bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction and evaluation of response to selection with overlapping generations
Authors: Hill William G. 
Published: September 2010

SUMMARYIn a population in which generations overlap the improvement in performance in successive years resulting from a single year of selection is not constant, for the genes from a group of selected individuals may take many years to pass through the population. A formal method is developed for predicting responses and discounted returns from improvement in populations with overlapping generations including, if necessary, generations of multiplication of breeding stock.The method is based on a matrix which specifies the passage of genes between the different age groups and sexes. Simple matrix operations can be used to compute the proportion of genes in animals of both sexes and each age in the population at any time which derive from a group of selected animals at an earlier time. The response produced by these selected animals equals the product of their genetic selection differential and the proportion of genes deriving from them. Comparisons are made between responses predicted using this theory and the classical theory of uniform rates of response, and a method is given for computing the time lag of genes passing through the population.The results are extended to enable computation of discounted returns from improvement.
Nutrition and reproductive performance of dairy cattle 2. Prediction of reproductive performance in first lactation dairy heifers subjected to controlled nutritional regimes
Authors: Ducker M. J. , Morant S. V. , Fisher W. J. , Haggett Rosemary A. 
Published: September 2010

ABSTRACTOne hundred first lactation Friesian dairy heifers were used to investigate the effect of level of feeding n i late pregnancy (83·6 or 64·6 MJ metabolizable energy (ME) per head daily and around the time of first artificial insemination (AI) (weeks 6 to 18 of lactation: 146·8 or 119·8 MJ ME per head daily) on reproductive performance.Heifers receiving the high level of feeding in lactation had a successful pregnancy rate to first AI of 0·42 compared with 0·63 for heifers receiving the lower level of feeding. Heifers receiving the higher level of feeding in late pregnancy followed by the lower level in lactation had a pregnancy rate of 0·72 o t first AI resulting in a median interval from calving to pregnancy of 75 days compared with figures of 0·35 and 95 days respectively, for heifers receiving the higher levels of feeding throughout the experiment (P< 0·001).Blood samples were taken from all heifers 2 weeks before and on weeks 1, 5, 9, 13 and 18 after calving, and were analysed for 13 components. Of the blood components measured, only p"-hydroxy-butyrate concentrations, particularly at week 9, were affected by the nutritional treatments imposed and consistently related to fertility (P< 0·01 toP< 0·001).Milk yield and live-weight change, individually and as the components of net energy output, showed the strongest relationships with reproductive performance (P< 0·01 toP< 0·001). The three variables which together accounted for the highest proportion (0·30) of the variation in days to successful pregnancy were net energy output at AI, (3-hydroxy-butyrate at week 9, and mean tail score in weeks 10 o t 13. These enabled the calving to successful pregnancy interval for an individual or 100 first lactation heifers to be predicted with a 95% confidence interval of ±58 days or ±8·6 days, respectively.
Energy utilization by Hereford and Simmental males and females
Authors: Ferrell C. L. , Jenkins T. G. 
Published: September 2010

ABSTRACTPost-weaning metabolizable energy intake, growth of empty-body chemical components and efficiencies of energy utilization were evaluated for Hereford intact males (17) and females (16) and Simmental intact males (15) and females (16) during a 212-day feeding period. Within each breed × sex subclass, animals were assigned to one of three levels of metabolizable energy (ME) intake: (1) 544 kJ/kg M0·75 per day, (2) 795 kJ/kg M0·75 per day, and (3) ad libitum. Body composition of each animal was estimated at the beginning and end of the feeding period by deuterium oxide dilution.Protein and water gain of Hereford and Simmental cattle were similar at restricted levels of intake but were greater for Simmental than for Hereford cattle at ad libitum intakes. Similarly, rates of protein and water gain tended to increase more rapidly in response to increased energy intake by males than by females. Hereford males gained fat and energy slightly more rapidly than Hereford females, but Simmental males gained fat and energy at slower rates than Simmental females.Males had higher maintenance requirements and tended to use ME with less efficiency for maintenance and gain than females. Hereford cattle had lower maintenance requirements and used ME with greater efficiency for both maintenance and gain than Simmental cattle.
Relationships between some estimates of growth hormone and prolactin secretion and rates of accretion of constituents of body gain in rams
Authors: Klindt J. , Jenkins T. G. , Leymaster K. A. 
Published: September 2010

ABSTRACTRelationships between estimates of some factors affecting growth hormone (GH) and prolactin (PRL) secretion and rates of deposition of fat, protein and ash and rate of gain were investigated in Suffolk ram lambs. Factors affecting secretion were determined from measurements made by radioimmunoassay on blood samples collected at 15-min intervals during a 6-h period at a body weight of 43 to 58 kg. Depositional traits were estimated over the period of growth from 32 to 73 kg. The endocrine secretory measurements were adjusted statistically for weight at blood sampling. The only single endocrine secretory measurement that significantly correlated with a growth or depositional trait was frequency of GH peaks which was negatively related to rate of ash accretion. Multiple regression analysis was used to estimate the association between endocrine secretory measurements and rates of gain and accretion. R2 values were 0·43, 0·29, 0·42 and 0·70 for average daily gain and accretion rate of protein, fat and ash, respectively. Models with minimal error mean squares contained linear, quadratic and/or crossproduct terms for the independent variables, thus suggesting nonlinear relationships of the hormones in the mediation of rate and pattern of growth. These results emphasize the value of assay of multiple samples from each animal, the subsequent estimation of secretory characteristics and the use of expanded statistical models to determine the relationship present in the system under investigation.
The feeding value of straw from different genotypes of barley when given to Awassi sheep
Authors: Capper B. S. , Thomson E. F. , Rihawi S. , Termanini A. , Macrae R. 
Published: September 2010

ABSTRACTBarley straw constitutes up to half of the dry-matter intake of Awassi sheep in areas of Syria where the rainfall is 200 to 350 mm. The genotype of barley planted could therefore, through the nutritive value of its straw, significantly affect flock production levels. Selection of suitable barley genotypes may have greater economic potential as a means of improving roughage feeding quality in these areas than chemical or physical processing.The voluntary intake and digestibility of the unsupplemented straw of three genotypes of barley was evaluated with Awassi castrated male sheep. The voluntary organic-matter (OM) intakes of handharvested Beecher, Arabic Abied and ER/Apam straw were 22·2, 34·7 and 27·0 g/kg M0·75 per day and OM digestibility coefficients were 0·39, 0·44 and 0·42. The factors affecting voluntary intake and digestibility appeared to be the proportions of leaf and stem. Beecher straw had less leaf and more stem than the other two genotypes. The chemical composition and in vitro cellulase digestibility of the leaf indicated that it had a higher potential feeding value than stem.ER/Apam appears to be an example of a genotype which under dry environmental conditions combines higher barley grain yields with more acceptable straw feeding value than several other genotypes evaluated.
Effect of ionophores on the accumulation of copper in the livers of sheep
Authors: van Ryssen J. B. J. , Barrowman P. R. 
Published: September 2010

ABSTRACTLambs were allocated to three treatments: control (C), monensin (M) and lasalocid sodium (L) in a concentrate diet containing 36 mg copper per kg food. After 2 months deaths from copper toxicity occurred and the trial was terminated. All lambs were slaughtered. The mean liver copper concentration (mg/kg dry matter) of 1907 in the M treatment was higher than the mean concentrations of 1342 and 1229 in the C and L groups respectively (P < 0·01). Total liver copper was 234, 260 and 230 mg and the retention of dietary copper in the liver was 93·5, 108·5 and 93·3 g/kg for the C, M and L treatments respectively. These differences were not significant. From reduced liver size (as a proportion of body weight) and high copper levels in the kidneys, it was concluded that the group given monensin had accumulated copper to a level closer to the toxicity threshold than the other two groups.
A comparison of the early behaviour of intensively and extensively reared calves
Authors: Kerr Sheila G. C. , Wood-Gush D. G. M. 
Published: September 2010

ABSTRACTThis study involved two groups of calves, one group consisted of eight Angus × (Friesian × Hereford) calves born in the late summer and kept with their dams in the field. The other group consisted of 20 autumn-born Friesian calves kept indoors in individual stalls. Similar ethograms and techniques were used to study their behaviour up to 8 weeks of age, thus allowing comparisons to be made of the proportion of time spent in various activities, as well as changes in the sequences of behaviour with age. In general, the activity of the calves of both groups showed a similar trend in development. However, the field calves spent significantly more time in investigatory behaviour while the confined calves showed a significantly higher frequency of investigatory behaviour and indulged in more self grooming. The analysis of behavioural sequences showed few differences in focal points or direction of transitions from one behavioural pattern to another, suggesting that the integration of activities into developing motor patterns in the calf is determined ontogenetically with little modification by the environmental factors encountered in this study. However, the confined calves showed a greater mean number of transitions per hour. The findings are discussed in relation to the welfare of the confined calf.
Varietal differences in rumen degradation of barley, wheat and hard wheat straws
Authors: Ramanzin M. , Bailoni L. , Beni G. 
Published: September 2010

AbstractThe rumen dry-matter degradation of straw from nine varieties of barley, nine varieties of wheat and seven varieties of hard wheat was studied to provide further information on varietal differences and their relationships with agronomic characteristics.In all the cereals there were significant differences in in situ dry-matter disappearance between varieties. The range of differences was lower in hard wheat varieties compared with the other cereals. There were no significant correlations between straw degradability and plant height, days from sowing to heading and grain production and quality. Lignin concentration was significantly correlated to straw degradability (r = −0·937 in barley, −0·675 in wheat and −0·987 in hard wheat).Leaf had lower concentrations of lignin and higher degradability than stem in barley and wheat but the two fractions were similar in hard wheat straws. The differences in degradation between the most and the least degradable straw varieties of each cereal species were mainly due to differences in degradability of both the fractions whereas the role of leaf and stem proportions was of minor importance.
Animal production and food: real problems and paranoia
Authors: Blaxter K. L. , Webster A. J. F. 
Published: September 2010

AbstractThe scientific and technological expansion of British agriculture between the mid 1930s and mid 1980s can be attributed primarily to the provision of favourable and stable prices and only secondly to government support of research and development. These conditions have changed. Most government-funded research in agriculture is now directed to the new biological sciences, molecular biology and transgenics. It is uncertain whether those at the frontiers of biotechnology are aware of the limits and constraints placed on animal production. Equally, it is uncertain whether the commercial supply services to agriculture will be prepared to meet the costs of transferring this new technology into production. These real problems facing agriculture are amenable to rational solutions. Of greater concern are food scares whipped up by pressure groups and government responses taken in the absence of, or in defiance of, scientific evidence.Two examples are considered, one trivial, the other deadly serious. The first involves the recommendation that pregnant women ‘should not eat liver’ based on an unpublished report of a single case of birth defects. The second example chosen for discussion is the alleged causal relationship between the intake of saturated fatty acids (SFA) and coronary heart disease. The inadequacy of the simple distinction between saturated and unsaturated fats is briefly reviewed in the light of new knowledge relating to specific SFA, monounsaturates and the distinction between polyunsaturates of the linoleic and linolenic series. Evidence from large epidemiological studies is marshalled to demonstrate that there is no good case to support the conclusion of the Committee on Medical Aspects of Food Policy (COMA, 1984) that the nation's diet should be changed to reduce the proportion of saturated fats. The Department of Health is invited to recall COMA to reconsider their recommendations in the light of new evidence.
Effect of feeding whole and rolled barley to steers in the morning or afternoon in diets containing differing proportions of hay and grain
Authors: Mathison G. W. , Engstrom D. F. , Macleod D. D. 
Published: September 2010

AbstractA 2 × 2 × 2 factorial experiment was conducted with 128 growing-finishing steer calves to examine the effects of feeding whole v. rolled barley in diets containing either a constant proportion of concentrate (0·67) or proportionately 0·33 concentrate for 56 days followed by 0·90 concentrate for 83 days, with the concentrate being given at either 08.00 or 15.30 h. Steers given hay at 08.00 h and concentrate at 15.50 h grew proportionately 0·05 faster (P < 0-05) and had better dry matter (DM): gain ratios (P < 0·05) during the first 56 days than those given concentrate at 08.00 h and hay at 09.00 h. By the end of the trial steers fed at 15.50 h had similar daily gains to steers fed at 08.00 h but required proportionately 0·02 less DM: gain (P <0·05). No significant difference in gain was detected between steers given whole (1·30 kg/day) or rolled (1·38 kg/day) barley, but those given whole barley ate proportionately 0-08 more DM daily and had a proportionately 0-15 poorer DM: gain ratio (P < 0-05). The digestibility of diets containing whole grain was reduced (P < 0-05). Thirty-six steers given whole barley bloated compared with nine given rolled barley (P < 0·05). No significant differences were found either in DM intake or in final proportion of concentrate in the diet between steers given the diet containing proportionately 0·67 concentrate throughout the feeding period and those given the variable concentrate diets. There was a trend for DM: gain ratios to be poorer for steers given the constant proportion of concentrate (6·89 v. 6·65).
The influence of the fat concentration of the diet on the response by dairy cows to body condition at calving
Authors: Garnsworthy P. C. , Huggett C. D. 
Published: September 2010

AbstractTwenty-four Friesian dairy cows were divided into two groups of 12 between 12 and 18 weeks prior to calving and fed to achieve condition scores at calving of 3·2 (F) or 2·3 (T). For the first 11 weeks of lactation, six cows from each group (H) were given daily 9 kg of a high-fat compound (acid ether extract (AEE) 96 g/kg dry matter (DM)), 3 kg molassed sugar-beet pulp and hay ad libitum. The other six cows in each group (L) were given 10 kg of a low-fat compound (AEE 29 g/kg DM), 2 kg sugar-beet pulp and hay ad libitum. Allowances of compound and sugar-beet pulp were designed to provide equal amounts of energy, neutral-detergent fibre and protein. The fat source used in compound H was a calcium salt of palm acid oil (Megalac®).DM intake was not affected by treatment but fat intake was significantly higher on diet H (P < 0·001). Group TH had higher intakes of digestible energy (DE) than group FH (249 v. 229 MJ/day; P < 0·05), but condition at calving did not affect DE intake with diet L (FL = 230, TL = 233 MJ/day). Milk yield was not significantly affected by treatment, although cows in group TL tended to yield less milk than other groups (28·3, 27·3, 28·0 and 24·3 kg/day for FH, FL, TH and TL respectively). The concentration of milk fat was higher and of milk protein lower with diet H compared with diet L (milk fat 48·1, 42·2, 42·9 and 39·6; milk protein 28·0, 31·0, 28·4 and 30·5 g/kg for FH, FL, TH and TL respectively). Loss of condition score was greater for cows in group F (0·65 units) than for those in group T (0·04 units). Within group F, loss of condition tended to be greater with diet L.It is concluded that the increased intake of fat with diet H tended to decrease loss of condition in cows that were fat at calving but increase milk yield in cows that were thin at calving. It also tended to increase milk fat concentration but decreased milk protein concentration.
A note on the effects of pattern of food intake and body condition on the duration of the post-partum anoestrous period and LH profiles in beef cows
Authors: Wright I. A. , Rhind S. M. , Whyte T. K. 
Published: September 2010

An experiment was conducted to determine the effect of level and pattern of food intake in post-partum beef cows on the length of the post-partum anoestrous period and associated luteinizing hormone profiles. Forty-six multiparous cows were allocated at calving to one of three feeding regimes: 55 MJ metabolizable energy (ME) per day throughout (LL), 145 M] ME per day throughout (HH), or 55 M] ME per day until 6 weeks post partum and then 145 M] ME per day thereafter (LH). The duration of the post-partum anoestrous period was assessed from plasma progesterone profiles. Luteinizing hormone profiles in the peripheral circulation were determined at weeks 3, 6, 8 and 11 post partum from samples collected every 20 min for 10 h.Feeding regime had no effect on either the length of the post-partum anoestrous period, being 99, 89 and 91 (s.e.d. 12·2) days for the LL, LH and HH cows respectively, or on any aspect of luteinizing hormone pulsatility. Body condition at calving was negatively correlated with the duration of the post-partum anoestrous period, each unit increase in body condition at calving being associated with a decrease in the post-partum anoestrous period of 86 (s.e. 21·8) days. Luteinizing hormone pulse frequency at 6 weeks post partum was positively correlated with body condition at calving.This experiment confirms the importance of body condition at calving in influencing the duration of the post-partum anoestrous period and indicates that level and pattern of feeding post partum has little effect when cows calve at a body condition of approximately 2·25.
Asymptotic response to selection on best linear unbiased predictors of breeding values
Authors: Dekkers J. C. M. 
Published: September 2010

AbstractFormulas were derived to predict asymptotic response to selection on best linear unbiased predictors (BLUP) of breeding values that account for selection-induced gametic phase disequilibrium, also known as the ‘Bulmer’ effect. Breeding programmes in populations of infinite size and with discrete generations were considered. For two-path breeding programmes with equal male and female accuracy of selection, relative reductions in response due to gametic phase disequilibrium were independent of heritability. Reductions in response depended only on intensities of selection and ranged from 0·22 to 0·27 when selected proportions were less than 04 for both males and females. With unequal accuracy of males and females, relative reductions in response depended on the ratio of accuracies, in addition to selection intensities. For given selection intensities, reductions were up to proportionately 0·08 larger with unequal accuracies than reductions obtained for equal accuracies. Relative reductions in response for breeding programmes with four paths of selection depended on intensity and accuracy of selection in each path, but were within a range similar to that observed for two-path programmes. Gametic phase disequilibrium will, therefore, not greatly affect ranking and relative differences among alternative breeding programmes.Gametic phase disequilibrium had a larger effect on response with selection on BLUP than on phenotype, which is largely due to larger relative reductions in accuracy of selection with BLUP. Despite larger relative reductions, asymptotic response to selection on BLUP is expected to be larger than selection on phenotype.
Electrocardiogram parameters of piglets during housing, handling and transport
Authors: Villé H. , Bertels S. , Geers R. , Janssens S. , Goedseels V. , Parduyns G. , van Bael J. , Goossens K. , Bosschaerts L. , de Ley J. , Heylen L. 
Published: September 2010

AbstractTelemetric techniques for the monitoring of physiological parameters during housing, handling and transport may help producers to reduce mortality and improve meat quality. In order to know the reliability of electrocardiogram parameters as stress indicators, piglets (12 to 23 kg) being different with respect to the halothane gene (homozygous halothane sensitive (nn) and non-sensitive (NN), heterozygotes (nN)), and thus different with respect to stress susceptibility, were monitored with an ambulatory ECG device during housing, handling and transport. Skeletal muscularity of all animals was measured with an ultrasound device.Heterozygotes and homozygote halothane sensitive piglets had a higher muscularity, but only the homozygotes had a higher ST-elevation from the isoelectric line of the QRST-complex of the electrocardiogram when measured within housing conditions. This means a different propagation of the electric current related to the activation of the ventricle. Halothane gene carriers (Nn and nn piglets) had a statistically significant higher mean maximal heart rate during housing conditions. During handling heart rate rose by 14·8%, 0·61% and 42·9% respectively for NN, nN and nn piglets, with nn piglets having the highest values. During transport these measurements were respectively 6·88%, 3·66% and 9·7% higher for lines NN, nN and nn as compared with those in housing conditions. Heart arrhythmicity parameters were not different between housing and transport, but during handling up to a 23-fold increase could be observed.Heart rate and arrhythmicity parameters may generate reliable information to monitor stress during housing, handling and transport of piglets through genotypes and skeletal muscularity.