></td><td>0.575</td></tr><tr><td>Group</td><td></td><td></td><td>0.107</td><td>0.137</td><td>0.674</td><td>0.964</td><td>0.744</td></tr><tr><td>Genotype x Sex x Group</td><td></td><td></td><td>0.990</td><td>0.790</td><td>0.161</td><td>0.859</td><td>0.915</td></tr></tbody></table>

**Conclusions**

Based on the obtained results it can be concluded that feed restriction significantly decreased mortality without negative effect on growth performance, feed conversion ratio and carcass composition.

**Acknowledgement**

The study was supported by the Ministry of Agriculture of the Czech Republic (Project NAAR No. QJ1510192).

**References**

BENYI, K., ACHEAMPONG-BOATENG, O., NORRIS, D., MATHOHO, M., MIKASI, M. S., 2009: The response of Ross 308 and Hybro broiler chickens to early and late skip-a-day feed restriction. Trop. Anim. Health Prod. **41**, 1707 – 1713.

LIPPENS, M., ROOM, G., DE GROOTE, G., DECUYPERE, E., 2000: Early and temporary quantitative food restriction of broiler chickens. 1. Effects on performance characteristics, mortality and meat quality. Br. Poult. Sci. **41**, 343 – 354.

SAS Institute Inc., 2003: The SAS System for Windows. Release 9.1.

URDANETA-RINCON, M., LEESON, S., 2002: Quantitative and qualitative feed restriction on growth characteristics of male broiler chickens. Poult. Sci. **81**, 679 – 688.

ZHAN, X. A., WANG, M., REN, H., ZHAO, R. Q., LI, J. X., TAN, Z. L., 2007: Effect of early feed restriction on metabolic programming and compensatory growth in broiler chickens. Poult. Sci. **86**, 654 – 660.
P-270 (ID 153)

EFFECTS OF DIFFERENT FEEDING STRATEGIES DURING REAR AND LAY ON EGG WEIGHT, AGE OF SEXUAL MATURITY AND PEAK PRODUCTION IN BROILER BREEDER FEMALES

R.A. van Emous<fnref n="1" />, R.P. Kwakkel<fnref n="2" />, and M.M. van Krimpen<fnref n="1" />

**Corresponding author:** rick.vanemous@wur.nl

**Summary**

An experiment was conducted to investigate the effects of different feeding strategies during rear and lay on egg weight (EW), age of sexual maturity (ASM) and peak production (% and age) of broiler breeder females. A 2 × 3 × 2 factorial design was used with 2 crude protein (CP) levels (high = CPh; low = CPI) during rearing; high, standard and low dietary energy levels (3,000 = MEh1; 2,800 = MEs1; 2,600 = MEI1) during the first phase of lay; and standard and high dietary energy levels (2,800 = MEs2; 3,000 = MEh2) during the second phase of lay. A total of 2,880 one-day old Ross 308 breeder female chicks were placed in 36 pens and followed until 60 wk of age. EW was recorded on a daily basis. Weekly and average EW per phase was calculated. ASM was defined as age at 50% production. Peak production was determined as a 3-wk rolling average. No effects of rearing treatments were found. Dietary energy level during the first phase of lay did not affect EW during that period. However, a linear decrease in dietary energy level during the first phase of lay resulted in a linear decrease in EW during the second phase of lay. Birds fed the MEI1 diet showed a delayed ASM of 1.2 and 1.6 d, while age at peak production was advanced by 11.1 and 5.8 d compared to the MEh1 and MEs1 birds, respectively. Feeding birds the MEh2 diet decreased EW during the second phase of lay. It was concluded that different feeding strategies during rear and lay can affect EW, ASM and early production traits.

**Keywords:** broiler breeder, rearing, laying, feeding strategies, production traits

**Introduction**

Modern broiler strains show a 4 times higher daily growth while feed conversion ratio is less than half compared to strains in use 60 year ago (ZUIDHOF et al., 2014). This selection on increased growth efficiency has not only affected the progeny but also the parent stock (broiler breeders). The main goal in broiler breeder production is to provide fertilized eggs to produce maximum number of healthy and robust day-old broiler chicks. Besides a wide range of different methods, feed also play an important role in optimizing reproduction. For example, egg weight is affected by daily dietary protein and amino acids intake (LOPEZ and LEESON, 1995). More specific, a higher egg weight is caused by a higher daily intake of sulphur amino acids (effect on albumen and yolk) and/or higher daily intake of linoleic acid (effect on yolk). Daily protein intake during initial lay is important as a stimulus for development of the reproductive tract (LILBURN and MYERS-MILLER, 1990). Therefore, the objective of the study was to determine the effects of different dietary protein levels during rear and different dietary energy levels during lay on egg weight, age of sexual maturity and peak production in Ross 308 broiler breeder females.

**Materials and methods**

The effects of different dietary protein levels during rearing and different dietary energy levels during lay on body composition and reproduction were studied using a 2 × 3 × 2 factorial design with 2 CP levels (CPh = high protein; or CPI = low protein) during rearing between 2 and 22 wk of age; high, standard and low dietary energy levels during the first phase of lay between 22 and 45 wk of age (3,000, MEh1; 2,800, MEs1; and 2,600, MEI1, kcal/kg AME<sub>n</sub>, respectively); and standard and high dietary energy levels during the second phase of lay between 45 and 60 wk of age (2,800, MEs2; and 3,000, MEh2, kcal/kg AME<sub>n</sub>, respectively). A flock of 3,000 Ross 308 female broiler breeder day-old chicks was allotted to 36 floor pens (4.5 × 2.5 m) in two identical climate controlled rooms. The experiment started at d 14 with 80 pullets per pen. Due to mortality, sex errors and culling (removing the smallest), the number of pullets was gradually reduced to 70 at 22 wk of age. Males were reared elsewhere and introduced into the pens at 22 wk of age. Egg weights of all hatching eggs (settable and small) were recorded on a daily basis. Weekly and average egg weight per phase were calculated. Age of sexual maturity (ASM) was defined as age at 50% production and was determined by a linear interpolation of the week (in days) where birds passed 50% rate of lay. Peak egg production was determined as a 3-wk rolling average.

<footnote n="1">¹Wageningen UR Livestock Research, PO Box 338, NL-6700 AH Wageningen, the Netherlands</footnote>

<footnote n="2">²Animal Nutrition Group, Department of Animal Sciences, Wageningen University, PO Box 338, NL-6700 AH Wageningen, the Netherlands</footnote>
## Results and discussion

No effects of rearing diets were found on egg weight, ASM, and peak production (Table 1). Dietary energy level during the first phase of lay did not affect egg weight during that period. However, a carryover effect on increased egg weight (+0.6 g) during the second phase of lay was found when birds were fed the MEh1 diet during the first phase of lay (low daily CP/AA intake) compared to the MEI1 birds (high daily CP/AA intake). A comparable effect was observed by SUN and COON (2005) when birds were fed a 5.5% higher dietary energy level. They found no effect on egg weight between 24 to 30 wk of age, however, egg weight between 30 and 65 wk of age was increased when birds received an isonitrogenous diet with a higher energy level during lay. No effect on egg weight between 23 and 48 wk of age was observed by JOSEPH et al. (2002) when birds received an 8% decreased daily CP intake. However, in an earlier experiment they observed a decreased effect on egg weight during initial lay (24 to 29 wk of age) when birds receive an approximately 10% lower daily CP intake (JOSEPH et al., 2000).

<table><caption>**Table 1.** Egg weight, ASM, peak egg production, and age at peak egg production as affected by dietary protein level (CP) during rearing (2 to 22 wk of age), dietary energy level (ME1) during the first phase of lay (22 to 45 wk of age), and dietary energy level (ME2) during the second phase of lay (45 to 60 wk of age) of Ross 308 broiler breeders¹</caption><thead><tr><th>Source</th><th>Egg weight phase 1 (g)</th><th>Egg weight phase 2 (g)</th><th>Egg weight laying period (g)</th><th>ASM (d)</th><th>Peak egg production (%)<sup>4</sup></th><th>Age at peak egg production (d)</th></tr></thead><tbody><tr><td>Protein rearing</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>CPh</td><td>60.2</td><td>69.0</td><td>63.7</td><td>181.3</td><td>90.3</td><td>217.7</td></tr><tr><td>CPI</td><td>60.2</td><td>68.8</td><td>63.7</td><td>180.8</td><td>89.2</td><td>221.7</td></tr><tr><td>SEM</td><td>0.1</td><td>0.1</td><td>0.1</td><td>0.3</td><td>0.4</td><td>2.4</td></tr><tr><td>Energy lay 1</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>MEh1</td><td>60.3</td><td>69.2<sup>a</sup></td><td>63.9</td><td>180.8<sup>b</sup></td><td>89.8</td><td>225.2<sup>a</sup></td></tr><tr><td>MEs1</td><td>60.3</td><td>68.9<sup>ab</sup></td><td>63.8</td><td>180.4<sup>b</sup></td><td>89.6</td><td>219.9<sup>b</sup></td></tr><tr><td>MEI1</td><td>60.1</td><td>68.6<sup>b</sup></td><td>63.5</td><td>182.0<sup>a</sup></td><td>89.9</td><td>214.1<sup>c</sup></td></tr><tr><td>SEM</td><td>0.1</td><td>0.1</td><td>0.1</td><td>0.4</td><td>0.5</td><td>2.9</td></tr><tr><td>Energy lay 2</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>MEs2</td><td>-</td><td>69.1<sup>a</sup></td><td>63.8</td><td>-</td><td>-</td><td>-</td></tr><tr><td>MEh2</td><td>-</td><td>68.7<sup>b</sup></td><td>63.7</td><td>-</td><td>-</td><td>-</td></tr><tr><td>SEM</td><td>-</td><td>0.1</td><td>0.1</td><td>-</td><td>-</td><td>-</td></tr><tr><td>P-value</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>CP</td><td>0.68</td><td>0.35</td><td>0.84</td><td>0.24</td><td>0.094</td><td>0.25</td></tr><tr><td>ME1</td><td>0.41</td><td>0.012</td><td>0.099</td><td>0.019</td><td>0.91</td><td>0.037</td></tr><tr><td>ME2</td><td>-</td><td>0.024</td><td>0.40</td><td>-</td><td>-</td><td>-</td></tr><tr><td>CP x ME1</td><td>0.70</td><td>0.47</td><td>0.50</td><td>0.10</td><td>0.38</td><td>0.006</td></tr><tr><td>CP x ME2</td><td>-</td><td>0.68</td><td>0.60</td><td>-</td><td>-</td><td>-</td></tr><tr><td>ME1 x ME2</td><td>-</td><td>0.37</td><td>0.11</td><td>-</td><td>-</td><td>-</td></tr></tbody></table>

Birds fed the MEI1 diet showed a small delayed sexual maturity of, on average, 1.4 d compared to those fed the MEh1 and MEs1 diets (Table 1). Contrary to our findings, PISHNAMAZI et al. (2011) found that providing a low energy diet (2,800 vs. 2,900 kcal/kg ME) advanced sexual maturity with 2 d, while SUN and COON (2005) did not find an effect on sexual maturity when different dietary energy levels were provided. Thereafter the increase in rate of lay in the current

<footnote>a-cMeans within a column and within a source without a common superscript differ significantly (P < 0.05).</footnote>
study differed between the treatment groups. An opposite effect of 11.1 and 5.8 d on age at peak production was found for the ME11 birds compared to the MEh1 and MEs1 birds, respectively (Table 1). This may be due to the fact that birds fed the ME11 diet received a 7.3 or 14.6% higher daily CP intake compared to the MEh1 and MEs1 diet, respectively. A high daily CP intake during initial lay could be a stimulus for development of the reproductive tract, resulting in an earlier peak egg production (LILBURN and MYERS-MILLER, 1990). Moreover, PISHNAMAZI et al. (2011) stated that a lower protein intake (19.7 vs. 20.4 g/d) during initial lay may hamper ovary development and, as a consequence, egg production.

Feeding birds the MEh2 diet decreased egg weight during the second phase of lay which was affected by a lower daily intake of sulphur amino acids and linoleic acid. In contrast to the current study, SUN and COON (2005) found an increased egg weight when birds received a high energy diet. The difference between the current study and the study of SUN and COON (2005) is that in the latter study, not only energy intake was increased, but also CP intake.

## Conclusions

A low protein diet during the prebreeder period did not affect egg weight, age of sexual maturity and peak production. A low energy diet (high daily protein intake) during the first phase of lay decreased egg weight during the second phase of lay, delayed ASM and advanced age at peak egg production. A high energy diet (low daily protein intake) during the second phase of lay decreased egg weight.

## Literature

* JOSEPH, N.S., F.E. ROBINSON, D.R. KORVER, R.A. RENEMA, 2000: Effect of dietary protein intake during the pullet-to breeder transition period on early egg weight and production in broiler breeders. Poult. Sci. **79**, 1790-1796.

* JOSEPH, N.S., A.A.J. DULANEY, F.E. ROBINSON, R.A. RENEMA, M.J. ZUIDHOF, 2002: The effects of age at photo-stimulation and dietary protein intake on reproductive efficiency in three strains of broiler breeders varying in breast yield. Poult. Sci. **81**, 597-607.

* LILBURN, M.S., D.J. MYERS-MILLER, 1990: Effect of body weight, feed allowance, and dietary protein intake during the prebreeder period on early reproductive performance of broiler breeder hens. Poult. Sci. **69**, 1118-1125.

* LOPEZ, G., S. LEESON, 1995: Response of broiler breeders to low-protein diets. 1. Adult breeder performance. Poult. Sci. **74**, 685-695.

* PISHNAMAZI, A., E.T. MBA, T.G.V. MORAES, R.A. RENEMA, M.J. ZUIDHOF, 2011: Broiler breeder composition restriction. 1: Do attempts to shift body composition using dietary protein and energy affect early production traits? Poult. Sci. **90**(Suppl. 1), 105. (Abstr.)

* SUN, J., C.N. COON, 2005: The effects of body weight, dietary fat, and feed withdrawal rate on the performance of broiler breeders. J. Appl. Poult. Res. **14**, 728-739.

* ZUIDHOF, M.J., B.L. SCHNEIDER, V.L. CARNEY, D.R. KORVER, F.E. ROBINSON, 2014: Growth, efficiency, and yield of commercial broilers from 1957, 1978, and 2005. Poult. Sci. **93**, 2970-2982.
P-272 (ID 323)

# THE EFFECT OF INCREASING METABOLIZABLE ENERGY, LEVEL AND DURATION OF FEED RESTRICTION ON PERFORMANCE AND INTESTINAL MORPHOLOGY IN BROILER CHICKENS

Z. Zanganeh, S. Moradi, and A. Abdolmohammadi

Department of Animal Science, Faculty of Agriculture and Natural Resources, Razi University, Kermanshah, Iran

**Corresponding Author:** s.moradi@razi.ac.ir

## Abstract

The effect of increasing metabolizable energy (ME), level and duration of feed restriction on performance, intestinal morphology and gastrointestinal pH was studied in broiler chickens fed pellet diets. A total of 480 Ross 308 male broiler chickens were allocated to 12 treatments, arranged factorially, with two levels of metabolizable energy (normal, and +100kcal/kg), two levels of feed restriction (90% and 85% restricted feed than recommended of Ross 308 management guide), and three periods of feed restriction duration including 14, 21 and 28 days. Each treatment was replicated 4 times. Results showed that BW was increased significantly in broilers fed on high-ME diets and 10% feed restriction (P<0.01). High-ME diets increased FCR at 7 days and reduced FCR at 14 and 21 days of age (P<0.05). Relative weight of ileum, duodenum, jejunum and cecum in birds fed high-ME diets with 85% feed restriction during 8-28 days were significantly increased (P<0.05). The depth of crypt in jejunum and ileum and villi/crypt index in jejunum increased with increasing ME level and decreased in 90% feed restriction at 42 of age (P<0.05). Increasing duration of feed restriction, elevated digesta pH of the crop at 42 days of age (P<0.01). Also, digesta PH of ileum at 42d of age was significantly decreased in 90% and 28d of feed restriction (P<0.01). In conclusion, Energy level and feed restriction affected weight gain, relative weight of intestinal parts, also pH of digesta in broiler chickens.

**Keywords:** Metabolizable energy, pellet, feed restriction, intestinal morphology

## Introduction

Feeding strategies including pelleting and increasing metabolizable energy in broiler chickens resulted in higher growth performance and improving feed conversion ratio, while, increasing occurrence of metabolic disorders, fat deposition and mortality. One possible nutritional approach to reduce feed cost, improvement FCR and decreases the occurrence of metabolic disorders and mortality is to restrict feed intake of the birds. Improvement in FCR and decrease in metabolic disorders noted with the use of feed restriction programs is due to reduced overall maintenance requirements and basal metabolic rate in feed-restricted birds linked with a smaller body weight during early growth (Rincon and Lesson, 2002). The GIT of chickens responds very quickly and dramatically to changes in nutrient status and feed intake (Thompson and Applegate, 2006). Therefore, the main objective of this study was to determine the suitable level and timing of feed restriction (FR) regimes and level of metabolizable energy (ME) content on productivity and gastro intestinal tracts characteristics in broiler chickens.

## Material and Methods

The research protocol was approved by the Razi university animal care and use committee. A total of 480 one-d-old Ross 308 male broilers were placed in 48 individual cages and 12 treatments, arranged factorially including: 2 levels of ME (normal, and normal+100 kcal.kg⁻¹), 2 levels of restriction level (90% and 85% restricted feed than recommended of Ross 308 management guide), and 3 periods of restriction duration (8-21, 8-28 and 8-35d of age). Each treatment replicated 4 times. Body weight and feed intake were recorded weekly. At 42d of age one chick per each replicate was randomly selected and dissected and tissue samples for intestinal morphology were collected (Barri et al. 2011). Measurement of pH were done based on Walk et al. (2012) procedure. Data analyzed using GLM procedure of SAS software (2011).

## Results

No interaction between ME content of the diet and FR was observed for BW and FCR (Table 1). Increasing ME level of diet significantly improved BW and FCR from 8 to 21 and 1 to 42d of age (P<0.01), but interestingly, except for first week that decreased BW and elevated FCR (P<0.05). level of FR had no significant effect on BW and FCR at 8 to 21 and 22 to 42d of age but from 1 to 42d of age, high-restriction level (85%) decreased BW (P<0.01). Chickens subjected to 85% FR, needed to more time for complete recovery of BW rather than 90% FR (Lippenz et al., 2000). Applying feed
restriction during ages 8-35 days significantly affected performance and decreased BW (P<0.01), also increased FCR (P<0.05) at 22-42 and 1-42 days of age.

There was no significant difference between broilers fed high-ME diets or FR regimen in regard to villus height (VH), and villus to crypt rate (VCR) within ileum (Table 2). An interaction between dietary ME and level of FR was observed for crypt depth (CD) of jejunum (P<0.05). Birds fed norm-ME diet and 90% FR had higher CD of jejunum that had significant difference with 85% and norm-ME bird groups (Table 4). Results of increase in ME and decrease in level of FR (90%) showed higher VH of jejunum and CD of ileum (P<0.05). Also, larger VCR in jejunum observed in broiler with high-ME that was 5.85 (P<0.01).

Influence of FR level (P<0.05) and interaction of level of FR × duration of FR (P<0.01) was significant for digesta pH of ileum (Table 2). In treatment with 28d of FR, ileum digesta pH in 90% FR groups was lowest content (Table 3). Gizzard digesta pH was not affected by ME, level and duration of FR. Minimum digesta pH of crop observed in birds received 14d restriction (8-21 days of age) that had significant difference with 21 and 28 days of restriction (P<0.01). Lower pH of the contents in ileum in treatment with norm-ME during 28d of restriction was seen, may be indicating higher population of lactic acid bacteria and better fermentation of food.

## Conclusions

According to the results, elevating energy content in the first week of age, reduced BW, while improved BW and FCR during 2 to 6 w of age. Elevating dietary ME content increased crypt depth of ileum and villus height and villi/crypt rate in jejunum. Maximum villus height of jejunum and crypt depth observed in treatment with lower level of restriction. Also, pH of the crop was lowest in birds received 14 d of restriction. It seems, higher ME content and applying feed restriction in 90% of ross recommendation during 8-28 days (3 week) provide better productivity of birds fed pellet diet.

<table><caption>Table 1. Influence of metabolizable energy, level and duration of feed restriction on performance of broilers</caption><thead><tr><th rowspan="2">variable</th><th colspan="4">FCR</th><th colspan="4">BW (g)</th></tr><tr><th>1-7 d</th><th>8-21d</th><th>22-42d</th><th>1-42d</th><th>1-7 d</th><th>8-21d</th><th>22-42d</th><th>1-42d</th></tr></thead><tbody><tr><td><strong>ME</strong><br>(kcal/kg)</td><td>*</td><td>**</td><td>NS</td><td>**</td><td>*</td><td>**</td><td>NS</td><td>**</td></tr><tr><td></td><td></td><td>1.53±</td><td></td><td></td><td></td><td>565.4±</td><td></td><td></td></tr><tr><td>Norm</td><td>1.03±0.05<sup>b</sup></td><td>0.04<sup>a</sup></td><td>1.85±0.05</td><td>1.73±0.04<sup>a</sup></td><td>145.4±7.1<sup>a</sup></td><td>24.0<sup>b</sup></td><td>1797.4±66.1</td><td>2508.3±75.3<sup>b</sup></td></tr><tr><td>High</td><td>1.07±0.05<sup>a</sup></td><td>1.40±0.04<sup>b</sup></td><td>1.82±0.08</td><td>1.68±0.06<sup>b</sup></td><td>141.0±6.1<sup>b</sup></td><td>618.7±26.5<sup>a</sup></td><td>1827.1±103.4</td><td>2586.2±119.0<sup>a</sup></td></tr><tr><td><strong>Level of FR (%)</strong></td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>**</td></tr><tr><td><strong>90</strong></td><td>1.05±0.05</td><td>1.46±0.07</td><td>1.84±0.08</td><td>1.70±0.06</td><td>143.9±7.5</td><td>611.8±30.7</td><td>1826.6±91.1</td><td>2582.3±106.1<sup>a</sup></td></tr><tr><td><strong>85</strong></td><td>1.06±0.05</td><td>1.47±0.08</td><td>1.83±0.06</td><td>1.70±0.05</td><td>142.5±6.3</td><td>571.7±30.7</td><td>1797.9±82.5</td><td>2512.1±95.9<sup>b</sup></td></tr><tr><td><strong>Duration of FR (age)</strong></td><td>NS</td><td>NS</td><td>*</td><td>*</td><td>NS</td><td>NS</td><td>**</td><td>**</td></tr><tr><td>8-21</td><td>1.04±0.03</td><td>1.46±0.07</td><td>1.80±0.07<sup>b</sup></td><td>1.68±0.05<sup>b</sup></td><td>143.9±4.6</td><td>592.7±35.6</td><td>1862.7±67.6<sup>a</sup></td><td>2599.3±84.8<sup>a</sup></td></tr><tr><td>8-28</td><td>1.05±0.05</td><td>1.46±0.08</td><td>1.84±0.08<sup>ab</sup></td><td>1.71±0.07<sup>ab</sup></td><td>142.6±6.6</td><td>595.4±39.4</td><td>1837.3±89.0<sup>a</sup></td><td>2575.3±114.6<sup>a</sup></td></tr><tr><td>8-35</td><td>1.05±0.07</td><td>1.48±0.08</td><td>1.86±0.05<sup>a</sup></td><td>1.72±0.04<sup>a</sup></td><td>143.1±9.2</td><td>587.2±36.5</td><td>1736.8±43.0<sup>b</sup></td><td>2467.1±66.1<sup>b</sup></td></tr><tr><td>SEM</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.10</td><td>5.3</td><td>12.6</td><td>15.3</td></tr></tbody></table>

No interaction between were observed for BW and FCR. *significant at P ≤0.05. **significant at P ≤0.01. NS: not significant.

<footnote><sup>a-b</sup> Means within columns with different superscripts are significantly different (P < 0.05).</footnote>
<table><caption>**Table 2.** Influence of ME content, level and duration of feed restriction on jejunal and ileal morphology and digesta pH in intestine of broilers at d 42</caption><thead><tr><th rowspan="2">variable<br>ME<br>(kcal/kg)</th><th rowspan="2">Crop</th><th rowspan="2">Gizzard</th><th rowspan="2">Ileum</th><th colspan="6">Intestine Morphology</th></tr><tr><th>pH</th><th colspan="3">Jejunum</th><th colspan="3">Ileum</th></tr><tr><th></th><th></th><th></th><th></th><th>VH(mm)</th><th>CD(mm)</th><th>VCR</th><th>VH(mm)</th><th>CD(mm)</th><th>VCR</th></tr></thead><tbody><tr><td>Norm</td><td>5.16±0.96</td><td>4.31±0.33</td><td>5.06±0.46</td><td>121.2±23.7<sup>b</sup></td><td>23.5±3.1</td><td>5.32±1.24<sup>b</sup></td><td>103.9±15.0</td><td>23.4±2.0<sup>b</sup></td><td>4.45±0.66</td></tr><tr><td>High</td><td>5.17±0.73</td><td>4.12±0.42</td><td>5.13±0.59</td><td>139.1±18.8<sup>a</sup></td><td>23.8±2.0</td><td>5.85±0.63<sup>a</sup></td><td>108.5±19.1</td><td>24.7±2.3<sup>a</sup></td><td>4.36±0.59</td></tr><tr><td>Level of<br>FR (%)</td><td>NS</td><td>NS</td><td>*</td><td>*</td><td>NS</td><td>NS</td><td>NS</td><td>*</td><td>NS</td></tr><tr><td>90</td><td>5.14±0.81</td><td>4.12±0.43</td><td>4.94±0.49</td><td>135.<br>8±19.4<sup>a</sup></td><td>24.1±2.9</td><td>5.70±1.01</td><td>108.4±19.0</td><td>25.0±2.3<sup>a</sup></td><td>4.35±0.56</td></tr><tr><td>85</td><td>5.19±0.89</td><td>4.31±0.32</td><td>5.28±0.51</td><td>124.5±25.3<br><sup>b</sup></td><td>23.2±2.3</td><td>5.46±1.02</td><td>103.5±14.7</td><td>23.3±1.8<sup>b</sup></td><td>4.47±0.70</td></tr><tr><td>Duration<br>of FR<br>(age)</td><td>**</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>8-21</td><td>4.10±0.47<sup>b</sup></td><td>4.31±0.31</td><td>5.08±0.44</td><td>128.5±21.7</td><td>22.4±1.5</td><td>5.76±0.96</td><td>107.1±16.8</td><td>23.6±2.3</td><td>4.55±0.66</td></tr><tr><td>8-28</td><td>5.67±0.42<sup>a</sup></td><td>4.06±0.43</td><td>5.18±0.39</td><td>130.7±27.1</td><td>24.6±2.7</td><td>5.46±1.21</td><td>105.7±15.1</td><td>24.6±2.1</td><td>4.34±0.58</td></tr><tr><td>8-35</td><td>5.66±0.37<sup>a</sup></td><td>4.28±0.38</td><td>5.05±0.70</td><td>130.9±21.3</td><td>23.7±2.9</td><td>5.55±0.88</td><td>105.5±20.7</td><td>24.4±2.6</td><td>4.33±0.66</td></tr><tr><td>SEM</td><td>0.12</td><td>0.06</td><td>0.08</td><td>3.47</td><td>0.39</td><td>0.15</td><td>2.61</td><td>0.35</td><td>0.10</td></tr><tr><td>P-Values</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>E×I</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>*</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>E×D</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>I×D</td><td>NS</td><td>NS</td><td>**</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td></tr><tr><td>E×I×D</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td><td>NS</td></tr></tbody></table>

a-b Means within columns with different superscripts are significantly different (P < 0.05).

VH: villus height. CD: crypt depth. VCR: villus to crypt rate.

*: significant at P ≤0.05. **: significant at P ≤0.01. NS: not significant.

<table><caption>**Table 3.** Interaction of intensity FR and duration FR on pH of ileum at 42d of age</caption><thead><tr><th rowspan="2">Level of FR<br>(%)</th><th colspan="3">Duration of FR (age)</th></tr><tr><th><u>8-21d</u></th><th><u>8-28d</u></th><th><u>8-35d</u></th></tr></thead><tbody><tr><td>90</td><td>5.10±0.55<sup>a</sup></td><td>5.14±0.42<sup>a</sup></td><td>4.57±0.30<sup>b</sup></td></tr><tr><td>85</td><td>5.06±0.35<sup>a</sup></td><td>5.24±0.39<sup>a</sup></td><td>5.52±0.37<sup>a</sup></td></tr></tbody></table>

a-b Means within rows and columns with different superscripts are significantly different (P < 0.05).

<table><caption>**Table 4.** Interaction of ME level and intensity FR on jejunum CD (mm) of broilers at 42d of age</caption><thead><tr><th rowspan="2">ME (Kcal/kg)</th><th colspan="2">Level of FR (%)</th></tr><tr><th><u>90</u></th><th><u>85</u></th></tr></thead><tbody><tr><td>Norm</td><td>24.76±3.46<sup>a</sup></td><td>22.21±2.10<sup>b</sup></td></tr><tr><td>High</td><td>23.40±1.79<sup>ab</sup></td><td>24.11±2.17<sup>ab</sup></td></tr></tbody></table>

a-b Means within rows and columns with different superscripts are significantly different (P < 0.05).

## Literature

BARRI, A., C. F. HONAKER, J. K. SOTTOSANTI, R. M. HULET, A. P. MCELOTY, 2011: Effect of incubation temperature on nutrient transporters and small intestine morphology of broiler chickens. Pouly. Sci. 90, 118-125.

URDANETA-RINCON, M., S. LEESON, 2002: Quantitative and qualitative feed restriction on growth characteristics of male broiler chickens. Poult. Sci. 81(5), 679-688.

WALK, C. L., M. R. BEDFORD, A. P. MCELROY, 2012: Influence of limestone and phytase on broiler performance, gastrointes-tinal pH, and apparent ileal nutrient digestibility. Poult. Sci. 91, 1371-1378.
<figure><img src="image_90.png" /></figure>