bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting population gene frequency from sample data
Authors: Lewis R. M. , Grundy B. , Kuehn L. A. 
Published: May 2019

AbstractWith an increase in the number of candidate genes for important traits in livestock, effective strategies for incorporating such genes into selection programmes are increasingly important. Those strategies in part depend on the frequency of a favoured allele in a population. Since comprehensive genotyping of a population is seldom possible, we investigate the consequences of sampling strategies on the reliability of the gene frequency estimate for a bi-allelic locus. Even within a subpopulation or line, often only a proportion of individuals will be genotype tested. However, through segregation analysis, probable genotypes can be assigned to individuals that themselves were not tested, using known genotypes on relatives and a starting (presumed) gene frequency. The value of these probable genotypes in estimation of gene frequency was considered. A subpopulation or line was stochastically simulated and sampled at random, over a cluster of years or by favouring a particular genotype. Line was simulated (replicated) 1000 times. The reliability of gene frequency estimates depended on the sampling strategy used. With random sampling, even when a small proportion of a line was genotyped (0·10), the gene frequency of the population was well estimated from the across-line mean. When information on probable genotypes on untested individuals was combined with known genotypes, the between-line variance in gene frequency was estimated well; including probable genotypes overcame problems of statistical sampling. When the sampling strategy favoured a particular genotype, unsurprisingly the estimate of gene frequency was biased towards the allele favoured. In using probable genotypes the bias was lessened but the estimate of gene frequency still reflected the sampling strategy rather than the true population frequency. When sampling was confined to a few clustered years, the estimation of gene frequency was biased for those generations preceding the sampling event, particularly when the presumed starting gene frequency differed from the true population gene frequency. The potential risks of basing inferences about a population from a potentially biased sample are discussed.
Influence of salbutamol administered as the single active enantiomer (R-salbutamol) on the growth performance and carcass characteristics of broiler chickens
Authors: Fawcett J. P. , Ravindran V. , Morel P. C. H. , Zhang M. , Ciofalo V. B. , Spainhour C. B. , Aberg G. 
Published: May 2019

AbstractSalbutamol (albuterol) is a β-adrenergic agonist marketed as a racemic (50: 50) mixture of R- and S-enantiomers (rac-salbutamol). Since only R-salbutamol is pharmacologically active and S-salbutamol has a longer half-life in humans, we examined R-salbutamol as a performance enhancer and repartitioning agent in domestic chickens. The effects of feeding diets containing R-salbutamol (5, 10 and 15 mg/kg diet) and rac-salbutamol (10 mg/kg diet) from day 21 to 42 post hatching on growth performance, carcass characteristics and tissue concentrations of R- and S-salbutamol in male and female broilers were compared with a control diet. R-salbutamol in the diet lowered the weight gains in both sexes, but the magnitude of reduction was greater in males as indicated by a significant R-salbutamol ✕ gender interaction. R-salbutamol also lowered food intake and improved food conversion ratios in both sexes. The relative weights of breast muscle and leg muscle were significantly increased and the relative weight of the fat pad was significantly decreased in birds of both sexes given diets containing R-salbutamol. Carcass protein content increased and carcass fat content decreased but the differences were not statistically significant. A significant dose-response effect was observed for tissue concentrations of R-salbutamol in all tissues, except the fat. Performance and carcass parameters in chickens given the 5 mg/kg R-salbutamol diet were similar to those given the 10 mg/kg rac-salbutamol diet, but tissue concentrations of R-salbutamol were lower. Chickens given the 10 mg/ kg rac-salbutamol diet had higher tissue concentrations of salbutamol than chickens given the 10 mg/kg R-salbutamol diet and higher concentrations of S-salbutamol than R-salbutamol in liver and leg muscle. Overall, these results demonstrate that R-salbutamol is an effective repartitioning agent in broiler chickens.
Effects of substitution of barley with citrus pulp on diet digestibility and intake and production of lactating ewes offered mixed diets based on ammonia-treated barley straw
Authors: Castrillo C. , Barrios-Urdaneta A. , Fondevila M. , Balcells J. , Guada J. A. 
Published: May 2019

AbstractTwenty-eight lactating ewes (mean 48 (s.e. 0·37) kg live weight) were used from days 12 to 52 after lambing to evaluate the effects on digestibility and production performance of replacing barley grain with citrus pulp in diets based on ammonia-treated barley straw. Concentrates included 0·82 to 0·83 of different barley to citrus pulp proportions: 100: 0 (T1); 66: 33 (T2); 33: 66 (T3) and 0: 100 (T4), 0·115 of soya-bean meal, and urea to make diets isonitrogenous. Ewes were adapted to a common diet for 11 days after lambing, and then were given 850 g/day of each experimental concentrate together with 850 g/day of chopped barley straw for 14 days and milk production and lamb growth were recorded. During the following 14 days ewes received the same amount of concentrate but the straw was offered ad libitum and straw intake was recorded as well as milk production and lamb growth. After completing both periods, four ewes per treatment were used for total collections of faeces and urine. Apparent digestibility of organic matter and neutral-detergent fibre increased linearly (P < 0·05) with increasing levels of citrus pulp although no differences were found in the digestible organic matter content of dry matter of diets because of differences in ash content. Urinary excretion of allantoin and purine derivatives per unit of digestible organic matter intake tended to decrease with increasing inclusion of citrus pulp (proportionately by 0·15), suggesting a decrease in microbial protein synthesis, though this effect was not significant (P > 0·05). Faecal excretion of purine bases also decreased (P < 0·05) as citrus pulp inclusion increased. No treatment effect (P > 0·05) on ewe live weight, milk composition or serum glucose and 3–OH butyrate was observed when a 1: 1 straw to concentrate ratio was given, but milk production and lamb daily gain decreased linearly (P < 0·05) with increased proportions of citrus pulp in the concentrate. Similar responses were detected when straw was given ad libitum and differences among treatments in terms of straw intake were not identified. It is concluded that a lower microbial protein flow might explain in part the reduction in milk production observed when barley was replaced with citrus pulp.
Microbial contribution to duodenal purine flow in fattening cattle given concentrate diets, estimated by purine N labelling (15N) of different microbial fractions
Authors: Vicente F. , A. Guada J. , Surra J. , Balcells J. , Castrillo C. 
Published: May 2019

AbstractThe origin of duodenal purine bases (PB) was studied in a digestion experiment with four heifers, cannulated in the rumen and duodenum, which received a basal concentrate (152 g crude protein (CP) per kg dry matter (DM)) together with barley straw (85: 15 fresh weight basis) or the same concentrate supplemented with soya-bean meal, carbohydrate-treated soya-bean meal, maize gluten meal or fish meal to increase its protein content to 192 g/kg DM. Tr eatments were assigned to the four animals in five experimental periods according to an incomplete Latin-square design. Each 30-day period included 20 days of change-over adaptation and 10 days of experimental measurements. The flow of digesta entering the duodenum was estimated using Yb and acid-detergent insoluble ash as indigestible markers according to a double-marker system and microbial nitrogen (N) and PB were labelled with15N infused into the rumen. The proportion of duodenal PB of microbial origin estimated from15N enrichment of PB-N averaged 0·66 (s.e. 0·029) and did not differ between treatments nor when protozoa or bacteria associated with liquid (LAB) and solid (SAB) fractions were used as a reference sample. On average microbial contribution to duodenal non-ammonia N was higher when estimated from the PB/N ratio than from15N (0·67 v. 0·55 (s.e. 0·015)) although differences were small and not significant when LAB was the reference sample (0·58 v. 0·52 (s.e. 0·018)) reflecting the higher PB/N ratio of this fraction compared with SAB and protozoa (2·04 v. 1·65 and 1·60 (s.e. 0·04) mmol/g). Considering only the duodenal PB of microbial origin resulted in estimates of microbial N synthesis from the PB/N ratio of SAB similar to those derived from15N enrichment of both bacterial fractions (12·9 v. 13·5 and 13·3 (s.e. 0·83) g/kg of organic matter apparently digested in the rumen OMADR)) but underestimated the values derived from LAB (9·9 g/kg OMADR). Regardless of the estimation method, neither the duodenal flow of microbial N nor the efficiency of microbial synthesis differed between treatments. These results suggest that a significant proportion of duodenal PB have a non-microbial origin which may lead to overestimation of microbial yield when PB are used as a marker. Differences in PB/N ratio between microbial fractions is another important factor to be considered.
Effects of index selection on the performance and carcass composition of sheep given foods of different protein concentrationsad libitum
Authors: Lewis R. M. , Emmans G. C. , Simm G. 
Published: May 2019

AbstractSheep of a line selected on an index to increase carcass lean content at 150 days of age (selected (S); no. = 90), and an unselected control line (control (C); no. = 90), were given ad libitum foods of three different protein concentrations (192, 141 and 120 g/kg dry matter). Growth was measured from about 21 to 114 kg live weight. The carcasses of each line were analysed for lean, fat and bone at three widely varying weights in both males and females. Level of protein did not affect the extent to which S was superior to C in the content of fat (0.86 as much) or lean (1.08 as much) in the carcass. The fat concentration of the carcass increased, and the lean concentration decreased, as dietary protein concentration was reduced (P < 0.01). On the highest level of protein used, the S line grew 1.17 times as fast and was 1.10 times as efficient compared with C. The extent to which growth rate in S exceeded that in C was greater on the highest level of protein used (92.3 g/day) than on the two lower protein diets (26.4 g/day). The difference of 65.9 (s.e. 18.4) g/day was significant (P < 0.01). On the diet of highest protein concentration, growth was well described by a Gompertz function. The S line had an estimated maximum growth rate 1.25 times that of the C when averaged across males and females. A Spillman function was used to describe weight in terms of cumulative intake. It worked well for all three levels of dietary protein concentration. S sheep performed better than unselected sheep on foods differing in protein concentration and over a wide range of live weights, suggesting benefits are likely within the diverse farming environments found in practice.
Effects of age on plasma metabolites and hormones in finishing Belgian Blue double-muscled cull females
Authors: Cabaraux J.-F. , Dufrasne I. , Istasse L. , Hornick J.-L. 
Published: May 2019

AbstractTwo groups of 12 Belgian Blue double-muscled cull females were used successively in a 2-year repeated experiment and divided into three groups according to age, allowing four animals per group each year. The aim of the trial was to relate, during the finishing period, the metabolic and endocrine parameters with age. Females were fattened with a diet based on maize silage and were blood sampled on several occasions. The average daily gain (ADG) decreased with the age of the cows. Plasma glucose and triglycerides decreased also with age while the youngest females showed lower concentrations of urea than those older. The composition of plasma non-esterified fatty acids also differed considerably between groups. The hormones that best related with ADG were IGF-1 and insulin. Plasma concentrations of thyroid hormones were lower in the oldest animals. No difference between groups was found for GH. Heifers presented lower concentrations of GH and IGF-1 than those reported elsewhere in fattening bulls of the same breed. It may be concluded that in Belgian Blue double-muscled females, glucose, IGF-1 and insulin are good indicators of the growth potential. Young adult cows presented intermediate characteristics of metabolic and endocrine status that were close either to younger or to older cows.
Vitamin A regulation of stearoyl-CoA desaturase mRNA levels and fatty acid composition in sheep tissues
Authors: Daniel Z.C.T.R. , Salter A.M. , Buttery P.J. 
Published: May 2019

AbstractThe effect of vitamin A (retinol) on ovine stearoyl-CoA desaturase (SCD) mRNA levels and fatty acid composition was investigated. Sheep adipose tissue explants were maintained in culture for 24 h in the presence of all-trans retinoic acid (RA). Tissue SCD mRNA levels were increased with 25 μmol/l RA but the levels of SCD mRNA in tissue treated with 100 μmol/l RA were not different from control. The effect of vitamin A supplement on SCD mRNA levels in vivo was then characterized: growing lambs were given a concentrate diet (2 kg/day) containing 0, 0.225, 1.125 and 3.375 mg vitamin A per kg diet for 21 days. Treatment resulted in a concentration-dependent increase in adipose tissue and liver SCD mRNA levels, although the greatest effect was seen in the liver. SCD mRNA levels were highest in tissue from animals given 0.225 mg vitamin A per kg diet and further increases in vitamin A supplementation were not accompanied by corresponding increases in SCD gene expression. Fatty acid composition was also determined. Overall, tissue from animals given vitamin A had greater levels of both palmitoleic and oleic acid relative to their precursors. These data clearly show that SCD gene expression in adipose tissue and liver is regulated by retinoic acid and the liver appears to be most responsive. However, although significant, the change in the proportion of oleic acid was only small indicating that dietary manipulation with vitamin A is not a suitable method for increasing the unsaturated fat content of sheep meat.
Growth and carcass composition of tropical fat-tailed Menz and Horro sheep breeds
Authors: Negussie E. , Rottmann O. J. , Pirchner F. , Rege J. E. O. 
Published: May 2019

AbstractThe pattern of growth and carcass composition of indigenous Ethiopian fat-tailed Menz and Horro lambs were assessed through serial slaughter and carcass dissection of 147 lambs at five different growth phases. The GLM procedure of Statistical Analysis Systems Institute and allometric growth equations were used to assess the effects of various factors and differential growth of carcass components, respectively. Results showed that the growth and carcass composition of Menz and Horro lambs was significantly (P < 0.05 to P < 0.001) affected by the genotype, growth phase and season of birth of lambs. The effects of growth phase clearly showed that slower growth of the body and of carcass components was observed during the third phase (i.e. after weaning). Although there was an effect on fat to lean ratios (P < 0.05), growth phase had no significant effect on dressing out proportion, and lean to bone ratios. A significant influence of genotype (P < 0.001) and sex (P < 0.05) on lean to bone ratios indicated that the Horro sheep and ram lambs had a much more developed and heavier skeleton than the Menz sheep and ewe lambs. Higher pre-slaughter, hot carcass, lean and bone and fat weights of May/June born lambs revealed significant advantages of wet season lambing for fast growth and improved carcass composition. The log/log regression of weights of dissectible carcass components on hot carcass and empty body weight showed that the differential growth of bone was declining and that of lean was isometric relative to the growth of empty body weight. For carcass fat, the allometric growth coefficients (b) of 1.5 and 1.8 for Menz and Horro sheep, respectively indicated that fat is a late maturing body component. Moreover the growth of carcass fat relative to empty body weight in the Menz and Horro sheep is slower than that reported for tropical sheep breeds.
Long-term response to feeding level in lactational performance of Boran (Bos indicus) and Boran ✕ Holstein cows
Authors: Jenet A. , Yimegnuhal A. , Fernandez-Rivera S. , Tegegne A. , Osuji P.O. , McCrabb G. , Kreuzer M. 
Published: May 2019

AbstractIn an experiment lasting from 1.5 years before first calving until third parturition, 24 purebred indigenous Bos indicus (Boran) cows and 24 Boran crosses with Holstein (proportionately 0.50 and 0.75 Holstein blood level) were given a diet composed of Bermuda grass hay and wheat bran (0.65: 0.35) offered at low, medium and high level. This level was adapted in amount to actual body weight every 2nd week corresponding to assumed 1.0, 1.2 and 1.4 times maintenance energy requirements. Cows were subjected to working exercise before and after first parturition. Body weight differences (lower with low and medium feeding level) developed mostly before calving for the first time and showed the typical decline at the start of lactation and increase in the dry period. Additionally, Boran cows given the high level increased their body weight from the first to the second lactation cycle. Body condition scores were higher in the Boran cows and, in both genotypes, with high feeding level. Independent of feeding level and genotype, calving intervals in cycles 1 and 2 were 530 and 421 days, respectively. Lactation length was considerably shorter in the Boran cows than in the crossbred cows. Milk yield, calculated over the first 13 weeks of lactation and over the whole lactation in both cycles, was 2.06 and 3.06 times higher in the crossbreds than in the Boran. Milk of Boran cows had 1.30, 1.15 and 1.20 times higher contents of fat, total solids and protein. In the first 13 weeks of lactation, milk yield of crossbreds with high feeding level (8.7 kg/day) was higher (P < 0.05) than that of the crossbreds with medium (6.5 kg/day) and low feeding level (5.4 kg/day), respectively. Boran cows never showed a significant response in milk yield to feeding level. Accordingly, the amount of organic matter intake required per kg milk increased with feeding level in the Boran cows while it remained unaffected in the crossbreds. Organic matter digestibility, as measured in lactation cycle 1, was higher (P < 0.01) in Boran. Response to high feeding level and estimated maintenance requirements of crossbred cows corresponded with current assumptions, but crossbreds subjected to medium feeding level expressed unexpectedly little difference from those receiving the low level. It seems that current recommendations are not generally applicable to indigenous tropical breeds as these responded differently from crossbreds to feeding level.
Effects of habituation to the milking parlour on the milk production and reproductive performance of first calving Holstein-Friesian and Norwegian dairy herd replacements
Authors: Wicks H. C. F. , Carson A. F. , McCoy M. A. , Mayne C. S. 
Published: May 2019

AbstractTwenty-nine Holstein-Friesian and 20 Norwegian dairy herd replacements were used to investigate the effect of habituating heifers to the milking parlour environment prior to calving on subsequent lactational performance. The heifers commenced the study at 3 weeks prior to calving when they were allocated on the basis of breed, genetic merit and live weight to either a habituation or no habituation (control) treatment. Heifers were housed together in cubicle accommodation with grass silage offered ad libitum along with 1 kg of concentrates per head per day offered in the feeding passage (control treatment) or in the food managers in the milking parlour (habituation treatment). Animals in the habituation treatment were exposed to the full milking parlour routine once daily (afternoon milking) in a 20-point rotary herringbone parlour. Holstein-Friesian heifers averaged 2.6 kg/day more milk than the Norwegian replacements. Holstein-Friesian heifers also had higher fat and protein yields than Norwegian heifers, however they also lost more body condition during the first 3 months of lactation. Habituated heifers yielded on average 1.3 kg/day more milk (P < 0.001) than the control group of heifers over the first 100 days of lactation (26.7 v. 25.4 (s.e.d. 0.38) kg/day), with the difference being greatest in the first 2 to 3 weeks of lactation. In early lactation, animals on the habituation treatment lost more live weight (0.16 v. 0.02 (s.e.d. 0.061) kg/day) (P < 0.05) and body condition than those on the control treatment. Duration of milking was longer (P < 0.001) (378.4 v. 340.5 (s.e.d. 6.53) s) and milk flow rate slower (P < 0.001) (2.20 v. 2.46 (s.e.d. 0.041) kg/min) respectively for the habituation compared with control group. Somatic cell counts (SCC) were lower (P < 0.001) for habituation group (1.66 v. 1.79 (s.e.d. 0.037) log10SCC per ml), but there was no significant treatment effect on locomotion scores. Reproductive performance was lower for habituated heifers, with increased intervals to conception (P < 0.05) (102 v. 83 (s.e.d. 9.22) days). Habituating heifers to the milking parlour environment prior to calving increased milk production but appeared to have some detrimental effects on reproductive performance.
Genetic parameters forNematodirusspp. egg counts in Romney lambs in New Zealand
Authors: Morris C. A. , Bisset A. , Vlassoff A. , West C. J. , Wheeler M. 
Published: May 2019

AbstractGenetic analyses were carried out on Nematodirus spp. egg counts (NEM) of lambs from a set of Romney breeding lines. The lines had been under selection for 22 seasons (1979 to 2000) for divergence in resistance to infection by strongyle nematodes other than NEM, using faecal egg count (FEC) as the selection criterion. Heritabilities and genetic correlations for NEM were estimated using residual maximum likelihood procedures. Correlated responses in NEM were also determined. Heritability estimates for loge(NEM + 100) in lambs at 4 months of age (NEM1) or 6 months of age (NEM2) were 0·15 (s.e. 0·03) and 0·26 (s.e. 0·04) respectively (c.f. 0·28 (s.e. 0·02) and 0·35 (s.e. 0·02) for loge(FEC + 100)). The genetic correlation between loge(NEM1 + 100) and loge(NEM2 + 100) was 0·85 (s.e. 0·08), while the genetic correlations between measurements of loge(NEM + 100) and loge(FEC + 100) on both sampling occasions had a weighted average of 0·43, with estimates ranging from 0·30 (s.e. 0·08) to 0·52 (s.e. 0·07). Divergence in loge(NEM + 100) between the high and low FEC lines, estimated over both sampling times combined, was 1·07 phenotypic standard deviations, compared with 3·6 phenotypic standard deviations for loge(FEC + 100). Expressed in terms of back-transformed eggs per g, the high and low FEC lines differed by factors of 7·6 and 32·2 for NEM and FEC, respectively. The results support earlier parasitological data indicating that the genetic mechanisms in sheep which are responsible for resistance to other strongyle nematodes probably also influence resistance to Nematodirus infection.