bluuebunny/crossref_metadata_2025 huggingface dataset:
Milk production, milk composition, and reproductive function of dairy cows fed different fats
Authors: Petit H. V. , Dewhurst R. J. , Proulx J. G. , Khalid M. , Haresign W. , Twagiramungu H.
Published: April 2011

Thirty-five non-gestating multiparous Holstein cows averaging 571 kg of BW (SE = 8) were allotted at 9 wk postpartum to one of two dietary fat supplements based on either Megalac® (Volac Ltd., Roston, Hertfordshire, UK) and solvent extracted flaxseed meal (MEGA) or whole flaxseed treated with formaldehyde (FLAX) to determine the effects on milk production and composition, follicular development, gestation rate, and fatty acid (FA) composition of blood. Cows were fed a total mixed diet based on ryegrass silage and fat supplements for ad libitum intake. The experiment was carried out between weeks 9 and 19 of lactation. Dry matter (DM) intake and change in body weight were similar for cows fed MEGA and FLAX. Milk production was higher for cows fed MEGA than for those fed FLAX (19.8 vs. 18.6 kg d–1) as was 4% fat-corrected milk yield (22.9 vs. 20.2 kg d–1). Increased fat mobilization could have contributed to increased milk yield when cows were fed MEGA compared with when they were fed FLAX as plasma concentrations of non-esterified FA and cholesterol increased more from weeks 9 to 19 of lactation for cows fed MEGA. Milk fat percentage tended (P = 0.06) to be greater for cows fed MEGA (4.62%) compared with those fed FLAX (4.37%). Milk protein percentage was higher for cows fed FLAX (3.09%) than for those fed MEGA (2.95%), indicating that formaldehyde protection of flaxseed was adequate to partly prevent ruminal degradability of protein in the seed. Milk fatty acid concentrations of C8:0, C10:0, C12:0, C14:0, C14:1, C18:0, C18:3, and C20:5 were higher for cows fed FLAX than for those fed MEGA while the inverse was observed for C16:0, C16:1, C18:1, and C18:2. Cows fed FLAX had lower blood concentrations of C16:0 than those fed MEGA. There was a significant interaction (P < 0.05) between week and diet for C18:0 and C18:2 with a decrease in C18:0 blood concentration for cows fed MEGA and an increase for those fed FLAX between weeks 9 and 19, while the inverse was observed for C18:2. Blood concentrations of C18:1 were similar for both treatments. Conception rate was significantly lower for cows fed MEGA (50.0%) compared to those fed FLAX (87.5%). Diet had no effect on the size of the largest and second largest follicles, or on the difference between the diameter of the largest and second largest follicles. The number of class 1 (1.09 vs. 0.86), 2 (1.33 vs. 0.86), and 3 (1.28 vs. 0.98) follicles was similar for MEGA and FLAX although the total number (3.70 vs. 2.70) of follicles tended (P = 0.09) to be greater for cows fed MEGA than for those fed FLAX. These data suggest that dietary FA have an effect on gestation rate, but this could not be explained by differences in follicle dynamics or number. However, additional trials with greater numbers of animals are needed to confirm the reproductive results. Key words: Dairy, flaxseed, milk production, reproduction, fatty acids
The effect of transport time from the assembly yard to the abattoir and resting time at the abattoir on pork quality
Authors: Fortin André
Published: April 2011

Over 1900 pigs, supplied by two producers, were first delivered to an assembly yard and then transported to a commercial abattoir. Transport times were 50 min and 2 h, and resting periods at the abattoir were < 30 min, 3 h and 6 h. Times were chosen to represent normal practices in Ontario. The colour and structure of the boneless loins were as sessed subjectively 24 h postmortem.

The shorter (50 min) transport time was associated with the highest (P ≤ 0.05) incidence of pale and soft/exudative loins. A longer transport time reduced the incidence of pale and soft/exudative loins; it also increased (P ≤ 0.05) the incidence of dark and firm/dry loins; particularly during winter. A resting period of < 30 min resulted in the highest (P ≤ 0.01) incidence of pale and soft/exudative loins. A 3 h resting period significantly improved (P ≤ 0.01) quality by reducing the incidence of pale loins and soft/exudative loins. Extending the resting period from 3 h to 6 h provided inconsistent improvements in quality due to interactions with season (P ≤ 0.05) and producer/management (P ≤ 0.05). Considering transport time and resting period together further highlighted the importance of resting period at the abattoir. Three h resting period always improved (P ≤ 0.05) quality regardless of transport time, season or producer. Key words: Transport, resting period, pork quality, pale, soft and exudative, DFD
Efficacy of Rumensin controlled release capsule for the control of alfalfa bloat in cattle
Authors: Hall J. W. , Majak W. , McAllister T. A. , Merrill J. K.
Published: April 2011

Rumensin controlled release capsule (CRC) was evaluated in grazing trials and in confinement with fistulated steers fed alfalfa at the vegetative to early bud stage of growth. These stages promoted a high incidence of bloat, both in animal days of bloat and in daily frequency of distension. The bolus reduced the incidence of bloat by an average of 50% in five trials, the difference being statistically significant in four of them. The cultivars AC Grazeland and Alfagraze did not differ significantly in daily bloat incidence when evaluated at early stages of growth. Key words: Cattle, bloat, legumes, Medicago sativa L.
A comparison of washed and unwashed bags to determine the apparent fecal digestibility of dry matter, energy and crude protein in feeds for swine using the mobile nylon bag technique
Authors: Qiao Shiyan , Thacker P. A.
Published: April 2011

Five feeds and five castrates were used to study the effects of washing rather than scrapping feces fr om bags on nutrient digestibility obtained with the mobile nylon bag technique (MNBT). Using unwashed bags, the MNBT and the conventional indicator method (CON) produced similar dry matter digestibility (DMD) with barley being the only ingredient where a difference (P < 0.05) was obtained between the two techniques. The linear regression equation was CON DMD = 5.39 + 0.92 MNBT DMD (r2 = 0.95). The MNBT overestimated DMD with a bias of less than 0.1%. When washed bags were used, differences (P < 0.05) were obtained between the two techniques for barley, corn and oats and the MNBT overestimated DMD with a bias of 6.6%. There were no differences in gross energy digestibility (GED) when obtained with the indicator method or the MNBT using unwashed bags. The regression line equation was CON GED = 3.85 + 0.94 MNBT GED (r2 = 0.95) and the MNBT overestimated GED with a bias of 1.4%. When washed bags were used, significant (P < 0.05) differences were obtained between techniques for GED with barley, corn, and oats. The MNBT overestimated GED with a bias of 7.3%. With unwashed bags, there were no differences in crude protein digestibility (CPD) obtained with the indicator method or the MNBT, with the exception of the mixed diet. The regression line equation was CON CPD = 28.16 + 0.60 MNBT CPD (r2 = 0.53) and the MNBT overestimated CPD with a bias of 3%. When washed bags were used, significant (P < 0.05) differences were obtained between techniques for barley, corn, oats, wheat and the mixed diet, and the MNBT overestimated CPD with a bias of 12.8%. The overall results of this experiment indicate that washing bags greatly overestimates nutrient digestibility coefficients obtained with the MNBT. Key words: Nylon bag, pigs, digestibility, protein, energy, cannula
Measurements of enzyme response with hulless barley-based diets full-fed to Leghorn and broiler chicks or restricted-fed broiler chicks
Authors: Scott T. A. , Leslie M. A. , Karimi A.
Published: April 2011

Broiler chicks fed diets high in soluble non-starch polysaccharides (NSP; e.g., wheat- and/or barley-based diets) have a higher capacity to ingest, digest and absorb nutrients when diets are supplemented with appropriate NSP enzymes. However, this same enzyme response is typically reduced or non-significant in older birds, Leghorn chicks and turkey poults. We hypothesise that the enzyme response in the latter classes of poultry is reduced because feed intake is lower in comparison to feed intake by broilers. In the present study, the hypothesis that restricted feeding of broilers would reduce the enzyme response typically observed in full-fed broilers was tested.

Two experiments were conducted to determine the feeding value of hulless barley supplemented or not supplemented with enzyme (Avizyme 1100, Finnfeeds Int, UK). In Study 1, eight sources of hulless barley were included at 80% in each diet and fed to four groups of six male broilers or Leghorn chicks from 4 to 17 d of age. The response to enzyme in hulless barley-based diets by broilers was approximately twofold that of Leghorns for growth and feed intake. The Leghorns had higher digesta viscosity than broilers, although the relative drop in digesta viscosity with enzyme supplementation was equal.

In a second study (Study 2) broiler chicks were fed one of four diets (two hulless barley cultivars with or without enzyme) at three feed allotment levels (ad libitum, R1 and R2) from 4 to 21 d of age. The R1 and R2 feed allotments were pre-determined fixed daily feed amounts. Actual feed restriction in the R1 group was only achieved for diets with, but not without, an enzyme. At the lowest feed allotment (R2) actual feed intake of diets with or without enzyme were lower than that recorded for ad libitum fed birds. Study 2 demonstrated that restricted-fed broilers had a lower growth response to enzyme supplementation compared to birds allowed ad libitum intake, in part due to improved retention of energy, either directly in response to feed restriction or because digesta viscosity in diets without enzyme was lowered. Although digesta viscosity of restricted-fed birds was lower, it is still high enough to be considered problematic. In determining feeding value of cereal grains or supplements such as enzymes, especially those directed for use with broilers, it is imperative that a broiler chick bioassay be used and that they have ad libitum access to the diets. Key words: Enzyme, hulless barley, viscosity, feed intake
Hormonal response of pregnant gilts fed a high fiber or a concentrate diet once or twice daily
Authors: Farmer C. , Meunier-Salaün M. C. , Bergeron R. , Robert S.
Published: April 2011

The effects of fiber intake and feeding frequency on endocrine status were studied. Gilts were fed 2.2 kg d-1 of a concentrate diet (n = 6; 5.3% crude fiber) or 3.1 kg d-1 of a high-fiber diet (n = 7; 18.2% crude fiber) as of day 23 of gestation. For a 1-mo period, starting on day 60 of gestation, three or four animals within each dietary treatment received one daily ration at 0800 h while the others received two meals at 0800 and 1430 h. Feeding frequency was then reversed for the following 1-mo period. Jugular catheters were inserted on day 23 of each 1-mo period and serial blood samples were obtained from 0730 to 1630 h on day 25, to measure cortisol, insulin, glucose and free fatty acids (FFA). The mean of three samples obtained before the morning or afternoon mealtime was used to establish a preprandial baseline and samples thereafter were used to measure area under the curve (AUC) and maximal values. Fiber intake had no effect on any baseline values (P > 0.1), but decreased overall insulin AUC (P < 0.05) and glucose maximal values (P < 0.05) and increased morning FFA AUC (P < 0.05). Compared to one daily meal, twice daily feeding increased afternoon baseline cortisol (P < 0.05) and decreased morning cortisol AUC and baseline FFA (P < 0.001). It also increased afternoon insulin maximal values and AUC (P < 0.05) as well as morning and afternoon maximal glucose (P < 0.05) and decreased morning maximal FFA (P < 0.05). Insulin was the only variable affected by the fiber intake × number of meals interaction with twice daily feeding lowering morning maximal (P < 0.05) and AUC (P < 0.001) values in concentrate-fed gilts while not altering those values in gilts fed a high-fiber diet. Addition of fiber to the diet of pregnant gilts altered their hormonal response to meals, while once daily feeding created a post-absorptive state in the morning and increased cortisol concentrations postprandially. Key words: Gestation, pigs, fiber intake, feeding frequency, insulin, glucose
Performance of laying hens fed wheat, wheat-barley or wheat-barley-wheat bran based diets supplemented with xylanase
Authors: Mathlouthi N. , Larbier M. , Mohamed M. A. , Lessire M.
Published: April 2011

Two experiments were conducted to study the response of laying hens to a commercial enzyme preparation (Safizyme XP20) containing 70 000 IU g-1 xylanase. In the first experiment, 270 laying hens (ISA Brown), aged 28 wk, were fed basal diets of wheat (W), wheat-barley (WB) or wheat-barley and wheat bran (WBB) without xylanase, or supplemented with 1400 IU xylanase kg-1 in 3 × 2 factorial arrangement. In the second experiment, 180 ISA Brown laying hens, aged 28 wk, were assigned to 2 × 2 factorial arrangement and fed wheat-based diets containing 2753 or 2653 kcal metabolizable energy (ME) kg-1 without xylanase, or supplemented with 1400 IU xylanase kg-1. Egg production (% hen-day), egg weight, egg mass, feed conversion ratio and changes in body weight were recorded for 12 wk. The effects of xylanase on true metabolizable energy (TME) values of wheat, barley and wheat bran were determined using roosters.

Layers fed W-, WB- or WBB-based diets had similar egg mass. The feed conversion ratio of layers fed the WBB-based diet was better (P ≤ 0.05) than that of the other groups. Xylanase improved (P ≤ 0.05) egg mass of layers fed W- or WB-based diets, but it did not affect the performance of hens fed the WBB-based diet.

Low dietary ME significantly (P ≤ 0.05) reduced the performance of laying hens. Xylanase supplementation improved (P ≤ 0.05) egg production, egg mass and feed conversion ratio of layers fed the low energy diet. It did improve the feed conversion ratio of layers fed the high-energy diet. Addition of 1400 IU xylanase kg-1 to the low-energy diet was equivalent to an increase of at least 100 kcal ME kg-1. Xylanase increased (P ≤ 0.05) the TME values by 5.2 and 2.44% for wheat and barley, respectively, and did not affect the TME value of wheat bran. Key words: Xylanase, hens, laying, wheat, barley, wheat bran, metabolizable energy.
Behavioural, health and cortisol responses of young calves to tail docking using a rubber ring or docking iron
Authors: Tom E. M. , Rushen J. , Duncan I. J. H. , de Passillé A. M.
Published: April 2011

The acute responses of thirty-six 7- to 17-d-old Holstein calves to tail docking using a rubber ring or a hot docking iron were examined. Plasma cortisol concentrations were measured on day 0 and day +1. Behaviour was examined on days –1, 0, +1, +2, and +5 after treatment. Milk intake, weight gain, body temperature and faeces scores were monitored. Rubber ring application caused an increase in tail grooming up to day +5 after treatment. Shorter standing and lying periods as well as higher frequencies of standing and lying on day 0 were seen in the rubber ring group. No significant differences in behaviour were observed between the control group and the docking iron group. No significant differences in plasma cortisol concentrations were found between any groups except for 60 min after treatment when the rubber ring group exhibited a significantly higher concentration than the control group. No differences in milk intake, weight gain, body temperature or faeces score were found. Tail docking with a rubber ring causes a more pronounced behavioural and physiological response than docking with a docking iron. However, long-term effects need to be investigated. Key words: Calves, tail docking, pain, behaviour, cortisol, stress
Validation of the sulphur hexafluoride (SF6) tracer gas technique for measurement of methane and carbon dioxide production by cattle
Authors: Boadi D. A. , Wittenberg K. M. , Kennedy A. D.
Published: April 2011

Methane (CH4) and carbon dioxide (CO2) production from six crossbred yearling beef heifers (400 ± 13.0 kg) were measured, using the sulphur hexafluoride (SF6) tracer gas technique (Tracer) and open-circuit hood calorimetry (Cal) to validate the former in estimating rumen CH4 and CO2 production in the field. Animals were individually fed a diet consisting of 50% barley concentrate and 50% alfalfa cubes at 1.3 × ;maintenance requirements daily. Hifers were divided into two groups for individual animal 24- h gas measurements by each method. Each group of heifers was rotated between the Cal and Tracer techniques for 6 consecutive days in an incomplete block design. Methane production ranged from 108 to 145 L d-1 (mean 130 ± 4.0 L d-1) using the Cal technique, and 90 to 167 L d-1 (mean 137 ± 4.0 L d-1) using the Tracer technique. The mean CH4 production (L d-1) was not different (P = 0.24) between the two methods. Carbon dioxide production with the Tracer technique was 20% higher than CO2 production with the Cal technique (P < 0.01). The range of CO2 production was 1574 to 2049 L d-1 (mean 1892 ± 74.0 L d-1) by Cal, and 1541 to 3330 L d-1 (mean 2353 ± 74.0 L d-1) by Tracer. Day-to-day variation in CH4 production was not different within each method (P > 0.05); however, animal-to-animal variation (11.7%) was significant for the Tracer technique (P = 0.04), but not for the Cal technique (P = 0.53). Comparison of the equality of variance between the two methods showed that there were no differences in variations (P > 0.05) between Cal and Tracer for CH4 production. On the other hand, variations in CO2 production were not equal (P > 0.05) between methods. Day-to-day variation in CO2 production was significant using Cal, but not Tracer (P > 0.05). Animal-to-animal variation in CO2 production was 1.6 and 11.8% by Cal and Tracer techniques, respectively. It can be concluded that the SF6 tracer technique accurately estimated rumen CH4 production, but CO2 production was 20% higher. The study suggests that for CH4 measurements using the SF6 tracer technique, more animal numbers are needed than for Cal to reduce animal-to-animal variation. Key words: Methane, carbon dioxide, SF6 tracer technique, validation, cattle
Effects of food texture on meal duration and behaviour of sows fed high-fibre or concentrate diets
Authors: Bergeron R. , Meunier-Salaün M. -C. , Robert S.
Published: April 2011

The impact of food texture (meal vs. pellets) on meal durationand behaviour was examined in seven pregnant sows fed either a very high-fibre diet (29% acid detergent fibre (ADF), 50% neutraldetergent fibre (NDF)], a high-fibre diet (23% ADF, 43% NDF) or concentrate (control, 8% ADF, 20% NDF). Serving diets in mash instead of pellets increased meal duration and reduced the time spent performing stereotypies in the 20-min post-feeding period, suggesting a beneficial effect of this texture. High-fibre diets increased meal duration, and when they were fed in pellet form, they increased the time spent lying. Key words: Sow, gestation, food texture, high-fibre diet, behaviour
In vitro ruminal methane suppression by lauric acid as influenced by dietary calcium
Authors: Machmüller A. , Soliva C. R. , Kreuzer M.
Published: April 2011

The effect of Ca supplementation on the methane-suppressing effect of lauric acid was investigated in an experiment based on a 2 × 2-factorial arrangement using the in vitro system Rusitec. Additional Ca was supplemented at 1 g kg-1 diet in the form of compounds of relatively low solubility in rumen fluid. Lauric acid (C12:0), the predominant effective medium-chain fatty acid in coconut oil, was added at a level of 50 g kg-1. Adding C12:0 did not affect bacterial count, but eliminated ciliate protozoa from fermenters. Ammonia concentration in fermentation mixture declined and volatile fatty acid pattern changed with C12:0. The apparent degradation rate of total organic matter was not altered by C12:0, but fiber fermentation was depressed (P < 0.001). Effects of Ca on microbial counts and fermentation characteristics remained low. Without additional Ca, C12:0 reduced the average daily methane release (mmol g-1 organic matter degraded) by 76%. In comparison, C12:0 only reduced methane production by 47% when additional Ca was included in the diet (interaction of C12:0 and Ca, P < 0.05). The present results suggest that the dietary content of soap-forming Ca has to be kept low in order to achieve a high methane-suppressing effect of lauric acid. Key words: Methane, lauric acid, lipids, calcium, Rusitec, ruminants
Effect of dietary particle size and nutrient supply on energy digestibility and nitrogen excretion in ileal cannulated grower pigs
Authors: Oryschak M. A. , Zijlstra R. T.
Published: April 2011

Diets with two particle sizes (600 and 900 µm) and two nutrient supply levels [digestible energy (DE)-limiting and amino acid (AA)-limiting; 2.8 and 1.8 g digestible lysine Mcal-1 DE, 3.15 and 3.40 Mcal DE kg-1, respectively] were used. Eight ileal cannulated pigs (25 ± 2 kg) had restricted access to feed (3 × maintenance DE) for three periods (N = 6 per diet). Reducing particle size from 900 to 600 µm did not alter urinary or total N excretion (P > 0.10), reduced faecal N excretion 11%, increased total-tract digestibility of N and energy 3%, and increased ileal digestibility of N 9% and energy 11% (P < 0.05). Reducing particle size increased energy digestibility but did not reduce total N excretion. Key words: Particle size, pig, nitrogen, excretion, energy, digestibility
Transmission and control of Escherichia coli O157:H7 — A review
Authors: Bach S. J. , McAllister T. A. , Veira D. M. , Gannon V. P. J. , Holley R. A.
Published: April 2011

Escherichia coli 157:H7 has evolved as an important foodborne pathogen since its initial description in 1982. Outbreaks of illness associated with E. coli O157:H7 have been reported throughout the northern hemisphere, most frequently in Canada, the United States, Japan, and the United Kingdom. In Canada, infections due to E. coli O157: H7 appear to be more common in the western provinces than in the east, in rural vs. urban environments, and during summer as opposed to winter months. Undercooked ground beef has been implicated as the primary vehicle in E. coli O157:H7 infection, but contaminated fruits, vegetables and water have also been linked to E. coli O157:H7 outbreaks. Epidemiological investigations demonstrate that dairy and beef cattle are primary reservoirs of this organism, carrying it asymptomatically and shedding it intermittently and seasonally in their feces. Surveys in Canada and the United States indicate widespread distribution of E. coli O157:H7 in cattle operations. The prevalence of E. coli O157:H7 in cattle has been increasing in recent reports, likely due to the development of more sensitive methods for the detection of the organism. Escherichia coli O157:H7 has been isolated from feed, water for livestock, manure, soil and flies, all of which represent potential sources of contamination for cattle and their environment. To date, effective methods for controlling E. coli O157:H7 in cattle have not been identified, although dietary manipulation, vaccination and bacteriophage therapy have been reported to have potential as intervention strategies. Effective control of E. coli O157:H7 requires reducing the frequency and intensity of fecal shedding of this pathogen by cattle, in addition to targeting environmental sources of the organism. Key words: Escherichia coli O157:H7, cattle, sources, diet, transmission
In vitro degradation of fresh substrates treated with exogenous fibrolytic enzymes
Authors: Bowman G. R. , Beauchemin K. A. , Shelford J. A.
Published: April 2011

An exogenous fibrolytic enzyme product was applied to three different proportions of a total mixed ration (TMR) and fed to dairy cows. There was no enhancement of the hydrolytic capacity of rumen fluid from cows serving as inoculum donors as a result of enzyme supplementation. In vitro dry matter degradation of the TMR at 12 h of incubation was increased by 15% when enzymes were added to the concentrate portion, and by 17% when added to the premix portion of the TMR (P < 0.05), but adding enzymes to the supplement (pelleted portion of the concentrate) had no effect. Key words: Enzymes, fresh substrate, dry matter degradation
Effect of dietary cereal on intestinal bacterial populations in weaned pigs
Authors: Drew M. D. , Van Kessel A. G. , Estrada A. E. , Ekpe E. D. , Zijlstra R. T.
Published: April 2011

Diets containing corn, barley or wheat as the main carbohydrate source were formulated to a similar nutrient content and fed for 3 wk to weaned pigs. Gut bacterial populations differed significantly between the three diets and these differences were correlated with the fibre contents of the diets. Key words: Corn, wheat, barley, intestinal bacteria, pigs
Degree of connectedness among groups of centrally tested beef bulls
Authors: Roso V. M. , Schenkel F. S. , Miller S. P.
Published: April 2011

The degree of connectedness among test groups (TG) of bulls tested in central evaluation stations from 1988 to 2000 in Ontario, Canada, was evaluated using the following methods: average prediction error variance of the difference between estimated breeding values (PEVD), variance of estimated differences between test group effects (VED), connectedness rating (CR), and total number of direct genetic links between test groups (GLT). The model used in the analysis included the effects of breed and TG (fixed) and animal (random). PEVD was assumed the most adequate measure of connectedness and results from the alternative methods VED, CR, and GLT were compared against it. Models to predict the average PEVD of pairs of TG and the average PEVD of each TG with all other TG on the basis of VED, CR, and GLT were developed. Results from all measures of connectedness indicated an unfavorable trend in the degree of connectedness after 1994. The average PEVD of pairs of TG can be better predicted on the basis of the model that includes GLT. The average PEVD of each TG with all other TG can be better predicted on the basis of models that include either CR or GLT. Connectedness among TG of centrally tested beef bulls can be adequately assessed for specific pairs of TG or overall for each TG with all other TG using GLT. Key words: Accuracy, central test, genetic evaluation, harmonic mean
Mode of action of exogenous cell wall degrading enzymes for ruminants
Authors: Beauchemin K. A. , Colombatto D. , Morgavi D. P. , Yang W. Z. , Rode L. M.
Published: April 2011

Recent studies have shown that adding exogenous fibrolytic enzymes to ruminant diets can increase milk production of dairy cows and weight gain of growing beef cattle as a result of enhanced feed digestion. While much progress has been made in terms of advancing feed enzyme technology for ruminants, considerable research is still required to develop more effective enzyme products. The mode of action whereby exogenous enzymes improve digestion of plant cell wall is complex, and there is evidence for numerous potential modes of action suggesting they are interdependant. A mode of action that accounts for the most critical factors that explain the observed increases in feed digestion is presented. Adding exogenous enzymes to the diet increases the hydrolytic capacity of the rumen mainly due to increased bacterial attachment, stimulation of rumen microbial populations and synergistic effects with hydrolases of ruminal microorganisms. The net effect is increased enzymic activity within the rumen, which enhances digestibility of the total diet fed. Thus, improvements in digestibility are not limited to the dietary component to which the enzymes are applied, which explains why fibrolytic enzymes can be effective when added to supplement or grain. The magnitude of the improvements in feed digestibility reported in some research studies using feed enzymes suggests a viable future for enzyme products in commercial ruminant production systems. A more complete understanding of the mode of action of these products will allow development of low-cost enzyme products designed specifically to improve feed digestion by ruminants. Key words: Cattle, digestion, fibre digestion, enzymes, cellulases, hemicellulases
A rationale for the development of feed enzyme products for ruminants
Authors: Beauchemin K. A. , Colombatto D. , Morgavi D. P.
Published: April 2011

The use of exogenous cell wall degrading enzymes is an emerging technology that shows potential in terms of improving feed utilization by ruminants. This review discusses current information related to enzyme product formulation for ruminants, and addresses the conditions necessary to ensure effective and consistent in vivo results of providing feed enzymes to ruminants. Research has demonstrated that, in some cases, adding fibrolytic enzymes to dairy cow and feedlot cattle diets improves cell wall digestion and, consequently, weight gain or milk production are enhanced. However, considerable research is required to develop more effective enzyme products and to ensure consistency of responses in vivo. There is a need to identify the key enzyme activities involved in the positive responses observed in vivo and these enzyme activities should be assessed using a temperature and pH representative of the conditions in the rumen. However, to date, it has not been possible to accurately evaluate exogenous enzymes based only on their biochemical characterization because the model substrates used do not represent the complexity of plant cell wall material. In vitro techniques using feed substrates, buffer and ruminal fluid can be used more reliably as a bioassay to predict in vivo response to exogenous enzymes, however, other factors, including under or over-supplementation of enzyme activity, method of providing the enzyme product to the animal, composition of the diet, and the target animals must also be considered. Key words: Cattle, digestion, fibre digestion, enzymes, cellulases, hemicellulases
Seasonal herbage dynamics on Aspen Parkland landscapes in central Alberta
Authors: Asamoah S. A. , Bork E. W. , Irving B. D. , Price M. A. , Hudson R. J.
Published: April 2011

We evaluated the temporal dynamics of herbage biomass and protein within riparian meadows and upland grasslands of native Aspen Parkland rangeland to understand the contribution of each to lives tock foraging. For the growing season monitored, meadows were greater in forage yield and crude protein (P < 0.05), leading to important implications for sustainable livestock production and rangeland conservation. Key words: Crude protein, forage production, riparian meadow, upland grassland
Predicted methane emissions and metabolizable energy intakes of steers grazing a grass/alfalfa pasture and finished in a feedlot or at pasture using the GrassGro decision support tool
Authors: Cohen R. D. H. , Stevens J. P. , Moore A. D. , Donnelly J. R. , Freer M.
Published: April 2011

Dry matter intakes (DMI) and methane (CH4) emissions from steers grazing alfalfa/(Medicago sativa L)/meadow bromegrass (Bromus biebersteinii Roem & Schult.)/Russian wild ryegrass [Psathyrostachys juncea (Fisch.) Nevski] at 1.1 and 2.2 steers ha-1 in continuous and rotational grazing systems at Brandon, Manitoba, during the 1994 grazing season were predicted using the GrassGro decision support tool and compared with those reported from a field experiment. Observed DMI (13.82 ± 0.39 kg d-1) did not differ significantly (P = 0.052) from predicted DMI (12.10 ± 0.19 kg d-1). Mean predicted CH4 (278.5 ± 2.2 g d-1) was greater (P < 0.002) than field observations (195.8 ± 9.7 g d-1). This difference may reflect the difficulty of ensuring total collection of all CH4 emitted in a field experiment. GrassGro predicted that feeding a barley supplement to the steers while at pasture would cause a small though significant increase (P < 0.001) in mean daily emissions of CH4 (287.8 ± 1.9 g d-1) compared with unsupplemented steers (274.1 ± 2.9 g d-1). However, when CH4 emissions were compared as g kg-1 liveweight gain (LWG), they were less (P < 0.0001) for supplemented (133.2 ± 6.4 g kg-1 LWG) than unsupplemented steers (199.1 ± 5.9 g kg-1 LWG). In addition, supplementing barley at pasture would reduce (P < 0.0001) the total emissions of CH4 (38.7 ± 2.1 kg) compared with backgrounding at pasture and finishing in a feedlot (54.4 ± 1.1 kg). This would also reduce (P < 0.001) the metabolizable energy intake (MEI) required for liveweight gain (68.3 ± 1.94 vs. 87.2 ± 1.20 MJ MEI kg-1 liveweight gain). We conclude that finishing cattle at pasture will reduce the total emissions of CH4 and increase the efficiency of conversion of feed energy to liveweight gain when compared with backgrounding at pasture and finishing in a feedlot. Key words: Methane, steers, grass, alfalfa, pasture, barley, feedlot, metabolizable energy intake
Effect of supplementing high levels of vitamin D3 on calcium homeostasis of steers fed barley-based finishing diets
Authors: Aranda-Osorio G. , Olkowski A. A. , McAllister T. A. , Van Kessel A. , McKinnon J. J.
Published: April 2011

The objective of this study was to evaluate the effect of supplementing high levels of vitamin D3 to steers fed barley-grain-based finishing diets on Ca metabolism. Fifteen Hereford steers (607 ± 12 kg) were individually penned and fed at 0800 and 1600 with a ration consisting of 90% barley-grain-based concentrate and 10% barley silage [dry matter (DM) basis]. Steers were randomly assigned to one of three treatments: 0, 2.5 or 5 million IU (MIU) of vitamin D3 steer-1 d-1 for 7 d. Daily blood samples were obtained for measurement of serum for total and ionized Ca, parathyroid hormone (PTH) and calcitonin and plasma for vitamin D3 and 25(OH)D3. Data were analyzed by repeated measures analysis and single degree of freedom contrasts. Feed intake was depressed relative to control animals by 18 and 37% for the 2.5 and 5 MIU D3 treatments, respectively. Relative to controls, total and ionized Ca increased (P < 0.05) by 8 and 19% and 6 and 18% for the 2.5 and 5 MIU D3 treatments, respectively. Serum PTH concentrations were reduced (P < 0.05) by vitamin D3 feeding with the greatest reduction seen with animals fed the 5 MIU treatment. Calcitonin values were not (P > 0.05) affected. Relative to controls, plasma vitamin D3 concentrations increased (P < 0.05) in a quadratic fashion over time with vitamin D3 supplementation, while that of 25(OH)D3 increased (P < 0.05) in a linear fashion. It was concluded that the increase in serum calcium was stimulated by a rise in plasma vitamin D3 and the resulting increased 25(OH)D3 concentrations, which have been shown to influence calcium absorption either directly or via induced synthesis of 1,25(OH)2D3. Key words: Calcium homeostasis, vitamin D3, cattle, beef tenderness
Lipogenic activity in Rasa Aragonesa ewes of different body condition score
Authors: Arana A. , Mendizabal J. A. , Delfa R. , Eguinoa P. , Soret B. , Alzon M. , Purroy A.
Published: April 2011

The aim of the study was to assess the effect of body condition score on tissue and metabolic characteristics of the adipose depots in sheep of Rasa Aragonesa breed. Ewes were uniformly assigned according to their body condition score (BCS) (scale 0 to 5), to four groups: 0.75–1.75, 2–2.75, 3–3.75, and 4–4.5. The amount of fat and the adipocyte size in the different adipose depots increased as BCS did (P < 0.001) while the number of adipocytes did not change. The greatest ability to accumulate or mobilize fat was the subcutaneous depot (slope of the regression between amount of fat and BCS, b = 1.92; P < 0.001). Fatty acid synthase (FAS) lipogenic enzyme activity was affected by BCS, while G3-PDH and G6-PDH activities were not. Key words: Adipose tissue, body condition score, adipocyte size, lipogenic enzyme activity, ewes
Behaviour of mink kits and dams (Mustela vison) in the lactation period
Authors: Brink A. -L. , Jeppesen L. L.
Published: April 2011

This study describes the development of the behaviour of mink kits and dams from the fourth to the eighth respectively seventh week after delivery. The study is based on scan observations of 72 mink dams and their kits at a conventional Danish mink farm. The kits started eating when they were about 30 d old. Drinking started almost 2 wk later. During these 2 wk there was a peak in the licking of saliva from the dam and of the inter-litter agonistic behaviour. A causal relationship between experienced thirst and agonistic behaviour is suggested. The kits’ sucking declined to only 5% of the time budget in the seventh week and the stereotypy frequency of the dams increased to about 4% of the time budget. It is suggested that some dams are frustrated by the forced cohabitation with their nutritionally independent kits already in the seventh week and that this should be taken into account when deciding time of weaning. Key words: Animal welfare, behaviour, mink dam, mink kit, Mustela vison, weaning
Effects of dietary sunflower seeds on lactation performance and conjugated linoleic acid content of milk
Authors: He M. L. , Mir P. S. , Beauchemin K. A. , Ivan M. , Mir Z.
Published: April 2011

The conjugated linoleic acid (CLA) concentration in milk and the lactation performance of cows fed either a control (CON) or a sunflower seed [SS; 7% of dietary dry matter (DM)] containing diet were compared in a 12-wk lactation trial, starting from week 3 after calving, with 17 multiparous and 8 primiparous cows. The CON and SS diets were isonitrogenous and provided 4 and 6% crude fat in the total mixed rations and were fed to 13 and 12 cows, respectively. Daily DM intake (DMI ), milk production and weekly body weights were recorded. Milk samples collected weekly at four consecutive milkings were individually analyzed for fat, protein and lactose content, and fatty acid composition. The DMI and milk production of the cows fed t he CON and SS diets were 20.5 ± 0.80 and 20.2 ± 0.80 kg d-1 (P > 0.05) and 38.2 ± 1.71 and 38.2 ± 1.71 kg d-1 (P > 0.05), respectively. No differences due to diet were observed for cow body weight, body condition score, or for content and yield of milk fat, protein and lactose. The CLA cis-9, trans-11 concentration in milk from cows fed the CON and SS diets was 3.9 and 7.9 mg g-1 fatty acids (P < 0.01), respectively. The average CLA cis-9, trans-11 yield in milk from cows fed CON and SS diets was 5.1 ± 0.07 and 10.9 ± 0.07 g d-1, respectively, or 114% greater (P < 0.05) for cows fed the SS diet. The study indicates that sunflower seed inclusion at 7% of dietary DM to dairy cows increases the CLA concentration and yield in milk, without affecting DMI, milk production or composition. Key words: Conjugated linoleic acids, cow, milk, sunflower seed
Comparison of models and impact of missing records on genetic evaluation of calving ease in a simulated beef cattle population
Authors: Wang Yachun , Schenkel Flávio S , Miller Stephen P , Wilton James W
Published: April 2011

This study compared the application of a bivariate linear-linear (LL) and a linear-threshold (LT) sire-maternal grandsire model for genetic evaluation of calving ease (CE), using birth weight (BW) as a correlated trait, and assessed the impact of missing records on genetic evaluation of CE in a simulated multi-breed beef population that mimicked phenotypic and genetic parameters of beef cattle in Ontario. Models included fixed age-of-dam by sex-of-calf, management group, breed and heterosis effects, and random direct and maternal genetic, maternal permanent environment and residual effects. The LL model was applied to BW and CE Snell scores, and LT model was applied to BW and CE raw scores. CE evaluations were similar between the LL and LT models with no obvious advantage for either model. The two models performed similarly with respect to accuracy and rank correlation of predicted genetic effects and recovered true values of genetic parameters and fixed effects, except for CE maternal heterosis from LL model. The effect of missing records was assessed using the LT model. All dispersion and location parameters were generally well recovered, even when the total proportion of missing records of both traits was up to 41%. Levels of missing CE and BW records that exist in Ontario do not seem to adversely affect genetic evaluation of CE. Key words: Accuracy, Gibbs sampling, heterosis, Snell score
Effect of cultivar and enzyme supplementation on nutrient availability and performance of broilers fed Maritime Canadian wheat
Authors: Rafuse J. L. , Silversides F. G. , Bedford M. R. , Simmins P. H.
Published: April 2011

The feeding value of wheat is affected by the content of soluble non-starch polysaccharides (NSP), which varies among cultivars and the environment in which they are grown. Dietary enzymes can reduce the negative effects of NSP and improve the apparent metabolizable energy (AME) content of the wheat. This study examined differences in feeding value of four wheat cultivars grown in 2 crop years in the Maritime provinces of Canada and the need for enzymes. In a growth trial, diets containing one of the Maritime wheats or corn were fed with or without commercial enzymes containing, for wheat-based diets a mixture of xylanase and protease, and for corn-based diets a mixture of xylanase, protease, and amylase. In a broiler chick bioassay, diets containing 80% wheat were fed with or without a commercial enzyme with xylanase and protease activities. Enzymes significantly lowered body weight gain of birds fed Walton wheat in the second year, and improved the grower feed conversion ratio of birds fed Norboro wheat. Enzyme supplementation significantly improved apparent metabolizable energy and digestibility of crude protein. The AME content did not appear to be a direct indicator of performance. There were significant differences in AME content among the wheat samples. Enzymes generally did not improve performance in this study, possibly due to the relatively low in vitro viscosity values of these samples. Maritime wheats were equal or compared favourably with the sample of wheat from Western Canada and to locally obtained corn. Key words: Wheat, broiler performance, apparent metabolizable energy, enzyme
Lysine requirements of young broiler chickens are affected by level of dietary crude protein
Authors: Urdaneta-Rincon M. , de Lange K. , Peña-Ortega Luis , Leeson S.
Published: April 2011

Growth and body nitrogen and fat deposition in response to dietary lysine were assessed in chicks to 21 d of age when fed dietary crude protein (CP) at 170, 210, 250 or 290 g kg-1 diet. Response variables were evaluated using linear and quadratic regression, and linear-plateau models. In all cases, a better fit was observed with quadratic regression and linear-plateau models. Weight gain, F:G, and body nitrogen and fat deposition plateaued as dietary lysine was increased regardless of CP. Lysine requirements for weight gain to 21 d were significantly different when comparing 170 vs. 210 and 210 vs. 250 g CP kg-1 diets, although no differences were found when 250 and 290 g CP kg-1 were fed. Feed efficiency and body nitrogen responded in a similar manner to diet CP and lysine levels. Dietary lysine requirement increased as CP increased (170 vs. 210, and 210 to 250 g kg-1), although lysine requirement was unaffected when 250 or 290 g CP kg-1 diets are used. The requirements for lysine at low CP levels are better expressed as a percentage of CP. However, when dietary CP intake no longer limits growth, lysine needs should be specified as a diet percentage. Key words: Lysine, broiler chickens, nitrogen
Validation of the cannulated pig model for determining intestinal nutrient disappearance in cattle
Authors: Loveday D. M. , Thacker P. A. , Wilson D. G. , McKinnon J. J.
Published: April 2011

The mobile nylon bag technique was used to determine the potential of cannulated pigs to model intestinal dry matter (DM) and crude protein (CP) digestibility of ruminal undegradable residues (RUDR) of various feed samples in cattle. A total of 11 feeds (six protein supplements and five forages) varying in rumen degradability were utilized: canola meal (regular vs. heated); soybean meal (regular vs. heated); distillers’ grains (regular vs. heated ); alfalfa hay (regular vs. dehydrated alfalfa pellets); barley silage (regular vs. heated); and barley straw. Ruminal undegradable residues of each feedstuff were placed into eight polyester bags and inserted into the duodenum of two cannulated Hereford steers (644 ± 14 kg). Another eight bags for each RUDR sample were randomly allocated to six crossbred gilts (Camborough 15 line female × Canabred sire; 50 ± 1.2 kg body weight) and inserted into the pigs’ duodenum via duodenal cannulas. Bags were recovered in the feces from both the cattle and pigs. Regression analysis was used to relate intestinal DM and CP digestibility obtained in pigs with those obtained in steers. Intercepts not different from zero were forced through the zero intercept to obtain a measure of bias and loss of precision resulting from forcing the zero intercept. The non-zero regression equations relating steer estimates to those obtained from pigs were -3.17 + 0.95 X [r2 = 0.98, residual standard deviation (RSD) = 3.84] and 0.35 + 0.96 X (r2 = 0.98, RSD = 6.16) for DM and CP disappearance, respectively. Forcing the non-zero intercept resulted in pigs over predicting intestinal DM disappearance in cattle by 10.6% with a RSD of 4.30. Using the pig model, intestinal CP disappearance of cattle was over predicted by 3.1% with a RSD of 5.85. It was concluded that pigs can be used to model intestinal DM and CP disappearance of ruminal undegraded feed residues in cattle. Key words: Cattle, pigs, mobile nylon bag technique, intestinal nutrient availability
Phytase activity along the digestive tract of the broiler chick: A comparative study of an Escherichia coli-derived and Peniophora lycii phytase
Authors: Onyango E. M. , Bedford M. R. , Adeola O.
Published: April 2011

Residual activity of an Escherichia coli-derived phytase and a commercially available Peniophora lycii phytase along the digestive tract of broiler chicks was compared in order to evaluate their relative resistance to hydrolysis in the digestive tract. Seventy-two 7-d-old male broiler chicks were grouped by weight into six blocks of three cages with four birds per cage. Three corn-soybean meal-based diets were randomly assigned to cages within each block. The three diets were a low P diet containing 3.9 g P kg-1 diet; and low P diet plus either E. coli-derived phytase or the P. lycii phytase at 1000 units kg-1 of feed. The chicks were fed experimental diets from 8 to 22 d of age. At the end of the study, chicks were killed and the contents of the crop, proventriculus and gizzard, jejunum and ileum were collected, freeze-dried, ground and analyzed for phytase activity. Escherichia coli-derived phytase had more residual activity at the proventriculus and gizzard, jejunum and ileum when compared with the P. lycii phytase (P < 0.0001). The E. coli-derived phytase may be more resistant to hydrolysis in the digestive tract when compared with the P. lycii phytase. Key words: Broiler chick, Escherichia coli phytase, residual phytase activity
Efficacy of Alfasure™ for the prevention and treatment of alfalfa bloat in cattle
Authors: Majak W. , Lysyk T. J. , Garland G. J. , Olson M. E.
Published: April 2011

Alfalfa was grazed at early stages of growth to test the efficacy of field application of the pluronic detergent Alfasure™. Bloat was prevented under optimal weather conditions in the absence of rain but heavy rains could disperse the water-soluble product. A new route of administration of Alfasure™ was also examined for the treatment of bloat. Intraruminal injection of Alfasure™ was completely effective in the treatment of bloat, as was intraruminal injection of an industry standard product but on average the response time of Alfasure™ was significantly faster. Key words: Steers, frothy bloat, Medicago sativa L., feed supplements, Alfasure™