In three trials, two with suckler cows and one with lambs, supplementary forms of dietary nitrogen and/or energy were added to a basal diet of barley straw offered ad libitum. The nitrogenous supplements appeared to have a small effect on the intake of straw but only when they were available for frequent consumption. The addition of cereals to the diet did not affect the intake or digestibility of the straw but reduced the live-weight losses.

In two experiments the growth, body composition and behaviour of steers and heifers kept in a building with natural day length only (average 9·7 h/day, treatment N) were compared with similar groups of animals kept in identical housing with the day length artificially extended to 16 h/day, (treatment L). The effects were recorded for 126 days in steers and 180 days in heifers, with both groups of animals being slaughtered in March when the two experiments ended. There were no effects over the entire experiment on the growth rate or food intake of either steers or heifers. The growth of the steers was reduced in the first 2 weeks after the lights were switched on but they gained more weight to compensate over the next 8 weeks. Over the whole experiment there was no treatment effect on food conversion ratio for either steers or heifers but it was reduced for steers on treatment L over the first 10 weeks. Steers in treatment N produced fatter carcasses than those on treatment L. Ultrasonic scanning of the heifers showed that those on treatment N deposited more fatty tissue between autumn and winter and less between winter and spring compared with those on treatment L.

The behaviour of steers on treatment L did not vary over the experiment but steers on treatment N changed their behaviour with season. They slept for more time in winter and less in spring. Over the whole experiment steers on treatment L slept less and spent more time lying ruminating than those on treatment N but the total time spent lying was not affected by treatment. In contrast, the heifers on treatment L lay down for longer than those on treatment N, suggesting that the effect of supplementary light on lying time, which has been observed previously with dairy cows, is confined to female cattle. Heifers on treatment L started mounting each other earlier than heifers on treatment N and, like the steers, they spent less time sleeping It is concluded that extending the photoperiod for cattle in winter reduced body fatness in both steers and heifers and increased the time heifers spend lying down but that there were no major effects on growth rate or food intake.

Measurements of growth rate, food intake and food conversion efficiency on 235 Hereford bulls, from the first 4 years of a selection experiment, were used to assess the effects of rearing method, dam age and year/season of birth. Bulls were either reared artificially from birth to 84 days of age, or reared on their own dam to 84 or 168 days of age, to examine whether non-genetic effects on performance could be reduced by early weaning. All bulls were performance tested on ad libitum feeding from 200 to 400 days of age. Artificially-reared bulls had lower live weights at the start of test, which led to higher food conversion efficiency on test. Bulls reared naturally to 84 days of age were least affected by dam age and year/season of birth and performed as well as those weaned at 168 days of age. Earlier weaning of bulls entering central performance tests would reduce these environmental effects on performance, and may increase the accuracy of identifying bulls with genetically-superior growth and efficiency.

The effect of rate of substitution of processed, urea-treated whole-crop wheat (pWCW) for grass silage on intake, performance and whole-tract digestibility was evaluated using 44 dairy cows. Cows received 10.5 kg of concentrates per day and one of the following forage mixtures (dry matter (DM) basis): grass silage alone (W-0); 0.75 grass silage, 0.25 pWCW (W-25); 0.5 grass silage, 0.5 pWCW (W-50) or 0.25 grass silage, 0.75 pWCW (W-75). Forage DM intake increased linearly with inclusion rate of pWCW from 9.7 kg DM per day in cows fed W-0 to 14.6 kg DM per day in W-75. By contrast, milk and protein yield (kg/day) were higher (P < 0.05) in cows receiving W-25 compared with W-0, but there was no effect (P>0.05) of treatment on fat yield (kg/day). From week 11 of the experiment onwards, body condition score increased with rate of inclusion of pWCW (P < 0.05). Whole-tract apparent digestibility of organic matter (OM) and fibre (kg/kg), decreased linearly with rate of inclusion of pWCW. Assuming a constant digestibility of starch in the other diet components, the apparent digestibility of starch in pWCW was 0.95 kg/kg and was not affected by rate of inclusion (P>0.05). Four continuous culture vessels were used to determine the effect of rate of inclusion of pWCW on ruminal metabolism in four periods, each of 14 d duration with sampling conducted on days 9 to 14. Vessel ammonia concentration increased linearly (P < 0.05) with rate of inclusion of pWCW whilst mean pH tended (P = 0.06) to decrease. The ratio of acetate to propionate increased from 2.5 in vessels receiving W-0 to 3.2 in those receiving W-75 (P < 0.001). There was no effect (P>0.05) of treatment on digestibility (g/g) of OM, fibre or starch or microbial protein flow (g/day). It is concluded that forage DM intake increased linearly with rate of inclusion of pWCW, but there was no further improvement in milk yield from inclusion rates above 0.25 of the forage DM, with body condition score increasing instead. Increasing the inclusion rate of pWCW resulted in a more ketogenic volatile fatty acid profile but did not affect the efficiency of microbial protein synthesis when determined in vitro.

Immunocastration provides a less invasive means of castrating lambs. Considering increasing consumer awareness, the efficacy of this technique on commercial slaughter lambs needs to be further investigated and its effects on growth and stress responses need to be established. This study compared the growth rate, testes size and stress responses of immunocastrated lambs with that of lambs physically castrated with a Burdizzo clamp, as well as intact rams. A total of 40 Dohne Merino ram lambs (average live weight = 45.4±3.68 kg) were randomly allocated to the following four treatment groups: control (intact; R), Burdizzo-castrated (on day 2; B), immunocastrated with a 4-week (ICS4), or a 6-week (ICS6) interval between the second immunocastration vaccination and slaughter. Within the immunocastration treatments, the reaction to vaccination was assessed through injection site scoring, recording the local injection site surface temperature and assigning a walking score. The response to Burdizzo castration was assessed by scoring the reaction during the procedure, testes palpation reaction, walking gait and measuring testis temperature. Additional parameters recorded included BW, serum cortisol concentration, scrotal circumference and rectal temperature. Pain behaviours were described for the short-, medium- and long-term effects after the two methods of castration. Predominantly, tissue-hardening and bruising occurred at the injection sites of immunocastrates, but little effect was observed on walking comfort and no effect on injection site temperature or rectal temperatures. After Burdizzo castration, lambs spent more time in abnormal postures, and from day 3 (D3) to D8 of the trial, discomfort was observed during testes palpation and walking in B lambs. Serum cortisol concentrations were elevated in B lambs on D3 and D15, indicating physiological stress. Thus, immunocastration improved the welfare of castrated lambs as assessed by cortisol secretion, scrotal swelling and pain behaviours, without influencing growth rate.

Normal and dexamethasone-induced parturition were compared in Merino and prolific Booroola Merinos carrying crossbred foetuses. Behavioural observations were recorded for 42 single-, 27 twin- and 10 triplet-bearing ewes. After treatment on day 144 of gestation, ewes injected with dexamethasone lambed 41 h earlier than ewes injected with phosphate buffer. On the phosphate-buffer treatment, Booroola Merino ewes lambed 22 h earlier than Merino ewes. Twin- and triplet-bearing ewes which were induced to lamb had a significantly longer duration of labour than ewes bearing singles which were induced to lamb, and ewes, regardless of litter size, which lambed naturally. Induction of parturition had no significant effect on the lambs' behaviour subsequently. Lamb survival was not influenced by dexamethasone treatment but was significantly influenced by lamb birth weight, which declined as litter size increased.

Six cereal straws and two traditional hays were used to study the relationship between voluntary dry matter (DM) intake and chemical composition and ruminal degradation characteristics. The voluntary DM intake was measured during 60 days using Barbarin adult ewes given food individually in four groups of six animals. The forages were offered to the ewes twice daily and were supplemented with 10 g DM of soya-bean meal per kg M0·75 per day and 30 g per ewe per day of a commercial mixture of minerals and vitamins. The chemical composition and the leaf/stem (L/S) ratio of the forages were determined. Their ruminal degradation characteristics were measured by using the nylon bag technique according to the exponential model Dg = a + b (1 – e−ct). Crude protein contents of straws ranged from 22 to 35 g/kg DM and that of hays from 35 to 57 g/kg DM. The corresponding values of L/S ratio varied from 0·68 to 0·88. The voluntary DM intake was highly variable and the hays were ingested at greater amounts than the straws, although their degradable (b) and their rate of digestion (c) were not significantly different (P > 0·05).

Significant relationships were established between voluntary DM intake and the neutral-detergent fibre (R2 = −0·72; P < 0·001), acid-detergent fibre (R2 = −0·75; P < 0·001) and a values (R2 = 0·83; P < 0·001). The precision of the prediction was significantly improved using ruminal degradation characteristics (Syx = 4·42) compared with the chemical composition (Syx = 5·60).

The aim of the investigation was to evaluate the specific effect, if any, of grass protein on the birth weight of lambs born to ewes wintered indoors. Grass meal was used as a substitute for fresh grass, and soya bean meal—representing a more conventional source of protein for winter diets—was compared with it. Both sources of protein were included at two levels, providing a high (90 g or 0·2 lb/day) and a low (45 g or 0·1 lb/day) intake of digestible crude protein.

The digestibility of dry matter was significantly higher for the diets containing soya bean meal (67·7%) than for those containing grass meal (58·2%). Dry-matter digestibility was not affected by level of protein intake. The digestibility of crude protein was significantly affected by protein source and level of intake.

Lamb birth weights were not significantly affected by source or level of dietary protein. There was a tendency for birth weights to be higher on the diet containing grass meal at low protein intakes. Ewe weight gains during the last eight weeks of gestation were significantly affected by level of dietary protein, and net body weight change was significantly affected by both source and level of protein. Gestation treatments had no effect on the performance of ewes or lambs during the first three weeks of lactation.

The retention of nitrogen during the 18th–20th weeks of gestation was affected by both source and level of dietary protein. Mean nitrogen retention was higher with diets containing soya bean meal (5·8 g per day) than with diets containing grass meal (3·6 g per day). There was no correlation between nitrogen retention and lamb birth weight.

The growth rate and food conversion efficiency of fattening lambs given all-concentrate diets have been reported by Philip Preston and Greenhalgh (1964). The lambs were weaned abruptly at 8 weeks old and fed thereafter ad libitum on cereal and protein supplement. Owen, Davies and Ridgman (1965) have reported the same measures of performance for artificially reared lambs fed from 30 lb. to slaughter at 75 lb. on diets varying indigestibility. A considerable amount of information has been obtained recently on the nitrogen metabolism of young calves fed on all-concentrate diets (see Preston, Whitelaw, MacLeod and Philip, 1965, and Bowers, Preston, McDonald, MacLeod and Philip, 1965) but there is less information of a similar nature for lambs fed on such diets. The following experiment was carried out to assess the intake of energy and utilisation of dietary nitrogen by lambs fed ad libitum on three simple all-concentrate diets during the latter stages of fattening.

This report gives an account of the paternal half-sib analysis of carcass quality, based on commercial joint dissection, on Down cross sheep collected in the four years 1962–65 inclusive. It also includes a discussion of the multiplicative correction factors used, and the phenotypic and genetic correlations between all the traits, estimated from the pooled within-farm, within-year analysis. It shows that there is very little genetic variation for many of the characters but that the percentage leg, percentage best end, age at slaughter and eye-muscle area have much additive genetic variation remaining for worthwhile response to be expected from selection. These three carcass traits are also the most important characters in determining the commercial value and saleability of lamb. From the results obtained it is argued that there is still much genetic variation for fat development in sheep.

We studied the ontogenetic growth of goat wethers (castrated male goats) of the Saanen and Swiss Alpine breeds based on a large range of intraspecific body mass (BM). The body parts and the chemical constituents of the empty body were described by the allometric function by using BM and the empty body mass (EBM) as the predictors for morphological traits and chemical composition, respectively. We fitted the allometric scaling function by applying the SAS NLMIXED procedure, but to evaluate assumptions regarding variances in morphological and compositional traits, we combined the scaling function with homoscedastic (MOD1), and the heteroscedastic exponential (MOD2) and power-of-the-mean (MOD3) variance functions. We also predicted the ontogenetic growth by using the traditional log-log transformation and back-transformed results into the arithmetic scale (MOD4). We obtained predictions from MOD4 in the arithmetic scale by a two-step process, and evaluated MOD1, MOD2 and MOD3 by a model selection framework, and compared MOD4 with MOD1, MOD2 and MOD3 based on goodness-of-fit measures. Based on information criteria for model selection, heterogeneous variance functions were more likely to describe 10 over 36 traits with a low level of model selection uncertainty. One trait was predicted by averaging the MOD1 and MOD2 variance functions; and nine traits were better described by averaging the MOD2 and MOD3 variance functions. The predictions for other 16 traits were averaged from MOD1, MOD2 and MOD3. However, MOD4 better described 11 traits according to the goodness-of-fit measures. Depending on the variable being analyzed, the body parts and the chemical amounts exhibited the three types of allometric behavior with respect to BM and EBM, that is, positive, negative and isometric ontogenetic growth. Reference BMs, that is, 20, 27, 35 and 45 kg, were used to compute the net protein and energy requirements based on the first derivative of the scaling function, and the results were presented in reference to the EBM and EBM0.75. Both the net protein and energy requirements scaled to EBM0.75 increased from 20 to 45 kg of BM.

Previous studies have demonstrated that sperm head morphometry can be used as a potential diagnostic tool for detecting biophysical changes associated with sperm viability in bovine spermatozoa. In this study, sperm head morphometry was used to investigate its value as a biophysical marker for detecting volumetric changes in bovine spermatozoa under in vitro capacitating and non-capacitating incubation conditions. To further test this hypotesis, aliquots of pooled, washed bovine sperm were incubated in either Tyrode’s complete medium with heparin (TCMH; a capacitating medium containing Ca2+, NaHCO3 and heparin), Tyrode’s complete medium heparin-free (TCM; a medium containing just Ca2+ and NaHCO3) or Tyrode’s basal medium (TBM; a non-capacitating medium free of Ca2+, NaHCO3 and heparin, used as control). Aliquots of sperm were processed for morphometric analysis at different incubation-time intervals (0, 3 and 6 h at 38°C), and the chlortetracycline assay was used simultaneously to confirm the ability of the sperm to undergo capacitation (B pattern) and the acrosome reaction (AR pattern) status in each medium. After 3 h of incubation under TCMH conditions, a significant increase was observed in the percentage of B and AR patterns and a significant decrease was found in all sperm morphometric parameters (P<0.01). Interestingly, after 6 h of incubation in TCMH, the percentage of B and AR patterns increased drastically over time and marked differences were found in the dimensional and shape parameters, which were significantly smaller compared with TBM or TCM media (P<0.001). Significant correlations were observed between sperm size and AR pattern (r=−0.875, P<0.01). In conclusion, sperm head morphometry can be used as a potential biophysical marker for detecting volumetric changes during capacitation process in bovine spermatozoa.

The value of a selection index for 8-week litter weight as a trait of the ewe, combining information on the ewe and on five classes of female relatives, was considered. Adding records on the dam and on paternal half sibs to those of the ewe gives increases of 10 to 50% in the rates of genetic response. The index can be simplified with little loss in efficiency by weighting all records equally for relatives with 1, 2 or more records within each class of relative. In selecting breeding replacements, information on the parents of the sire of the individual being selected may increase the rates of response by a further 20 to 30 %.

This study aimed to identify and better understand management strategies that help livestock farmers adapt to changes in their production contexts, a fundamental challenge. A total of nine beef-cattle farmers were interviewed three times over 1 year to discuss 13 dimensions of livestock farming (e.g. reproduction, feeding, sales, etc.). Characterisation of management strategies rested on three main factors: (i) ranking of the dimensions according to the degree to which farmers desired to control them, (ii) reasons for the ranking and (iii) management guidelines. Although farmers agreed upon the rank of certain dimensions, such as herd management, they differed on that of others, such as sales and administration/regulations. Four motivation categories were identified: risk, pleasure, efficiency and ability to control the dimension. Three management guidelines were identified, which indicated that farmers managed for future survival of their farms at different scales (animal/herd v. whole-farm), involving different resources (biological v. financial) and based on different animal categories (reproductive cows v. animals sold). These results improve understanding of individual livestock farmers and their current management strategies by integrating the motivations behind their strategies. For this reason, they constitute methodological elements that agricultural advisors can use to provide relevant information to farmers while accommodating differences in farm management.

This exploratory holo-analysis of the efficacy of Bio-Mos®, (BM), an outer cell wall derivative of a strain of Saccharomyces cerevisiae, is part of an empirical modelling research programme comparing the efficacies of potential replacements for veterinary prescription-free pronutrient antibiotics in pig production. The data resource was mined from 128 saccharide publications of which 31/97 on BM (1997 to 2003) provided 69 negatively controlled start-to-finish tests from 10 countries (USA 71%) using 3778 pigs(30·5 per treatment). Respective food intake, live-weight gain and food conversion responses of 0·0075 kg/day (0·99%), 0·0145 kg/day (3·58%) and −0·0526 (3·07%) have coefficients of variation of 511, 163 and 229% and beneficial gain and conversion frequencies of 73 and 68%, 54% jointly. Holo-analytical multiple regression models of BM food intake, live-weight gain and food conversion effects using conventional and less stringent probabilities contain significant independent variables for negative control performances, dosage, discontinuous dosage, test duration, year of test, non-USA test, male, grower-finisher, slatted floor, processed food, antibacterial foods, animal protein food, main vegetable protein not soya bean, added oil/fat food and factorial data, which account for 11 to 68% of variations in response. The models quantify differences in research and praxis and indicate areas for future modelling research on BM dose-response relations, effects of ration ingredient and nutrient contents, other saccharide efficacy comparisons, including lactose, and BM comparisons and interactions with other proposed antibiotic replacements.

A trial was carried out over a 7-year period (1999 to 2005 calf crops) to compare indicators of seasonality in Angus cattle, which were part of a long-term genetic selection experiment. Divergent selection was applied for early (‘AGE−’) or late (‘AGE+’) age at puberty (AP) in heifers, and selection lines differed over the 7-year period by 62 days (15% of the mean). The primary measures of seasonality studied in 629 heifer progeny (59 sire groups) were serum concentration of prolactin (PRL), and winter and summer hair growth. Serial samples were obtained for PRL from 11 to 18 months of age, and data were analysed with adjustment for cortisol concentration. Using restricted maximum likelihood procedures with an animal model, heritability estimates were: AP, 0.26 ± 0.03; logePRL concentration, 0.23 ± 0.07; logecortisol concentration, 0.22 ± 0.07; hair weight, 0.21 ± 0.04; and hair length, 0.09 ± 0.05. Corresponding repeatability estimates for the last four traits were 0.49 ± 0.03, 0.38 ± 0.03, 0.21 ± 0.04, and 0.64 ± 0.02, respectively. The genetic correlation between AP and logePRL concentration was estimated at −0.29 ± 0.13 (P < 0.05). PRL concentration in the AGE− line after passing through puberty was 11 ± 5% lower than in the AGE+ line (P < 0.05). Line effects were not significant for hair weight or hair length. It was concluded that divergent selection for AP changed PRL concentration, which may partly reflect sensitivity to changing day length.

The response of pigs to supplemental biotin (500 μg/kg diet) was studied in a growth trial from 15 to 88 kg live weight. Food: gain ratio was significantly improved during the grower phase and there was a tendency for improvement in the starter and finisher phases. There was also a tendency towards improved carcass grading.

Data were collected during 1961–2 on the live-weight, age and warm carcass weights of 83 lots of Israel-Friesian bull calves, 525 animals in all, the offspring of 26 sires. For varying numbers of these animals weight of various non-saleable fat components, including ruminal fat, kidney fat, inguinal fat and scapular fat were also obtained. Ruminal fat alone and ruminal fat plus kidney fat were found to be highly correlated with total non-saleable fat (r = 0·84 and 0·94, respectively). Heritability of dressing percentage was 0·20, of live-weight rate-of-gain 0·92, and of carcass rate-ofgain 0·49. The genetic correlation between live-weight and carcass weight was 0·7. Between-lot correlations indicated that increased rate-of-gain achieved through management will be accompanied by decreased dressing percentage and increased non-saleable fat content.

The mapping of complete sets of genes, transcripts and proteins from many organisms has prompted the development of new ‘-omic’ technologies for collecting and analysing very large amounts of data. Now that the tools to generate and interrogate such complete data sets are widely used, much of the focus of biological research has begun to turn towards understanding systems as a whole, rather than studying their components in isolation. This very broadly defined systems approach is being deployed across a range of problems and scales of organisation, including many aspects of the animal sciences. Here I review selected examples of this systems approach as applied to poultry and livestock production, product quality and welfare.

A high-fat diet is known to induce atherosclerosis in animal models. Dietary factors and timing of atherogenic food delivery may affect plasma lipoprotein content composition and its potential atherogenic effect. Increasingly often, humans spend periods/days eating in a completely unregulated way, ingesting excessive amounts of food rich in oils and fats, alternating with periods/days when food intake is more or less correct. We investigate the effect on lipid homeostasis of a high-fat diet administered either continuously or intermittently. We investigated control pigs receiving standard diet (C, n=7), pigs receiving a high-fat diet every day for 10 weeks (CHF, n=5), and pigs receiving a high-fat diet every other week for 10 weeks (IHF, n=7). IHF animals were shown to have a different lipid profile compared with CHF animals, with a significant increase in high-density lipoproteins (HDL) levels with respect to C and CHF groups. CHF also showed significantly higher values of TC/HDL cholesterol compared with C and IHF. Hepatic expression analysis of genes involved in lipid homeostasis showed an increasing trend of nuclear receptor LXRα along with its target genes in the CHF group and in the IHF group, whereas SREBP2 and LDLr were significantly inhibited. A significant correlation was found between ABCA1 expression and circulating levels of HDL-C. Periodic withdrawals of a high-fat atherogenic diet compared with a regular administration results in a different adaptive response of lipoprotein metabolism, which leads to a significantly higher plasma level of HDL-C and lower TC/HDL-C.