A whole-farm, stochastic and dynamic simulation model was developed to predict biophysical and economic performance of grazing dairy systems. Several whole-farm models simulate grazing dairy systems, but most of them work at a herd level. This model, named e-Dairy, differs from the few models that work at an animal level, because it allows stochastic behaviour of the genetic merit of individual cows for several traits, namely, yields of milk, fat and protein, live weight (LW) and body condition score (BCS) within a whole-farm model. This model accounts for genetic differences between cows, is sensitive to genotype × environment interactions at an animal level and allows pasture growth, milk and supplements price to behave stochastically. The model includes an energy-based animal module that predicts intake at grazing, mammary gland functioning and body lipid change. This whole-farm model simulates a 365-day period for individual cows within a herd, with cow parameters randomly generated on the basis of the mean parameter values, defined as input and variance and co-variances from experimental data sets. The main inputs of e-Dairy are farm area, use of land, type of pasture, type of crops, monthly pasture growth rate, supplements offered, nutritional quality of feeds, herd description including herd size, age structure, calving pattern, BCS and LW at calving, probabilities of pregnancy, average genetic merit and economic values for items of income and costs. The model allows to set management policies to define: dry-off cows (ceasing of lactation), target pre- and post-grazing herbage mass and feed supplementation. The main outputs are herbage dry matter intake, annual pasture utilisation, milk yield, changes in BCS and LW, economic farm profit and return on assets. The model showed satisfactory accuracy of prediction when validated against two data sets from farmlet system experiments. Relative prediction errors were <10% for all variables, and concordance correlation coefficients over 0.80 for annual pasture utilisation, yields of milk and milk solids (MS; fat plus protein), and of 0.69 and 0.48 for LW and BCS, respectively. A simulation of two contrasting dairy systems is presented to show the practical use of the model. The model can be used to explore the effects of feeding level and genetic merit and their interactions for grazing dairy systems, evaluating the trade-offs between profit and the associated risk.

This study was undertaken to further develop our understanding of the links between breed, diet and the rumen microbial community and determine their effect on production characteristics and methane (CH4) emissions from beef cattle. The experiment was of a 2×2 factorial design, comprising two breeds (crossbred Charolais (CHX); purebred Luing (LU)) and two diets (concentrate-straw or silage-based). In total, 80 steers were used and balanced for sire within each breed, farm of origin and BW across diets. The diets (fed as total mixed rations) consisted of (g/kg dry matter (DM)) forage to concentrate ratios of either 500 : 500 (Mixed) or 79 : 921 (Concentrate). Steers were adapted to the diets over a 4-week period and performance and feed efficiency were then measured over a 56-day test period. Directly after the 56-day test, CH4 and carbon dioxide (CO2) emissions were measured (six steers/week) over a 13-week period. Compared with LU steers, CHX steers had greater average daily gain (ADG; P<0.05) and significantly (P<0.001) lower residual feed intake. Crossbred Charolais steers had superior conformation and fatness scores (P<0.001) than LU steers. Although steers consumed, on a DM basis, more Concentrate than Mixed diet (P<0.01), there were no differences between diets in either ADG or feed efficiency during the 56-day test. At slaughter, however, Concentrate-fed steers were heavier (P<0.05) and had greater carcass weights than Mixed-fed steers (P<0.001). Breed of steer did not influence CH4 production, but it was substantially lower when the Concentrate rather than Mixed diet was fed (P<0.001). Rumen fluid from Concentrate-fed steers contained greater proportions of propionic acid (P<0.001) and lower proportions of acetic acid (P<0.001), fewer archaea (P<0.01) and protozoa (P=0.09), but more Clostridium Cluster XIVa (P<0.01) and Bacteroides plus Prevotella (P<0.001) than Mixed-fed steers. When the CH4 to CO2 molar ratio was considered as a proxy method for CH4 production (g/kg DM intake), only weak relationships were found within diets. In conclusion, although feeding Concentrate and Mixed diets produced substantial differences in CH4 emissions and rumen characteristics, differences in performance were influenced more markedly by breed.

The effects of mycotoxins in the production of animal feed were investigated using broiler chickens. For the feeding trial, naturally Fusarium mycotoxin-contaminated wheat was used, which mainly contained deoxynivalenol (DON). The main effects of DON are reduction of the feed intake and reduced weight gain of broilers. At the molecular level, DON binds to the 60 S ribosomal subunit and subsequently inhibits protein synthesis at the translational level. However, little is known about other effects of DON, for example, at the transcriptional level. Therefore, a microarray analysis was performed, which allows the investigation of thousands of transcripts in one experiment. In the experiment, 20 broilers were separated into four groups of five broilers each at day 1 after hatching. The diets consisted of a control diet and three diets with calculated, moderate concentrations of 1.0, 2.5 and 5.0 mg DON/kg feed, which was attained by exchanging uncontaminated wheat with naturally mycotoxin-contaminated wheat up to the intended DON concentration. The broilers were held at standard conditions for 23 days. Three microarrays were used per group to determine the significant alterations of the gene expression in the liver (P < 0.05), and qPCR was performed on the liver and the jejunum to verify the results. No significant difference in BW, feed intake or feed conversion rate was observed. The nutrient uptake into the hepatic and jejunal cells seemed to be influenced by genes: SLC2A5 (fc: −1.54, DON2.5), which facilitates glucose and fructose transport and SLC7A10 (fc: +1.49, DON5), a transporter of d-serine and other neutral amino acids. In the jejunum, the palmitate transport might be altered by SLC27A4 (fc: −1.87, DON5) and monocarboxylates uptake by SLC16A1 (fc: −1.47, DON5). The alterations of the SLC gene expression may explain the reduced weight gain of broilers chronically exposed to DON-contaminated wheat. The decreased expressions of EIF2AK3 (fc: −1.29, DON2.5/5) and DNAJC3 (fc: −1.44, DON2.5) seem to be related to the translation inhibition. The binding of DON to the 60 S ribosomal subunit and the subsequent translation inhibition might be counterbalanced by the downregulation of EIF2AK3 and DNAJC3. The genes PARP1, MPG, EME1, XPAC, RIF1 and CHAF1B are mainly related to single-strand DNA modifications and showed an increased expression in the group with 5 mg DON/kg feed. The results indicate that significantly altered gene expression was already occurring at 2.5 mg DON/kg feed.

Phosphorus (P) is an essential nutrient in livestock feed but can pollute waterways. In order for pig production to become less of a threat to the environment, excreta must contain as little P as possible or be efficiently used by plants. This must be achieved without decreasing the livestock performance. Phosphorus and calcium (Ca) deposition in the bones of growing pigs must be optimised without affecting the muscle gain. This requires precision feeding based on cutting-edge techniques of diet formulation throughout the animal growth phase. Modelling and data mining have become important tools in this quest. In this study, a mechanistic model taking into account the distribution of P between bone and soft tissues was compared to the established factorial models (INRA (Jondreville and Dourmad, 2005) and NRC (National Research Council, 2012)) that predict P (apparent total tract digestible, ATTD-P; or standardised total tract digestible, STTD-P) and Ca (total and STTD) requirements as a function of BW and protein deposition. The requirements for different bone mineralisation scenarios, namely, 100% and 85% of the genetic potential, were compared with these two models. Sobol indices were used to estimate the relative impact of growth-related parameters on mineral requirements at 30, 60 and 120 kg of BW. The INRA showed the highest value of ATTD-P requirement between 29 and 103 kg of BW (6%) and lower for lighter and higher BW. Similarly, the model for 85% bone mineralisation showed lower STTD-P requirement than NRC between 29 and 93 kg of BW (7%) and higher for lighter and higher BW. Contrary to other models, the Ca requirement of the proposed model is not fixed in relation to P. It increases from 95 kg of BW while the others decrease. The INRA showed the highest Ca requirements. The model Ca requirements for 100% bone mineralisation are higher than NRC from 20 to 38 kg of BW similar until 70 kg of BW and then higher again. For 85% objective, the model showed lower Ca requirements from 25 to 82 kg of BW and higher for lighter and higher BW. The potential Ca deposition in bones is the most sensitive parameter (84% to 100% of the variance) of both ATTD-P and Ca at 30, 60 and 120 kg. The second most sensitive parameter is the protein deposition, explaining 1% to 15% of the ATTD-P variance. Studies such as this one will help to usher in a new era of sustainable and eco-friendly livestock production.

This study aimed to assess the merit and suitability of individual functional units (FU) in expressing greenhouse gas emissions intensity in different dairy production systems. An FU provides a clearly defined and measurable reference to which input and output data are normalised. This enables the results from life-cycle assessment (LCA) of different systems to be treated as functionally equivalent. Although the methodological framework of LCA has been standardised, selection of an appropriate FU remains ultimately at the discretion of the individual study. The aim of the present analysis was to examine the effect of different FU on the emissions intensities of different dairy production systems. Analysis was based on 7 years of data (2004 to 2010) from four Holstein-Friesian dairy systems at Scotland’s Rural College’s long-term genetic and management systems project, the Langhill herd. Implementation of LCA accounted for the environmental impacts of the whole-farm systems and their production of milk from ‘cradle to farm gate’. Emissions intensity was determined as kilograms of carbon dioxide equivalents referenced to six FU: UK livestock units, energy-corrected milk yield, total combined milk solids yield, on-farm land used for production, total combined on- and off-farm land used for production, and the proposed new FU–energy-corrected milk yield per hectare of total land used. Energy-corrected milk was the FU most effective for reflecting differences between the systems. Functional unit that incorporated a land-related aspect did not find difference between systems which were managed under the same forage regime, despite their comprising different genetic lines. Employing on-farm land as the FU favoured grazing systems. The proposed dual FU combining both productivity and land use did not differentiate between emissions intensity of systems as effectively as the productivity-based units. However, this dual unit displayed potential to quantify in a simple way the positive or negative outcome of trade-offs between land and production efficiencies, in which improvement in emissions intensity using one FU may be accompanied by deterioration using another FU. The perceived environmental efficiencies of different dairy production systems in terms of their emissions intensities were susceptible to change based upon the FU employed, and hence the FU used in any study needs to be taken into account in the interpretation of results.

The EU project Welfare Quality® proposes an overall assessment system for animal welfare based on animal outcomes. The objective of this study was to test inter-observer reliability (IOR) when assessing lameness, fear and slipping and falling scores as parameters for monitoring the welfare of killing pigs during arrival at the slaughterhouse. Two Belgian and two Spanish slaughterhouses were visited by six to seven observers. Lameness, slipping and falling were assessed twice; during unloading and in the passageway to the lairage zone (lairage). Fear, which was assessed in the unloading area, was based on four indicators: reluctance to move, retreat attempts, turning back and vocalisations. Lameness had low-to-moderate IOR when observed in the passageway to lairage (r = 0.46), but the IOR was low during unloading (r = 0.25). IOR for slipping and falling was moderate to high (r = 0.71 and r = 0.50, respectively), when assessed in the unloading area, but low for observations in the passageway (r = 0.13). Fear indicators had only moderate or low IOR. Turning back was the measure with the highest IOR (r = 0.43) and retreat attempts had the lowest IOR (r = 0.25). Based on these results, we concluded that scoring lameness could be reliable when assessed from the unloading bay to lairage, whereas slipping and falling should be scored in the unloading area of the slaughterhouse. We suggest scoring a maximum of two measures of fear on the same animals at the unloading area, with the most reliable parameters being turning back and reluctance to move. The three indicators of animal welfare (lameness, fear and slipping and falling) should be measured in a way to reduce overtax of the observers in order to achieve accurate results.

The lipid content and fatty acid (FA) profile in pig tissues are strongly influenced by genotype and nutrient supply, with implications in meat quality. The de novo lipid synthesis and pattern of FA unsaturation could be an important cause of variation in the overall efficiency of energy utilization among breeds. To test the effects of pig genotype and CP supply on the evolution of back-fat tissue FA profile throughout the growing and finishing stages, 32 Iberian (IB) and Landrace × Large White (LR × LW) barrows were offered one of two diets differing in CP content (13% or 17% as fed). A pair-fed procedure (0.8 × ad libitum intake of IB pigs) was used. Subcutaneous fat samples were taken at the dorso-lumbar region at ∼38, 50, 65, 90 and 115 kg BW. Higher proportions of total monounsaturated FA (MUFA; P < 0.01) and lower proportions of total saturated FA (SFA; P < 0.01 to 0.05) were found in the outer back-fat layer of pigs both at 50 and 115 kg BW. Pig genotype affected the FA composition of both subcutaneous back-fat layers. The proportions of C18:0 and SFA in fat tissue were higher in IB than in LR × LW pigs from 38 to 65 kg BW, especially in the outer layer. In addition, MUFA contents were higher in IB pigs at 115 kg BW in both layers (+5% on average; P < 0.01). Increased proportions of C18:2 n-6 and polyunsaturated FA (PUFA) were found in LR × LW pigs, irrespective of the stage of growth and back-fat layer (P⩽0.02). At 50 kg BW, pigs receiving the high-protein diet presented the highest C18:2 n-6, C18:3 n-3, C20:5 n-3 and PUFA contents. A significant genotype × CP content interaction was observed for C18:3 n-3 because of the increased concentration of this FA in LR × LW pigs when offered the 17% CP diet (P < 0.05). Higher C16:0 and SFA contents (+5%; P = 0.03) were found in pigs offered the 13% CP diet and slaughtered at 115 kg BW. There was a genotype × CP interaction for MUFA concentration because of the higher MUFA content observed in IB pigs offered the highest protein content diet (P = 0.03). Our results suggest that genetic variation in de novo lipid synthesis and pattern of FA unsaturation might contribute to explain differences in back-fat FA profile of IB and LR × LW pigs under identical nutritional management. They could be also relevant to explain the low efficiency of nutrient and energy utilization in the IB pig.

A study was conducted to evaluate the effect of pre-weaning concentrate feeding in early-weaned (EW, day 90) or traditionally weaned (TW, day 150) autumn-born beef calves on growth, feed intake and feed efficiency, and carcass and meat quality. Twenty-eight male calves were either EW or TW, and offered a starter concentrate (S) or no additional feed (NS) during the pre-weaning period. Therefore, four management strategies were tested: EWS, EWNS, TWS and TWNS. Growth patterns were affected by management strategy. From day 90 to 150, TWNS calves presented a substantially lower average daily gain (ADG) than their counterparts, which had similar performance. During the finishing phase (from day 150 to slaughter at 450 kg live weight), EWS calves had the lowest ADG. Daily feed intake or efficiency in the finishing phase was unaffected by previous management. Serum IGF-I concentrations at day 90 and slaughter did not differ with management strategy, but early weaning and pre-weaning concentrate feeding increased IGF-I concentrations at day 150. Circulating leptin concentrations were unaffected by age at weaning and pre-weaning concentrate feeding, except for leptin concentrations at slaughter, which were higher in S calves than in NS calves. Total concentrate intake from birth to slaughter and the concomitant feed costs were higher for EWS and EWNS calves than for TWNS and TWS ones. However, cow feed costs were lower for cows whose calves had been early weaned. Concerning carcass quality, early weaning improved dressing percentage and increased fatness score, and particularly TWNS calves presented a poorer conformation. Meat quality was not affected by management strategy. Considering the economic performance, TWS, EWNS and EWS strategies yielded a similar economic margin, whereas TWNS would be the least advisable strategy when calves are fattened in the farm until slaughter.

Systems biology is a rapidly expanding field of research and is applied in a number of biological disciplines. In animal sciences, omics approaches are increasingly used, yielding vast amounts of data, but systems biology approaches to extract understanding from these data of biological processes and animal traits are not yet frequently used. This paper aims to explain what systems biology is and which areas of animal sciences could benefit from systems biology approaches. Systems biology aims to understand whole biological systems working as a unit, rather than investigating their individual components. Therefore, systems biology can be considered a holistic approach, as opposed to reductionism. The recently developed ‘omics’ technologies enable biological sciences to characterize the molecular components of life with ever increasing speed, yielding vast amounts of data. However, biological functions do not follow from the simple addition of the properties of system components, but rather arise from the dynamic interactions of these components. Systems biology combines statistics, bioinformatics and mathematical modeling to integrate and analyze large amounts of data in order to extract a better understanding of the biology from these huge data sets and to predict the behavior of biological systems. A ‘system’ approach and mathematical modeling in biological sciences are not new in itself, as they were used in biochemistry, physiology and genetics long before the name systems biology was coined. However, the present combination of mass biological data and of computational and modeling tools is unprecedented and truly represents a major paradigm shift in biology. Significant advances have been made using systems biology approaches, especially in the field of bacterial and eukaryotic cells and in human medicine. Similarly, progress is being made with ‘system approaches’ in animal sciences, providing exciting opportunities to predict and modulate animal traits.

The value of a parameter such as heritability (h2) or intra-dass correlation in best linear unbiased prediction (BLUP) with the animal model or a family selection index affects both the rate of response achieved and the rate of inbreeding. If in BLUP an estimate of h2 is used which is biased upwards above its actual value, the rate of inbreeding can be substantially reduced with little reduction in the rate of response. Further, by mating individuals from families in which many are selected to others from families with few selected (compensatory mating), rates of inbreeding can be further reduced without substantial effect on response.

Two experiments were conducted to determine whether the depression in fibre digestion caused by inclusion of fat in diets could be alleviated by addition of urea and whether the physical incorporation of fat in itself caused a reduction in rate of fibre digestion.

Early-weaned lambs were given dried grass containing either 65 or 130 g/kg of tallow with or without 15 g/kg of urea. Fat inclusion caused a linear depression in intake and fibre digestibility. The depression in intake was partly alleviated by urea inclusion, but urea did not affect fibre digestibility.

The physical incorporation of fat into dried grass did not in itself appear to depress rate of digestion. It is suggested that if coating of feed particles is important then this would be due to non-esterified fatty acids in the rumen and not to triglycerides.

It has been suggested that feeding motivation, and hence the incidence of certain abnormal behaviours, may be reduced by the gastro-intestinal distension which results from the ad libitum provision offoods with a high water-holding-capacity (WHO. Therefore, the aim of this experiment was to test the hypothesis that feeding motivation is inversely proportional to the WHC of meals which supply the same level of nutrients. Eight male pigs (initial body weight 54·0 (s.d. 5·76) kg) were offered a series of four foods which possessed increasing WHC due to a linearly increasing inclusion of dried citrus-pulp (2·18, 3·52, 5·60 and 6·92 g water per g dry food for LB, MLB, MHB and HB), but all with similar ratios of digestible energy (DE) to crude protein and minerals. The experimental treatments were allocated in two 4X4 Latin squares with blocks of 6 days separated by a 4-day change-over period. On each day the pigs were given food twice (09.00 h and 16.00 h) to provide the same level of scaled DE across the meals of each treatment. The resulting level offeeding motivation was measured in two successive tests at 30-min intervals before, and eight successive tests at 30-min intervals after, the ingestion of the first meal using a second-order operant conditioning schedule; a methodology which requires pigs to press a paddle to obtain a feeding-related stimuli (CS). It was found that the number ofCS earned pre-feeding was not affected by treatment (17·2, 17·2, 17·6 and 17·5 (s.e.d. 1·58) CS per test for LB, MLB, MHB and HB; P > 0·05), whereas, the number of CS earned post feeding was significantly affected by treatment (16·6, 15·5, 14·6 and 13·8 (s.e.d. 1·15) CS per test for LB, MLB, MHB and HB; P < 0·001). Within each treatment, the number ofCS earned did not alter significantly across any of the time-periods post feeding. As the number of CS earned has been shown to be a reliable indicator of feeding motivation, the results from this experiment support the hypothesis that feeding motivation is inversely proportional to the WHC of iso-energetic meals.

Genetic variation is vital for the populations to adapt to varying environments and to respond to artificial selection; therefore, any conservation and development scheme should start from assessing the state of variation in the population. There are several marker-based and pedigree-based parameters to describe genetic variation. The most suitable ones are rate of inbreeding and effective population size, because they are not dependent on the amount of pedigree records. The acceptable level for effective population size can be considered from different angles leading to a conclusion that it should be at least 50 to 100. The estimates for the effective population size can be computed from the genealogical records or from demographic and marker information when pedigree data are not available. Marker information could also be used for paternity analysis and for estimation of coancestries. The sufficient accuracy in marker-based parameters would require typing thousands of markers. Across breeds, diversity is an important source of variation to rescue problematic populations and to introgress new variants. Consideration of adaptive variation brings new aspects to the estimation of the variation between populations.

The effects of soluble fiber inclusion in gestation diets with varying fermentation characteristics (fermentation kinetics and short-chain fatty acids (SCFA)-profile) on lactational feed intake of sows and their piglet growth over two parities were investigated using an in vitro–in vivo methodology. After breeding, 90 multiparous Landrace sows were randomized to one of three experimental diets: the control (CON) diet, konjac flour (KF) diet or sugar beet pulp (SBP) diet. All diets had similar levels of net energy, CP, insoluble fiber and NDF, but KF and SBP diets had higher soluble fiber levels than the CON diet. During gestation, the sows were restrictively fed with three different diets, but during lactation, all the sows were similarly fed ad libitum. The three gestation diets were enzymatically hydrolyzed using pepsin and pancreatin, and enzymolyzed residues were used in in vitro fermentation. Gas and SCFA production were monitored during fermentation. After fermentation, enzymolyzed residues of KF or SBP diets resulted in higher final asymptotic gas volume than those of the CON diet. The enzymolyzed residues of KF diet were mainly part of rapidly fermented fractions, whereas those of SBP diet were mainly part of slowly fermented fractions. In addition, the acetic acid, butyric acid and total SCFA concentrations of enzymolyzed residues of KF diet were higher (P<0.01) than the control and SBP diets. In the in vivo studies, on day 90 of gestation, the KF diet sows had higher plasma SCFA concentration (P<0.05) at 4 h after feeding than the CON diet sows. Furthermore, the KF diet sows had lower plasma free fatty acid (FFA) concentration (P<0.01) at 4 h after feeding, and a lower value of homeostasis model assessment (HOMA)-insulin resistance (P<0.05), but a higher value of HOMA-insulin sensitivity (P<0.01). The KF diet sows also consumed more feed during lactation (P<0.01) and weaned significantly heavier pigs (P<0.01) than the CON diet sows. The overall results showed that the high fermentation capacity KF diet contributed to an increased lactational feed intake and improved performance of piglets in the second reproductive cycle.

Failure to recycle after weaning and the interval from weaning to oestrus were studied using sows representing 28 crosses from eight breeds at three stations. Of the sows farrowing their first litter, 12·9% failed to recycle within 50 days. The least squares mean for weaning to oestrus interval for all crosses was 13·5 days. Hampshire × Landrace, followed by Hampshire × Yorkshire sows had the shortest intervals (8·0 and 8·7 days respectively) whereas Large Black × Lacombe sows had the longest interval (22·1 days). Crosses involving the Yorkshire, Hampshire, Berkshire and Tamworth breeds had shorter intervals than those involving Landrace, Duroc, Large Black and Lacombe. Season of farrowing had significant effect (P < 0·05), with the shortest interval (11·4 days) occurring in autumn and the longest (15·1 days) in spring and summer. Weaning to oestrus interval increased with the increase in litter size. The interval was longer (15·7 days) at Lennoxville but similar at the other stations. There was a steady increase in size in the following litter with the increase in the weaning-oestrus interval. The heritability estimate (full-sib analysis) for the weaning-oestrus interval was 0·25 ± 0·10. Repeatability based on limited data was calculated at 0·28.

The effective degradability (Dg) of dry matter (DM), nitrogen (N) and amino acids (AA) in soya-bean meal (SBM), fish meal (FM), dried brewers' grains (DBG) and ensiled lucerne (EL) was measured using polyester bags suspended in the rumens of six cows given a basal diet of maize silage, hay and concentrate. Rumen outflow rate was measured using chromium-mordanted SBM.

AA were grouped into essential (EAA), non-essential (NEAA) or branched chain (BrAA). The AA concentration in DM varied from 88 g/kg DM for EL to 566 g/kg for FM. The proportion of determined AA in crude protein (CP) was similar for SBM, FM and DBG and always higher than 0·85. EL had the lowest A A concentration in CP, partly due to the presence of ammonia N (170 g/kg total N).

Methionine always had a higher, and threonine a lower Dg than total AA in all foods. Dg of other AA was generally food dependent.

SBM always had the highest EAA, BrAA, NEAA, mean AA and total N degradability, whilst FM always had the lowest Dg for EAA, BrAA, mean AA and total N, and these values were significantly different in comparison with SBM. The effective Dg of BrAA in DBG was significantly lower than in SBM and significantly higher than in FM. In EL, NEAA and mean AA Dg were significantly lower compared with SBM.

Effective Dg of total AA in SBM and EL was significantly lower than the CP Dg; this difference was not apparent in DBG or FM.

The undegraded fraction of FM and EL had a significantly higher proportion of EAA whilst DBG and EL had a higher proportion of BrAA when compared with the unexposed food. Isoleucine concentration, highest in EL, and lysine and methionine contents, highest in FM, differed significantly between the four protein source residues.

The first limiting AA after rumen incubation, in relation to casein and meat, was always methionine. The essential amino acid index of the food residues post incubation, relative to casein and meat, was lower in SBM, DBG and EL but higher in FM.

Interrelationships between carcass measurements were studied in 83 purebred Clun Forest lambs slaughtered at approximately 80 lb. live-weight and ranging in carcass weight from 29 to 42 lb. Individual carcass measurements did not have a worthwhile predictive value; apart from loin (C) and rib (J) fat depths none of 12 external or internal carcass measurements showed a correlation with carcass composition greater than r = 0·70. Similarly, none of 9 offal measurements recorded had a worthwhile predictive value. In multiple regression certain combinations of these measurements accounted for as much as 77% of the variation in carcass fat, 64% in carcass muscle and 64 % in carcass bone.

The predictive efficiency of sample joint composition, specific gravity determinations and carcass measurements were evaluated in terms of the increased error variance using predicted values and the effect of this increase on sample size in treatment comparisons. Generally the results indicated that increasing treatment group size by relatively few animals is sufficient to absorb the additional error variance arising from the use of predicted values. This is particularly true where treatment differences of the order of one standard deviation exist and where part-carcass dissection values are used.

Genetic relationships among leg and performance traits were estimated for 23 975 Large White and Landrace boars fed twice daily to appetite from 27 to 91 kg live weight at Meat and Livestock Commission testing stations between 1966 and 1972. For each boar, an overall leg score was derived as the sum of scores for 19 individual leg traits categorized as ‘absent’ (0), ‘slight’ (1) or ‘severe’ (2) at 91 kg. Heritabilities of leg score were 017 ± 0·03 in Large White and 0·19 ± 0·04 in Landrace. Genetic correlations with a visual ‘leg action’ score on a scale from 1 to 5 averaged 0·93 ± 0·02 over breeds. Genetic and phenotypic correlations between leg scores on the same boars at 27 and 91 kg averaged 0·50 ± 0·17 and 0·15 ± 0·01 respectively.

Both breeds showed significant adverse genetic correlations ranging from 0·20 ± 0·10 to 0·40 ± 0·08 between leg score and boar ultrasonic backfat. From slaughtered littermates, leg scores showed favourable genetic correlations with eye-muscle area (0·30 ± 0·10) and killing-out proportion (0·35 ± 011) in Large White and unfavourable correlations with carcass length (0·31 ± 0·10), lean content (0·30 ± 0·14) and backfat (0·33 ± 0·11) in Landrace. There were no associations with growth rate, feed efficiency or the performance index on which boars are selected. The study indicates that leg condition and fatness are adversely genetically related, but that selection on the present national performance index would not be expected to cause a rapid decline in leg condition. Culling on leg score would be expected to reduce the frequency of leg weakness.

Recent genomic evaluation studies using real data and predicting genetic gain by modeling breeding programs have reported moderate expected benefits from the replacement of classic selection schemes by genomic selection (GS) in small ruminants. The objectives of this study were to compare the cost, monetary genetic gain and economic efficiency of classic selection and GS schemes in the meat sheep industry. Deterministic methods were used to model selection based on multi-trait indices from a sheep meat breeding program. Decisional variables related to male selection candidates and progeny testing were optimized to maximize the annual monetary genetic gain (AMGG), that is, a weighted sum of meat and maternal traits annual genetic gains. For GS, a reference population of 2000 individuals was assumed and genomic information was available for evaluation of male candidates only. In the classic selection scheme, males breeding values were estimated from own and offspring phenotypes. In GS, different scenarios were considered, differing by the information used to select males (genomic only, genomic+own performance, genomic+offspring phenotypes). The results showed that all GS scenarios were associated with higher total variable costs than classic selection (if the cost of genotyping was 123 euros/animal). In terms of AMGG and economic returns, GS scenarios were found to be superior to classic selection only if genomic information was combined with their own meat phenotypes (GS-Pheno) or with their progeny test information. The predicted economic efficiency, defined as returns (proportional to number of expressions of AMGG in the nucleus and commercial flocks) minus total variable costs, showed that the best GS scenario (GS-Pheno) was up to 15% more efficient than classic selection. For all selection scenarios, optimization increased the overall AMGG, returns and economic efficiency. As a conclusion, our study shows that some forms of GS strategies are more advantageous than classic selection, provided that GS is already initiated (i.e. the initial reference population is available). Optimizing decisional variables of the classic selection scheme could be of greater benefit than including genomic information in optimized designs.

The present study aimed to identify the factors that affect immediate (within 24 h after farrowing onset) postnatal piglet mortality in litters with hyperprolific sows, and investigate their associations with behaviour of postpartum sows in two different farrowing housing systems. A total of 30 sows were housed in: (1) CRATE (n=15): the farrowing crate closed (0.80×2.20 m) within a pen (2.50×1.70 m), and (2) OPEN (n=15): the farrowing crate open (0.80×2.20×1.80 m) within a pen (2.50×2.40 m) with a provision of 20 ls of hay in a rack. A total of 518 live born piglets, produced from the 30 sows, were used for data analyses during the first 24 h after the onset of parturition (T24). Behavioural observations of the sows were assessed via video analyses during T24. Total and crushed piglet mortality rates were higher in OPEN compared with CRATE (P<0.01, for both). During T24, the OPEN sows tended to show higher frequency of postural changes (P=0.07) and duration of standing (P=0.10), and showed higher frequencies of bar-biting (P<0.05) and piglet trapping (P<0.01), when compared with the CRATE sows. During T24, the mortality rates caused by crushing were correlated with the piglet trapping event (r=0.93, P<0.0001), postural changes (r=0.37, P<0.01), duration of standing (r=0.32, P<0.01) and frequency of bar-biting behaviour (r=0.51, P<0.01) of the sows (n=30). In conclusion, immediate postnatal piglet mortality, mainly due to crushing, may be associated with potential increases in frequency of postural changes, duration of standing and incidence of piglet trapping in postpartum sows in the open crate system with large litters.