Residual feed intake (RFI), defined as the difference between observed and expected feed intake based on growth and backfat, has been used to investigate genetic variation in feed efficiency in cattle, poultry and pigs. However, little is known about the biological basis of differences in RFI in pigs. To this end, the objective of this study was to evaluate the fifth generation of a line of pigs selected for reduced RFI against a randomly selected Control line for performance, carcass and chemical carcass composition and overall efficiency. Here, emphasis was on the early grower phase. A total of 100 barrows, 50 from each line, were paired by age and weight (22.6 ± 3.9 kg) and randomly assigned to one of four feeding treatments in 11 replicates: ad libitum (Ad), 75% of Ad (Ad75), 55% of Ad (Ad55) and weight stasis (WS), which involved weekly adjustments in intake to keep body weight (BW) constant for each pig. Pigs were individually penned (group housing was used for selection) and were on treatment for 6 weeks. Initial BW did not significantly differ between the lines (P > 0.17). Under Ad feeding, the low RFI pigs consumed 8% less feed compared with Control line pigs (P < 0.06), had less carcass fat (P < 0.05), but with no significant difference in growth rate (P > 0.85). Under restricted feeding, low RFI pigs under the Ad75 treatment had a greater rate of gain while consuming the same amount of feed as Control pigs. Despite the greater gain, no significant line differences in carcass composition or carcass traits were observed. For the WS treatment, low RFI pigs had similar BW (P > 0.37) with no significant difference in feed consumption (P > 0.32). Overall, selection for reduced RFI has decreased feed intake, with limited differences in growth rate but reduced carcass fat, as seen under Ad feeding. Collectively, results indicate that the effects of selection for low RFI are evident during the early grower stage, which allows for greater savings to the producer.

This study investigated the effects of disodium fumarate (DF) on methane emission, ruminal fermentation and microbial abundance in goats under different forage (F) : concentrate (C) ratios and fed according to maintenance requirements. Four ruminally fistulated, castrated male goats were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments and the main factors being the F : C ratios (41 : 59 or 58 : 42) and DF supplementation (0 or 10 g/day). DF reduced methane production (P < 0.05) on average by 11.9%, irrespective of the F : C ratio. The concentrations of total volatile fatty acids, acetate and propionate were greater in the rumen of goats supplemented with DF (P < 0.05), whereas the abundance of methanogens was lower (P < 0.05). In high-forage diets, the abundance of Selenomonas ruminantium, a fumarate-reducing bacterium, was greater in the rumen of goats supplemented with DF. The abundance of fungi, protozoa, Ruminococus flavefaciens and Fibrobacter succinogenes were not affected by the addition of DF. Variable F : C ratios affected the abundance of methanogens, fungi and R. flavefaciens (P < 0.05), but did not affect methane emission. The result implied that DF had a beneficial effect on the in vivo rumen fermentation of the goats fed diets with different F : C ratios and that this effect were not a direct action on anaerobic fungi, protozoa and fibrolytic bacteria, the generally recognized fiber-degrading and hydrogen-producing microorganisms, but due to the stimulation of fumarate-reducing bacteria and the depression of methanogens.

The objective of this study was to investigate relationships between ovulation rate (OR) and embryonic and placental development in sows. Topigs Norsvin® sows (n=91, parity 2 to 17) from three different genetic backgrounds were slaughtered at 35 days of pregnancy and the reproductive tract was collected. The corpora lutea (CL) were counted and the number of vital and non-vital embryos, embryonic spacing (distance between two embryos), implantation length, placental length, placental weight and embryonic weight were assessed. The difference between number of CL and total number of embryos was considered as early embryonic mortality. The number of non-vital embryos was considered as late mortality. Relationships between OR and all other variables were investigated using two models: the first considered parity as class effect (n=91) and the second used a subset of sows with parities 4 to 10 (n=47) to analyse the genetic background as class effect. OR was significantly affected by parity (P<0.0001), but was not affected by the genetic background of the sows. Parity and genetic background did not affect embryonic and placental characteristics at 35 days of pregnancy. OR (varying from 17 to 38 CL) was positively related with early embryonic mortality (β=0.49±0.1 n/ovulations, P<0.0001), with late embryonic mortality or number of non-vital embryos (β=0.24±0.1 n/ovulations, P=0.001) and with the number of vital embryos (β=0.26±0.1 n/ovulations, P=0.01). However, dividing OR in four classes, showed that the number of vital embryos was lowest in OR class 1 (17 to 21 CL), but not different for the other OR classes, suggesting a plateau for number of vital embryos for OR above 22. There was a negative linear relationship between OR and vital embryonic spacing (β=−0.45±0.1 cm/ovulation, P=0.001), implantation length (β=−0.35±0.1 cm/ovulation, P=0.003), placental length (β=−0.38±0.2 cm/ovulation, P=0.05) and empty space around embryonic-placental unit (β=−0.4±0.2 cm/ovulation, P=0.02), indicating uterine crowding. Further analyses showed that effects of OR on embryonic and uterine parameters were related with the increase in late mortality and not early embryonic mortality. Therefore, we conclude that a high OR results in an moderate increase in the number of vital embryos at day 35 of pregnancy, but compromises development in the surviving embryonic/placental units, suggesting that the future growth and survival of the embryos might be further compromised.

Forty-two New-Zealand x Californian young female rabbits of 4·5 months of age were used to evaluate the use o f a computerized ultrasound system in estimating changes in body condition. In order to get a wide range of fatness, animals were randomly subjected to four food restriction regimes for 2 weeks. Female rabbits were scanned at six different back sites to estimate perirenal fat thickness, using a real-time ultrasound unit equipped with a 5·0-MHz sector probe. After scanning, all animals were weighed and slaughtered. The weights of hot carcass, cold carcass, perirenal fat, scapular fat, liver and kidneys were recorded. There was a large variation in the weight of the main fat deposits, especially for the perirenal fat (CV = 0·632), indicating its suitability for estimating changes in body condition. Ultrasound measurements of perirenal fat thickness correlated strongly with all carcass fat weight values (r = 0·692 to 0·959; P < 0·001) and the estimated carcass energy content (r = 0·777 to 0·866; P < 0·001) and seem to be more precise predictors than live weight measurements. Multiple regression equations for estimating the main fat deposit weight and estimated carcass energy content using only the live weight as an independent variable had R2 values ranging from 0·47 to 0·59. The accuracy of estimates was improved when ultrasound measurements were used in the regression model (R2 values ranging from 0·81 to 0·95). Ultrasound measurement of mean perirenal fat deposit thickness at 3 cm ahead of the 2nd to 3rd lumbar vertebrae was the best predictor for perirenal fat weight (R2 = 0·95; P < 0·001), total fat weight (R2 = 0·93; P < 0·001) and estimated carcass energy content (R2 = 0·90; P < 0·001). A validation group of 11 rabbit does was used to validate the ultrasound regression equations, showing that their mean accuracy was approximately 0·895 and 0·967 for total fat weight and estimated carcass energy content, respectively. Results suggest that ultrasound measurements of perirenal fat thickness may be an accurate method for studying changes in body condition of young female rabbits at different times.

Female pigs of the Pietrain and Large White breeds, 18 from each, selected to form a logarithmic weight range, were dissected into their major carcass tissues. Relative to carcass growth, fat was the fastest developing tissue in both breeds; fat and muscle grew at a rate higher, and bone at a rate lower, than the carcass. The growth of bone relative to carcass growth was faster in the Large White; differences between breeds in the growth of muscle and fat were not significant. Muscle weights and muscle: bone ratios, estimated at the same empty body weight, were greater for the Pietrain over the entire body weight range studied. There was no significant difference in muscle: bone ratio between the Large Whites used in the present study and those dissected by McMeekan over 30 years previously. The breed difference in the proportion of muscle and bone at the same body weight is attributed to a greater maturity of the Pietrain.

Two in vitro and one in vivo experiments were conducted to investigate the effects of a selection of plant compounds on rumen fermentation, microbial concentration and methane emissions in goats. Treatments were: control (no additive), carvacrol (CAR), cinnamaldehyde (CIN), eugenol (EUG), propyl propane thiosulfinate (PTS), propyl propane thiosulfonate (PTSO), diallyl disulfide (DDS), a mixture (40 : 60) of PTS and PTSO (PTS+PTSO), and bromochloromethane (BCM) as positive control with proven antimethanogenic effectiveness. Four doses (40, 80, 160 and 320 µl/l) of the different compounds were incubated in vitro for 24 h in diluted rumen fluid from goats using two diets differing in starch and protein source within the concentrate (Experiment 1).The total gas production was linearly decreased (P<0.012) by all compounds, with the exception of EUG and PTS+PTSO (P⩾0.366). Total volatile fatty-acid (VFA) concentration decreased (P⩽0.018) only with PTS, PTSO and CAR, whereas the acetate:propionate ratio decreased (P⩽0.002) with PTS, PTSO and BCM, and a tendency (P=0.064) was observed for DDS. On the basis of results from Experiment 1, two doses of PTS, CAR, CIN, BCM (160 and 320 µl/l), PTSO (40 and 160 µl/l) and DDS (80 and 320 µl/l) were further tested in vitro for 72 h (Experiment 2). The gas production kinetics were affected (P⩽0.045) by all compounds, and digested NDF (DNDF) after 72 h of incubation was only linearly decreased (P⩽0.004) by CAR and PTS. The addition of all compounds linearly decreased (P⩽0.009) methane production, although the greatest reductions were observed for PTS (up to 96%), DDS (62%) and BCM (95%). No diet–dose interaction was observed. To further test the results obtained in vitro, two groups of 16 adult non-pregnant goats were used to study in vivo the effect of adding PTS (50, 100 and 200 mg/l rumen content per day) and BCM (50, 100 and 160 mg/l rumen content per day) during the 9 days on methane emissions (Experiment 3). The addition of PTS and BCM resulted in linear reductions (33% and 64%, respectively, P⩽0.002) of methane production per unit of dry matter intake, which were lower than the maximum inhibition observed in vitro (87% and 96%, respectively). We conclude that applying the same doses in vivo as in vitro resulted in a proportional lower extent of methane decrease, and that PTS at 200 mg/l rumen content per day has the potential to reduce methane emissions in goats. Whether the reduction in methane emission observed in vivo persists over longer periods of treatments and improves feed conversion efficiency requires further research.

The increased demand for animal-derived protein and energy for human consumption will have to be achieved through a combination of improved animal genetic merit and better management strategies. The objective of the present study was to quantify whether differences in genetic merit among animals materialised into phenotypic differences in commercial herds. Carcass phenotypes on 156 864 animals from 7301 finishing herds were used, which included carcass weight (kg), carcass conformation score (scale 1 to 15), carcass fat score (scale 1 to 15) at slaughter as well as carcass price. The price per kilogram and the total carcass value that the producer received for the animal at slaughter was also used. A terminal index, calculated in the national genetic evaluations, was obtained for each animal. The index was based on pedigree index for calving performance, feed intake and carcass traits from the national genetic evaluations. Animals were categorised into four terminal index groups on the basis of genetic merit estimates that were derived before the expression of the phenotypic information by the validation animals. The association between terminal index and phenotypic performance at slaughter was undertaken using mixed models; whether the association differed by gender (i.e. young bulls, steers and heifers) or by early life experiences (animals born in a dairy herd or beef herd) was also investigated. The regression coefficient of phenotypic carcass weight, carcass conformation and carcass fat on their respective estimated breeding values (EBVs) was 0.92 kg, 1.08 units and 0.79 units, respectively, which is close to the expectation of one. Relative to animals in the lowest genetic merit group, animals in the highest genetic merit group had, on average, a 38.7 kg heavier carcass, with 2.21 units greater carcass conformation, and 0.82 units less fat. The superior genetic merit animals were, on average, slaughtered 6 days younger than their inferior genetic merit contemporaries. The superior carcass characteristics of the genetically elite animals materialised in carcasses worth €187 more than those of the lowest genetic merit animals. Although the phenotypic difference in carcass traits of animals divergent in terminal index differed statistically by animal gender and early life experience, the detected interactions were generally biologically small. This study clearly indicates that selection on an appropriate terminal index will produce higher performing animals and this was consistent across all production systems investigated.

Competition for oat grain between sheep grazing on scant, poor quality pasture was studied in three flocks of sheep. A daily feed of 450 g per head was fed in troughs with the space per sheep varying from 4 to > 50 cm. Records were taken of sheep behaviour during the first 3 min of feeding.

There was no fighting in the competition for feed, but dominance of individuals and of groups of sheep occurred. With abundant trough space, certain sheep led the way to the feed trough and were termed leaders, but ‘leadership’ was a characteristic unrelated to competitiveness during feeding. With restricted trough space most sheep raced to the feed trough at feeding time. The rate of disturbance of the sheep from the feed trough increased with decreased space per sheep, particularly below 12 cm/sheep. As the rate of disturbance increased a progressively greater proportion of sheep stopped competing for feed and became non-feeders. Neither the rate of disturbance of the sheep nor the proportion not feeding was related to body weight, but these were largely individual characteristics of sheep.

In a flock of mixed age Merino wethers, the 1-year-old and 7-yearold sheep were the least competitive, while in a flock of wether sheep of seven different breeds but of similar age, Merinos were least competitive.

From these experiments it is suggested that a minimum trough space of 16 cm be allowed when daily grain supplements are fed to grazing sheep.

Male piglets are castrated to reduce boar taint and also to reduce aggressive and sexual behaviour. However, the procedure as traditionally performed is painful and negatively affects performance. Large-scale results about the consequences of implementing alternatives on farms are lacking. We, therefore, investigated the practical applicability of the following five alternatives that can be implemented in the short term: surgical castration (1) without pain relief (CONT, control group), (2) with analgesia (MET, Metacam, 0.2 ml, 10 to 15 min before castration), (3) with general anaesthesia (CO2, inhalation, 100% CO2, 25 s, 3 l/min), (4) vaccination against boar taint (IM, two injections with Improvac) and (5) production of entire males (EM). The study consisted of the following two trials: (1) an experimental farm trial with 18 animals/treatment and (2) a large field trial on 20 farms with ~120 male pigs/farm per treatment and all treatments performed on each farm. Performance results as well as data on carcass traits, boar taint (hot-iron method) and testes development and weight were collected in both trials. Neither castration nor administration of analgesia or anaesthesia had an effect on daily gain of the piglets in the farrowing crates (P>0.05). Farmer records indicated that mortality in the farrowing crates (1.1%), nursery pens (1.8%) and fattening stable (2.2%) was not influenced by MET or CO2 compared with EM, IM or CONT (P>0.05). No significant differences were found for daily gain (P>0.05) nor slaughter age (P>0.05). Immunocastrates and EM had a better gain-to-feed ratio (P<0.05) compared with the groups of barrows (CONT, MET and CO2). Lean meat percentage was higher for EM compared with the barrows, and intermediate for IM (P<0.05). Carcass yield was lowest for IM (P<0.05). The hot-iron method indicated that boar taint was eliminated in barrows and IM compared with EM (P<0.001). Average prevalence of strong boar taint was 3% for EM, but varied from 0% to 14% between farms. As the effect of treatment on performance as well as the level of boar taint of EM was farm dependent, farmers should be encouraged to pre-test the different alternatives in order to make a well-considered choice for the best practical and profitable alternative for their farm.

Validation of economic indexes under a controlled experimental environment, can aid in their acceptance and use as breeding tools to increase herd profitability. The objective of this study was to compare intake, growth and carcass traits in bull and steer progeny of high and low ranking sires, for genetic merit in an economic index. The Beef Carcass Index (BCI; expressed in euro (€) and based on weaning weight, feed intake, carcass weight, carcass conformation and fat scores) was generated by the Irish Cattle Breeding Federation as a tool to compare animals on genetic merit for the expected profitability of their progeny at slaughter. A total of 107 male suckler herd progeny, from 22 late-maturing ‘continental’ beef sires of high (n = 11) or low (n = 11) BCI were compared under either a bull or steer production system, and slaughtered at approximately 16 and 24 months of age, respectively. All progeny were purchased after weaning at approximately 6 to 8 months of age. Dry matter (DM) intake and live-weight gain in steer progeny offered grazed grass or grass silage alone, did not differ between the two genetic groups. Similarly, DM intake and feed efficiency did not differ between genetic groups during an ad libitum concentrate-finishing period on either production system. Carcasses of progeny of high BCI sires were 14 kg heavier (P < 0.05) than those of low BCI sires. In a series of regression analyses, increasing sire BCI resulted in increases in carcass weight (P < 0.01) and carcass conformation (P = 0.051) scores, and decreases in carcass fat (P < 0.001) scores, but had no effect on weaning weight or DM intake of the progeny. Each unit increase in sire expected progeny difference led to an increase in progeny weaning weight, DM intake, carcass weight, carcass conformation score and carcass fat score of 1.0 (s.e. = 0.53) kg, 1.1 (s.e. = 0.32) kg, 1.3 (s.e. = 0.31) kg, 0.9 (s.e. = 0.32; scale 1 to 15) and 1.0 (s.e. = 0.25; scale 1 to 15), respectively, none of which differed from the theoretical expectation of unity. The expected difference in profitability at slaughter between progeny of the high and low BCI sires was €42, whereas the observed phenotypic profit differential of the progeny was €53 in favour of the high BCI sires. Results from this study indicate that the BCI is a useful tool in the selection of genetically superior sires, and that actual progeny performance under the conditions of this study is within expectations for both bull and steer beef production systems.

On-farm hatching systems for broiler chicks are increasingly used in practice. We studied whether or not performance, health and welfare aspects differed between commercial flocks hatched on-farm or in a hatchery (control). In two successive production cycles on seven farms, a total of 16 on-farm hatched flocks were paired to 16 control flocks, housed at the same farm. Paired flocks originated from the same batch of eggs and were subjected to similar on-farm management. On-farm hatched and control flocks only differed with respect to hatching conditions, with on-farm hatched flocks not being exposed to, for example, chick handling, post-hatch feed and water deprivation and transport, in contrast to control flocks that were subjected to standard hatchery procedures, subsequently transported and placed in the poultry house. Day-old chick quality (navel and hock scores), 1st week mortality, total mortality, BW at day (d) 0, d7 and at depopulation, and (total) feed conversion ratio were determined. Prevalence of footpad dermatitis, hock burn, breast discoloration/blisters and cleanliness, litter quality and gait score were determined at d21 of age and around depopulation (d39 on average). Gross pathology and gut morphology were examined at depopulation age in a sample of birds of five flocks per treatment. On-farm hatching resulted in a higher BW at d0 (Δ=5.4 g) and d7 (Δ=11.5 g) (P<0.001), but day-old chick quality as measured by navel (P=0.003) and hock (P=0.01) quality was worse for on-farm hatched compared to control birds. Body weight, 1st week and total mortality, and feed conversion ratio at slaughter age were similar for both on-farm hatched and control flocks. On-farm hatched flocks had less footpad dermatitis (P=0.05), which indicated a better welfare. This was likely related to a tendency for better litter quality in on-farm hatched flocks at 21 days of age in comparison to control flocks (P=0.08). No major differences in gross pathology or in intestinal morphology at depopulation age were found between treatments. In conclusion, on-farm hatching resulted in better 1st week broiler performance and better welfare compared to conventional hatching in a hatchery.

The effects of two concentrations of disodium malate on the in vitro fermentation of three substrates differing in their forage: concentrate ratio (0·8: 0·2, 0·5: 0·5 and 0·2: 0·8; g/g dry matter; low-, medium- and high-concentrate substrates, respectively) by rumen micro-organisms were studied using batch cultures. Rumen contents were collected from four Merino sheep offered lucerne hay ad libitum and supplemented daily with 400 g concentrate. Disodium malate was added to the incubation bottles to achieve final concentrations of 0, 4 and 8 mmol/l malate and 15N was used as a microbial marker. Gas production was measured at regular intervals from 0 to 120 h of incubation to study fermentation kinetics. When gas production values were corrected for gas released from added malate, no effects (P > 0·05) of malate were detected for any of the estimated gas production parameters. In 17-h incubations, the final pH and total volatile fatty acid (VFA) production were increased (P < 0·001) by the addition of malate, but no changes (P > 0·05) were detected in the final amounts of ammonia-N and lactate. When net VFA productions were corrected for the amount of VFA produced from malate fermentation itself, adding malate did not affect (P > 0·05) the production of acetate, propionate and total VFA. Malate reduced methane (CH4) production by proportionately 0·058, 0·013 and 0·054 for the low-, medium- and high-concentrate substrates, respectively. Adding malate to batch cultures increased (P < 0·01) rumen microbial growth (mean values of 16·6, 18·3 and 18·4 mg of microbial N for malate at 0, 4 and 8 mmol/l, respectively), but did not affect (P > 0·05) its efficiency of growth (55·5, 56·7 and 54·3 mg of microbial N per g of organic matter apparently fermented for malate at 0, 4 and 8 mmol/l, respectively). There were no interactions (P > 0·05) malate × substrate for any of the measured variables, and no differences (P > 0·05) in pH, CH4 production and microbial growth were found between malate at 4 and 8 mmol/l. The results indicate that malate had a beneficial effect on in vitro rumen fermentation of substrates by increasing VFA production and microbial growth, and that only subtle differences in the effects of malate were observed between substrates. Most of the observed effects, however, seem to be due to fermentation of malate itself.

Eighty-two Merino sheep from birth to 517 days old were dissected into individual muscles. A system of overlapping growth coefficients was used to classify the growth patterns of 96 muscles and nine muscle groups. The relative size of muscles and groups at birth and one year are expressed as percentages of total half-carcass muscle weight.

Some differences were noted from the previously recorded growth patterns of bovine muscles. The groups of muscles in the proximal part of the pelvic limb and those surrounding the spinal column were relatively faster-growing in sheep than in cattle.

The patterns of the muscle groups are discussed relative to their function and it is shown that the patterns of growth of muscles within some groups are markedly different from the pattern of the whole group. This is most apparent in those groups with complex functions, and it is clear that anatomical grouping of muscles and functional grouping of muscles will be similar only in those regions of the body with relatively simple actions.

(-)-Epigallocatechin-3-gallate (EGCG), the major phenolic compound of green tea, and hydroxytyrosol (HTyr), a phenol found in olive oil, have received attention due to their wide-ranging health benefits. To date, there are no studies that report their effect in bovine mammary gland. Therefore, the aim of this study was to evaluate the anti-oxidative and anti-inflammatory effects of EGCG and HTyr in bovine mammary epithelial cell line (BME-UV1) and to compare their antioxidant and anti-inflammatory in vitro efficacy. Sample of EGCG was obtained from a commercially available green tea extract while pure HTyr was synthetized in our laboratories. The mammary oxidative stress and inflammatory responses were assessed by measuring the oxidative stress biomarkers and the gene expression of inflammatory cytokines. To evaluate the cellular antioxidant response, glutathione (GSH/GSSH), γ-glutamylcysteine ligase activity, reactive oxygen species and malondialdehyde (MDA) production were measured after 48-h incubation of 50 µM EGCG or 50 µM of HTyr. Reactive oxygen species production after 3 h of hydrogen peroxide (50 µM H2O2) or lipopolysaccharide (20 µM LPS) exposure was quantified to evaluate and to compare the potential protection of EGCG and HTyr against H2O2-induced oxidative stress and LPS-induced inflammation. The anti-inflammatory activity of EGCG and HTyr was investigated by the evaluation of pro and anti-inflammatory interleukins (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10) messenger RNA abundance after treatment of cells for 3 h with 20 µM of LPS. Data were analyzed by one-way ANOVA. (-)-Epigallocatechin-3-gallate or HTyr treatments induced higher concentrations of intracellular GSH compared to control cells, matched by an increase of γ-glutamylcysteine ligase activity mainly in cells treated with HTyr. Interestingly, EGCG and HTyr prevented oxidative lipid damage in the BME-UV1 cells by a reduction of intracellular MDA levels. (-)-Epigallocatechin-3-gallate and HTyr were able to enhance cell resistance against H2O2-induced oxidative stress. It was found that EGCG and HTyr elicited a reduction of the three inflammatory cytokines TNF-α, IL-1β, IL-6 and an increase of the anti-inflammatory cytokine IL-10. Hydroxytyrosol has proved to be a strong antioxidant compound, and EGCG has shown mainly an anti-inflammatory profile. These results indicated that EGCG and HTyr may provide dual protection because they were able to attenuate oxidative stress and inflammatory responses, suggesting that these phenolic compounds are potential natural alternatives to be used in dairy cattle as feed supplement for reducing the development of oxidative and inflammatory processes related to parturition or as topical treatments for the control of bovine intramammary inflammation.

Polynomial models with random regression coefficients were used to describe cumulated food intake and gain as a function of number of days on test for gilts and castrated male pigs which were on test from 30 to 115 kg live weight. Growth rate and daily food intake were expressed as the derivative of the curves. The applied models allowed a separation of between and within animal variation. Confidence limits for average curves and prediction limits for individual curves were also obtained. A similar model was used to describe gain as a function of cumulated food intake. From this function food efficiency was obtained. The application of the results in stochastic simulation models is discussed.

Growth rate and daily food intake had a more curvilinear progress for castrated males than for gilts. It was estimated that 98% of the castrated males and 96% of the gilts had a lower growth rate at day 80 than at day 50; 74% of the castrated males and 48% of the gilts had a lower daily food intake at day 100 than at day 80. On average food efficiency of gilts was higher than food efficiency of castrated males and the difference increased through the test period.

The main aim was to assess the impact of mastitis on technical and economic results of a dairy herd under current Swedish farming conditions. The second aim was to investigate the effects obtained by withdrawing milk with high somatic cell count (SCC). A dynamic and stochastic simulation model, SimHerd, was used to study the effects of mastitis in a herd with 150 cows. Results given the initial incidence of mastitis (32 and 33 clinical and subclinical cases per 100 cow-years, respectively) were studied, together with the consequences of reducing or increasing the incidence of mastitis by 50%, modelling no clinical mastitis (CM) while keeping the incidence of subclinical mastitis (SCM) constant and vice versa. Six different strategies to withdraw milk with high SCC were compared. The decision to withdraw milk was based on herd-level information in three scenarios: withdrawal was initiated when the predicted bulk tank SCC exceeded 220 000, 200 000 or 180 000 cells/ml, and on cow-level information in three scenarios: withdrawal was initiated when the predicted SCC in an individual cow’s milk exceeded 1 000 000, 750 000 or 500 000 cells/ml. The accuracy with which SCC was measured and predicted was assumed to affect the profitability of withdrawing milk with high SCC and this was investigated by applying high, low or no uncertainty to true SCC. The yearly avoidable cost of mastitis was estimated at €8235, assuming that the initial incidence of mastitis could be reduced by 50%. This cost corresponded to 5% of the herd net return given the initial incidence of mastitis. Expressed per cow-year, the avoidable cost of mastitis was €55. The costs per case of CM and SCM were estimated at €278 and €60, respectively. Withdrawing milk with high SCC was never profitable because this generated a substantial amount of milk withdrawal that was not offset by a sufficient increase in the average price per delivered kg milk. It had the most negative impact on net return when high incidence of mastitis was simulated. Withdrawing milk with high SCC based on low-uncertainty information reduced the amount of withdrawn milk and thus resulted in less negative effect on net return. It was concluded that the current milk-pricing system makes it more profitable for farmers to sell a larger amount of milk with higher SCC than to withdraw milk with high SCC to obtain payment premiums, at least in herds with mastitis incidences within the simulated ranges.

Seventy-two British Friesian cows, with a mean calving date of 21 January, were used in a 3 × 2 factorial design experiment to assess the effects of the interval between harvest and wilting on the value of grass silage for milk production. Three regrowth intervals of 5, 7 and 9 weeks were used with each material ensiled both unwilted and after wilting to a dry-matter content of approximately 450g/kg. The six silages were offered ad libitum in addition to 7·6 kg concentrates per day, from day 8 of lactation until 13 April, with a mean experimental period of 67·5 days. The mean intakes of silage dry matter were 11·2, 9·8 and 8·7 kg/day for the 5-, 7 and 9-week regrowth intervals respectively and 9·6 and 10·2kg/day for the unwilted and wilted silages respectively. Regrowth interval significantly affected milk yield with mean yields of 24·7, 24·2 and 22·5 (s.e. 047) kg/day being obtained for the 5-, 7- and 9-week intervals respectively. Wilting significantly depressed milk yield with mean yields of 24·8 and 227 (s.e. 0·39) kg/day being recorded with the unwilted and wilted materials respectively. Live weight at the end of the experiment was not significantly affected by any of the treatments but the rate of live-weight loss, calculated by linear regression over the experiment, and loss in body condition score both significantly increased with increasing regrowth interval. Wilting had no effect on live weight or body condition. Increasing the regrowth interval also significantly reduced the solids-not-fat and protein contents of the milk produced during the final week of the experiment but no other significant effects were recorded on milk composition.

Blood analysis data are presented: blood urea was the only component affected by the treatments and decreased significantly as regrowth interval increased.

Genetic parameters were estimated for early lamb growth and ultrasonic measurements taken on Scottish Blackface lambs reared under extensive conditions on two Scottish hill farms. Measurements were taken on approximately 2000 lambs born to unselected ewes, and sired by 32 rams previously selected for divergent predicted carcass lean content. Heritabilities for birth weight, marking iveight (at approx. 6 weeks of age) and weaning weight (at 17 weeks) were 0·07 (s.e. 0·04), 0·02 (s.e. 0·03), and 0·14 (s.e. 0·05), respectively. Heritabilities for ultrasonic muscle and fat depths at weaning were 0·27 (s.e. 0·09) and 0·16 (s.e. 0·06), respectively. There was a strong maternal effect on weight which declined from birth with lamb age and was relatively unimportant for the ultrasonic measurements. The rearing environment of the lambs (hill pasture v. ‘improved’ (or ‘inbye’) pasture) was an important environmental effect on the heritability estimate for backfat thickness, with that for lambs reared on improved pasture being twice that of hill-reared lambs. The implications of the results from this work on genetic improvement of sheep in liill environments are discussed.

The aim of this study was to assess the effect of weaning weight and post-weaning diet on the performance of weaned pigs. In experiment 1, 30 litters with more than 10 pigs born alive per litter were selected. At 11 days of age, pigs of average weight for the litter were removed from 15 litters so that eight pigs remained per sow. These litters were given access to creep food (16·5 MJ digestible energy (DE) per kg and 18·7 g/kg lysine). The remaining litters were left complete and were not given creep food. Pigs were weaned at 28 days of age and pairs of pigs (a male and a female littermate of similar weight) were formed from each litter (no. = 54 pairs). Pairs were blocked on the basis of litter origin and weight and assigned at random to one of the following treatments: (1) 10 kg starter diet (16·1 MJ DE per kg and 17·4 g/kg lysine) followed by link diet (15·3 MJ DE per kg and 15·0 g/kg lysine) to 27 days (high dietary regimen; HDR); or (2) 4 kg starter diet, 10 kg link diet and weaner diet to 27 days (low dietary regimen; LDR). Thereafter pigs were given common diets to slaughter at about 95·6 kg live weight. On experiment 2, four pigs (two light and two heavy) were taken from each of 32 litters (no. = 128 pigs; age = 22 days), blocked on sex, litter origin, and weaning weight and within weight category individually assigned at random to two dietary treatments: (1) high density diet (16·1 MJ DE per kg and 17·4 g/kg lysine); and (2) low density diet (15·1 MJ DE per kg and 15·7 g/kg lysine). The duration of the experiment was 26 days. In experiment 1, reducing litter size and creep feeding increased weaning weight by 0·6 kg (P 0·05). This weight advantage at weaning was lost by day 14 post weaning (P > 0·05). From day 0 to day 27 post weaning daily gain was 472 and 427 g/day (s.e.12·8; P 0·05) and food conversion efficiency was 1·26 and 1·36 g/g (s.e. 0·026; P 0·05) for HDR and LDR, respectively. In experiment 2, weaning weight was 7·1 and 5·8 kg (s.e. 0·08; P 0·01) and pig weight at day 26 post weaning was 17·5 and 15·4 kg (s.e.0·23; P 0·01) for heavy and light weight categories, respectively. In the period from day 0 to 26, food intake was 440 and 396 g/day (s.e. 8·0; P 0·01) and daily gain was 389 and 355 g/day (s.e. 8·0; P < i 0·01) for heavy and light weight categories, respectively. Weaning weight was found to be a good determinant of weight at day 26 when terms for litter origin were included (R2 = 0·67; P 0·001 for the high density diet and R2 = 0·77; P 0·001 for the low density diet). It is concluded that weaning weight can be increased by pre-weaning management but that this weight advantage is lost in the early post-weaning period. Where weaning weight was naturally higher the weight advantage was still evident at day 26 post weaning.

The ability of live yeasts to modulate pig intestinal cell signals in response to infection with Escherichia coli F4ac (ETEC) has not been studied in-depth. The aim of this trial was to evaluate the effect of Saccharomyces cerevisiae CNCM I-4407 (Sc), supplied at different times, on the transcriptome profile of the jejunal mucosa of pigs 24 h after infection with ETEC. In total, 20 piglets selected to be ETEC-susceptible were weaned at 24 days of age (day 0) and allotted by litter to one of following groups: control (CO), CO+colistin (AB), CO+5×1010 colony-forming unit (CFU) Sc/kg feed, from day 0 (PR) and CO+5×1010 CFU Sc/kg feed from day 7 (CM). On day 7, the pigs were orally challenged with ETEC and were slaughtered 24 h later after blood sampling for haptoglobin (Hp) and C-reactive protein (CRP) determination. The jejunal mucosa was sampled (1) for morphometry; (2) for quantification of proliferation, apoptosis and zonula occludens (ZO-1); (3) to carry out the microarray analysis. A functional analysis was carried out using Gene Set Enrichment Analysis. The normalized enrichment score (NES) was calculated for each gene set, and statistical significance was defined when the False Discovery Rate % was <25 and P-values of NES were <0.05. The blood concentration of CRP and Hp, and the score for ZO-1 integrity on the jejunal villi did not differ between groups. The intestinal crypts were deeper in the AB (P=0.05) and the yeast groups (P<0.05) than in the CO group. Antibiotic treatment increased the number of mitotic cells in intestinal villi as compared with the control group (P<0.05). The PR group tended to increase the mitotic cells in villi and crypts and tended to reduce the cells in apoptosis as compared with the CM group. The transcriptome profiles of the AB and PR groups were similar. In both groups, the gene sets involved in mitosis and in mitochondria development ranked the highest, whereas in the CO group, the gene sets related to cell junction and anion channels were affected. In the CM group, the gene sets linked to the metabolic process, and transcription ranked the highest; a gene set linked with a negative effect on growth was also affected. In conclusion, the constant supplementation in the feed with the strain of yeast tested was effective in counteracting the detrimental effect of ETEC infection in susceptible pigs limits the early activation of the gene sets related to the impairment of the jejunal mucosa.