bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of rapid inbreeding and of crossing of inbred lines on the body weight growth of sheep
Authors: Wiener G. , Lee G. J. , Woolliams J. A. 
Published: September 2010

AbstractSheep of three hill breeds, Scottish Blackface, Cheviot and Welsh Mountain and the reciprocal crosses among these breeds were inbred (mostly by parent × offspring mating) for four generations to five levels with inbreeding coefficients ofO, 0·25 (I1), 0·38 (I2), 0·50 (I3) and 0·59 (I4). Inbred females were also mated to unrelated inbred males of the same breed type to produce line crosses (LC). Each type of dam (except LC and I4) was mated to produce lambs of up to three different inbreeding levels thus allowing the effects of the individual's own inbreeding to be separately assessed from the effects of maternal inbreeding. This study examined body weight at a sequence of ages from birth to 4 years of age with 2369 animals (ages up to 78 weeks old) or 1062 animals (2 to 4 years old) contributing to the analyses.Inbreeding of the individual had a highly significant retarding effect on body weight and growth rate up to the I2 level for weights of lambs up to 24 weeks old, with a slight recovery in performance thereafter. For the later ages examined, the maximum depression was reached at the I3 stage. The partial recovery in performance at the higher levels of inbreeding for lambs less than 24 weeks of age was also noted within lines and did not therefore appear to arise only from a loss of lines as inbreeding proceeded. The effect of dam's inbreeding was to depress growth up to the I3 level and at most ages up to I4. Line-cross lambs were generally heavier (but not significantly so) than non-inbred (F2 and the pure equivalent, O2) and progeny of line-cross dams were similar in weight to those from other non-inbred (F1, or F2 and O1, or O2 dams) or slightly better. The more highly inbred the individuals the more, in general, they fell behind the weights of the corresponding non-inbreds as they grew older. Inbreeding may thus have permanently stunted the sheep.There were no significant differences between purebred and crossbred sheep in the rate of inbreeding depression. Only at the ages of 3 and 6 weeks was there a significant difference between the three pure breeds in the changes in weight attributable to inbreeding. Up to the age of weaning (15 weeks) the changes with inbreeding of individuals could not be explained statistically in terms of dominance effects alone and non-allelic interactions may therefore also be involved. At all ages the effect of inbreeding of the dam was consistent with dominance effects alone.
Individual variation in feeding and growth of piglets: effects of increased access to creep food
Authors: Appleby M. C. , Pajor E. A. , Fraser D. 
Published: September 2010

AbstractConsumption of solid food before weaning and growth before and after weaning were studied in 24 litters of eight to 13 Yorkshire × Landrace piglets per litter. From day 21 until weaning at day 28,12 litters were provided with a single two-space feeder, while the other 12 litters were provided with four similar feeders. Daily food intake by each litter was recorded throughout this period and feeding behaviour of individual piglets was filmed during the final 24 h. On the one-feeder treatment there were 4·1 (s.e. 0·6) piglets per litter which fed very little on the day before weaning (< 0·005 of sample video frames). These tended to have high birth weights and high growth rates on days 0 to 21, but low growth rates on days 28 to 42. Conversely, piglets which fed most on creep food were often those which had gained least on days 0 to 21. The four-feeder treatment increased average intake in the last 3 days before weaning and reduced the number of piglets which fed very little in the final 24 h to 0·6 (s.e. 0·3) per litter. However, neither average growth after weaning nor the occurrence of poorly performing individuals was different between treatments. Furthermore, regression analysis of factors related to weight gain from days 28 to 42 showed that feeding behaviour proportionately accounted for 0·02 only of within-litter variation and food intake on days 21 to 28 did not contribute significantly to between-Utter variation. These results suggest that low consumption of solid food before weaning is a predictor of poor growth after weaning, but not a cause.
Energy and protein utilization and partition in rabbit does concurrently pregnant and lactating
Authors: Parigi-Bini R. , Xiccato G. , Cinetto M. , Dalle Zotte A. 
Published: September 2010

AbstractChanges in body composition during lactation in 40 primiparous rabbits were studied by comparative slaughter. The results were used to determine the utilization of digestible energy (DE) and digestible protein (DP) and their partitioning between maternal body, milk and foetal tissues.Twelve does were slaughtered immediately after their first parturition (first slaughter group) to estimate initial body composition. The 28 remaining does were remated 1 to 3 days after parturition and divided into two groups offered a pelleted diet at different levels: group L, fed ad libitum and group R, fed 0·75 of ad libitum. The 19 does that were pregnant (10 of L group, 9 of R group) were kept in individual metabolism cages until their second parturition. They were then slaughtered with their litters.Milk yield was higher (147·0 v. 117·2 g/day, P < 0·02) and live-weight loss was lower (–42 v. –294 g) in group L than in group R. The food intakes were 304·7 and 234·4 g/day, respectively. Body composition of the does changed substantially between the first and second parturition, with a considerable loss of fat and some loss of protein. A large decrease in empty body (digesta-free body) weight was observed in both groups. The loss of energy corresponded to proportionately 0·32 and 0·41 of the initial body energy, in L and R groups respectively.The DE requirement for maintenance was estimated to be 468 kj/day per kg M0·75 and the efficiencies of utilization of DE and body energy for milk production were 0·63 and 0·76, respectively. The efficiency of utilization of DE for foetal tissue synthesis was estimated to be 0·27 throughout pregnancy. The DP requirement for maintenance was 3·80 g/day per kg M0·75 and the efficiency of utilization of DP for milk protein production was 0·76 and of body protein 0·61. The efficiency of utilization of DP for foetal protein synthesis was 0·46.
Carry-over of aflatoxin from cows' food to milk
Authors: Veldman A. , Meijs J. A. C. , Borggreve G. J. , Heeres-van der Tol J. J. 
Published: September 2010

AbstractTwo experiments were made. In experiment 1, dairy cows in early lactation (2 to 4 weeks) and dairy cows in late lactation (34 to 36 weeks) were given aflatoxin B, (AFBt)at a level of 34 to 39 fig/day by feeding them contaminated compound food. The aflatoxin Mrcontent(AFMj) of raw milk was determined four times during the experimental period of 14 days. The milk yield was measured daily.The carry-over rate of aflatoxin was proportionately 0·062 and 0·018 for cows in early and late lactation respectively. This difference was not only due to milk production level but possibly also associated to AFB, liver metabolism.In experiment 2, eight high (40 kg milk per day) and eight low (16 kg milk per day) milk yielding cows, carry-over of AFB1 from compound food into AFM, in milk was measured at different levels ofAFB7 intake ranging from 7 to 57 fig/day. Independent of AFBj-intake, high-producing dairy cows had a higher carry-over rate than low producing animals (proportionately 0·038 v. 0·025). Carry-over ofAFB1 to AFM, was linearly correlated with milk yield. Variations in the level of AFM1 in milk of individual cows were not due to variations in milk yield. The relationship between AFB2 intake per day and AFM^content in milk per kg could be described by the formula: AFMj (ng/kg milk) = 119 AFB, intake (fig per cow per day) + 1·9. This means that in order to produce milk with less than 0·05 fig AFM, per kg milk the average daily individual intake in a herd should be limited to 40 fig AFB7 per day.As dairy cows in their early to mid lactation period consume large quantities of compound food, a maximum level of AFB3 in dairy foods has to be set at an acceptable daily intake (ADI) value to guarantee that AFM1 levels in milk do not exceed tolerable levels.
Effect of dietary fat and α-tocopherol level in the lactation diet on the performance of primiparous sows and their piglets
Authors: Babinszky L. , Verstegen M. W. A. , den Hartog L. A. , Zandstra T. , van der Togt P. L. , van Dam J. T. P. 
Published: September 2010

AbstractA total of 63 primiparous hybrid sows were used in two experiments to study the effect of different fat and α-tocopherol levels in the lactation diet on the performance and milk production of sows and on the performance of sucking piglets. In experiment 1, the major differences in energy sources in the lactation diets were tapioca starch or animal fat. Fifteen sows received the low-fat diet (starch and fat content: 396 and 43 g/kg dry matter (DM)) and 16 sows were given the moderate-fat diet (starch and fat content: 286 and 75 g/kg DM) during 4 weeks of lactation. In experiment 2,16 sows were given a low-fat diet (diet 1: starch and fat content: 418 and 37 g/kg DM) and 16 were given a high-fat diet (diet 2: starch and fat content: 266 and 125 g/kg DM) during 4 weeks of lactation. In diet 2, 68 g animal fat replaced the 200 g starch present in diet 1. The mean α-tocopherol contents of foods in experiment 1 were 14 and 126 mg/kg diet and in experiment 2, 22 and 151 mg/kg diet. The live weight, backfat thickness and milk production of sows were not significantly affected by the different dietary fat levels (P > 0·05). The high dietary fat level increased the DM, fat and energy content of milk and the daily gain of piglets in the second part of lactation in experiment 2 (P < 0·05). The correlation between piglet growth and milk fat and milk energy intake (r) in experiment 1 were: 0·57 and 0·66 and in experiment 2 were 0·41 and 0·40 respectively. The utilization of whole milk and DM, fat, protein and energy content of milk for piglet growth was not influenced by dietary fat level. Varying the level of dietary α-tocopherol did not affect the variables investigated.
Variation during growth of twin cattle
Authors: Taylor C. S. , Craig Jean 
Published: September 2010

Phenotypic variances within pairs of monozygotic and dizygotic twin heifers and also genetic variances and heritabilities were calculated for 12 linear body measurements at a sequence of eight ages up to two years old. The 60 pairs of fraternal and 60 pairs of identical twins used were reared as part of a larger uniformity trial in which feeding was effectivelyad libitumthroughout.Size differences between members of DZ twin pairs were found to be approximately normally distributed with about the same variance for all breeds and crosses. The variance within DZ pairs increased strongly with age, with a marked increase between 9 and 12 months of age and with most body measurements showing a broadly similar trend. On a logarithmic scale DZ variances increased roughly linearly with degree of maturity and at about the same rate in each body measurement. Coefficients of variation within DZ pairs corrected for measuring error had an average value of 2%. They did not change greatly with age, and were roughly the same for most body measurements although width measurements tended to be more variable than average.Coefficients of variation within MZ pairs had a corresponding overall average of 1·4%; they declined rapidly with age from 2·0% to 1·1%, were roughly the same for all body measurements, but at early ages tended to be greater in late than in early maturing body parts. However, they showed no association with the earliness of maturing of a body part provided variation was measured at the same degree of maturity for each body part.Genetic variation increased rapidly with age in all body measurements. The rate of increase with age was greater for late than for early maturing parts. The rate of increase with degree of maturity, however, was about the same for all body measurements. Coefficients of genetic variation increased slowly with age; they had an average value of 1·6%.Estimates of heritability are given at a sequence of eight ages for each of 12 body measurements. They increased strongly with age from 0·14 on average at three months of age to 0·67 on average at two years of age. At any fixed age, early maturing body parts tended to have higher heritabilities than later maturing body parts. However, if heritability was measured at the same degree of maturity in each body part, early and late maturing parts had about equal heritabilities.The present results are compared with those obtained from twin cattle studies in New Zealand, Sweden and Wisconsin, U.S.A.Inferences from twins about genetic variances and heritabilities for unrelated animals are discussed.
Prediction of the voluntary intake of food by dairy cows: 1. Stall-fed cows in late pregnancy and early lactation
Authors: Curran M. K. , Wimble R. H. , Holmes W. 
Published: September 2010

SUMMARYData from 22, 28, 36 and 41 pregnant cows in weeks 4, 3, 2 and 1 before calving respectively and 51, 65, 56 and 36 cows in weeks 1 to 4, 5 to 8, 9 to 12 and 13 to 16 of lactation respectively were used in multiple regression analyses to study the feasibility of predicting the daily total and the roughage organic matter and digestible organic matter intakes of cows given known weights of concentrates plus roughage ad libitum. The digestibility of the total intake and of the roughage component, the weight of concentrates eaten per day, the proportion of roughage in the total intake, age, milk yield, fat-corrected milk yield, live-weight gain and the 1·0, 0·73 and 0·66 exponents of live weight were used as independent variables.The accuracy of the models was assessed from the significance of the partial regression coefficients, the size of the residual standard errors, and the population tolerance limits about predicted values, and by applying selected models to a set of data not included in the study. The results indicated that the precision likely to be achieved in the prediction of intake for individual cows was of limited practical application, but the mean intakes of groups of 30 similar cows could be predicted with an acceptable level of accuracy for practical application. In general, weight of concentrates offered and the digestibility of the roughage were the most effective independent variables in all cows, together with milk yield in lactating cows. The application of the results to conventional feeding systems and to complete diets offered ad libitum is discussed.
The relationship between the month of calving and milk production
Authors: Wood P. D. P. 
Published: September 2010

SUMMARYA sample of 6846 Friesian heifers recorded in 672 herds during the year ending 30 September 1968, taken from two areas of England and Wales, has been used to estimate the effect of the calving month on total lactation yield. In both areas, the North and the South-West, a variation amounting to nearly 12% of the mean yield was estab-lished, with lactations resulting from October-December calvings the highest and those from May-June calvings the lowest. There was no evidence of association with particular levels of management, or management systems, as exemplified by a seasonal calving pattern.
Influence of litter size and breed of sire on carcass weight and quality of lambs
Authors: Donald H. P. , Read J. L. , Russell W. S. 
Published: September 2010

SUMMARYIn order to obtain a wide range of live weights, two Oxford Down, two Southdown, and two Soay rams of recent feral origin, were used to sire lambs from 169 crossbred ewes. These ewes had been bred from Blackface ewes mated to Border Leicester, Dorset Hora, Clun Forest, Finnish Landrace and Tasmanian Merino rams. Of the 282 lambs weaned by the crossbred ewes, 61 were singles, 166 twins, 51 triplets and 4 quadruplets. Carcass data were obtained from all but three of them.Oxford Down cross lambs were, in terms of fitted values, 10 kg heavier and 4 days younger than Soay cross lambs and 6 kg heavier and 2 days younger than Southdown cross lambs when slaughtered. Twins and triplets were 1·4 and 2·1 kg, respectively, lighter than singles and were 37 and 58 days older than singles. Ewes of the heaviest groups produced heavier lambs in a shorter time than ewes of the lightest groups.The Soay cross lambs showed a higher killing-out percentage, less tail fat, and more kidney fat, than the Southdown and Oxford Down cross lambs.Carcass characters made little if any difference to the price paid for the lambs which depended mainly on weight. Receipts from lambs were highest when the most fertile ewes were mated to the largest rams.
A note on rumen ammonia and blood urea levels in steers administered urea or sparingly soluble urea derivates as nitrogen supplements
Authors: Pal R. N. , Negi S. S. 
Published: September 2010

SUMMARYRuminal ammonia and blood urea levels were compared in fistulated steers eating paddy straw to appetite and given urea alone, urea plus oxalate, and complexes of urea with either formaldehyde (UFC) or oxalate (UOC), introduced into the rumen in a single daily dose. The solubilities of UFC and UOC in rumen liquor were 23·7 and 4·6% respectively of that of urea. Higher levels of ruminal ammonia and blood urea were recorded on urea than on other supplements.
Some optimum selection strategies and age structures with overlapping generations
Authors: Hopkins I. R. , James J. W. 
Published: September 2010

SUMMARYGenetic responses from selection strategies based on selection among all potential parents of the following year's crop were compared with those based on selection only within progeny crops. In the former group of strategies the duration of stay of an individual in the breeding herd is determined by the estimated breeding value of that individual, whereas in the classic model selected individuals of the same sex all remain in the breeding population for the same period. The former group of strategies, termed ‘parent selection’ strategies, were consistently superior in genetic response to the progeny selection strategies with a very large relative advantage under some conditions. The superiority of strategies that make more efficient use of genetic differences between own or parental age was greater among parent selection strategies than among progeny selection strategies. Similarly, increases in female to male mating ratios, fertility and survival rate generally resulted in larger increases i n genetic response in the more efficient strategies. The effect of changes in number of male and female age groups differs markedly between strategies.
Genetic and phenotypic parameters in performance-tested pigs
Authors: Walters J. R. , Curran M. K. , Kentish P. A. 
Published: September 2010

SUMMARYData were available from 11 474 gilts performance-tested on 137 farms. The data were analysed to provide pooled within-farm sire component estimates of h2and genetic correlations.Estimates of h2of 0·43 ± 0·10, 0·44 + 0·09 and 0·49 ±009 were obtained for weight for age, C + K and shoulder fat depths respectively in 3583 gilts in 49 Large White herds. Comparable Landrace values derived from 2810 gilts in 43 herds were 0·44 + 0·11, 0·40 ±0·10 and 0·51 ±0·12 respectively. Estimates were consistent from herd to herd.Estimates of h2made on data from 5081 crossbred pigs, of mainly Large White and Landrace parentage, varied with herd from 0·10 to 0·40 for weight for age and from 0·08 to 0·96 for shoulder fat depth. Significant differences between breeds were found for the genetic correlations between weight for age and the fat depths, and between shoulder and mid-backfat depths. The variance was partitioned into various components. For index score, the within-herd variance averaged 73% of the total variance.
The effect of inflation and form of investment on the estimated value of genetic improvement in farm livestock
Authors: Smith C. 
Published: September 2010

ABSTRACTHigh rates of interest (8 to 15%) commonly used in discounted cash flow analysis of genetic improvement schemes have tended to underestimate the value of the returns and to favour breeding programmes with short-term returns. It is shown that inflation should be removed from the interest rate, and an inflation-free rate used in discounting future returns to present-day value.Various methods for choosing discount rates are discussed. It is concluded that the appropriate rate is the real opportunity cost rate, that is the market cost of borrowing in real terms, in terms of goods rather than money. Taking account of inflation the average cost of borrowing in real terms in the United Kingdom over the past 32 years (1945 to 1976) is estimated as 2 to 3%. This also provides the best available estimate for discounting future returns, and it brings the opportunity cost rate into line with the social time preference rate often proposed for public investments.The contrast is made between the value of improvements made in the national interest and of those made by breeders or firms. The former benefit from returns on all national commercial production of improved stocks and the returns accumulate and are recouped over many years. On the other hand breeders and firms benefit only from the extra sales of breeding stock due to their temporary marginal superiority over competition and they are often at high risk of getting no returns. Implications to the form and amount of investment in animal improvement are discussed.
The effect of breed and of dried seaweed meal in the diet on the levels of copper in liver, kidney and plasma of sheep fed on a high copper diet
Authors: Herbert J. G. , Wiener G. , Field A. C. 
Published: September 2010

ABSTRACTTwenty-one mature ewes of each of two breeds, the Scottish Black-face and the Welsh Mountain, were allocated in equal numbers to three diets based on a complete cobbed feed with a 0, 5 and 15% inclusion of dried seaweed meal (Ascophyllum nodosum). All diets were made up to a Cu content of approximately 30 mg/kg by adding CuSO4 to the mix. Sheep were housed and fed individually for 15 weeks.There was a significant breed difference in the Cu level of the liver dry matter; the Welsh increased by 316 mg/kg compared with 240 mg/kg in the Blackface and the amount of Cu accumulated in the liver per kg feed consumed was 0·66 mg in the Welsh and 0·46 in the Blackface. Diets also had a significant effect; the Cu levels in liver dry matter rose by 323, 293 and 220 mg/kg for the 0, 5 and 15% seaweed diets respectively and the Cu stored per kg feed consumed was 0·66, 0·61 and 0·41 mg respectively. There was no corresponding effect of diet on plasma Cu level, but there was a breed difference with Welsh higher than Blackface. Cu level in kidney dry matter showed a breed-by-diet interaction. Total food consumption did not differ among the treatments, and live-weight and carcass-weight data suggested no adverse effects from the inclusion of seaweed meal in the diet.