As part of the requirements of the Convention on Biological Diversity, Canada has been investigating the genetic diversity of its native equine and pony populations. Along with examining four indigenous Canadian equine populations (Canadian horse, Lac La Croix pony, Newfoundland pony and Sable Island population), another 10 Mountain and Moorland, three Nordic, four horse and two feral equine populations (thought to have influenced some pony breeds) were also investigated. In total, 821 individuals were genotyped at 38 microsatellite loci. Results of the analysis of molecular variance indicated that 13.3% of genetic diversity was explained by breed differences, whereas 84.6% and 2.1% of diversity came from within and among individuals, respectively. The average effective number of alleles and allelic richness was the lowest in the Eriskay (2.51 and 3.98) and Lac La Croix (2.83 and 4.01) populations, whereas it was highest in the New Forest (4.31 and 6.01) and Welsh (4.33 and 5.87) breeds, followed closely by the Newfoundland-CDN (4.23 and 5.86) population. Expected heterozygosities varied from 0.61 in the Lac La Croix to 0.74 in the Welsh and in Newfoundland. Observed heterozygosities ranged from 0.57 in the Exmoor and 0.58 in the Sable Island herd to 0.77 in the Kerry Bog and 0.76 in the New Forest breeds. Structure and admixture analyses revealed that the most likely number of clusters was 21, although some substructure was also observed when K = 16, compared with the 24 predefined populations. Information gathered from this study should be combined with other available phenotypic and pedigree data to develop, or amend, a suitable conservation strategy for all populations examined.

Reproductive performance, body growth, wool production and ewe survival were examined in Scottish Blackface sheep. The data set was from a large randomly selected population maintained under hill conditions between 1954 and 1974. Paternal half-sib analyses of variance were used to estimate heritabilities and genetic correlations, while maternal half-sib analyses of variance indicated the relative importance of maternal effects (both genetic and environmental).

Among reproductive components, the heritability of fertility (ewes lambing per ewe mated) and lamb survival (lambs weaned per lamb born) were about zero. Litter size (lambs born per ewe lambing) had an estimated heritability of 0·12 (s.e. 0·04) and a repeatability of 0·22 (s.e. 0·02), indicating some scope for improvement. Additionally, the strong genetic correlation between adult body weight and litter size (0·66, s.e. 0·18) suggested greater response from a combination of indirect selection (on body weight) and direct selection (on dam's litter size). Prior to weaning, direct genetic effects on body weight were very small (heritability less than 0·1) with a large influence of maternal environment. After weaning, these maternal influences gradually diminished and the heritability of weight increased. Genetic correlations between body weights showed a similar increasing trend with age. Genetic improvement of early growth rate would be more effective by selecting on a post-weaning rather than a pre-weaning body weight. Fleece weight had a high heritability (about 0·5) but was genetically uncorrelated with other measures of performance. Ewe survival had a small genetic component although estimates of heritability were very imprecise.

An experiment was carried out on pigs to provide a test of two current conceptual frameworks available for the understanding and prediction of food intake. Framework 1 assumes that food intake will be that which allows potential (genetic) performance to be achieved. If this is not achieved then it is because intake is being constrained. Framework 2 sees food intake as being a consequence of a process of optimization such that biological efficiency (the ratio of net energy ingested to oxygen consumed) is maximized. Both frameworks predict that a reduction in temperature will increase the intake of a high quality food. For a food of low quality framework 2 predicts that intake will also be increased when temperature is decreased while framework 1 predicts that it will not. This difference between the predictions of the two frameworks allows them to be tested by means of an experiment in which foods of different quality were given to animals at different environmental temperatures.

Forty pigs were randomly allocated to a control (C) food based on micronized wheat with 13·1 MJ digestible energy (DE) and 232 g crude protein (CP) per kg fresh food, or one of two high bulk foods. The high bulk foods contained either 650 g/kg of unmolassed sugar-beet pulp (SBP) or 650 g/kg of wheat bran (WB). Half the pigs were maintained at a thermoneutral temperature of 22ºC for 14 days followed by a cold temperature of 12ºC for 14 days. The other half were maintained at 12ºC for a period of 14 days followed by a temperature of 22ºC for 14 days. Food intake was recorded daily and live weight twice weekly.

There was a highly significant food ✕ temperature interaction ( P < 0·001) for food intake. A reduction in temperature resulted in an increase in food intake on C and WB but had no effect on the intake of SBP. There was a highly significant effect of both temperature and food on intake ( P < 0·001). A reduction in temperature resulted in a significant increase in food intake, intake on WB was higher than that of either C or SBP. There was no overall effect of temperature on live-weight gain although a reduction in temperature resulted in a non-significant increase in the gain of C and reduction in the gain of WB and SBP. There was a highly significant effect of food ( P < 0·001) on live-weight gain, as gain on C was higher than that on either WB or SBP.

The results of the experiment were in agreement with the predictions set forward by the first framework that growing pigs are eating to achieve maximum performance subject to constraints.

Two experiments were conducted with dairy cows to examine the effects of including white clover in perennial ryegrass swards and of offering the cows a choice between tall and short mixed perennial ryegrass/white clover swards. In the first experiment, cows grazed a perennial ryegrass sward (treatment Prg); a mixed sward of perennial ryegrass and white clover (treatment WC); treatment Prg during the night and treatment WC during the day (treatment Prg night/WC day); or they were offered a choice between Prg and WC (treatment Prg/WC). Cows in treatment WC produced more milk than cows in treatment Prg, with cows in Prg night/WC day and Prg/WC intermediate. The milk fat content of cows in treatment Prg was greater than in the other three treatments. When cows were offered both mixed grass/clover and pure grass swards (treatments Prg night/WC day and Prg/WC) they exhibited a partial preference for the WC sward and grazed it to a lower herbage height than the pure grass sward. In the second experiment, cows were offered a WC sward at 6 or 3·5 cm sward surface height, or a choice between pastures at the two heights. Cows offered only the tall sward produced most milk, and those offered only the short sward produced the least. Milk fat content was reduced for cows offered only the tall sward. Cows offered a choice of the tall or short swards spent longer grazing in total than the cows offered only tall or only short swards but there was no difference in the time spent grazing the tall and short swards.

To measure the effect of stage of maturity of whole-crop (WCW) on its composition, digestibility and feeding value winter wheat was harvested at different maturities in two successive years. In year 1 WCW was harvested at 301(low dry matter (DM)) and 511(high DM) g DM per kg and ensiled and at 584 g DM per kg and treated with 40 kg urea per t DM before being stored (urea-treated WCW). Part of the high DM WCW was treated with an additive containing Lactobacillus buchneri at harvest. In year 2 WCW was harvested at 321 (low DM) and 496 (high DM) g DM per kg and ensiled before both crops were offered to the cows with or without a fibrolytic enzyme sprayed on the forage just before feeding. In both years the WCW was offered ad libitum in a 2: 1 WCW: grass silage DM ratio with 10 kg fresh weight concentrates per day to 40 early-lactation Holstein-Friesian cows in a 13-or 15-week production study with a continuous design and to four fistulated lactating cows in a 4 ✕ 4 Latin-square experiment for measurement of diet digestibility. In both years neutral-detergent fibre (NDF) content decreased and starch content increased with advancing maturity. In the production trials, DM intake increased (P 0·01) with advancing maturity but milk yield was not significantly affected. Milk protein yield was increased by urea-treated WCW. The additives had no effect on food intake or milk production. In year 1, digestibility of all fractions except starch was lower for high DM WCW than low DM WCW but for urea-treated WCW only the digestibility of starch and energy was lower than digestibility of the low DM WCW fractions. The inoculant had no significant effect. In year 2 crop maturity had no significant effect on digestibility but the enzyme reduced the digestibility of neutraland acid-detergent fibre (NDF and ADF, P 0·05). In year 1, each of the forage mixtures was offered to sheep at 12 g DM per kg live weight per day. There were significant treatment effects on the digestibility of DM (P 0·05) and organic matter (OM) (P 0·01) and on DOMD (digestible OM in the DM) (P 0·01) with the highest values being obtained for urea-treated WCW and the lowest for the inoculant-treated high DM WCW. Digestibility coefficients for NDF and ADF were highest for the urea-treated WCW while starch digestibility was essentially complete for all the WCW treatments. The metabolizable energy value (MJ/kg corrected DM) of the WCW decreased with advancing maturity when measured with both the lactating cows (10·4, 9·3 and 9·0) and the sheep (11·4, 10·8 and 10·3) in contrast to the predictions based on the chemical composition (9·6, 10·4 and 12·4). It is concluded that food intake increases with advancing crop maturity but milk production responses are small. Effects on digestibility were inconsistent but the energy value measured in the cows fell with advancing maturity in both years. The increase in crop yield per ha with advancing maturity is likely to be the most important factor influencing the decision to harvest later. The silage additives tested were not beneficial.

Lameness is an important economic problem in the dairy sector, resulting in production loss and reduced welfare of dairy cows. Given the modern-day expansion of dairy herds, a tool to automatically detect lameness in real-time can therefore create added value for the farmer. The challenge in developing camera-based tools is that one system has to work for all the animals on the farm despite each animal having its own individual lameness response. Individualising these systems based on animal-level historical data is a way to achieve accurate monitoring on farm scale. The goal of this study is to optimise a lameness monitoring algorithm based on back posture values derived from a camera for individual cows by tuning the deviation thresholds and the quantity of the historical data being used. Back posture values from a sample of 209 Holstein Friesian cows in a large herd of over 2000 cows were collected during 15 months on a commercial dairy farm in Sweden. A historical data set of back posture values was generated for each cow to calculate an individual healthy reference per cow. For a gold standard reference, manual scoring of lameness based on the Sprecher scale was carried out weekly by a single skilled observer during the final 6 weeks of data collection. Using an individual threshold, deviations from the healthy reference were identified with a specificity of 82.3%, a sensitivity of 79%, an accuracy of 82%, and a precision of 36.1% when the length of the healthy reference window was not limited. When the length of the healthy reference window was varied between 30 and 250 days, it was observed that algorithm performance was maximised with a reference window of 200 days. This paper presents a high-performing lameness detection system and demonstrates the importance of the historical window length for healthy reference calculation in order to ensure the use of meaningful historical data in deviation detection algorithms.

Dietary fat influences the physico-chemical properties of meat, and fatty acid (FA) composition may have implications on human health. The objectives of the experiment were to study tissue FA partitioning and the effect of dietary fat source on tissue FA composition. Seventy crossbred gilts (61.8 ± 5.2 kg BW average) were fed one of seven treatments: a diet containing a very low level of fat (no fat (NF)) and six fat-supplemented diets (10%: tallow (T), high-oleic sunflower oil (HOSF), sunflower oil (SFO), linseed oil (LO), fat blend (FB: 55% tallow, 35% SFO, 10% LO) and fish oil blend (FO: 40% fish oil, 60% LO). Differential tissue FA depositions were observed, with flare fat being the most saturated, followed by intermuscular, and subcutaneous being the least saturated. Monounsaturated fatty acid (MUFA) deposition showed an opposite tissue pattern. Subcutaneous fat showed the highest MUFAs, intermuscular fat showed intermediate values and flare fat showed the lowest MUFAs. Intramuscular polyunsaturated fatty acid (PUFA) content was less susceptible to dietary treatment modifications compared with other depots. Significant tissue FA modifications were observed due to dietary treatments, mainly in diets rich in PUFA. The saturated fatty acids (SFA) were high in NF-fed and low in HOSF-fed animals, MUFA were high in HOSF-fed and low in SFO-, LO- and FO-fed animals, while PUFA were high in SFO- and LO-fed and low in HOSF-, T- and NF-fed animals. Pigs fed LO and FB showed detectable levels of EPA, which depended on the linolenic content of the diet. The only effective way to increase tissue DHA contents was to add DHA in the diet through FO feeding. Araquidonic acid was high in SFO diets and low in LO and FB diets, and also high in intramuscular fat compared with other tissues. EPA and DHA were also high in intramuscular fat compared with other fat depots. The deposition of oleic and linoleic acids depended on the composition of dietary fat, as their deposition varied between diets, even at similar levels of intake of each FA. The NF diet resulted in the greatest proportion of SFAs (palmitic and stearic) of all treatments tested. SFAs were less susceptible to modification than MUFA in response to the different PUFA levels supplemented in the diet. T resulted in less fat deposition in some of the fat depots and more in others, suggesting that T could partition fat differently among fat depots.

Infection with Eimeria sp. results in the activation of multiple facets of the host immune system; the use of phytogenics can modulate the inflammatory response and improve the performance of the challenged animal. The aim of this study was to evaluate the effect of a commercial blend of cashew nut shell liquid (CNSL) and castor oil on the immune response of broilers challenged with coccidiosis. A total of 864 one-day-old male chicks (Cobb 500) were randomly distributed into six treatment groups (8 pens/treatment and 18 chicks/pen) in a three-by-two factorial design with three additives: control (non-additive), 100 ppm of monensin or 0.15% CNSL–castor oil. Challenge status was determined twice at 14 days of age. Unchallenged birds were inoculated by gavage with oocysts sporulated with Eimeria tenella, Eimeria acervulina and Eimeria maxima. Although the positive control (non-additive and challenged) and CNSL–castor oil treatment groups exhibited similar variation in weight gain (ΔBWG) compared to unchallenged birds fed without additives, the variation observed in birds fed diets containing CNSL–castor oil was associated with a higher maintenance requirement and not feed efficiency. In the second week after infection, ΔBWG of the CNSL–castor oil treatment group did not significantly change compared to the other treatment groups. At days 7 and 14 post-challenge, there was a higher excretion of oocysts in the control group, whereas the CNSL–castor oil and monensin groups did not differ. The CNSL–castor oil group exhibited increased gene expression of interferon (IFN), interleukin 6 (IL-6) and tumor necrosis factor (TNF), while the control group exhibited increased expression of cyclooxygenase (COX) and IL-1. The heterophils/lymphocyte ratio was low for the monensin treatment group. The unchallenged birds that received monensin treatment presented higher gene expression of IFN, COX and IL-1 compared to the other treatments, while the CNSL–castor oil group exhibited reduced gene expression, except for TNF. The commercial blend of cashew nut liquid and castor oil modulated the inflammatory response against Eimeria spp. In the absence of the parasite, there was no stimulation of genes involved in the inflammatory response, demonstrating that the blend is an effective tool in specifically modulating the immune system of birds afflicted with coccidiosis.

Orexin A and B are hypothalamic peptides derived from the prepro-orexin (PPO) precursor. Orexins stimulate food intake and arousal. Those peptides bind and activate two G protein-coupled receptors: orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R). Numerous authors have suggested that orexins play an important role in the regulation of the reproductive functions. The objective of the present study was to analyse the presence of and changes in the gene and protein expression pattern of the orexin system in the porcine uterus, conceptus and trophoblast (chorioallantois) during early pregnancy. In the endometrium, the highest PPO and OX1R gene expression was detected on days 15 to 16 of gestation. The OX2R mRNA content in the endometrium was higher on days 10 to 11 and 15 to 16 than on days 12 to 13 and 27 to 28. In the trophoblasts, PPO gene expression was higher on days 30 to 32 than on days 27 to 28. The highest PPO protein content in the endometrium was noted on days 12 to 13. The highest OX1R protein content in the endometrium was detected on days 10 to 11, whereas OX2R protein on days 15 to 16. In the trophoblasts, PPO and OX1R protein levels were more pronounced on days 27 to 28 than on days 30 to 32, but OX2R expression was higher on days 30 to 32. The expression of PPO, OX1R and OX2R was different in the conceptuses and trophoblasts during early pregnancy. Local orexin production and the presence of the specific orexin receptors suggest that the orexin system may participate in the control of porcine reproductive functions by exerting endocrine and auto/paracrine effects on the uterus, conceptuses and trophoblasts during early pregnancy. This study provides the first evidence for the presence of orexins and their receptors in the uteri, conceptuses and trophoblasts in pigs during early pregnancy. The local orexin system is dependent on the stage of pregnancy.

The effect of carbohydrate supplementation on rumen utilization of ammonia-treated straw was studied in four rumen-cannulated ewes (42•0 (s.e. 2•80) kg live weight) in a Latin-square design. Diets were a 50: 50 mixture of ammoniated barley straw and a concentrate made up with different ratios of barley grain and citrus pulp, namely M1 (100: 0), M2 (66: 33), M3 (33: 66) and M4 (0: 100). Concentrates also included soya-bean meal and urea to make diets isonitrogenous. Diets were given in one meal in the morning at 0•8 kg/day. There were no significant differences among treatments in daily weighted means of rumen pH and concentration of volatile fatty acids. Acetate, propionate and butyrate molar proportions were not different among treatments, but proportions of isobutyrate (P < 0•05) and isovalerate (P < 0•10) were higher for M1 and M2. Ammonia concentration immediately before feeding was lower (P < 0•05) for M3 and M4 (72•1 and 51•3 mg/l) than for M1 and M2 (97•0 and 107•9 mg/ l). Total rumen bacterial concentration was higher (P < 0•05) with the highest barley proportion, whereas enzymatic activity against structural carbohydrates of particle-associated bacteria did not differ significantly among treatments. Digestibility of neutral-detergent fibre increased (P < 0•05) with the increase in the proportion of citrus pulp in the concentrate (0•647, 0•674, 0•684 and 0•693 for M1, M2, M3 and M4; s.e. = 0•0086). Urinary excretion of purine derivatives decreased linearly (P < 0•05) as the proportion of citrus pulp in the diet increased, while faecal excretion of purine bases was not significantly affected by dietary treatments.

The ability to accumulate intramuscular fat (IMF) is a highly variable characteristic in beef cattle. In breeds with a low tendency to accumulate IMF, this can lead to compromised meat quality because of the contribution of fat to such organoleptic attributes as juiciness and taste. This study considered adiposity and gene expression of some of the main markers involved in adipogenesis and lipid metabolism in the subcutaneous (SC) adipose tissue (AT) and the longissimus thoracis muscle (LM) and investigated differences in adipogenic regulation between the tissues during growth and fattening under different conditions. Pirenaica beef cattle were chosen for the study due to the breed’s low tendency to accumulate IMF and the breed’s regional importance. The young Pirenaica bulls used (n=16) were allocated to four groups and slaughtered at 6, 12 and 18 months. From 12 months onwards the bulls slaughtered at 18 months were fed diets having different energy densities. Backfat thickness increased from 6 to 12 months (P<0.05) but then was unchanged, while other fattening parameters such as percentage chemical fat and marbling did not vary. The adipose cell size distribution displayed a bimodal distribution for SC adipocytes and a unimodal distribution for IMF cells, suggestive of tissue-specific hyperplasia. Gene expression of peroxisome proliferator-activated receptor γ (PPARG), CCAAT/enhancer-binding protein α (CEBPA), sterol regulatory element-binding transcription factor 1 (SREBF1), wingless-type MMTV integration site family 10B (WNT10B), fatty acid-binding protein 4 (FABP4), acetyl Co-A carboxylase α, lipoprotein lipase and fatty acid synthase (FASN) were determined by real-time quantitative PCR. Expression did not differ between the experimental groups within the tissues but did differ between the tissues: PPARG, FABP4 and FASN were upregulated in the SC AT, while CEBPA, WNT10B and SREBF1 were upregulated in the LM. Although age and diet energy density did not have a significant effect on increasing the amount of IMF, these factors could have influenced adipocyte development in this tissue differently than in the SC AT. This was evidenced by the different size distributions of the cells in the two tissues, and the differing expression patterns of certain markers in the SC AT and the LM, which may indicate a differential role of PPARG and WNT10B in triggering adipocyte proliferation and fat accumulation capacity.

Organic pig husbandry systems in Europe are diverse – ranging from indoor systems with concrete outside run (IN) to outdoor systems all year round (OUT) and combinations of both on one farm (POUT). As this diversity has rarely been taken into account in research projects on organic pig production, the aim of this study was to assess and compare pig health, welfare and productivity in these three systems. Animal health and welfare were assessed using direct observation and records of 22 animal-based measures, comprising 17 health-, 3 productivity- and 2 behavioural measures. These were collected in pregnant sows, weaners and fattening pigs during direct observations and from records within a cross-sectional study on 74 farms (IN: n = 34, POUT: n = 28, OUT: n = 12) in eight countries. Overall, prevalence of several animal health and welfare issues was low (e.g. median 0% for pigs needing hospitalisation, shoulder lesions, ectoparasites; <5% for runts, tail lesions, conjunctivitis). Exceptions in particular systems were respiratory problems in weaners and fatteners (IN: 60.0%, 66.7%; POUT: 66.7%, 60.0%), weaning diarrhoea (IN: 25.0%), and short tails in fatteners (IN: 6.5%, POUT: 2.3%). Total suckling piglet losses (recorded over a period of 12 months per farm) were high in all three systems (IN: 21.3%; POUT: 21.6; OUT: 19.2%). OUT had lower prevalences of respiratory problems, diarrhoea and lameness of sows. POUT farms in most cases kept sows outdoors and weaners and fatteners similar to IN farms, which was reflected in the results regarding several health and welfare parameters. It can be concluded, that European organic pigs kept in all three types of husbandry system showed a low prevalence of health and welfare problems as assessed by our methodology, but respiratory health and diarrhoea should be improved in weaners and fatteners kept indoors and total piglet mortality in all systems. The results provide benchmarks for organic pig producers and organisations which can be used in strategies to promote health and welfare improvement. Furthermore, in future research, the identified health and welfare issues (e.g. suckling piglet mortality, weaning diarrhoea) should be addressed, specifically considering effects of husbandry systems.

Dairy systems are a source of pollutant emissions, such as greenhouse gases (GHG) and NH3 that are associated with impacts on the environment. Gas emissions in barns are related mainly to diet intake and chemical composition, N excretion and manure management. A reduction in dietary N is known to be an effective way to reduce N excretion and the resulting NH3 emissions. However, most studies consider manure in liquid form with frequent removal from the barn. In deep litter systems, several processes can occur during the accumulation of solid manure that result in variable gas emissions. The objective of this experiment was to investigate the influence of the interaction between dietary CP (low or high) and manure management (liquid or solid) on gas emissions (NH3, N2O, CH4) at the barn level. Dietary treatments provided either low (LowN; 12% CP) or high (HighN; 18% CP) degradable protein to modify the amount of total ammonia nitrogen (TAN) excreted. The cows were housed for two 8-week periods in two mechanically ventilated rooms equipped to manage manure either in liquid (LM; slurry) or solid form (SM; deep litter). In the LM treatment, N balance was measured for 4 days. As expected, animals fed the LowN diet ingested 35% less N and excreted 65% less N in their urine, with no reduction in faecal N excretion and N secretion in milk. On the LowN diet, excretion of urea-N and NH3-N emissions were reduced regardless of the manure management. On the HighN diet, urinary urea-N excretion was three times as high, while NH3-N emissions were 3.0 and 4.5 times as high in LM and SM, respectively. Manure management strongly influenced CH4-C emissions, which were 30% higher in SM than in LM, due to the accumulation of litter. Moreover, gas emissions from solid manure increased over the accumulation period, except for NH3 on the LowN diet. Finally, our results suggest that methods used for national inventories would become more accurate by considering the variability in TAN excretion, which is the primary factor that influences NH3 emissions.

Enormous progress has been made in the selection of animals, including cattle, for specific traits using traditional quantitative genetics approaches. Nevertheless, considerable variation in phenotypes remains unexplained, and therefore represents potential additional gain for animal production. In addition, the paradigm shift in new disciplines now being applied to animal breeding represents a powerful opportunity to prise open the ‘black box’ underlying the response to selection and fully understand the genetic architecture controlling the traits of interest. A move away from traditional approaches of animal breeding toward systems approaches using integrative analysis of data from the ‘omic’ disciplines represents a multitude of exciting opportunities for animal breeding going forward as well as providing alternatives for overcoming some of the limitations of traditional approaches such as the expressed phenotype being an imperfect predictor of the individual’s true genetic merit, or the phenotype being only expressed in one gender or late in the lifetime of an animal. This review aims to discuss these opportunities from the perspective of their potential application and contribution to cattle breeding. Harnessing the potential of this paradigm shift also poses some new challenges for animal scientists – and they will also be discussed.

Two trials were carried out to compare the effects of fat or starch inclusion in sow’s diet on sow and litter performance. In each trial, sows were assigned to one of two treatments. In trial 1, the sows were fed diets containing either soybean oil (5%, treatment GL5) or cornstarch (11.3%, GL0) from day 35 of gestation to weaning. Daily net energy and nutrient allowance were equalised during gestation. In trial 2, the same treatments were applied only after farrowing (treatments L5 and L0, respectively). Within each trial, a batch of piglets was studied until slaughter. In trial 1, adipose cell development and total lipid content were determined on some pigs at weaning (n = 6/treatment) and at slaughter in dorsal subcutaneous adipose tissue (n = 13/group at least) and in muscle (n = 46/group at least). Piglets’ birth weight was not affected by treatment in trial 1. Survival rates at birth and after 24 h of life were higher in treatment GL5 (4.0% v. 7.5% stillborn piglets in GL0 treatment, P < 0.05; 8.7% v. 12.6% of piglets alive at 24 h of age died in treatment GL0, P = 0.06). Subsequently, overall survival rate until weaning was higher in treatment GL5 (81.4% v. 75.7% of total born piglets, P = 0.03), but litter size at weaning was not significantly affected (11.3). Litter growth rate before weaning was increased when a fat-enriched diet was provided during gestation and lactation (+140 g/day per litter; P < 0.01) and to a lower extent when provided only after farrowing (+90 g/day; P < 0.05). Energy supply through fat did not decrease the mobilisation of the sow’s body reserve and backfat thickness loss was even higher with treatment GL5 (P < 0.05). After weaning, pigs’ average daily gain, feed : gain ratio and carcass lean content were not affected by the energy source supplied before and/or after farrowing. At weaning, the number of adipose cells in the dorsal subcutaneous adipose tissue and in the Longissimus dorsi muscle was higher in the GL5 pigs. Muscle lipid content at weaning did not differ between treatments, but it was higher at slaughter, around 110 kg, in the GL5 pigs (3.46% v. 2.58%, P < 0.001).

One hundred and thirty-two young rabbits were divided into two groups at weaning and given ad libitum a control diet (C), or an experimental diet (M) in which lucerne hay was substituted by mulberry leaves in order to examine their effects on fattening rabbit performance, carcass characteristics and meat quality.

Digestibility coefficients of dry matter (DM), crude protein and gross energy were similar in both groups but digestibility of crude fibre in the experimental diet was higher in line with a lower food intake in this group of animals, while ether extract digestibility of mulberry leaves was very low.

Food conversion ratio was similar in the two groups (3.1 g DM per g gain) but rabbits given the experimental diet had lower food intake (102 v. 144 g/day) and impaired live-weight gain. The rate of mortality was similar in the two groups. The substitution of lucerne with mulberry in the diet may have induced a higher retention time of digesta, as seems to be indicated by a higher weight of digestive tract contents recorded at slaughter (proportionately 0.32 more) in mulberry group. Live weight at slaughter of animals in control group was higher (2680 v. 2211 g) and also skin weight was proportionately 0.5 higher and its carcasses were proportionately 0.41 heavier than those of animals in experimental group (dressing yield 587 v. 503 g/kg). At constant carcass weight, the carcasses of rabbits of the mulberry group were longer than the lucerne group, but lumbar circumference tended also to be higher (P = 0.09) and no differences were found in the length: circumference ratio. No differences were found in the weights of kidneys or thoracic viscera, but livers of rabbits of the lucerne group were heavier (proportionately 0.3 heavier). The more remarkable difference was that carcasses of rabbits given the experimental diet had markedly less fat in scapular (5.8 v. 10.0 g) and perirenal fat (9.0 v. 22.3 g) deposits.

No differences in cooking losses or water-holding capacity of the meat were found and also the colour was similar, but the b* parameter was a little lower for meat of the M group rabbits.

The proportion of protein in the meat was the same for rabbits of the two groups, but rabbits given the experimental diet which had leaner carcasses also had leaner meat (19 v. 37 g lipids per kg meat) and a little more moisture (755 v. 736 g/kg meat). Intra and intermuscular fat of hindleg meat from rabbits of group M was less saturated and more unsaturated than that of the conventional rabbits mainly due to its higher proportion of polyunsaturated fatty acids, ω6 (37·3 v. 29·1 g/100 g lipids) and ω3 (3·4 v. 2·2 g/ 100 g lipids). Polyunsaturated: saturated ratio was higher in the mulberry group than in the lucerne group (1·15 v. 0·85) indicating a more desirable value in rabbits given the experimental diet, so meat of these rabbits could be considered preferable for human nutrition from this point of view.

The three indigenous beef cattle breeds in Botswana, the Tswana, Africander and Tuli, were evaluated for reproductive performance, viability and growth. Over 3 yr the calving percentages of 1389 Africander cows, 305 Tswanas and 357 Tulis were 64·5, 70·6 and 85 respectively. These differences were significant (P<0·05). Mortality of the Africander calves was higher to 2 yr of age, being 11% compared with 7-5% for Tswana calves and 7·4% for Tulis. The 18 mo weight of 219 Tuli cattle was 284 kg, and of 454 Tswanas 279 kg, both superior to the 270 kg for the 786 Africanders. Productivity estimates combining these three traits demonstrate the value of the Tuli breed for Botswana conditions.

Comparisons of the crossbreds produced by the use of Simmental, Brahman, Bonsmara and Tuli sires on Tswana cows showed an advantage in growth to 18 mo through crossbreeding. The 18 mo weights of Simmental and Brahman crosses at 324 and 304 kg respectively were significantly different, and superior to the weight of pure Tswana at 279 kg. Bonsmara and Tuli crosses at 294 and 290 kg also showed a significant increase over the pure Tswana. The use of the Simmental is now recommended for better management conditions, with Brahman crossbreeding on a wider scale.

Variance components for litter size (total number of piglets born) were estimated from Danish purebred Landrace and Yorkshire litters by restricting maximum likelihood. The data were collected from the national Danish breeding programme and consisted of 19 666 litters in Danish Landrace and 29 336 litters in Danish Yorkshire. Four different analyses for litter size were conducted within breed. In the first two, genetic groups were included in the model in order to account for the importation of animals from other countries; in the other two, genetic groups were removed from the model. Within each case, herd-year-type of insemination effects were fitted as fixed (H-fixed models), or herd-year-season-type of insemination effects were fitted as random (H-random models). Estimates of heritability ranged from about 0·11 to 0·14 in Landrace and from 0·10 to 0·11 in Yorkshire. Variance due to herd-year-season-type of insemination ranged from 0·029 to 0·041 of total variance, values somewhat lower than those obtained for non-genetic permanent effects. In order to compare the four models, data were divided into different subsets, and records from one subset were predicted using parameters estimated from the other subset. Both the correlation between observed and predicted values, and the mean squared error of prediction indicated that predictive ability was higher in the case of H-random models. There was no evidence that genetic groups improved the predictive ability for litter size. However, group effects affected inferences about genetic trend, particularly in Landrace, where genetic group composition changed consistently over the years.

Myostatin (MSTN), a member of the TGF-β superfamily, is a negative regulator of skeletal muscle mass. We have previously shown that the cell survival/apoptosis pathway is a downstream target of MSTN loss-of-function in mice through the regulation of the expression or abundance of many survival and apoptotic factors. In this study, we used western-blot and quantitative PCR (qPCR) analyses to validate these novel downstream targets of MSTN in double-muscled (DM) cattle v. their controls including 260-day-old foetuses and adult cows from the INRA95 strain. MSTN loss-of-function in DM foetuses and DM cows resulted in a glycolytic shift of the muscles (e.g. upregulation of H-MyBP, PGM1 and SNTA1 and downregulation of H-FABP), activation of cell survival pathway through regulation of some components of the PI3K/Akt pathway (e.g. upregulation of DJ-1 and Gsk-3βser9/Gsk-3βtotal ratio and downregulation of PTEN) and upregulation of cell survival factors translationally controlled tumour protein (14-3-3E, Pink1). We also found a lower abundance of pro-apoptotic transcripts and/or proteins (Caspase-3, caspase-8, caspase-9, BID, ID2 and Daxx) and a higher expression of anti-apoptotic transcripts (Traf2 and Bcl2l2) in DM muscles. All together, these results are in favour of activation of the cell survival pathway and loss of apoptosis pathway within the muscles of DM animals. Alteration of both pathways may increase myonuclear or satellite cell survival, which is crucial for protein synthesis. This could contribute to muscle hypertrophy in DM foetuses and DM cows.

A numerical model of male and female replacement processes in a dairy cattle population was constructed in order to describe the long-term genetic and financial consequences of selection amongst bulls in AI.

Changes with time in the relative contribution of different generations of offspring to the total genetic improvement of the population were described. It was shown that the genetic change resulting from a single selection process amongst the males eventually approaches an equilibrium many years after selection is practised. Owing to the delays involved in the progeny test, individual males made no genetic contribution for a period of 10 years and a small but constant contribution thereafter.

The costs of bull testing and selection, and the monetary benefits obtained from it, were estimated. Current selection procedures proved to be highly profitable at prevailing market prices. Capital invested in the testing programme was recovered within 2 to 5 years of the first offspring calving.

The effect of changes in milk prices and feeding costs on monetary returns was examined. It was concluded that sire testing programmes are likely to prove unprofitable only under extremely adverse economic conditions.