Sixty castrated male lambs fca. 37 kg) were allocated to an initial slaughter group (no. = 12) or to one of six treatment groups (no. = 8). Chopped oaten hay (sprayed with 10 g urea per kg) was offered ad libitum with 57 gjday chopped lucerne hay. Additional supplements were 0 or 57 g/day formaldehyde-treated casein (protected casein) and volatile fatty acids (VFAs) at ca. 1·45 MJ gross energy per day. The VFAs given were acetate or propionate or a mixture of these (molar ratio 4: 1). Daily food intake and weekly live-weight (LW) gain were measured and rumen fluid and blood were collected. The lambs were shorn, slaughtered and body composition was determined.

Food intake (g/kg LW) was not affected by treatments. Supplementation with protected casein increased LW gain and wool growth. Supplementation with propionate reduced LW gain, but not when given with protected casein. Plasma concentrations of urea-nitrogen and insulin were increased, and plasma somatotropin decreased in lambs given protected casein. Final body content of water, fat, protein and gross energy, adjusted to the mean fleece/digesta-free body weight of 36·5 kg, was not affected by the treatments. The partitioning of water, fat and energy between the carcass and the rest of the body was affected by the treatments. Excretion of VFAs in urine was measured in two sheep in experiment 2, and was negligible compared with the quantity of VFAs given. It is concluded that energy from salts of VFAs, in particular propionate, is used inefficiently for body-weight gain in lambs given low-protein roughage diets. The nutritional treatments had only marginal effects on the composition of body gain.

Lifetime performance variability is a powerful tool for evaluating herd management. Although efficiency is a key aspect of performance, it has not been integrated into existing studies on the variability of lifetime performance. The goal of the present article is to analyse the effects of various herd management options on the variability of lifetime performance by integrating criteria relative to feed efficiency. A herd model developed for dairy goat systems was used in three virtual experiments to test the effects of the diet energy level, the segmentation of the feeding plan and the mean production potential of the herd on the variability of lifetime performance. Principal component analysis showed that the variability of lifetime performance was structured around the first axis related to longevity and production and the second related to the variables used in feed efficiency calculation. The intra-management variability was expressed on the first axis (longevity and production), whereas the inter-management variability was expressed on the second axis (feed efficiency) and was mainly influenced by the combination of the diet energy level and the mean production potential. Similar feed efficiencies were attained with different management options. Still, such combinations relied on different biological bases and, at the level of the individual, contrasting results were observed in the relationship between the obtained pattern of performance (in response to diet energy) and the reference pattern of performance (defined by the production potential). Indeed, our results showed that over-feeding interacted with the feeding plan segmentation: a high level of feeding plan segmentation generated a low proportion of individuals at equilibrium with their production potential, whereas a single ration generated a larger proportion. At the herd level, the diet energy level and the herd production potential had marked effects on production and efficiency due to dilution of fixed production costs (i.e. maintenance requirements). Management options led to similar production and feed efficiencies at the herd level while giving large contrasts in the proportions of individuals at equilibrium with their production potential. These results suggested that analysing individual variability on the basis of criteria related to production processes could improve the assessment of herd management. The herd model opens promising perspectives in studying whether individual variability represents an advantage for herd performance.

Two trials were conducted with eight yearling camels with an average intial body weight of 300 kg, to evaluate protein and energy values of lucerne hay and barley grains. In each trial, eight animals were randomly allotted to two different dietary treatments of coarsely ground lucerne hay or lucerne hay + barley grain (50:50) in such a way that two animals in each of the two blocks received the same ration. Each trial consisted of a 10-day preliminary period followed by a 7-day collection period during which total urine and faeces collections were made, and samples were processed and composited for later analysis.

All animals consumed daily an average of about 5 kg food divided in two equal meals. The apparent digestibility coefficients for organic matter, crude protein, neutral-detergent fibre and cellulose of the lucerne hay ration improved respectively from 0·615, 0·662, 0·455 and 0·555 to 0·736, 0·655, 0·547 and 0·589, as a result of incorporating 500 g/kg barley grain in place of hay in the diet. Even though there was no difference in the proportion of nitrogen retained relative to intake, the proportion of nitrogen retained relative to that absorbed was higher (P < 0·05) in the lucerne + barley group (0·769) than in the lucerne-only group (0·747). On a dry-matter basis, the feeding value in camels of digestible protein (g/kg), total digestible nutrients (g/kg), digestible energy (MJ/kg), metabolizable energy (MJ/kg), net energy maintenance (MJ/kg), net energy lactation (MJ/kg) and net energy gain (MJ/kg) were respectively 118, 552, 10·0, 8·4, 5·4, 5·0 and 2·1 for lucerne hay and 80, 800, 14·6, 12·1, 8·4, 8·8 and 5·0 for barley grain (calculated by difference).

Factors affecting survival to first and second calving and successful completion of a > 168-day first lactation were assessed in 3075 purebred and crossbred dairy heifer calves. Growth, disease, frequency, reproduction, calving, udder and lactation traits were examined in females of a breeding project conducted jointly at five research stations (herds) of Agriculture Canada. Losses included mortalities and non-discretionary culling. About 0·23 of potential heifers were culled or died before first calving, and 0·25 of those calving once did not calve a second time. Results from retrospective selection index and stepwise linear logistic analyses showed that predictability of culling prior to 308 days post partum was poor. With few exceptions, survival rates from birth to 82 weeks varied among herds (P < 0·001) and among lines (P < 0·05). Heterosis for the probability of completing a lactation and of survival to second calving was significant (P < 0·05) and positive (0·05 to 0·09). Heavier heifers were more likely to survive to first calving. Sire's estimated breeding values (SEBV) for milk yield and fat, protein and lactose concentration were not important in predicting survival to first calving. SEBV lactose was negatively associated with survival after first calving as predicted from data available at most preceding stages of life. An age greater than 82 weeks at last insemination was associated with a lower probability of survival to first and second calving (P < 0·001). Cows which conceived for a second gestation and subsequently aborted had a lower probability of survival to second calving than cows which did not abort (0·57 v. 0·76, P < 0·01). The only continuous traits with large effects on survival or the probability of completing a first lactation were days to last insemination (a measure of fertility) and milk yield. It was concluded that (1) there is considerable scope for improved management to increase survival in early life by prevention of calfhood diseases; (2) losses in early life do not bias sire evaluation on first lactation records; (3) improved reproductive success would greatly enhance overall survival rates; and (4) crossbreeding could have a large impact on overall herd profitability through increased survival.

1. Twenty spring-born Friesian calves, housed indoors, were divided into two groups each of 10 calves. During their first three weeks all calves were fed alike on whole milk containing 3·5% butterfat. At three weeks of age calves in one group were changed to a diet consisting of reconstituted buttermilk powder which was made up to the same energy content as the milk. Up to the 30th day intake was gradually increased to 20% of body weight; thereafter till slaughter of the calves at approximately 200 1b. live-weight both groups were fed to appetite twice daily.

2. Calves in both groups grew well and differences between groups in growth rate, and age at slaughter, food consumption and food conversion, were all statistically non-significant.

The pre-weaning records (birth weight, weaning weight and gain from birth to weaning) of 291 male and female lambs and the post-weaning records (body weight, feedlot gain and food conversion) of 136 male lambs were used to study relationships between different traits. The lambs were derived from three fat-tailed Iranian sheep breeds (Karakul, Mehraban and Naeini) and their crosses with Corriedale and Targhee rams. All lambs were weaned at 75 + 5 days of age and the males were fed in a feedlot for 100 days after weaning. Feedlot measurements were taken at 20-day intervals.

Weaning weight and pre-weaning average daily gain showed positive and significant associations with birth weight. Birth weight, weaning weight and gain from birth to weaning were positively associated with body weight at subsequent ages in feedlot as well as with final weight (P<0·01). Birth weight, weaning weight and pre-weaning average daily gain were positively and significantly associated with total feedlot gain.

Of the different traits, total gain during the first 20 days in feedlot (adjust period) had the lowest and total gain during the second 20 days had the highest association with total feedlot daily gain. There was no evidence that the heavier lambs at weaning and those showing high growth rate before weaning, were more efficient in the feedlot. Gain during the second 20-day period in the feedlot had a significant negative association with the total food conversion (unit food/unit gain) and therefore was a good predictor for food conversion.

When the feedlot period was divided into two 40-day periods, it was found that gain during both had a significant negative association with the corresponding food conversion. A similar association was observed between total feedlot gain and food conversion, indicating that the rate and efficiency of gain improved simultaneously.

The suggestion has been made (e.g. Anon, 1961; Brown, 1964; Spedding and Brown, 1961; Wixey, 1965) that a method of overcoming the inability of ewes to rear twin lambs well, may be to wean one lamb out of each pair at 2–4 weeks of age. The weaned lamb would be reared on concentrates and/or grass, and the remaining lamb, which would have access to the entire milk supply of the ewe, might then show a similar rate of growth to that of a lamb reared as a single from birth. Studies have also been made of the effect of the removal of one lamb out of twin pairs at 9 weeks of age (Cunningham and Maxwell, 1966) and at 12–16 weeks of age (Cunningham, 1964).

Results of studies in dairy cattle about the magnitude of the genotype–environment interaction (GEI) are variable, depending on the definitions of genotype and environment. Therefore, the objective of this study was to determine the magnitude of the interaction of genotype and feeding system (confinement and grazing) in the Mexican genetic evaluation of Jersey cattle for milk yield. The number of lactations and animals in the pedigree used were 5122 and 18 432. An animal model and the MTDFREML program were used to estimate genetic parameters and predict genetic values of the animals. Bivariate analysis was carried out considering the performance of confined and grazing cows as two different traits. Three indicator variables were used to assess GEI: (i) magnitude of the genetic correlation coefficients, (ii) correlation between predicted breeding values and (iii) frequency of coincidence in the ranking of top sires. The magnitude of GEI depended on the choice of the indicator variable. The estimate of genetic correlation coefficient less than unity (0.76; P < 0.05) suggested the presence of biologically important GEI. The differences in phenotypic averages and variances between confinement and grazing systems seem to be the main causes for the genotype by environment interaction detected. However, the correlation coefficient between breeding values from confined and grazing animals (0.96) and the frequency of coincidence between breeding values of common sires within the top 100 in confinement and grazing (0.86) indicated low-to-moderate re-ranking of animals or top sires. In addition, the high correlations between predicted breeding values of Mexican genetic evaluation and the two environments (0.99 and 0.93 for confinement and grazing) indicated that for the two feeding systems, breeding values from national analyses could be safely used.

The records of 873 lambs from Ossimi and Barki backcrosses to Merino, and the first and second generations of their interbreeding were analysed. The traits included were: birth, weaning and yearling weights, first fleece weight and lamb mortality.

The interbred groups had about 10–15% lower body and fleece weights than their backcross parents, and almost double the lamb mortality. Differences between the interbred groups and the back-cross parents were predicted from the performance of purebreds, first crosses and backcrosses. There was good agreement between prediction and observation for birth and fleece weights, fair agreement for weaning and yearling weights, but lamb mortality increased more than expected.

Maternal heterosis seems to be more important than individual heterosis for body weight, and the reverse for fleece weight. Both components are large for lamb viability.

Six adult and six juvenile goats were used to estimate their feeding preferences when three grasses (ryegrass, barley and brome) and two legumes (clover and alfalfa) were tested. Each grass was separately tested with both clover and alfalfa. A comparison between alfalfa and clover was also performed. The plants were harvested just before their utilization, chopped into 4- to 6-cm pieces and offered to the animals in plastic baskets. Preferences were evaluated by means of a series of seven short-term trials. Each short-term trial consisted of two single-food presentations and one choice-presentation. In the first single-food presentation animals received one of the two plants to be tested. In the second single-food presentation they were offered the alternative plant species. In the choice presentation they received the two species simultaneously. During each presentation animals were allowed to eat for 20 min or take a maximum of 50 bites. In the single-food presentations bite rate, bite mass and intake rate of both juvenile and adult animals were influenced by the plant species offered. Indeed, all goats tended to display a higher intake rate and bite mass for grasses than for legumes. A grass/legume ratio of the intake rates was also computed for each grass-legume comparison. These ratios tended to be higher for juvenile than for adult goats. The results of the choice presentations indicated that food preferences were not affected by age as all goats preferred grasses to legumes and clover over alfalfa. This experiment showed that age may not play an important role in the development of food preferences.

Variation in litter size in sheep is essentially attributable to variation in ovulation rate and embryo survival. Genetic variation in litter size, both among and within breeds, is largely attributable to variation in ovulation rate. While there is evidence for genetic differences among breeds in embryo survival the contribution of this component to within breed variation appears to be minor (Hanrahan, 1982). The impact of selection based on litter size on its component traits should reflect the relative contribution of these components to within breed variation. Data from two lines of Galway sheep, a Control line and one selected for increased prolificacy (Hanrahan and Timon, 1978), have been used to provide evidence on this point.

Details relating to the selection experiment which provided the data for the present study are in Hanrahan (1984). Briefly a flock of Galway sheep was assembled from industry sources (both pedigree and non-pedigree) between 1963 and 1965.

Gossypol ﹛2,2'-bi(8-Formyl-l,6,7 trihydroxy-5-isopropyl-3-methyl naphthalene)﹜ is a toxic polyphenolic factor indigenous to the cotton plant. Concentrations of free gossypol contained in such feed stuffs as whole cottonseed (WCS) vary considerably. WCS is fed widely to animals. Free gossypol is extractable with aceton-water (70:30) and is toxic to monogastric animals. Bound gossypol has been considered relatively non-toxic. Calhoun et al (1991) has demonstrated there was extensive binding of free gossypol in ruminant digestive system. But they did not support the suggestion that bound gossypol is released during digestion in the small intestine. The present experiment examined the effect of gossypol on the rumen microbial degradation of grass hay (GH) under CBC. In sacco rumen digestion was also conducted to examine DM, CP and ADF digestibilities of grass hay and whole cottonseed at 48 h.

The advent of the open access (OA) movement in publishing has been instrumental in causing a shift in the accessibility of research findings published in academic journals. The adoption of OA and other online publication models means that the results of scientific research published in journals using a free access (FA) framework are now available, free of charge, to anyone with access to the Internet. FA journals typically require a payment from the authors of a manuscript, which has raised concerns about the quality of work published in them; accepting payment from an author may compromise a journal’s acceptance criteria. This study addresses whether journal policy on the treatment of animals is influenced by whether a journal follows a FA publishing model, and whether a requirement to pay for publication has an influence. A random sample of 332 biomedical journals listed in the ISI Web of Knowledge and Directory of Open Access Journals databases were assessed for whether they had an ethical policy on publishing animal studies, and what form of publication framework they used (103 of the journals followed a FA framework; 101 charged in some way for publication). Only 135 (40.7%) of the journals surveyed demanded that submissions comply with a pre-defined ethical stance. FA journals are just as likely to have an ethical policy on the treatment and presentation of animal studies as ‘traditional’, non-FA journals (significance of there being a difference: P = 0.98), and there is no relationship between policy and whether an author is required to pay for publication (significance of there being a difference: P = 0.57). Older journals are more likely to have an ethical policy (P = 0.03). There is, therefore, no obvious compromise shown by FA journals in the explicit policies on reporting studies involving animals. However, since anyone can read published FA studies online, FA journals that do not have an explicit policy about publishing animal research are urged to consider adopting one.

An experiment was carried out to evaluate the effects of forage type and level of concentrate supplementation on forage intake, diet apparent digestibility, purine excretion and milk production. Twelve crossbred cows (Bos taurus × Bos indicus), in early lactation, were allocated to the following six dietary treatments: maize-lablab forage (ML) or oat-vetch forage (OV), offered ad libitum, and supplemented with either 0, 2·5 or 5·0 kg per cow per day of a supplement (wheat middlings). A four-period, partially balanced, change-over design was used and the treatments were arranged as 2 × 3 factorial.

Mean organic matter (OM) intake was 670 g higher with cows on ML-based diets compared with those on OV-based diets (P <0·02). The apparent digestibilities of crude protein (CP) and neutral detergent fibre (NDF) were similar for cows given ML- or OV-based diets but the apparent digestibility of OM was higher for ML diets (P <0·05). Values of the degradation parameters (a, b and c) of DM and NDF were greater for ML forage than for the OV forage. Forage type did not affect daily milk yield nor excretion of purine derivatives in urine used to estimate microbial-nitrogen supply (P >0·05). The concentration of milk fat and total solids in the milk were similar for the two forage types offered but the concentration of milk protein was slightly higher for the cows given ML-based diets (P <0·05).

Daily OM intake increased by 3·75 and 2·70 kg per cow per day (P <0·001) respectively, when the amount of concentrate increased from 0 to 5·0 kg per cow per day for the ML- and OV-based diets. The CP apparent digestibilities of the diets were higher when the diets were supplemented with concentrates but there was no effect of supplementation on the apparent digestibilities of OM and NDF. The supply of microbial-nitrogen increased linearly with increasing level of concentrate supplementation (P <0·05). Milk yield increased linearly when the level of concentrate supplement increased from 0 to 5 kg (P <0·001), resulting in 0·39 and 0·29 kg more milk per day per kg additional concentrate given in cows on ML and OV, respectively. There was also a tendency for a quadratic effect (P <0·12), especially with ML diets, showing that when the level of concentrate increased from 0 to 2·5 or from 2·5 to 5·0 kg/day, the milk yield increased respectively by 0·62 and 0·15 kg/day per kg additional concentrate given.

Central test data of two pig breeding companies were analysed to estimate sire × testing regime (S × T) interaction for ultrasonic backfat thickness (BT), life-time growth rate (GL) and growth rate during test (GT). Testing regime consisted of a combination of sex, test period and housing system (individual v. group housing). Data were analysed within five lines, with 5417, 8331, 3427, 2413 and 1263 records of progeny of 97, 162, 64, 69 and 33 sires, respectively. The data were collected from May 1983 until May 1987 (lines 1, 2 and 3) and from June 1985 until May 1987 (lines 4 and 5). Testing regime had a significant effect on BT (in three lines) and on GL and GT (in five lines). S × T interaction was significant only for BT in three lines and for GT in one line. Genetic correlations between identical traits, measured under the two testing regimes, varied from 0·64 to 1·00 for BT, from 0·65 to 1·00 for GL and from 0·62 to 1·00 for GT. Conclusively, within central test S × T interactions were relatively unimportant for BT, GT and GL.

One of the most debated topics in pig production is the need to study, understand and change the production system in order to improve nutrient efficiency, becoming more environmentally friendly. The nitrogen excretion has highly deleterious effects on the environment, and it is necessary to develop tools that help to reduce the excretion of this compound without compromising productivity. Therefore, two models were generated to estimate the efficiency of weight gain in relation to excreted nitrogen in post-weaning piglets. Data for testing these models were obtained from previous master and PhD studies carried out at the Federal University of Rio Grande do Sul, Animal Science Laboratory using piglets in the post-weaning phase with results for performance and digestibility. The database that was constructed was composed of raw data from 10 studies carried out between 2000 and 2016, on a total of 726 piglets weaned at ages between 17 and 28 days, and to which 62 different treatments were applied. An exploratory analysis of the data was done by evaluating scatter plots and histograms, and variables representing different treatments were used in a stepwise multiple linear regression analysis, with the F-test used as the selection criterion. Two models were generated that either considered the nitrogen retained or not, to estimate the ratio between weight gain and excreted nitrogen using generalized linear model procedure. The authors analyzed the behavior of each variable to evaluate whether the equation generated was biologically coherent. Weight gain, dry matter intake, nitrogen intake, metabolizable energy intake, retained nitrogen and urinary nitrogen were all significant (P<0.001) variables in model I, and in model II the variable fecal nitrogen was also included. The models had high coefficients of determination (R2 of model I and II were 0.9013 and 0.8271, respectively), and the nitrogen ingested variable was the one that most strongly influenced growth efficiency. When the retained nitrogen variable was removed from the model, there was a reduction in the fit of the equations. It was possible to conclude that both of the two models generated could be applied and the amount of nitrogen ingested had the greatest influence on growth efficiency related to nitrogen excretion.

Some mutations (or ‘major genes’) have a desirable effect in heterozygous carriers but an undesirable effect in homozygous carriers. When these mutations affect a trait of significant economic importance, their eradication, depending on their effect and frequency, may be counterproductive. This is especially the case of major genes affecting the ovulation rate and thus the prolificacy in meat sheep populations. To manage such situations, a mating design based on the major genotypes of reproducers has to be optimized. Both the effect of the major gene and the cost of genotyping candidates at this locus influence the expected genetic progress and profitability of the breeding plan. The aim of this study was to determine the optimal combination of matings that maximizes profitability at the level of the whole population (nucleus + commercial flocks). A deterministic model was developed and, using sequential quadratic programming methodology, the optimal strategy (optimal combination of matings) that maximized the economic gain achieved by the population across a range of genotype effects and genotyping costs was determined. The optimal strategy was compared with simpler and more practical strategies based on a limited number of parental genotype mating types. Depending on the genotype effect and genotyping costs, the optimal strategy varied, such that either the heterozygous frequency and/or polygenic gain was maximized with a large number of animals genotyped, or when genotyping costs were higher, the optimization led to lower heterozygous frequency and/or polygenic gain with fewer animals genotyped. Comparisons showed that some simpler strategies were close to the optimal strategy. An overlapping model was then derived as an application of the real case of the French Lacaune meat sheep OVI-TEST breeding program. Results showed that a practical strategy based on mating non-carriers to heterozygous carriers was only slightly less effective than the optimal strategy, with a reduction in efficiency from 3% to 8%, depending on the genotyping costs. Based on only two different parental genotype mating types, this strategy would be easy to implement.

This study investigated the potential application of genomic selection under a multi-breed scheme in the Spanish autochthonous beef cattle populations using a simulation study that replicates the structure of linkage disequilibrium obtained from a sample of 25 triplets of sire/dam/offspring per population and using the BovineHD Beadchip. Purebred and combined reference sets were used for the genomic evaluation and several scenarios of different genetic architecture of the trait were investigated. The single-breed evaluations yielded the highest within-breed accuracies. Across breed accuracies were found low but positive on average confirming the genetic connectedness between the populations. If the same genotyping effort is split in several populations, the accuracies were lower when compared with single-breed evaluation, but showed a small advantage over small-sized purebred reference sets over the accuracies of subsequent generations. Besides, the genetic architecture of the trait did not show any relevant effect on the accuracy with the exception of rare variants, which yielded slightly lower results and higher loss of predictive ability over the generations.

To show the importance of the level at which the pregnant ewe is fed in relation to :

• (1)The birth weight of her offspring,

• (2)The volume of milk which she produces during her lactation period,

• (3)The influence of these two upon the rate of growth of the lambs,

two experiments were carried out. In the first, a group of 4-year-old Border Leicester × Cheviot ewes from the same flock were mated to the same Suffolk ram. They were then split into two uniform groups. The ewes were fed individually and after service both lots were fed just sufficient sainfoin hay to keep them at constant body weight. Then, six weeks before lambing, the members of one group were given ½ lb. of concentrate daily and as much hay as they would eat. Upon this ration these ewes gained an average of 44 lb. At the same time the amount of hay fed to the second group was reduced so that over the last six weeks these ewes lost on the average 11 lb. weight.

Two 7 × 7 Latin square experiments were carried out with British Friesian steers (mean initial live weight 360 kg). In Experiment 1 the effects of different levels of dried grass or concentrate on the intake of silage dry matter (DM) were compared, and in Experiment 2 the effect of a supplement containing various proportions of dried grass: concentrate on the intake of silage DM was examined. In both experiments the digestibility of the ration and the rate of passage of digesta were measured.

In Experiment 1, supplementation depressed intake of silage DM, the difference being significant (P<0·05) at 5·0 and 7·5 kg/day, but there were no significant differences in silage intake between supplements given at the same level. Intake of silage was also significantly lower (P<0·05) in Experiment 2 when a supplement was offered, but differences between supplements were not significant. Total DM intake was increased significantly (P<00·5) by supplementation in both experiments. Supplementation increased energy digestibility but decreased crude fibre digestibility. In Experiment 1 nitrogen digestibility was significantly lower (P<0·05) with dried grass than with concentrate supplementation, but in Experiment 2 supplementation increased the digestibility of nitrogen. In both experiments the mean retention time was shorter, the time for the highest rate of excretion of stained particles was lower, and the maximum rate of excretion higher for dried grass than for silage.