bluuebunny/crossref_metadata_2025 huggingface dataset:
Responses in gilt traits measured during performance test, at mating and at farrowing with selection for components of efficient lean growth rate
Authors: Kerr J. C. , Cameron N. D.
Published: September 2010

The responses in traits measured at the start of the mating period and at farrowing were examined after seven generations of divergent selection for daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-\ibitum feeding and lean growth on scale feeding (LGS). Weight and backfat depth at mating were measured on 330 gilts and 74 boars, which were selected on the basis of performance test traits. Farrowing information was available on 259 gilts. At the start of the mating period, gilts selected for high DFI, LGA or LGS had similar live weights (135, 137 and 137 (s.e.d. 4·5) kg) but different backfat depths (20·3, 14·0 and 11·3 (s.e.d. 1·3) mm) while the corresponding low lines had different live weights (129, 117 and 124 kg), but similar backfat depths (17·5, 17·8 and 17·8 mm). Gilts selected for high LFC had lower mean live weight and backfat depth (114 kg and 10·7 mm) than gilts in the other selection lines. Conception rates of gilts selected for low DFI or high LGS were similar (0·62 and 0·64, s.e.d. 0·12) and lower than for the alternative selection strategies (0-78), but the low DFI gilts were significantly older at farrowing than gilts selected for high LGS (424 v. 408 (s.e.d. 5·5) days). Responses in live weight, backfat depth, age at mating and particular reproduction traits were selection strategy dependent, such that identification of relationships between growth and reproduction traits will require measurement of additional growth traits at an earlier age than in the current study
The effect of genotype and sex on the patterns of protein accretion in pigs
Authors: Thompson J. M. , Sun F. , Kuczek T. , Schinckel A. P. , Stewart T. S.
Published: September 2010

Protein accretion curves were derived using food intake, growth and body composition data from a total of 320 pigs, which comprised castrated males and gilts from five genotypes. The 32 pigs from each genotype/sex subclass were offered ad libitum a series of isoenergetic diets (13·8 MJ metabolizable energy per kg) designed to provide a non-limiting intake of nutrients and to allow maximum protein deposition rates. Four pigs from each subclass weren slaughtered at each of the live weights (kg) 25, 44, 65, 85, 100, 115, 130 and 150. Daily food intake (dF/dt) was described as an increasing exponential function of age (t), live weight (W) as an increasing exponential function of cumulative food consumed (F), and protein weight (Pr) as an allometric function of live weight (W). The rate of protein accretion in the body of pigs [d(Pr)/dt] was calculated as d(Pr)/dt = (dF/dt).(dW/dF).(dPr)/dW). Bootstrap procedures were used to estimate standard errors for the food intake, growth and compositional parameters and to obtain the confidence bands for the dependent variables (dF/dt, W, Pr and d(Pt)/dt).

Protein accretion rate as a function of live weight was curvilinear, increasing to a maximum, then decreasing with increasing live weight. There were significant differences between subclasses in the maximum rate of protein accretion, although there was no relationship between this rate and the live weight, stage of maturity, or age at which maximum protein accretion occurred. Describing protein accretion as a multiplicative function of food intake, food efficiency and the partitioning of nutrients in the body allowed changes in the magnitude and shape of the protein accretion curve to be ascribed to one, or a combination, of the above mechanisms.
Effect of energy intake on the performance of different types of pig from 45 to 100 kg body weight. 2. Tissue gain
Authors: Quiniou N. , Noblet J. , Dourmad J.-Y.
Published: September 2010

The effect of energy supply on physical composition of body weight gain between 45 and 100 kg was studied in Large White castrated males (cLW), crossbred Pietrain × Large White castrated males (cPPX) and boars (bPPX). The pigs were either given food ad libitum and kept in individual pens in experiment 1, or allocated to four energy levels (0·70, 0·80, 0·90, and 1·00 ad libitum) and kept in metabolism cages in experiment 2. Daily protein supplies were calculated to be the same at the four energy levels within each type of pig and non-limiting for growth. Five additional animals for each type of pig were slaughtered at 45 kg. Daily tissue gain was measured according to the comparative slaughter technique. The daily lean gain increased with metabolizable energy (ME) intake according to a linear-plateau relationship whereas the daily fat gain increased linearly. The type of pig significantly affected the slope of the relationship between lean gain and ME intake (from 15 to 22 g per extra MJ ME) but not the slope of the relationship between fat gain and ME intake (10 g per extra MJ ME on average). Increased energy intake was associated with increased fatness of body-weight gain, which was higher in cLW and cPP× than in bPP×.
The use of the excretion of nitrogen compounds as an indirect index of the adequacy of dietary protein in chickens
Authors: Fernández Fígares I. , Nieto R. , Aguilera J. F. , Prieto C.
Published: September 2010

An experiment was carried out to study the effect of changes in either the quality or the quantity of dietary protein intake on the excretion of nitrogen (N) compounds in the chicken. Thirty-two White Rock male broilers (1 day old) were raised in batteries and fed a commercial starter diet for 9 days. Then they were randomly divided into eight groups each of four birds, of similar body weight (mean live weight: 178 (s.e. 1·9) g), and individually housed in metabolism cages. Following a paired-feeding design based on metabolic body weight (kg M0·75), each group of birds was given, for an experimental period of20 days, each of four levels of protein (60, 120, 180 or 240 g/kg: 5 days each) in two groups of isoenergetic (14·5 kj metabolizable energy per g dry matter) and semisynthetic diets based on soya-bean meal, known to be first limiting in methionine, either unsupplemented (diets S) or supplemented with 2 g/kg DL-methionine (diets SM). Excreta were collected every 3 days for 48 h, frozen and stored at −20°C. The excreta samples were subjected to chemical analysis for uric acid by a rapid high-performance liquid chromatographic method, for urea and ammonia by a colorimetric method, and for total N by the Kjeldahl procedure. In general, the excretion of major N compounds was markedly affected by either the quality or the content of dietary protein. Overall, the excretion of total N, uric acid-N, ammonia-N and urea-N significantly (P < 0·05) decreased with improvement in dietary protein quality and significantly (P < 0·05) increased with increase in protein intake. Regression equations were obtained relating the excretion of uric acid, urea, ammonia and total N on protein supply. For the partition ofN compounds output, the ratios of uric acid-N and ammonia-N to total N significantly (P < 0·05) decreased on improving dietary protein quality and increased or remained unchanged, respectively, with the increase in dietary protein content. The use of the ratio of ammonia-N to total N is recommended as a rapid, easy and accurate indicator of dietary protein adequacy, as an alternative to measures based on total N balance, without the need for separation of urine and faeces.
Production, fertility and hatchability of ostrich (Struthio camelus) eggs on a farm in the United Kingdom
Authors: Deeming D. C.
Published: September 2010

The farming of ostriches is well established in South Africa and is gaining in popularity in agriculture around the world but few scientific data are available for rates of egg production and the factors affecting incubation and hatching. Production and hatchability of over 1200 ostrich eggs on a farm in the United Kingdom were recorded during the 1995 season. Females of breeding ages (no. = 43) were kept in 13 enclosures in sex ratios of 1: 1 or 1: 2 (M: F). Productivity of all ostriches over the laying season was 25·2% although when results from individual enclosures, and from individual birds, were examined higher rates of production were achieved although only one bird achieved her full laying potential. As group size increased productivity decreased. Overall fertility was 78·7% although fertility greater than 90% was achieved by females kept in pairs or trios. Larger group sizes had lower fertility. Mean weekly hatchability was only 24·1% with hatch of fertile eggs being 31·9%. Maximum hatchability of eggs produced from an individual female was 73% of fertile eggs. Microbial contamination of eggs was 32·6% and this was the biggest cause of failure to hatch, although rates of contamination varied between females. These results for productivity are similar to those published for ostriches in Israel and South Africa. Hatchability is lower, and microbial contamination is higher than published information although this is the most comprehensive study of ostrich production yet published. Future development of ostrich breeding programmes needs to concentrate on small breeding groups, preferably pairs, and on improvements in nest site hygiene and post-laying egg management.
Customized selection indices for dairy bulls in Australia
Authors: Bowman P. J. , Visscher P. M. , Goddard M. E.
Published: September 2010

Customized sire selection indices were developed for Australian dairy bulls in order to promote more objective use of estimated breeding values in commercial breeding programmes. It was assumed that the breeding goal for commercial dairy farmers is the profitability of a bull's progeny. Seven characteristics of the progeny were identified as having a major impact on profitability and were included in the breeding objective: milk, fat and protein yield, survival, body weight, milking speed and temperament. Traits in the selection indices used to predict profit were milk, fat and protein yield, survival, milking speed, temperament, size, overall type and fore teat placement. Size was included because of its correlation with body weight, and overall type and front teat placement because of their correlation with survival. To avoid double counting the benefits of milk production traits, temperament and milking speed, the survival trait in the objective was defined as survival independent of voluntary culling for these traits. Customization of the breeding objective was achieved by adjusting the economic weights for traits in the objective to take account of important characteristics of farmers' herds, the milk payment system under which they operate and make allowance for their own value judgements. An assessment of the impact of customization suggested that, even though there is a wide range in the economic weights that are applicable in different areas of Australia, there would be little loss of efficiency in using a single national index. However, customization is still believed to be desirable given that it is likely that a substantial proportion offarmers will be reluctant to use a national index, especially in those states which have quotas and focus on the liquid milk market. The algorithms described in the paper have been incorporated into a user-friendly microcomputer program called $electabull which is now commercially available to farmers.
Behavioural and hormonal responses of pigs during transport: effect of mixing and duration of journey
Authors: Bradshaw R. H. , Parrott R. F. , Goode J. A. , Lloyd D. M. , Rodway R. G. , Broom D. M.
Published: September 2010

Two experiments investigated the welfare of pigs during transport. In experiment 1, 12 groups offour 90-kg pigs were transported to slaughter in a commercial livestock lorry for 1·5 h. Half the animals were transported in their social groups (unmixed condition) and half were transported with groups of previously unfamiliar pigs mixed together (mixed condition). Behaviour was recorded, a general activity index scored and saliva samples taken at different stages of the journey for analysis ofcortisol. Pigs spent most of their time standing in both conditions. The journey was very rough (as revealed by characterization with an accelerometer) and in the unmixed condition the pigs appeared to stand to reduce travel sickness. In contrast, in the mixed condition, this preference for standing seemed to be due to fighting which stressed and exhausted the animals (the general activity index was three times the unmixed condition). Levels of salivary cortisol were higher in the mixed condition at the beginning, middle and end of the journey. In experiment 2, six 35-kg pigs, prepared in advance with jugular vein catheters, were loaded onto a commercial livestock lorry (09.30 h) where they were individually penned. The vehicle remained stationary with the engine off and blood samples were taken at 30-min intervals during the next 8 h (control). Two days later this procedure was repeated while the vehicle was driven for 8 h (on main roads and motorways). Plasma concentrations of cortisol and beta-endorphin increased markedly in both conditions immediately after loading. Cortisol levels were greater (relative to control) at the beginning, in the middle and at the end of the journey. Concentrations of beta-endorphin did not differ between control and experimental conditions except during the final 180 min of the journey when the control levels were higher.
Carcass composition and body fat depots of Galego Bragançano and crossbred lambs by Suffolk and Merino Precoce sire breeds
Authors: Teixeira A. , Delfa R. , Treacher T.
Published: September 2010

The main purpose of this work was to compare two breeds of improved rams (Suffolk and Merino Precoce) with the local Galego Bragangano breed for the production of crossbred slaughter lambs and to evaluate which cross was more adapted for meat production from the local breed in locations in the north-east of Portugal. The experiment was carried out over a 4-year period in three locations: (1) a farm with an intensive management; (2) an upland farm (400 to 600 m); and (3) a hill farm (above 800 m). Within each flock with 90 Galego Bragangano ewes, two rams of each of the sire breeds were used: Galego Bragangano, Suffolk and Merino Precoce. The lambs were slaughtered at 20 and 40kg, to obtain the carcass weight range of 8 to 14kg. The left sides of 151 carcasses were dissected into muscle, subcutaneous fat, intermuscular fat and bone. The lambs from location 1 had the highest carcass muscle proportion and the lowest carcass intermuscular fat proportion; their differences over locations 2 and 3 were 13 and 16 g/kgfor muscle proportion and 11 and 19 g/kgfor intermuscular fat proportion, respectively. The differences between breeds were relatively small and not significant. However the Suffolk crosses had less kidney, knob and channel fat than the other genotypes (5 and Uglkg less than Merino crosses and Bragangano, respectively). The Suffolk crosses tended to have less body fat.
Growth and food intake curves for group-housed gilts and castrated male pigs
Authors: Andersen S. , Pedersen B.
Published: September 2010

Polynomial models with random regression coefficients were used to describe cumulated food intake and gain as a function of number of days on test for gilts and castrated male pigs which were on test from 30 to 115 kg live weight. Growth rate and daily food intake were expressed as the derivative of the curves. The applied models allowed a separation of between and within animal variation. Confidence limits for average curves and prediction limits for individual curves were also obtained. A similar model was used to describe gain as a function of cumulated food intake. From this function food efficiency was obtained. The application of the results in stochastic simulation models is discussed.

Growth rate and daily food intake had a more curvilinear progress for castrated males than for gilts. It was estimated that 98% of the castrated males and 96% of the gilts had a lower growth rate at day 80 than at day 50; 74% of the castrated males and 48% of the gilts had a lower daily food intake at day 100 than at day 80. On average food efficiency of gilts was higher than food efficiency of castrated males and the difference increased through the test period.
Simulation of growth in pigs: approximation of protein turn-over parameters
Authors: Knap P. W. , Schrama J. W.
Published: September 2010

A dynamic model for simulation of growth in pigs was extended by a module to describe protein turn-over in six body protein pools (muscle, connective tissue, liver, blood plasma, gastro-intestinal, and 'other' proteins). The model describes protein deposition in these pools following different growth curves and differential rates of turnover. Growth curve parameters and turn-over rates were obtained from the literature.

In growing animals, experimentally measured turn-over rates represent a combination of turn-over of already-present body protein and fractional (repeated) synthesis of newly deposited protein. An attempt was made to distinguish between these processes by varying the values of the fractional rate of synthesis of newly deposited protein (FRSdrp) and of the proportionof maintenance energy requirements not related to protein turn-over (FrcMEmaint), and comparing the simulated outputto the output from the original model without the protein turnover module.

The turn-over rate (TRpres)of already present connective tissue protein reached unrealistic values for FRSdep > 2·5 per day, which puts an upper limit on FRSdep.

The output from the extended and the original models showed similar patterns for certain combinations of FRSdefl and FrcMEmaint, dependent on the levels of model input variables. For FRSdcp 2·5 perday, these similar patterns have their optimum at FrcME^^ = 0·65, coinciding with FRSdep =2·0 per day. The corresponding TRpres values were 0·060, 0·019, 0·585, 1·492, 0·582, and 0·016 per day for the above mentioned pools.
The effects of treating low dry matter herbage with a bacterial inoculant or formic acid on the intake and performance of lactating dairy cattle
Authors: Keady T. W. J. , Murphy J. J.
Published: September 2010

A randomized block design experiment involving 64 lactating dairy cattle was carried out to evaluate a bacterial inoculant and two rates of formic acid as silage additives. Herbage from the primary growth of a predominantly perennial ryegrass sward was ensiled unwilted using two precision-chop harvesters. Alternate loads of herbage were either untreated (UT) or treated with formic acid applied at the rate of 2·7 l/t grass (LF) and 5·7 l/t grass (HF) or an inoculant enzyme preparation applied at the rate of 2·2 l/t grass (I). The mean dry matter (DM) and water-soluble carbohydrate (WSC) concentrations and buffering capacity of the UT herbage were 148 g/kg, 151 g/kg DM and 638 mEq/kg DM. Inoculant treatment had no effect on the rate of silage fermentation post ensiling relative to the UT silage whereas HF treatment produced a restricted fermented silage. For silages UT, LF, I and HF, pH values were 4·53, 3·89, 4·32 and 4·05 (s.e.d. = 0·061); ammonia nitrogen (N) concentrations were 179, 89, 150 and 73 g/kg total N (s.e.d. = 10·4); butyrate concentrations were 6·0,1·9, 5·1 and 2·0 g/kg DM (s.e.d. = 1·24); and WSC concentrations were 14·4, 35·2, 18·0 and 100·7 g/kg DM (s.e.d. = 1·24), respectively. The silages were offeredad libitum. The UT silage was supplemented with either 2 (UT2), 4 (UT4) or 6 (UT6) kg concentrates per head daily while the LF, I and HF silages were supplemented with 4 kg (LF4,14, HF4) of concentrates. For treatments UT4, LF4, 14 and HF4, silage DM intakes were 9·69, 10·89, 9·93 and 10·89 (average s.e.d. = 0·465) kg/day; fat plus protein yields 1·39,1·44,1·32 and 1·49 (average s.e.d. = 0·057) kg/day; protein concentrations 29·2, 31·1, 29·9 and 30·2 (average s.e.d. = 1·01) g/kg. Inoculant treatment increased N apparent digestibility (P < 0·05) of the total diets relative to UT. The apparent digestibilities of neutral-detergent fibre (P < 0·05) and hemicellulose (P < 0·01) were decreased due to HF treatment. For the production of a constant milk fat plus protein yield it was estimated that an extra 0·63 kg per head per day and 1·04 and 1·77 kg per head per day less concentrate would be required for the I, LF and HF treatments, respectively. It is concluded that relative to the UT treatment, I treatment had no beneficial effects on silage fermentation, total diet apparent digestibility (other than N apparent digestibility) or animal performance. The LF treatment improve lage fermentation and intake, and tended to increase the yield of fat plus protein (P > 0·05) whereas HF treatment restricted silage preservation and increased silage intake and the yields of protein and fat plus protein.
Indoor space allowance: effects on growth, behaviour, adrenal and immune responses of finishing beef heifers
Authors: Fisher A. D. , Crowe M. A. , Prendiville D. J. , Enright W. J.
Published: September 2010

The objective was to determine the daily live-weight gain, behaviour, adrenal and immune responses of finishing beef heifers housed at two different space allowances. Heifers (no. = 32) with a mean live weight of466 (s.e. 3·6) kg were assigned to either 1·5 or 3·0 m2average individual space allowance in four slatted-floor pens (two per treatment) for a period of 104 days. On days 5, 40, 68 and 96, heifers (no. = eight per treatment, four per pen) were challenged with 1·98 i.u. ACTH per kg M0·75, and serial blood samples were analysed for plasma cortisol concentrations. The other 16 heifers were immunized against keyhole limpet haemocyanin (KLH) on day 28, and blood samples collected on days 28, 42, 56, 70, 84 and 98 were analysed for anti-KLH immunoglobulin (Ig) concentrations. All heifers were blood sampled on days 0, 14, 56 and 98, and red and white blood cell numbers, packed cell volume (PCV) and plasma concentrations of creatine kinase (CK), non-esterified fatty acids (NEFA) and urea were determined. Behavioural observations were conducted on days 8, 43, 71 and 99 by scan sampling for 24 h (10-min intervals), and continuous 4-h observations were conducted on days 100 and 101.

Heifers at 1·5 m2space allowance had a lower daily live-weight gain compared with those at 3·0 m2(0·60v.0·87 (s.e. 0·04) kg;P< 0·001). Heifers at 1·5 m2had lower pre-ACTH baseline cortisol concentrations (P < 0·05) and lower post-ACTH peak cortisol concentrations (P < 0·05). There were no effects of treatment on serum anti-KLH IgG1or IgG2responses (P > 0·05). Heifers at 1·5 m2had lower plasma NEFA concentrations (P < 0·05). Red and white blood cell numbers, PCV, CK and urea were not affected by treatment (P > 0·05). The time spent lying down was lower for heifers at 1·5 m2(10·0v.21·1 h/day;P< 0·05). Social interactions were fewer (P < 0·05), and incidence of head-resting behaviour was higher (P < 0·05) among heifers at 1·5 m2compared with 3·0 m2space allowance. In conclusion, the restricted space allowance resulted in a substantial decrease in daily live-weight gain, and changes in adrenal response and behaviour.
Passage rate of solids and fluids in the digestive tract of buffaloes, cattle and sheep: selection of non-linear model
Authors: Amici A. , Bartocci S. , Terramoccia S. , Martillotti F.
Published: September 2010

Five mathematical models were compared to select the most satisfactory model to describe digesta kinetics of solids and fluids in the gastrointestinal tract of buffaloes (Mediterranean bulls), cattle (Friesian bulls) and sheep (Delle Langhe rams) given food at maintenance level, according to a Latin-square arrangement for four consecutive periods of 21 days. Chromium mordanted alfalfa hay and cobalt-ethylenediamine tetraacetic acid were used as nonabsorbable markers and were administered through the rumen cannula in a single dose. Four different isonitrogenous diets (N × 6·25 = 140 g/kg dry matter) with different concentrate:forage ratios (12·5:87·5, 25:75, 37·5:62·5, 50:50) were used.

Faecal chromium and cobalt concentration curves were fitted with five non-linear models: three gamma (G2, G3, G4) age-dependent one-compartment, one gamma age-dependent/age-independent two-compartment (G2G1) and one multicompartment (MC).

Wilcoxon tests on residual sums of squares of the different models for solids showed that MC and G4 gave a better fit than G2G1, G2, G3 for all the data and within the species. The comparison of MC v. G4 did not show any significant difference (P > 0·05) for all the data computed together or within each species. Nevertheless, MC had a higher number of curves with lower residual sums of squares in comparison with G4 and was also able to produce estimates of digesta kinetics in the second compartment.

The cobalt excretion curves for fluids, considering all the data, and only within sheep, showed G4 as the best fitting model. When G4 was compared with other models no significant differences were recorded either for cattle: G4 v. G2 (F = 0·6645), G4 v. G2G1 (P = 0·0620) and for buffalo: G4 v. G2 (P = 0·1575), G4 v.G3(P = 0·0796) and G4 v. G2G1 (P = 0·1641).

It is concluded that the multicompartment model (MC) and G4 model were the best fits for solids and for fluids respectively.
Estimation of the mature weight of three breeds of Greek sheep using condition scoring corrected for the effect of age
Authors: Zygoyiannis D. , Stamataris C. , Friggens N. C. , Doney J. M. , Emmans G. C.
Published: September 2010

The objective of this study was to evaluate the influences of age and condition score on the live weight of ewes of three Greek dairy breeds. Boutsko (no. = 225), Serres (no. = 292) and Karagouniko (no. = 301) ewes from individually recorded purebred flocks were weighed (±0·5 kg) and condition scored, on a six-point scale, to the nearest 0·5 unit. Within each breed and age group the relationship between live weight and condition score was derived by linear regression. There was a highly significant relationship between condition score and live weight in all of the groups (P < 0·01). Live weight, adjusted to a standard condition score, increased with increasing age up to 3·5 years; beyond this age there was no effect of age on condition score. The live weight and condition score data for ages 3·5 years and upwards were used to derive a single regression between live weight and condition score for each breed. This provides a means to estimate adult live weights standardized to a given condition score. The values of the regression coefficients were directly proportional to the breed mature weight; on average the increase in live weight associated with a unit of condition score was 0·129 kg/kg of mature weight for the three breeds studied. Mature weight was estimated as the weight at a condition score of 5. Using published information, a similar value was found to apply to a wide range of sheep breeds and also to cattle. This robust value permits the live-weight change associated with a unit of condition score to be calculated, for any breed.
Effect of forage to concentrate ratio on comparative digestion in sheep, goats and fallow deer
Authors: Ramanzin M. , Bailoni L. , Schiavon S.
Published: September 2010

Three ewes, three female goats and three male fallow deer, aged between 7 and 12 months and weighing 24·0 to 32·2 kg, were used in this experiment to outline the main differences in digestion among the three species. Dietary treatments were three diets with three forage: concentrate ratios of 10: 90, 50: 50, and 90:10 and two different feeding levels (45 and 90 g/kg M0·75per day). The three diets were given to the three animals of each species in a Latin-square design; the two levels of feeding were compared ivithin diet in each period of the Latin square. The diet selected, apparent digestibility, and rumen retention time of Cr-mordanted neutral-detergent fibre were significantly different among species and dietary treatments. Interactions between species and dietary treatments were also significant for all the above variables. Sheep showed the highest intakes and apparent digestibilities of the forage-rich diets, and the longest rumen mean retention times. Goats tended to select diet components, despite allowance of diets being limited, and had lower food intakes than sheep. Apparent digestibility of forage-rich diet was also lower. Rumen mean retention times were shorter and less influenced by dietary treatments. Fallow deer had an apparent digestibility of forage-rich diets which was even lower than that of goats. Food intake was similar to that of sheep, with no evidence of selection. Rumen mean retention time was shorter than that of goats.
Effect of feeding diets high in monounsaturated fatty acids and α-tocopheryl acetate to rabbits on resulting carcass fatty acid profile and lipid oxidation
Authors: Lopez-Bote C. , Rey A. , Ruiz J. , Isabel B. , Sanz Arias R.
Published: September 2010

The effects of olive (MONO) or sunflower (POLY) oil-enriched (30 g/kg) diets with either a basal (10 mg/kg food) or supplemented (200 mg/kg) level of a-tocopheryl acetate on some measures of production, fatty acid composition of animal tissues and susceptibility to oxidation of rabbit meat and membrane extracts have been studied. MONO diet produced higher levels of C18:1 in animal tissues. Animals that received POLY diet had a higher level of C18:2 in perirenal and neutral fraction of intramuscular fat and higher levels of C18:2, C20:4, C22:4 and C22:5 in phospholipid, reaching a higher overall unsaturation (P = 0·001). Muscle samples from rabbits given the POLY diet were more susceptible to lipid oxidation (P = 0·0001). Differences in membrane lipid oxidation, between groups followed a similar pattern to that of meat. Diets rich in C18:2 resulted in increases in concentration of pentanal (P < 0·001), hexanal (P = 0·0001) and total volatile aldehydes (P = 0·0001) in meat as monitored by headspace gas liquid chromatography. Dietary supplementation with α-tocopheryl acetate reduced the overall concentration of volatile aldehydes (P < 0·05), particularly hexanal (P < 0·05). Dietary administration of monounsaturated fatty acids not only reduces membrane and meat lipid oxidation but also modifies the relative proportion of volatile aldehydes generated upon heating, with a specific decrease in those generally related to rancidity and off-flavour of meats.
Measuring diet selection in dairy cows: effect of training on choice of dietary protein level
Authors: Tolkamp B. J. , Kyriazakis I.
Published: September 2010

In a 7-week experiment, the ability of lactating Holstein-Friesian cows to select a consistent diet from two similar foods differing in calculated metabolizable protein to energy (MP/ME) yield was investigated. The effect on diet selection of training through previous access to foods separately, was measured. Food intake was recorded with 28 computer-linked feeders. All foods were mixtures of grass silage and concentrates. In week 1, all feeders contained a standard food. In weeks 2 to 7 a low protein food (LP) and a high protein food (HP) were offered in 14 feeders each. Group CHOICE had access to both foods as a choice from week 2. Group TR1 was trained by access to one food during days 8 to 10 and to the other during days 11 to 13. Group TR2 received the same training as group TR1 during days 8 to 13 which was repeated once during days 14 to 19. After training, TR groups had access to both foods as a choice. Groups LOPRO and HIPRO had only access to LP or HP, respectively in weeks 2 to 5 and to both foods as a choice in weeks 6 and 7. In weeks 2 to 5 LOPRO COWS consumed less dry matter and produced less milk than CHOICE or HIPRO cows. After a week of adaptation, untrained CHOICE COWS selected 662 (s.e. 27) g HP per kg of intake, a choice that differed significantly (P < 0·01) from random. In weeks 4 to 7 TR cows established similar diet choice: 696 (s.e. 21) g HP per kg intake and the proportion selected was unaffected by length of training. The between-day variation in diet choice within cows was not affected by treatment. It is concluded that, under the circumstances tested, training was not required for cows to distinguish between two mixed foods with different calculated MP/ME ratios and to select proportions significantly different from random.
The effect of body condition on the feeding behaviour of sheep with different times or access to food
Authors: Sibbald A. M.
Published: September 2010

Intakes and feeding patterns were studied in two groups of 24 Scottish Blackface ewes, with initial mean body condition scores of 2·15 (thin) and 3·15 (fat). Three treatments, allowing access to a dried-grass pellet diet ad libitum for 6, 12 or 24 h/day, were applied in a Latin-square design, with each sheep receiving each treatment for one 12-day period. Food intakes were measured daily and feeding activity was recorded automatically every minute for one 24-h period during the last 5 days of each 12-day treatment period.

Mean intakes were higher for thin than for fat ewes (1720 v. 1467 g dry matter (DM) per day; P < 0·001). There were no interactions between the effects of body condition and food access time and mean intakes over the last 7 days for the 6-, 12- and 24-h food access treatments were 1429, 1686 and 1805 g DM per day respectively (T < 0·001). Time spent feeding was higher for thin than for fat ewes, over the whole day (231 v. 197 mini day; P < 0·05) and in the first 6 h after the introduction of fresh food (140 v. 120 min; P < 0·05), but there were no differences between thin and fat ewes in the frequency of meals or in the rate of intake during meals. Intakes for the first 6 h were higher with restricted food access (1402, 1109 and 819 g DM per day for 6-, 12- and 24-h access; P < 0·001) but there were no differences in time spent feeding. The number of meals during the first 6 h was higher (10·4 v. 8·3; P < 0·05) and the rate of intake was higher (11·4 v. 7·8 g/min; P < 0·05) for 6-h compared with 24-h food access.

It was concluded that long-term differences in intake due to body condition and short-term changes due to restricting food access time, involve different behavioural responses and this may reflect differences in the mechanisms involved in the regulation of voluntary intake. Keywords: body condition, feeding behaviour, sheep.
Modelling responses to selection for resistance to gastro-intestinal parasites in sheep
Authors: Bishop S. C. , Stear M. J.
Published: September 2010

This paper describes a general framework which enables responses to selection for resistance to gastro-intestinal parasites in sheep to be stochastically modelled. The model incorporates between-animal variation for pasture intake, the proportion of larvae ingested from the pasture which survive to become adults, the fecundity of the mature worm, along with density-dependent control of this trait and the mortality rate of the worms. The between-animal variation for each component is partitioned into genetic, permanent and temporary environmental components which vary with age. Infection rates are estimated from existing pasture larval contamination and new contamination from infected animals. Using this framework, selection for reduced mean faecal egg count was practised, in silico, for a period of 10 years. Several general patterns emerged. First, a curvilinear response to selection was observed, with responses initially being large then declining over time. Mean faecal egg count declined from approximately 500 to 140 eggs per gin 10 years and worm burdens and pasture larval contamination showed similar patterns of response. The initial responses to selection were approximately 1·7 times that predicted by quantitative genetic theory because the epidemiology of the disease changed as the animals' genetic resistance improved. A method of partitioning selection responses into components due to the altered genotypes of the animals and components due to altered disease epidemiology is outlined. Secondly, the faecal egg count distribution became more aggregated, or skewed, as selection progressed. Thirdly, correlating pasture contamination levels across years (carry-over effects) resulted in even greater apparent responses to selection. Finally, regular anihelmintic treatment reduced mean faecal egg counts but did not alter the patterns of response to selection, indicating that selective breeding should be feasible under a variety of anthelmintic regimes.
Effects of isolation on the behaviour, live-weight gain, adrenal capacity and immune responses of weaned red deer hind calves
Authors: Hanlon A. J. , Rhind S. M. , Reid H. W. , Burrells C. , Lawrence A. B.
Published: September 2010

At weaning at 3 months of age (week 1), 30 red deer hind calves were housed in six groups of five animals at a stocking density of 1·5 m2 per head and maintained in these groups for 4 weeks. At the start of week 5, all calves were immunized with ovalbumin (OVA). Fifteen calves, from three groups, selected at random, were transferred to individual pens which restricted visual and tactile contact with others (ISO) while the remaining animals were kept in their groups (GP). The behaviour, food intake, live-weight gain, antibody and lymphocyte responses in vitro to OVA and lymphocyte responses in vitro to the non-specific mitogen, concanavalin A (ConA), of all calves were assessed in each of weeks 5 to 9. Isolated calves had a lower mean live-weight gain than GP calves (P < 0·001), although there were no differences in food intake. Significantly more time was spent lying (P < 0·001) but less time feeding (P < 0·05) and self-grooming (P < 0·001) by ISO than by GP calves. There was no significant difference between ISO and GP calves in the cortisol response to an ACTH challenge test (10 i.u.) at week 11. Lymphocyte responses and antibody titres to OVA were lower in GP than in ISO calves at weeks 7 (P < 0·05) and 8 (P < 0·05), respectively. In contrast, GP calves had greater lymphocyte responses to the non-specific mitogen, ConA, in weeks 7 (P < 0·05) and 10 (P < 0·001) but not in week 9 compared with ISO calves. Differences in lymphocyte stimulation were attributed to the non-specific mitogenic nature of ConA. Factors such as agonistic interactions evident in group housing may have compromised the antibody and lymphocyte responses to OVA by GP calves but conversely the lack of social contact may have also suppressed behavioural activity in ISO calves.
Use of near infrared reflectance spectroscopy to predict and compare the composition of carcass samples from young steers
Authors: Sanderson R. , Lister S. J. , Dhanoa M. S. , Barnes R. J. , Thomas C.
Published: September 2010

The aim of the current study was to investigate the effects of level of feeding and level offish-meal supplementation on the carcass composition of young steers and in doing so, to assess the potential for employing near infrared reflectance spectroscopy (NIRS) in such studies. In addition to wet chemical techniques, NIRS was used to examine carcass samples from animals offered silage-based diets at one of four levels of feeding ranging from near maintenance toad libitumand with one of four levels offish meal (0, 50,100 or 150 g/kg silage dry matter).

Wet chemical data indicated an increase in fat concentration (P < 0·001) and decrease in crude protein concentration (P < 0·05) in the fresh carcass in response to increasing level of feeding but no statistically significant effect of level of fish meal. Ash concentration was not affected significantly by either level of feeding or level of fish-meal supplementation. Ground, freeze-dried samples were scanned in the wavelength range 1100 to 2498 nm. Calibration equations for ash, fat and crude protein concentration (g/kg carcass) were derived using a modified partial least-squares regression technique. Equations were found to be superior for fat compared with those for crude protein and ash. Standard errors of calibration (g/kg carcass) and multiple correlation coefficients of 6·96 and 0·42, 6·61 and 0·95 and 4·36 and 0·61 were obtained for ash, fat and crude protein respectively with corresponding standard errors of cross validation of 7·71, 7·82 and 4·96 g/kg carcass respectively. Qualitative analysis of spectral information using multivariate techniques and difference spectra clearly showed differences in carcass composition resulting from the different levels of feeding and less so the different levels offish-meal supplementation.

It is shown, that NIRS can be used both quantitatively and qualitatively to study the effects of nutrition on carcass composition.
Influence of lambing date on subsequent ovarian cyclicity and ovulation rate in ewes
Authors: Mitchell L. M. , King M. E. , Aitken R. P. , Wallace J. M.
Published: September 2010

The effect of lambing date on the subsequent onset and duration of ovarian cyclicity in Mule (Bluefaced Leicester × Scottish Blackface) ewes was investigated. Nineteen ewes which had lambed in January (16 January 1993 (s.e. 3 days)) and been weaned in February-March and 22 comparable ewes which had lambed in May (14 May 1993 (s.e. 2 days)) and been weaned on 23 August were maintained at pasture as two isolated groups. A raddled vasectomized ram was continually present with each group from 14 July 1993 to 26 May 1994 and marked (oestrous) ewes were recorded twice weekly. Ovarian activity was assessed by measuring peripheral progesterone concentrations in blood samples collected twice weekly and by laparoscopic viewing of the ovaries of all ewes during October, January and March. The onset and duration of ovarian activity were significantly affected by the previous lambing date. For January and May lambing ewes, mean dates of onset were 5 September 1993 (s.e. 2 days) v. 25 September 1993 (s.e. 4 days) (P < 0·001) and of cessation were 5 April 1994 (s.e. 5 days) v. 10 April 1994 (s.e. 3 days). Mean durations of ovarian activity were 212 (s.e. 6) and 195 (s.e. 5) days (P < 0·05) during which 12·4 (s.e. 0·29) and 11·5 (s.e. 0·38) ovarian cycles respectively were recorded. Ovulation rate was not affected by previous lambing date but was significantly lower in March compared with October (January lambing ewes 1·7 (s.e. 0·1) v. 2·3 (s.e. 0·1) (P < 0·001); May lambing ewes 1·6 (s.e. 0·1) v. 2·1 (s.e. 0·1) (P < 0·01)). Results demonstrate that (i) Mule ewes have a potential breeding season of up to 8 months duration; (ii) the onset and duration of ovarian activity can be influenced by previous lambing date; and (Hi) a seasonal decline in ovulation rate may, in practical terms, result in a lower lambing percentage for animals bred towards the end of their natural breeding period.
Selective enhancement of growth in twin foetuses by shearing ewes in early gestation
Authors: Morris S. T. , McCutcheon S. N.
Published: September 2010

Shearing ewes during pregnancy frequently increases the birth weight of lambs. In housed ewes, the birth weight responses are greatest when shearing occurs relatively early in pregnancy. This study examined the effects of the timing and method of shearing on foetal growth, as measured by birth weight, in ewes at pasture. Border Leicester × Romney ewes were allocated at day 50 of pregnancy to: four ‘time of shearing’ treatments — pregnancy day 70 (P70), P100, P130 (no. = 60 for each treatment) and unshorn (no. = 34); two methods of shearing (by standard comb or cover comb); and two levels of pregnancy/rearing rank All ewes had been mated over a 14-day period and grazed pasture together throughout the trial The mid-point of lambing was 17 August.

At no time during pregnancy or lactation did ewe live weight differences between the groups exceed 4 kg. Ewes shorn by cover comb were heavier prior to lambing and during lactation than standard comb-shorn ewes. Time of shearing, method of shearing and ewe rearing rank had no effect on ewe annual greasy fleece production. There was a highly significant (P < 0·001) interaction between the effects of birth rank and time of shearing on lamb birth weight. Time of shearing did not affect birth weight of single-born lambs but birth weight of twin lambs increased with earlier maternal shearing to a maximum of 0·7 kg (per lamb) in those born to ewes shorn on P70. These results imply that shearing reduced the greater extent of maternal constraint which applies to the growth of twin v. single foetuses in utero. This selective increase in birth weights of twins achieved by early pregnancy shearing may have advantages in reducing lamb mortality.
Contribution of dietary nitrogen and purine bases to the duodenal digesta: comparison of duodenal and polyester-bag measurements
Authors: Pérez J. F. , Balcells J. , Guada J. A. , Castrillo C.
Published: September 2010

Four ewes fitted with ruminal and duodenalT-piece cannulas were given fourdietsin a 4 × 4 factorial design. Diets consisted of 700 (HF) or 400 (LF) g/day of ammonia-treated barley straw supplemented respectively with 150 or 600 g/day of concentrate made up with barley plus either soya-bean meal (SBM) or fishmeal (FM) as the protein source, offered at 2-h intervals. Duodenal flowsof digestawere estimated by the dual-phasetechniqueusing CoEDTAand Yb-acetate as markers and (15NH4)2SO4 was infusedinto the rumento label microbial N. Bacteria were isolated from the liquid (LAB) or solid (SAB) rumendigesta. Purinebases (PB) were isolated by precipitationin an acid solution of AgN03, and microbial contribution either to the duodenalnitrogen(N) or PB were determinedby 15N measurements induodenaldigesta and bacteria.Simultaneously, therumen degradation of Nand PB contained in SBM and FM was studiedby incubating supplements in polyesterbags in the rumen.PBcontent (mmol/g dry matter)and guanine: adenine(G/A) ratio of barley strawwas 2·89 and 5·23; barley grain,7·91 and 111;SBM, 18·8 and 1·26; and FM, 58·9 and 6·96, respectively. Duodenal flow ofPB(mmol/day)was significantly higher than PB intake on all diets and G/A ratio showed a meanvalue of 0·97, similarto the ratios determined in SAB(0·80) and LAB (1·04) and muchlower than diets(1·31 to 4·32). Microbial contribution to duodenal Nflow ranged from43·3% to 61·0%, beinghigherin SBM(59·0%)thanin FM(46·7%)diets. However, microbial contribution to duodenal PB was not affected by the experimentaltreatment, accounting for proportionately 0·77 of total PB at the duodenum. Rumen degradability of PB was much higher than that of total N and in both cases degradability was higher in SBM than FM. Direct measurements of non-microbialN were significantly higher than values determined by the polyester-bagmeasurements. However, once corrected forthe endogenousN (52 mgN per kg live weight)contribution, results show edan acceptable agreement. Duodenal flow of PB non-attributable to microbes (unlabelled PB) showed a mean value of 3·25 mmol/daywithouta significanteffect of dietary treatment. However, undegradablePBsupply determinedfor0·02, 0·05 and 0·08 per h fractional out flow rates were proportionately lower than 0·025 with SBM and 0·100 with FM diets of the estimated duodenalPB flow. Despite the magnitudeof the unlabelledduodenalPB, the close agreement between G/A ratios in duodenaldigesta and bacteria suggests thatthe contribution of dietary PB to the duodenalflow was low and seemsto confirm the reliability of values obtained from polyester-bag measurements.