bluuebunny/crossref_metadata_2025 huggingface dataset:
Expectation and variance of genetic gain in open and closed nucleus and progeny testing schemes
Authors: Meuwissen T. H. E.
Published: September 2010

Open and closed nucleus and conventional and modern progeny testing schemes were compared for expectation and variance of genetic gain. Generation intervals were optimized, with minimum values of 2 and 6 years (progeny test results available) for males in nucleus and progeny testing schemes, respectively. Females had a minimum generation interval of 2 years, except in the conventional progeny testing schemes, which had a minimum of 4 years (one individual record available). Apart from the generation intervals and the progeny test, open nucleus and progeny testing schemes were identical, since ‘nucleus females’ are also born in progeny testing schemes, being full-sibs of the young bulls and dispersed over commercial herds. The number of nucleus sires (bull sires) selected was varied between four and 32. Selection was for milk production.

A deterministic model was used, that accounted for variance reduction due to selection and the effects of finite size and family structure on the selection differentials. Prediction of the variance of the selection response accounted for selection of full- and paternal half-sibs.

Closed nucleus schemes gave a factor 0·03, 0·13 and 0·19 larger response rates than open nucleus and modern and conventional progeny testing schemes, respectively. Reduction of genetic variance of open nucleus schemes was larger than that of closed nucleus schemes, which caused the slightly higher response rates of closed nucleus schemes. Standard deviations of selection responses of closed nucleus schemes were a factor 0·46, 0·79 and 0·86 larger, respectively.

Preference for the schemes was assessed using a quadratic utility function expressing risk and inbreeding aversion. The increase in genetic gain due to shortening of generation intervals more than compensated for its increased variance. Whether the increased genetic gain due to closing the nucleus compensated for its increased variance depended on the amount of risk aversion. Selection of four sires and eight to 16 sires had the highest utility in progeny testing and nucleus schemes, respectively.
The effect of method of forage conservation and harvest season on the rumen degradation of forages harvested from permanent mountain meadows
Authors: López S. , Carro M. D. , González J. S. , Ovejero F. J.
Published: September 2010

An irrigated permanent mountain meadow (Leon, Spain) was cut twice in 1987, in late June, and again in early September after the summer regrowth. Herbage harvested from each season was preserved by different methods, namely freezing (fresh), ensiling in plastic bags (silage) and sun-curing (hay). Rumen degradation characteristics were determined by the nylon bag technique. Forages harvested in September had a higher crude protein (CP) concentration (153 v. 104 g/kg dry matter (DM)) and a lower cell wall concentration (467 v. 599 g/kg DM) than those from the June cut, resulting in a greater DM potential degradability (0·856 v. 0·751) and a faster degradation rate (0·088 v. 0·057 per h). Method of conservation did not affect the CP concentration of the forages, but had a significant effect on their nitrogen (N) solubility and protein degradability. Hay had the lowest N solubility (0·388) and CP degradability. Ensiling led to an increase in the N solubility (0·668 v. 0·554) compared with the fresh control, resulting in a higher effective degradability of CP estimated for different rates of passage. Forage conservation caused a slight increase in the relative proportion of the cell wall in the total DM (mean neutral-detergent fibre concentrations for fresh forage, hay and silage were 510, 548 and 536 g/kg DM, respectively) presumably due to loss of cell contents. Potential DM degradabilities of fresh forage, hay and silage were similar (0·805, 0·813 and 0·791 respectively). Although hay seemed to be degraded to a greater extent and at a faster rate than the other two types of forages, the rumen degradation characteristics were not consistently affected by the method of conservation to an extent that could have important nutritional implications.
Some effects of housing on the social behaviour of dairy cows
Authors: Miller K. , Wood-Gush D. G. M.
Published: September 2010

A herd of high-yielding Friesian dairy cows was observed outdoors and in a modern cubicle house. Indoors there was a much higher level of gross agonistic behaviour than at pasture (9·5 v. 1·1 per h). Furthermore, the use of continuous filming showed a high level of avoidance amongst the cows which impeded the movement of the more submissive cows. All cows spent proportionately 0·34 to 0·56 of their time indoors watching one another and 0·45 to 0·66 of their time in ‘social tension’. There was less synchrony of behaviour indoors than at pasture and despite the presence of one Calan Broadbent stall for each cow there was a high rate of displacement from the stalls involving cows of all degrees of dominance. The results are discussed in relation to housing design and husbandry practice.
Dairy herd life in relation to linear type traits and production 1. Phenotypic and genetic analyses in pedigree type classified herds
Authors: Brotherstone S. , Hill W. G.
Published: September 2010

The relation between survival to complete lactations 2, 3 and 4 and both linear type and production traits of pedigree Holstein-Friesian dairy cattle in the United Kingdom was analysed. There were records on 23 071 pedigree animals which were themselves type classified as heifers. The linear and quadratic phenotypic regressions of survival on most type traits were significant, even with yield fitted as a covariate. Phenotypic regressions of survival on milk, fat and protein yield were significantly positive, but that on protein content significantly negative. Phenotypic correlations with survival were under 0·1 for the linear traits, 0·16 for a subjective total type score, and 0·14 for milk yield. Genetic correlations between survival and type traits, estimated by multivariate restricted maximum likelihood, were as high as 0·4 for several traits of the udder and teats and for total score, and higher than for milk yield or composition. Regressions of survival on estimated sire transmitting abilities gave rather lower estimates of genetic correlations, except for total score. The results indicate that in these pedigree and classifying herds the total score is a culling criterion in its own right.
Dairy herd life in relation to linear type traits and production 2. Genetic analyses for pedigree and non-pedigree cows
Authors: Brotherstone S. , Hill W. G.
Published: September 2010

The relation between linear type traits and survival to complete lactations 2, 3 and 4 of pedigree and non-pedigree Holstein-Friesian dairy cattle in the United Kingdom was analysed. Regressions of survival on sire transmitting abilities for type, i.e. estimates of genetic regression, were obtained for different data sets, either pedigree or non-pedigree offspring of sires whose progeny had linear type assessments made by either the Holstein Friesian Society or the Milk Marketing Board, thereby spanning different segments of the cattle population. Results were not completely consistent either over lactations or over data sets. In general, however, there was a significant positive association between survival and angularity, fore udder attachment and udder depth scores, and a negative association with chest width, rump width, and teat length. Regressions on yield were positive, while those on fat and protein content were usually negative. Survival in the herd can be predicted, although not with high accuracy, using type traits.
The performance and body composition of young pigs following a period of growth retardation by food restriction
Authors: Stamatarist C. , Kyriazakis I. , Emmans G. C.
Published: September 2010

Pigs were fed either ad libitum or given 300 g/day of the same food (digestible energy 15·4M)/kg; crude protein 208 g/kg fresh food) from 6 to 12 kg live weight (LW). Four pigs were killed at 6 kg LWand eight (equal numbers from the two sexes) from each treatment at 12 kg LW. Eight pigs (three males and five females; AL) were continued on ad libitum feeding to 24 kg LW when they were killed. Ten (four males and six females; R) of the pigs which had been restricted to 12 kg LW, were fed ad libitum to 24 kg LW, when they were killed. The entire empty bodies of the pigs killed were chemically analysed and the weights of organs determined. The empty body was considered as three fractions: the entire skin, including the subcutaneous fat (SK); the internal organs and the empty gastrointestinal tract (INT) and the remainder (CARC). The distributions of the chemical components between these three fractions were determined.

The R pigs took 19 days longer and 2·6 kg more food to go from 6 to 12 kg LW. At 12 kg LWthey had less gut fill, lighter organs concerned with food processing and less lipid, more protein and heavier CARC weights than the AL pigs. The R pigs took 5·5 days less and 2·4 kg less food to go from 12 to 24 kg than the AL pigs. At 24 kg LW they had more gut fill, similar weights of the organs concerned with food processing, and slightly less lipid and protein. Over the 12 to 24 kg weight interval the R pigs gained lipid and protein at faster rates than the AL pigs. None of the increase in protein growth rate was in the CARC fraction.

It is concluded that pigs given a low intake of food adjust their organ weights to be sufficient to process the allowance. On being given ad libitum food they rapidly increase the weights of their organs to process the increased rate of intake, and increase their gut fill. These effects are seen as a short lived, greatly increased rate of LW gain. During rehabilitation lipid stores return to their normal level but carcass protein does not show an increased rate of growth.
Sucrose as an energy source for growing pigs: a comparison of the effects of sucrose, starch and glucose on energy and protein retention
Authors: Beech S. A. , Elliott R. , Batterham E. S.
Published: September 2010

The effects of dietary sucrose, glucose and starch were compared to determine whether sucrose as an energy source affected energy or protein metabolism of growing pigs given food either frequently or once daily. Three experiments were conducted using three diets (0·8 g lysine per MJ digestible energy (DE)) containing sucrose, starch or glucose, respectively. In the first experiment, the DE contents of the diets were determined. In the second, the diets were given either once daily (08.00 h) or frequently (3-h intervals) to growing pigs (20 to 45 kg live weight) and growth responses, blood characteristics and energy, protein and fat retention measured. In the third experiment, the three diets were given to seven pigs (50 kg live weight), either once daily or frequently to monitor further the effects on plasma triglycerides, glucose, urea and insulin levels.

Growth rate, on a carcass basis, was slightly lower in pigs given glucose relative to starch (P < 0·05) but there was no effect of carbohydrate source on the retention of energy, protein or fat. Plasma triglyceride levels were lower in pigs given starch (P < 0·05) whilst plasma glucose and insulin concentrations were higher immediately after feeding in pigs given food once daily (7 < 0·05, P < 0·01). All three carbohydrate sources were used less efficiently by the pigs for energy, protein and fat deposition with once daily compared with frequent feeding (V < 0·01). Overall, these results indicate that sucrose as an energy source does not effect energy or protein metabolism by the growing pig. It appears that the metabolism of fructose within sucrose had no effect on metabolism.
The performance of Hereford × Friesian offspring of bulls selected for lean growth rate and lean food conversion efficiency
Authors: Bishop S. C. , Broadbent J. S. , Kay R. M. , Rigby I. , Fisher A. V.
Published: September 2010

The performance of Hereford × Friesian calves sired by Hereford bulls selected for either lean growth rate (LGR) or lean food conversion ratio (LFCR), or by unselected Hereford bulls, was evaluated on 327 calves on three farms over 2 years. Animals started test at 130 days of age on average and remained on test for approximately 300 days, whereupon all animals were slaughtered and carcass dissections were undertaken. Individual food intake was measured on tioo of the farms (189 animals), but only intake per pen of animals was measured on the third farm and individual food intake had to be estimated. LGR, LFCR and other traits describing performance were calculated from the growth, food intake and carcass composition data.

If no breed or environment interactions exist it is expected that proportionately 0-5 of the genetic differences between selected and control line bulls would be transmitted to their offspring. For the LGR and LFCR line bulls these values were 0·38 and 0·44, respectively, however the LGR value had a much smaller confidence interval. Genetic correlations derived from regressing breeding values predicted from offspring performance on breeding values predicted from the bulk's own performance in the selection experiment were 0·62 (s.e. 0·28) and 0·96 (s.e. 0·28) for LGR and LFCR, respectively. Heritabilities were: live-weight gain on test, 0·27; daily gain, 0·48; food intake, 0·06; food conversion ratio, 0·46; predicted carcass lean content, 0·10; killing-out proportion, 0·10; LGR, 0·36 and LFCR, 0·48.
Growth performance and body composition of mature female sheep implanted with trenbolone acetate
Authors: Sulieman A. H. , Galbraith H. , Topps J. H.
Published: September 2010

The effect of the anabolic steroid trenbolone acetate (TEA) on growth and body composition was studied in Scottish Blackface mature female sheep weighing 45 kg. The sheep were blocked by weight and randomly allocated to be untreated controls (C) or subcutaneously implanted with 20 (Tl), 40 (T2) or 60 (T3) mg TBA 60 days before slaughter. The sheep were offered to appetite a loose-mix diet which contained an estimated 11 M] metabolizable energy and 120 g crude protein per kg dry matter. Live-weight gain and food intake, on average, were not significantly affected by the hormonal treatment which significantly reduced gut fill and significantly increased empty body and chilled carcass weights. Of the carcass tissues which were dissected only weights of total lean and intermuscular fat were significantly increased following TBA implantation. The relative development of fat, lean and bone in the carcass in the hormonally treated compared with control sheep was not significantly altered. The only effects on weights of organs and body parts associated with TBA implantation were increases in fat deposition in omental and perinephric and retroperitoneal depots. There was some evidence of an increasing response to TBA treatment with increasing dose level for weights of chilled carcass, carcass lean and the ratio of subcutaneous fat to intermuscular fat.
Energy: protein interactions in growing boars of high genetic potential for lean growth. 1. Effects on growth, carcass characteristics and organ weights
Authors: Rao D. S. , McCracken K. J.
Published: September 2010

Seven replicates of five littermate boar Landrace pigs were used to evaluate the effects of (a) reducing the food intake within the practical range or (b) reducing energy intake without reducing protein intake, between 33 and 90 kg live weight on growth, nitrogen balance and carcass characteristics. Three levels of food intake (ad libitum, 0·90 and 0·80ad libitum) were used and the dietary protein contents ranged from 250 to 312 g crude protein per kg dry matter (DM) to equalize protein intake with reduced food intake. All the diets were of similar amino acid composition, and lysine per kg DM ranged from 14·3 to 17·9 g. The food was given twice daily. Balance trials were conducted at 45 and 65 kg live weight and all pigs were slaughtered at 90 kg live weight to assess carcass characteristics. Reducing food intake or only energy intake significantly reduced live-weight gain (P< 0·001). Reducing food intake decreased nitrogen retention (P< 0·01) during the 65-kg balance period. Reducing food intake had no effect on fat thickness measurements but measurements at shoulder (P< 0·001), mid back (P< 0·001), C(P< 0·01) and P2 (P< 0·05) decreased and lean: fat in rumpback increased (P< 0·05) when energy intake was reduced. The weights of small intestine (P< 0·001), large intestine (P< 0·05), liver (P< 0·05) and kidneys (P< 0·05) were significantly reduced as food intake was reduced. Energy is more limiting than protein when the intake of a diet providing for optimal growth of high potential boars is reduced between 33 and 90 kg live weight.
Water intake patterns in the weanling pig: effect of water quality, antibiotics and probiotics
Authors: McLeese J. M. , Tremblay M. L. , Patience J. F. , Christison G. I.
Published: September 2010

ad libitumwater intake patterns in newly weaned pigs were investigated, with particular emphasis on the impact of water quality, the presence or absence of food antibiotics and the use of water soluble probiotic. Pigs were given water containing low (217 mg/l), medium (2350 mg/l) or high (4390 mg/l) levels of total dissolved solids (TDS), either with or without a water additive containing probiotic, and a medicated (experiment 1 and 3) or unmedicated (experiment 2) starter diet for 20 (experiments 1 and 2) or 5 (experiment 3) days immediately post weaning. Water intake, food intake, growth and faecal scores were recorded, and blood was sampled to determine ionic composition. There appeared to be two phases of water consumption: intake in the first 5 days post weaning did not appear to be related to apparent physiological need, whilst later, water consumption increased in parallel with food intake and body-weight gain. In the earlier period, behaviour may have been a primary influence; water intake was not related to faecal scores and water quality had no effect on consumption. In the later phase, intake increased at higher TDS concentrations. Water quality had no effect on performance when pigs were given medicated food; however, pigs receiving unmedicated food exhibited reduced gain (P> 0·05) and food efficiency (P< 0·05), and increased incidence of diarrhoea, when consuming water with elevated mineral levels. The probiotic did not improve performance or decrease scouring (P> 0·05). Blood composition was not affected by treatment (P> 0·05). Although physiological need may be fundamental in establishing water requirements, it appears that other factors such as water quality and the process of weaning influence consumption patterns. These data provide further encouragement for research to define true requirements for water, which by necessity would require identification of all mediating factors.
A comparison of soya-bean meal, fish meal and maize gluten feed as protein sources for calves offered grass silage ad libitum
Authors: Steen R. W. J.
Published: September 2010

Two experiments were carried out to evaluate extracted soya-bean meal, fish meal and maize gluten feed as protein supplements for calves offered grass silage ad libitum. The five treatments used in experiment 1 consisted of 1·4 kg per head daily of concentrate dry matter (DM) consisting of (g/kg) 50 molasses and 25 minerals and vitamins plus (1) 925 barley (B), (2) 700 B and 225 extracted soya-bean meal (SBM), (3) 785 B and 140 fish meal (FM), (4) 925 maize gluten feed (MGF) and (5) 2·25 kg DM per head daily of concentrate (1). Those used in experiment 2 consisted of 1·4 kg per head daily of concentrate DM consisting of (g/kg) (1) 1000 B, (2) 800 B and 200 SBM, (3) 860 B and 140 FM, (4) 1000 MGF and (5) 2·25 kg DM per head daily of B. In each experiment the diets were offered to 70 calves which were initially 131 and 130 kg live weight, for periods of 14 and 13 weeks in experiments 1 and 2 respectively. The silages contained 155 and 154 g crude protein (CP) per kg DM; 45 and 77 g ammonia-nitrogen per kg total nitrogen and 698 and 726 g digestible organic matter per kg DM in experiments 1 and 2. Concentrates 1 and 5 contained 104 to 110 g CP per kg DM and concentrates 2, 3 and 4 contained 195 to 204 g CP per kg DM in both experiments. For diets 1 to 5 respectively silage DM intakes were 2·31,2·50,2·53,2·59 and 1 -61 (s.e. 0·097) kg/day; live-weight gains were 0·84,0·98,1 -01, 0·88 and 0·95 (s.e. 0·032) kg/day in experiment 1 and 2·38, 2·53, 2·54, 2·82 and 1·77 (s.e. 0·045) kg/day and 0·90,1·04,1·03,1·05 and 0·99 (s.e. 0·038) kg/day for experiment 2. It is concluded that the use of soya-bean meal rather than fish meal did not affect silage intake or animal performance. Replacing mixtures of barley and soya-bean meal or barley and fish meal with an equal quantity of isonitrogenous maize gluten feed did not affect animal performance in one experiment but significantly reduced it in the other experiment.
Estimation of economic weights in genetic improvement using neoclassical production theory: an alternative to rescaling
Authors: Amer P. R. , Fox G. C.
Published: September 2010

This paper addresses the rescaling controversy in the estimation of economic weights for livestock improvement programmes. A model of genetic improvement based on the neoclassical theory of the firm and incorporating genetic improvement is proposed for the estimation of economic weights. Disparities between estimates of economic weights calculated per animal as opposed to per unit of product, per breeding female or per enterprise disappear when economic weights are calculated using this model. Equivalences of economic weights at the different bases of evaluation, previously obtained by rescaling the production enterprise to a fixed input, output or profit are compared with this model. The conventional approach to the derivation of economic weights is characterized as implicitly making unreasonable assumptions about the behaviour offarm firms.

Extension of the proposed model to the level of the farm product market allows assessment of the distribution of gains from genetic improvement between producers and consumers using the economic surplus approach. In an illustrative example, the distribution of benefits among producers and consumers from genetic improvement in the Ontario cow-calf sector is shown to depend on the elasticity of demand for beef products in the North American market. When the demand for farm output is elastic, a significant proportion of the benefits from genetic improvement would accrue to producers. Conversely, when demand is inelastic, the majority of benefits would accrue to consumers. Economic weights calculated from the perspective of all producers could thus be different from those calculated from the perspective of an individual farmer or society as a whole. Finally, the market level model is used to compare the effects of genetic improvement which enhance product quality with cost-reducing genetic improvements.
Effects of indoor or outdoor rearing on the chemical composition of lambs
Authors: Theriez M. , Touraine B. , Vigneron P. , Prud'hon M.
Published: September 2010

Pure Merinos d'Aries male lambs were reared indoors (IN), with hay and concentrates, or outdoor (OUT) on improved Mediterranean range (Garrigues) and slaughtered when they reached 25 (light) or 32 (heavy) kg live weight. The alimentary tract weight was significantly affected by slaughter weight and by rearing method, which also significantly modified rumen contents. IN lamb body composition was higher in fat and energy and lower in water and protein than OUT lambs but differences induced by the rearing method were reduced when slaughter weight was increased. Allometric equations established for each environment were used to determine body composition and body gain composition at 20 and 25 kg empty body weight. Changes were very limited for IN lambs but protein and fat content of OUT lambs changed greatly as a result of the tremendous increase of grass availability towards the end of the fattening period.
Hay intake, milk production and rumen fermentation in British Saanen goats given concentrates varying widely in protein concentration
Authors: Badamana M. S. , Sutton J. D.
Published: September 2010

About 8 weeks after parturition six multiparous British Saanen goats with permanent rumen fistulas were allocated to three dietary treatments in a random sequence for three successive 30-day periods. The treatments were perennial ryegrass hayad libitumwith 1000 glday of concentrates containing 112 (low-protein, LP), 182 (high-protein, HP) or 255 (very high protein, VHP) g crude protein (CP) per kg dry matter (DM) daily. The CP concentration was increased by substitution of soya-bean meal for cereals. From day 19 of each period, when measurements were made, concentrate allowance was reduced to 850 glday and hay intake was offered at proportionately 0·10 more than consumption in the previous 6 days. Hay intake and milk yield increased linearly with CP in the concentrates, but differences between HP and VHP were small and non-significant. Milk composition was unaffected by the treatments, so yields of milk solids followed the same trends as yields of milk, but these were only significant for solids-not-fat. The digestibility of neutral-detergent fibre, acid-detergent fibre and nitrogen (N) all increased with increasing CP, but significantly so only for N; the digestibility of DM and organic matter was unaffected.

The digestibility of the hay incubated in the rumen was unaffected by the treatments. With increasing N intake, faecal, urine and milk N increased linearly as did apparently digested N but N retention did not follow a consistent pattern. Rumen volatile fatty acids and pH were unaffected but concentration of rumen ammonia and blood urea increased with increasing CP as did rumen fluid dilution rate. The results suggest that, with lactating goats given diets of moderate quality grass hay and concentrates containing soya-bean meal, responses to concentrations of CP greater than about 180 g/kg DM in the concentrates or 140 g CP per kg DM in the total diet are likely to be small.
The effects of dietary fibre, lactose and antibiotic on the levels of skatole and indole in faeces and subcutaneous fat in growing pigs
Authors: Hawe S. M. , Walker N. , Moss B. W.
Published: September 2010

The effects on the production of indoles of dietary fibre, lactose and antibiotic were examined in a factorial design using 16 crossbred pigs (eight boars and eight gilts) from 40 to 90 kg live weight. The control diet was based on wheat and soya-bean meal which was partially replaced either by sugar-beet pulp (400 mg/g) or lactose (25 mg/g) or both. All diets were offered with or without the antibiotic tylosin phosphate (200 mg/kg diet). Animals were penned individually and the diet restricted to provide 1·3 M] digestible energy per kg M0·75. All faeces were collected for two 4-day periods at about 60 and 75 kg live weight. Animals were slaughtered on completion of the experiment and subcutaneous fat was sampled. Faeces and carcass fat were analysed for skatole and indole. There were no significant effects of treatments on growth rate but killing-out proportion was reduced (P< 0·05) on fibre or lactose diets with an additive effect (P< 0·001) of the combined ingredients. Dietary fibre significantly increased the daily elimination of skatole and indole and the concentration of indole in faeces but because of greater faecal bulk on the fibre diet the concentration of skatole in faecal dry matter was higher (P< 0·05) on the control diet. Dietary lactose had no effect on indole in faeces but significantly reduced the concentration and daily output of skatole. Levels of both skatole and indole in faeces tended to be reduced with dietary antibiotic which had a significant interaction with the fibre treatment on indole levels. The concentrations of skatole or indole in subcutaneous fat were neither affected by dietary treatment nor significantly correlated with concentrations or outputs in faeces.
Adjustment of birth weight for weighing age and relationship of standardized birth weight with early mortality in N'Dama calves under traditional husbandry systems in The Gambia
Authors: Agyemang K.
Published: September 2010

Birth-weight data recorded between 1986 and 1991 on 3453 N'Dama calves from the village production systems of The Gambia were analysed to identify major factors influencing this trait and to quantify the relationship between birth weight and early calf mortality. Birth weights were measured over a range of time, from a few hours to 14 days after birth. Least-squares analysis of the fixed effects of site, year and season of birth, parity of dam, sex, age in days at which birth weight was recorded and random effects of herd and cow nested within site showed that all these factors significantly influenced this trait.

A subset of these data (no. = 2452) was used to derive adjustment factors which were applied to the larger data set to standardize birth weights to a common age measurement. Results from these adjustments showed that birth weights recorded between the 7th and 14th day after birth should be decreased by proportionately 0·12 to 0·14 to be comparable with those measured on day of birth.

Maximum likelihood analyis of cumulative calf mortality to 30, 60, 90 and 120 days of age using age-standardized data (no. = 3156), which excluded deaths of traumatic origin, showed that mortality was highly influenced by birth weight. Calves were grouped into three classes, namely below-average, average and above-average of sitemates' values. Mortality rates among the three groups during the first 30 days of life were 3·6, 0·9 and 0·3%. The corresponding values at day 120 were 13·8, 6·3 and 5·0%. The average age at death during the first 120 days in the three groups were 51, 58 and 73 days. Mortality rates among calves born in the wet season were higher than those born in the dry season (e.g. 9·9 v. 5·9% for mortality to day 120).

Examination of data on calving distribution and milk production patterns of the dams of the calves used in this study as well as the causes of deaths among the calves indicated that although dam effect was an important determinant of calf survival other factors such as the vigour of the calf at birth, weather conditions and disease environment at the tethering and grazing areas were important as well.
The effect of increasing the interval between recordings on genetic parameters of test day yields of British Holstein-Friesian heifers
Authors: Pander B. L. , Thompson R. , Hill W. G.
Published: September 2010

The effect of increasing the interval between recordings from 1 month to 2 months was studied by analysis of milk, fat and protein yield records obtained in alternate monthly herd visits. The data comprised records on over 34 000 daughters of 40 proven and 705 young sires which were analysed by multivariate restricted maximum likelihood.

Heritability estimates of bimonthly test day records were similar to the average of the estimates for the two corresponding monthly test day records, as were genetic and phenotypic correlations between bimonthly test day and lactation records. A quartic regression removed most of the additional variance due to the wide range of days to first test and therefore the variance-covariance structure of bimonthly test day records could be predicted from that of monthly test day records.

The accuracies of prediction of breeding value for 305-day yields of milk, fat and protein using the sum of five bimonthly test day records and the sum of seven 6-weekly tests were estimated to be at least 0·97 and 0·99, respectively, of the accuracy of using 10 monthly test day records.

If milk yield were recorded daily, prediction of lactation fat or protein yield from the product of the sum of daily milk yields and the average fat or protein content would be more accurate than using yield and content records solely from test days.
Relationship of post-partum interval in mature beef cows with nutritional environment, biological type and serum IGF-1 concentrations
Authors: Nugent R. A. , Jenkins T. G. , Roberts A. J. , Klindt J.
Published: September 2010

Mature cows of nine breeds were fed (four cows per level within breed) at either 0·55, 0·71, 0·88 or 1·05 MJ metabolizable energy (ME) per kg initial body weight0·75 per day during non-lactational periods for an average of 4 years. During lactation, energy allowances were increased by 0·17 MJ ME per kg body weight0·75 per day. Breeds represented four biological types: moderate genetic potential for milk yield and growth (Angus, Hereford, Red Poll), moderate milk and high growth (Charolais, Eimousin), high milk and moderate growth (Braunvieh, Pinzgauer) and high milk and growth (Gelbvieh, Simmental). The objective was to test the effects of biological type and nutritional environment on length of post-partum interval as determined from serum progesterone levels. The potential of serum insulin-like growth factor-1 (IGF-1) level at 3 weeks post partum for predicting the length of the post-partum interval was also evaluated. Non-parametric statistical analyses appropriate for right-censored survival data were used to test effects on post-partum interval because collection of serum was terminated prior to ovulation in some cows.

Energy availability × biological type effects on post-partum interval were significant. Increased energy availability tended to decrease post-partum interval in all biological types with high potential growth types exhibiting the greatest positive response to increased food. Post-partum interval for types with high growth potential was shorter within food level when associated with high rather than moderate potential for milk yield. Serum IGF-1 was related to post-partum interval at lower energy availability but appeared to have limited usefulness for identifying cows with extended intervals. Inherent direct and maternal production potential interact with available food resources to influence the post-partum interval of mature beef cows.
Genetic variation in measures of food efficiency in pigs and their genetic relationships with growth rate and backfat
Authors: Mrode R. A. , Kennedy B. W.
Published: September 2010

Data on 3783 Yorkshire, 2842 Landrace and 937 Duroc littermate pairs of boars, station tested between 1976 and 1989, were used to measure genetic parameters of average daily gain (ADG) from 30 to 90 kg, live backfat at 90 kg (BF), estimated lean growth rate (LGR), average daily food intake, food conversion ratio (FCR) and lean food conversion ratio (LFCR), as well as measures of residual daily food intakes over and above requirements for growth and lean growth. A method was developed to obtain restricted maximum likelihood estimates of genetic variances and covariances under an animal model when observations are on the means of sib pairs. Heritabilities of ADG, BF, LGR, FCR and LFCR were 0·43, 0·59, 0·39, 0·28 and 0·34, respectively. Heritability of daily food intake was 0·45, and heritability of measures of residual daily food intake ranged from 0·30 to 0·38. About half of the variation in daily food intake was residual (0·48 to 0·56). Genetic correlations of ADG with daily food intake, FCR and LFCR were 0·80, −0·28 and −0·09, respectively, and were small and positive (0·18 to 0·34) with measures of residual daily food intake. Backfat had genetic correlations of 0·42, 0·24 and 0·52 with daily food intake, FCR and LFCR, respectively, and genetic correlations between backfat and measures of residual daily food intake ranged from 0·15 to 0·61. Selection against residual food intake may be a useful means of improving efficiency of food utilization.
Accuracy in measuring cattle with special reference to identical twins
Authors: Taylor C. S.
Published: September 2010

A study has been made of the relative accuracy of twelve linear body measurements of dairy cattle. The results of several repeatability trials are presented together with estimates of observer error derived from the routine measuring of identical twins. Various aspects of precision of measurement have been analysed. The accuracy found from any one trial can rarely be used as a reliable estimate of the accuracy of measuring in any subsequent experiment.

The importance of observer error in identical twin studies has been assessed. It was found that from 10% to 70% of the total variation within pairs of uniformly treated identical twins could be due to measuring error. It was therefore concluded that in such studies, where observer error is a fairly large part of the total variation, a single routine repetition of every measurement would be advisable in long term experiments and several in the case of short term experiments with a small number of animals.

Measurements have been ranked for relative accuracy and the ranking was found to be broadly similar on several different criteria: (a) relative to the variation within pairs of uniformly treated identical twins, (b) relative to the total variation in a population of unrelated animals and (c) relative to the mean size of the body part. The choice of measurements on the basis of relative accuracy is discussed.
The effect of method of rearing on the social behaviour of Scottish Blackface hoggets
Authors: Hunter R. F. , Davies G. E.
Published: September 2010

Four groups of Scottish Blackface ewe lambs were reared in the period 11–52 weeks old under different regimes. The regimes differed in the age of the lambs at which they were separated from their dams and whether having been separated they were together in a field and/or penned together n i a sheep shed.

These regimes caused differences in social behaviour among the four groups and also resulted in the groups adopting different parts (home ranges) of an enclosed 350 acre hill pasture. The various home ranges within the pasture are dissimilar environments and it is argued that home range and method-of-rearing effects will be confounded making statistical comparisons between the different rearing treatments impossible.
Heterosis in crossbred hill sheep
Authors: Donald H. P. , Read J. L. , Russell W. S.
Published: September 2010

1. For ten years purebred Blackface and Swaledale ewes have been kept on a small hill grazing together with first crosses and backcrosses to the Swaledale. The total flock of about 120 ewes was mated and lambed on sown pastures where ewes with twins remained from lambing until weaning. Four new rams (two of each breed) were used each year.

2. It is concluded that the Swaledales produced fewer lambs than the other ewes, but these were of greater birth weight (5 %) and cannon bone length (2 %); moreoever, they were better mothers than Blackface (4 %) when rearing singles on hill grazing but not if rearing twins on sown grass.

3. Blackface sheep showed greater weights at weaning (5%), at mating (5%), and of fleece (15%) than did pure Swaledales.

4. First cross sheep were equal to or slightly superior to the parental mean in birth weight, weaning weight and cannon-bone length. They exceeded the better parent in ewe weight, first fleece weight, and weight of weaned lambs.

5. Backcross sheep although not always statistically distinguishable from Swaledale in cannon-bone length and fleece weight or from first cross sheep in reproductive characters tend to confirm the interpretations placed on the relations between the purebred and first cross sheep.

6. Heterosis estimated as a superiority of first cross sheep over the mean of the two parental breeds varied from 0% for cannon-bone length to 9·5% for prolificacy of 4-year-old ewes.
Crossbred sheep production. III. Selection for growth rate and carcass attributes in the second-cross lamb
Authors: Bichard Maurice , Yalçin B. C.
Published: September 2010

Results have been presented from a small scale investigation into operational and theoretical aspects of progeny testing Down rams as sires of crossbred fat lambs. Twenty-six Suffolk rams were evaluated from the growth records of 922 lambs out of Border Leicester × Cheviot ewes. In addition measurements were recorded on 260 carcasses. Significant differences were found between corrected progeny means, which were equivalent t o heritabilities of between 0·03 and 0·13 for live-weights up to 15 weeks, and o t higher values for skeletal measurements.

A scheme for the selection of Down rams was considered which involved measuring the individual performance of all ram lambs and then progeny testing the best of these by measuring a fixed total number of crossbred lambs. It was concluded that the proportion to be progeny tested could be varied within quite wide limits without seriously changing the genetic merit of the selected group.
The effect of treatment during first winter on the subsequent performance of Scottish Blackface ewes
Authors: Purser A. F. , Roberts R. C.
Published: September 2010

Data on 1,795 Scottish Blackface sheep were examined to see what effect treatment during the animal's first winter had on subsequent performance. Two treatments were used, wintering on the hill with the breeding ewe flock, or wintering away on low-ground farms. Away-wintered sheep gained on average about 16 lb. more than hill-wintered sheep between 6 and 12 months of age. These live-weight differences declined with age to about ⅔lb. at 5–6 years of age. Away-wintered sheep also had heavier first fleeces by about fIb. on average and had a lower mortality rate. However, differences in subsequent fleece weights and lamb production were small and not sufficient to cover the cost of away wintering.
Effects of castrating lambs on growth and body composition
Authors: Bradford G. E. , Spurlock G. M.
Published: September 2010

Effects of castration on growth, wool production, carcass characteristics, and meat quality in sheep were investigated.

The experiment included two flocks (similar in their effect on pre-weaning performance, but representing high and low planes of nutrition after weaning), two years, and two slaughter ages. Rams weighed approximately 5 % more thanwethers at weaning, and 15 % and 23 % more as yearlings on the low- and high planes of nutrition respectively. Differences in favour of rams in terms of skeletal and muscle size and wool production were also greater on the higher plane of nutrition. Carcass weight was approximately 4%, 8% and 19% higher for rams among lambs, low plane and high plane yearlings, respectively. Proportion of carcass weight in the forequarters was 0·5 %, 1·1 % and 2·3 % higher for rams in these three groups. Rams had less kidney fat and the same percentage of the carcass weight in loin and trimmed leg as wethers in all groups.

Carcass grade and eating quality as evaluated by a taste panel did not differ between ram and wether lambs. Among the lighter yearling group, meat from the loin of ram carcasses was less tender. Quality was appreciably lower for rams in the heavier yearling group. Meat from ram carcasses had 1 to 2% higher cooking loss than that from wethers.
A note on the distribution of scrapie in sheep of different ages
Authors: Dickinson A. G. , Young G. B. , Stamp J. T. , Renwick C. C.
Published: September 2010

Natural scrapie can develop in sheep at any age later than about 18 months old. In order to formulate a realistic policy for experimental investigation of the disease as it occurs naturally, it is necessary to understand what factors might affect the incidence in sheep of different ages. Any attempt to use data from commercial sheep flocks to draw conclusions about the age distribution of scrapie cases must make allowance for the fact that the population at risk is being culled on commercial criteria and incurs losses by death from various causes.
The value of feather meal as a protein supplement for growing pigs
Authors: Barber R. S. , Braude R. , Chamberlain A. G. , Hosking Zena D. , Mitchell K. G.
Published: September 2010

The results of a nitrogen balance experiment with growing pigs have shown that 5 % feather meal was inferior to 7 % white-fish meal, when both supplements supplied the same amount of total crude protein in a barleyweatings- minerals-vitamins ration.

A comparative feeding trial in which white-fish meal was partially replaced by feather meal in the diets given to growing pigs gave inconclusive results.
A note on sustained release of chromic oxide in the rumen of sheep from a chromic oxide-dental plaster pellet
Authors: Troelsen J. E.
Published: September 2010

Pellets of chromic oxide (Cr2O3) and dental plaster for administration of Cr2O3 to ruminants were developed by Pigden and Brisson (1957). When Cr2O3 was administered to sheep in this manner, Troelsen (1961) observed that digestibility coefficients determined by the Cr2O3-ratio method were very variable, and deviated from those obtained by total collection of faeces. It was also observed that the rate at which the pellets disappeared from the rumen or reticulum was correlated with the percentage of alfalfa hay (r = 0 83) and oat grain (r = –0 80) in the diet and that the abomasal ingesta contained pellets or pieces of same in the process of disintegration.
A note on variations in the level of aggression within a herd of goats
Authors: Syme G. J. , Syme L. A. , Jefferson T. P.
Published: September 2010

Changes in the level of aggression in a restricted feeding situation were examined in a herd of goats with a stable dominance hierarchy. It was found that the number of butts occurring (the level of aggression) depended on both the nature and novelty of the various feeds presented. In general the highest number of butts and the lowest consumption were recorded on the first occasion that each feed was presented. The introduction of unfamiliar or highly desirable feeds to livestock may require special precautions if increased aggression is to be avoided.
Body size and conformation in sheep from birth to maturity as affected by breed, crossbreeding, maternal and other factors
Authors: Wiener G. , Hayter Susan
Published: September 2010

Body weight was studied from birth to 5½ years of age and six linear measures of body size from birth to 4¼ years for sheep of five breeds, Scottish Blackface, Cheviot, Welsh Mountain, Lincoln Longwool and Southdown, and of crosses of these breeds with each other and with the Tasmanian Merino, but not in all possible combinations. The sheep were run as a single flock. Numbers ranged from 753 at birth to 150 at the end of the experimental period.

There were marked differences among the breeds and crosses in all aspects of body size and some differences in rate of maturity. They also differed in conformation independently of body weight. Crosses of the hill breeds with the Lincoln and probably with the Southdown were heavier than the average of the parental breeds and larger in some linear body measurements from about weaning onwards. The weights of crosses of Blackface and Cheviot with Lincoln eventually exceeded those of the heavier parent of the cross. For the crosses among the three hill breeds only the Blackface Cheviot cross showed significant deviations from mid-parent values for weight and size.

Maternal effects were important for all traits studied from birth to weaning and for weight up to a year old. In relation to mature size, Welsh dams produced the biggest and Lincoln the smallest lambs. The data did not permit Southdown maternal effects to be estimated. The effects of birth type and rearing were apparent for late maturing body parts up to a year old and for weight up to 3 years. Males, measured only from birth to weaning, were heavier and generally larger than females.

Residual correlations between the various measures of size varied from 0·1 to 0·7.
A new net energy system for ruminants
Authors: Harkins J. , Edwards R. A. , Mcdonald P.
Published: September 2010

A simplified Net Energy system for ruminants is described. It is based on the Metabolizable Energy system outlined by the Agricultural Research Council (1965) and enables a non-iterative approach to be used in the formulation of rations. The method is suitable for use in linear programming work and is illustrated, with appropriate tables, for growing cattle.