Three experiments were carried out to determine plasma amino acids concentrations in circulating, portal and hepatic blood of growing male Wistar rats given diets containing lactalbumin, faba beans or chickpeas as the only protein source. Diets contained the same amount of digestible energy (15·5 kJ/g) and protein (lactalbumin in controls or legume proteins in the experimental diets; 100 g/kg). Appropriate amounts of essential synthetic amino acids were also added to legume-based diets taking into account their amino acid composition to equalize them to control (lactalbumin) diets. Portal blood flow (8·7±0·3 ml/min) was measured by using a transit-time ultrasound flow probe. Higher (P < 001) plasma concentrations of methionine than of controls were determined in hepatic veins of legume-fed rats. In contrast, lower (P < 001) concentrations of threonine, proline, valine, leucine, phenylalanine and lysine than those of controls were found in faba bean- and chickpea-fed rats. The same result as hepatic was obtained for portal and circulating plasma samples except that alanine and histidine values of legume-fed rats were also lower (P < 001) than controls. Calculated net afferent appearance rates of amino acids to the liver were lower (P < 001) than controls in rats given faba bean and chickpea diets for threonine, alanine, proline, valine, leucine, phenylalanine and lysine. This lower contribution of amino acids to the liver mainly via the portal vein in faba bean or chickpea-fed rats might explain previously reported differences in protein utilization and growth in comparison with animals given other protein sources (lactalbumin).

Genetic parameters were estimated for wool quality, fleece characteristics and lamb production traits for Scottish Blackface sheep reared under extensive hill conditions in the UK. In two separate studies, heritabilities and genetic correlations were estimated for wool quality traits measured on lambs at 5 months of age and again on the shorn fleece a year later. The wool traits included birth coat length (BCT), 10-point scores for proportion of grey and kemp fibres present in the fleece (grey, kemp), British Wool Marketing Board (BWMB) recommendation (REC), greasy fleece weight (FLWT), BWMB fleece grade (FLGR), and average staple length (ASL). Genetic and phenotypic correlations were estimated between lamb wool traits and lamb live weights at birth (BWT), marking (at mid lactation with an average age of 7 weeks) (MWT), weaning (at an average age of 17 weeks) (WWT) and slaughter (SLWT), average fat depth (AVFD) and average muscle depth (MD). Individual lamb carcass measurements included Meat and Livestock Commission (MLC) conformation score (CONF) and fat class (FATC). Heritability estimates measured on 2524 or more live lambs were 0·69, 0·52, 0·26, 0·42 and 0·31 for BCT, ASL, grey, kemp and REC respectively. Heritability estimates for traits measured on the shorn fleece a year later for 1415 ewes were 0·37, 0·02, 0·57, 0·43, 0·46 and 0·14 for ASL, grey, kemp, REC, FLWT and FLGR respectively. Genetic correlations between FLWT in hoggets and other wool were positive and moderate to high in magnitude, ranging from 0·22 for kemp in lambs to 0·48 for grey in hoggets. Genetic correlations between REC and live-weight traits were 0·39 for MWT, 0·37 for WWT and 0·44 for SLWT. Genetic correlation between ASL and ultrasonic fat depth was 0·15 and for ASL and ultrasonic muscle depth was -0·30. The results indicate that the simple scoring systems derived to assess these traits are useful indicators of fleece quality, are highly repeatable over time and are a good gauge of likely future wool production. The results indicate that selection for heavier, leaner lambs should not compromise fleece quality, as assessed in this study.

Genetic associations were estimated between pathogen-specific cases of clinical mastitis (CM), lactational average somatic cell score (LACSCS), and patterns of peaks in somatic cell count (SCC) which were based on deviations from the typical lactation curve for SCC. The dataset contained test-day records on SCC in 94 781 lactations of 25 416 cows of different parities. Out of these 94 781 lactations, 41 828 lactations had recordings on occurrence of pathogen-specific CM and on SCC, and 52 953 lactations had recordings on SCC only. A total of 5 324 lactations with cases of CM were recorded. Analysed pathogens were Staphylococcus aureus, coagulase negative staphylococci, Escherichia coli, Streptococcus dysgalactiae, Streptococcus uberis, and culture-negative samples. Pattern definitions were based on three or five consecutive test-day recordings of SCC. They differentiated between short or longer periods of increased SCC, and also between lactations with and without recovery. Occurrence of pathogen-specific CM and presence of patterns of peaks in SCC were both scored as binary traits. Variance components for sire, maternal grandsire, and permanent animal effects were estimated using AS-REML. The estimated heritability for overall CM was 0·04, and similar heritabilities for pathogen-specific CM were estimated. Heritabilities for the patterns of peaks in SCC ranged from 0·01 to 0·06. Heritabilities for LACSCS were 0·07 to 0·08. Genetic correlations with patterns of peaks in SCC differed for each pathogen. Generally, genetic correlations between pathogen-specific CM and patterns of peaks in SCC were stronger than the correlations with LACSCS. This suggests that genetic selection purely on diminishing presence of peaks in SCC would decrease the incidence of pathogen-specific CM more effectively than selecting purely on lower LACSCS.

The litter size (LS), or its equivalent the number of kids born in the litter (NB), of Creole goats in Guadeloupe was studied by two procedures. The first approach considered LS as a single trait and as a characteristic of the mother of the litter, and was studied by an univariate animal model (UAM). The second procedure treated NB, the individual birth weight (BW) and loss of kids (LK) as traits belonging to the animals born in the litter and their dam, in a multitrait animal model (MAM). The heritability for genetic direct effect (h2a) for LS estimated by UAM (0·14) was 40% lower than the corresponding value for NB estimated by MAM. The most appropriate of the 6 MAMs tested estimated heritabilities (h2a) of 0·24, 0·22 and 0·17 for NB, BW and LK, respectively, while maternal effects (h2m) were 0·20, 0·24 and 0·09 for the same characters. The genetic correlations between direct and maternal effects (ram) were negative –0·611 and –0·725 for NB and LK, respectively, and not significantly different from zero for BW. This study explored the possibility of using the information on NB, BW and LK recorded in each animal born in the litter in order to analyse the genetic variability of these traits.

Twelve 6-month-old growing female goats and sheep were used in this study. Blood samples were obtained in the morning before goats and sheep were given food and then at 2-h intervals for 24 h (part I). This procedure was repeated 2 weeks later (part II). Concentrations of osteocalcin (OC), activities of total (tAP) and bone-specific alkaline phosphatase (bAP), degradation products of C-terminal telopeptide of type-I collagen (CrossLaps™ CL), and carboxyterminal telopeptide of type-I collagen (ICTP) were measured in serum.

In both parts of the study, all bone marker concentrations were significantly higher in goats than in sheep. The OC concentrations in goats increased in the late afternoon/evening and decreased thereafter to reach values similar to those obtained at the beginning. The ICTP concentrations in goats slowly decreased until 14:00 h, increased, and decreased again. The concentrations in sheep decreased continuously but not significantly, towards the morning sampling. The CL concentrations increased in both sheep and goats during the night but at 06:00 h started to decrease to levels found at the beginning of testing. The bAP activities decreased in goats from 20:00 to 22:00 h. Changes in the concentrations of bone markers were mainly observed in goats of this study. As documented for bone resorption and formation in other species, circadian rhythms were evident for concentrations of ICTP, CL, bAP and OC. The present study indicates that growing goats may have a physiologically higher bone turn-over than growing sheep, because the bone marker concentrations were always higher.

The effects of terminal sire line, halothane genotype and age on feeding patterns and growth performance were studied in 208 castrated growing-finishing pigs distributed in two batches. In batch 1 (no. = 130), pigs came from crosses of NN Landrace × Large White sows with a Pietrain Nn (Pi-Nn) or a Large White × Pietrain Nn terminal sire line (LwPi-Nn). In batch 2 (no. = 78), the same sows were used but crossed with three different terminal sire lines : a Pietrain nn (Pi-nn), and two Pietrain NN (Pi-NNa and Pi-NNb). Growth performance and feeding patterns of the progeny (Nn or NN for the halothane gene) were measured from 67 to 166 days of age. Pigs were housed in groups of 10 and 13 individuals in Batch 1 and 2, respectively, with a random mixed-breed and halothane genotype sample in each group (space allowance 1·3 m2 per pig and 1·1 m2 per pig, respectively). Feeding patterns were monitored with a computerized food intake recording system (IVOG®-station) and every 3 weeks pigs were weighed and backfat and loin-muscle depth were ultrasonically recorded (PIGLOG®). Carcass quality was assessed with the Fat-o-Meater grading probe. In batch 1, halothane genotype did not have a significant effect on any of the feeding patterns recorded, but Nn individuals had a significantly higher body weight (P <0·05), loin-muscle depth (P <0·05) and lower backfat thickness (P <0·01) in the last measurement taken, 3/4 carcass loin depth (P <0·05) and lower carcass last rib backfat (P <0·05) than NN pigs. Terminal sire line had a significant effect on all feeding patterns recorded except for feeding rate, Pi-Nn sired pigs showing a significantly higher food intake per visit (P <0·05) and feeder occupation time per visit (P <0·05) and lower number of visits (P <0·001) compared with LwPi-Nn sired pigs which, in turn, showed significantly higher food intake per day (P <0·001) and feeder occupation time per day (P <0·01). Terminal sire also affected growth performance and body composition, Pi-Nn sired pigs having a significantly lower body weight (P <0·001) and backfat thickness (P <0·001) but higher killing-out proportion and 3/4 loin depth (P <0·01) than LwPi-Nn sired pigs. In batch 2, Pi-NNb sired pigs showed a significantly lower food intake per day compared with the progeny of the other two terminal sires lines at some of the age measurements taken (P <0·05). The rest of the feeding patterns was not affected by terminal sire line. Body and carcass weights were also significantly lower (P <0·01) for Pi-NNb sired pigs, but their killing-out proportion was higher than Pi-NNa sired pigs. With regard to these variables, Pi-nn sired pigs held an intermediate position between the two NN terminal sire lines. In both batches, age was associated with a significant increase in food intake per visit and per day and feeding rate (P <0·001) and a decrease in feeder occupation time per visit and per day and frequency of visits to the feeder (P <0·001). Overall, the present results suggest differences between terminal sire lines for feeding patterns and confirm their evolution with age from short and frequent meals to long and larger ones in growing-finishing pigs. Under our conditions, the effects of terminal sire line on feeding patterns and growth performance surpassed those of the halothane genotype.

The effects of different sequences of food restriction and fattening have been studied on plasma metabolites and hormones in double-muscled Belgian Blue bulls. Twenty animals were divided into five groups. The first group (control, CG) was given, ad libitum, a fattening diet based on sugar-beet pulp. In G2 and G3, fattening was interrupted after 103 and 187 days, respectively, by a period of food restriction lasting about 2 months during which the animals received a maintenance ration. They were finished with the same diet as CG. The last two groups, G4 and G5, received a limited amount of the restriction diet to support 0·5 and 0 kg gain per day, respectively, for 4 months, before being fattened as CG. Plasma glucose, alpha-amino nitrogen, non-esterified fatty acids, urea, creatinine, thyroxine (T4), 3, 3’, 5’-tri-iodothyroxine (T3), and insulin-like growth factor-1 (IGF-1) were measured in blood samples taken every 2 weeks. Plasma GH and insulin profiles were measured in serial blood samples obtained at three different times during growth. Animals that showed compensatory growth had lower plasma urea, associated with high levels of T3, T4 and IGF–1. Animals from G2 and G3 failed to show compensatory growth. In Belgian Blue bulls, compensatory growth is markedly affected when food restriction is severe or fattening interrupted.

The aim of this study was to evaluate secondary fibre shedding in relation to seasonal hormonal changes in young cashmere-bearing goats reared in southern Italy. We used 14 cashmere-bearing kids, seven males and seven females, of a Scottish breed-population of goats specialized in cashmere production. Monthly, a hair patch of 4 cm2 was clipped from both left and right mid sides alternately and cashmere length and its yield were determined. Blood samples were taken every 2 weeks and plasma was assayed for prolactin (PRL), growth hormone (GH), tri-iodothyronine (T3), thyroxine (T4), progesterone and testosterone. With the same frequency, animals were monitored for onset of moult. Our data indicate that in young cashmere goats at their first moult, secondary fibre shedding is a seasonal event that is strictly related to changes in photoperiod and that PRL has a pivotal rôle in regulating this phenomenon. This corresponds with findings in adults. The observation that both thyroid hormones and sex steroids varied seasonally suggests that they are involved in the regulation of the moult cycle, but their precise rôle remains to be elucidated. Our data also indicate that GH seems to be implicated in the control of the moult cycle. The finding that maximal fibre shedding occurred earlier in males than females could be ascribed to differences in GH levels and to the earlier increase in plasma concentration of PRL observed in males.

The objective of this work was to evaluate the ultrasound method as a tool for in-vivo breast and abdominal fat prediction on Campero-INTA broilers. Breast length (mm), width (mm), surface (mm2; ultrasound) and depth (mm; ultrasound), and abdominal fat depth (mm; ultrasound) were measured at 65-66 and 72-73 days of age on 96 males. At 79 days of age, the broilers were weighed and slaughtered. Breast and abdominal fat weights (g) were obtained. Multiple regression equations were fitted using live weight (g) and in-vivo measurements to predict breast and abdominal fat weights and proportions (g/g). The best model for each case was selected by the Stepwise procedure. Equations fitted were verified using another set of data. Breast weight prediction using live weight and breast length in the model was as accurate as using live weight and breast depth. The former is recommended for breeding work. Abdominal fat weight prediction using ultrasound measurements of fat was less accurate than breast weight prediction. Repeatabilities for ultrasound breast measurements were higher (0·72 to 0·73) than those for abdominal fat (0·51 to 0·52). Operator effect may be important when training levels are different.

We aimed to determine whether the dietary carbohydrate source altered body fat composition and distribution in finishing lean (Landrace) and obese (Iberian) swine. To this end, twenty-four finishing castrated male pigs (12 Iberian and 12 Landrace; 108 kg live weight) were offered two diets differing in the main carbohydrates source, maize (diet M) or acorn-sorghum-maize (diet A). Diets were formulated to have the same nutrient content, except for carbohydrate fractions: diet M contained higher amount of starch (537 v. 389 g/kg) but less non-starch polysaccharides (118 v. 148 g/ kg) than diet A. At an average weight of 133 kg live weight pigs were slaughtered and their carcasses were sampled to study lipogenesis, backfat and intramuscular fat composition. Iberian pigs showed a higher voluntary food intake than Landrace pigs (3·6 v. 2·4 kg/day; P < 0·001) but no significant differences in the daily weight gain. Diet M tended to promote the highest food intake (P = 0·09). Iberian pigs showed higher (P < 0·01) lipogenic enzyme activities, backfat thickness (71·7 v. 31·9 mm) and intramuscular fat content (40 to 95 g/kg fresh muscle) than Landrace pigs, which was associated with their higher food intake. Furthermore, fat depots from Iberian pigs had higher (P < 0·001) monounsaturated fatty acids (MUFA) and lower (P < 0·05) polyunsaturated (PUFA) proportions than those from Landrace pigs. The backfat thickness of pigs given diet M tended to be higher (P = 0·07) than that of pigs given diet A, without differences in the intramuscular fat content. The higher backfat thickness found for diet M was correlated with a lower PUFA proportion in diet than for diet A (P < 0·001). We conclude that body fat content, composition and lipogenic enzyme activities are markedly influenced by the animal breed and to a lesser extent by dietary characteristics.

Forty-eight sucking lambs (26 males and 22 females) of the Manchega breed were used in this work. Lambs were slaughtered at 10, 12 and 14 kg live weight. Carcass degree of fatness was assessed by three assessors from colour photographs of the carcasses, using the European Union scale for light lambs (EU), the Colomer-Rocher method (CF) and another new scale developed by our group (sucking lambs scale, SL). Carcass conformation was assessed according to the Colomer-Rocher method (CC). Fatness and conformation scales were divided to give 0·25 points in each interval. Left half-carcasses were jointed and dissected into lean, fat and bone. Muscle proportion, bone proportion and whole fat proportion (obtained by addition of every fat depot: subcutaneous fat, intermuscular fat, inguinal fat and kidney knob and channel fat) were determined. Male and female carcasses showed a very different tissue composition: both groups had statistically significant differences (P < 0·05) in 20 out of 25 tissue composition variates. Males showed a higher number of variates that were well correlated with assessors’ scoring than females. Correlation coefficients between most of the tissue composition variates and assessors’ scores were higher in males. Furthermore, the number of variates that were significantly correlated with assessors’ scores was lower in females. Therefore, subjective methods for the estimation of carcass degree of fatness and of carcass conformation are poor predictors of tissue composition in female sucking lamb carcasses.

Two hundred and forty pigs of 56 ± 3 days of age were used to investigate the effects of sex (barrows; gilts), boar sire (DD, Danish Duroc; ND × LW, Dutch Duroc × Large White ; P × LW, Pietrain × Large White) and slaughter age (160; 175 days) on performance and carcass and meat quality. Treatments were arranged factorially (2 × 3 × 2) and there were four replicates (five pigs per replicate) per treatment. The female line was Landrace × Large White in all cases. Barrows had greater daily food intake (P <0·001) and average daily gain (P <0·01) and had poorer food conversion ratio (P <0·001) than gilts. Carcasses from castrates were fatter and had a lower yield of trimmed lean cuts than carcasses from females (P <0·001). Longissimus muscle from barrows had more intramuscular fat and higher a* value than muscle from gilts (P <0·05). Pigs from DD sire line grew faster (P <0·05) and had a better food conversion ratio (P <0·001) than pigs from the other two lines. Dressing proportion and backfat thickness were greatest for P × LW sired pigs (P <0·01) and proportion of trimmed lean cuts was greater for DD and P × LW than for ND × LW sired pigs (P <0·01). Longissimus muscle from DD sired pigs had less protein (P <0·01) and more intramuscular fat (P <0·001) than muscle from the remaining lines. Longissimus muscle from P × LW line had more intense colour than muscle from DD and ND × LW lines (P <0·01). Pigs slaughtered at 175 days had poorer food conversion ratio (P <0·01) and less trimmed primal cut proportion (P <0·001) than pigs slaughtered at 160 days. Also, increasing the age at slaughter increased intramuscular fat content (P <0·01), a* value (P <0·001) and colour intensity of the muscle (P <0·01). Danish Duroc boars are a good alternative to ND × LW or P × LW boars for production of heavy pigs whether the crossbreds are sacrificed at 160 or 175 days. Also, an increase in age at slaughter impairs growth efficiency and yield of lean cuts but improves some aspects of meat quality, which might be of interest in the production of heavy pigs destined for the dry-cured product industry.

A deterministic method of predicting numbers of each animal class present over time in a beef cow herd with multiple calving seasons per year is described. Breeding cow classes are defined according to the number of generations of descent from the cows in the herd prior to the introduction of a specific heifer replacement breeding policy. Cow classes are further divided into subgroups defined according to age of cow, calving interval and whether or not the cow was last mated to a terminal sire. The method is demonstrated by showing the evolution of herd breed make-up with several alternative replacement female breeding policies including grading-up, two-breed rotation and three-breed rotation breeding policies. For an example herd, the first generation of replacements peaked at approximately 0·4 of the herd at 6 years after the first matings for a new breeding system. Later generations of replacements reached equivalent proportions of the herd to the previous generation approximately 3·3 years later, with peak proportions at approximately 0·25 of the herd. Differences in the relative levels of expression of heterosis for grade up versus rotational replacement policies increased steadily from 5 years onwards with 0·17 of the heterosis expected in a herd of F1 cows remaining 20 years after the first matings of the new breeding system. The two-breed grading-up system showed less heterosis than the three-breed grading-up system only after 8 years, with the difference increasing to 0·16 of the heterosis in an F1 herd after 20 years. Results are also presented showing the difference in contributions of breeds to the herd gene pool over time with the different breeding systems. With the rotational systems, breeds lag by approximately 3 years in the timing of their contribution according to the order of their introduction to the rotation. The effects of faster heifer replacement rates on results were also discussed. It is concluded that short-to medium-term impacts of breed and replacement breeding system choices are likely to be more relevant in practical decision making by suckler herd managers than the characteristics of breeding systems once herds have reached genetic equilibrium.

The effects of dietary protein content and level of feeding on carcass characteristics and organs weight were evaluated in 72 male castrated Iberian pigs growing from 15 to 50 kg live weight. Animals were offered six diets providing 223, 192, 175, 156, 129 and 101 g crude ideal protein (CP) (N × 6·25) per kg dry matter (DM) and 14·64, 14·14, 14·37, 14·80, 15·36 and 15·53 MJ metabolizable energy (ME) per kg DM, respectively. Each diet was offered at three levels of feeding : 0·60, 0·80 and 0·95 × ad libitum intake. Mean values of protein, fat, ash and water contents in the carcass determined at 50 kg live weight were 130, 378, 28·2 and 458 g/kg, respectively, with a small but significant effect of CP content of the diet on carcass composition (P <0·001 to P <0·01) favouring both protein and fat content on decreasing dietary protein level. Protein deposition (PD) in the eviscerated carcass reached a maximum value when the diet containing 129 g CP per kg DM was offered (54·6 g/day at the highest feeding level). Nitrogen (N) retention in the carcass represented 70·9% of whole-body N retention and the efficiency of this process (carcass N retention : N intake) increased with declining dietary protein content (P <0·001). Carcass energy retention increased significantly with decreasing dietary CP content (P <0·001) and with feeding level (P <0·001). Raising energy intake resulted in a significant increase on total weight of viscera as proportion of empty body weight (P <0·001). Decreasing the CP content in the diet resulted in a lower proportional shoulder weight (P <0·01) meanwhile the proportion of ham decreased significantly (P <0·05) with increase in feeding level. The proportionate weights of dissectable fat in the shoulder and of intermuscular and subcutaneous fat in the ham increased significantly (P <0·05 and P <0·001) in response to decreasing dietary CP content meanwhile only ham intermuscular fat content increased with feeding level (P <0·001). Thus, decreasing dietary protein concentration from well in excess of requirements and increasing energy intake enhance N and fat retention in the carcass but also increases intermuscular fat content in the ham of the Iberian pig with possible implications for meat quality.

Carotenoid pigments are good biomarkers of grass-feeding in sheep. However, as grazing lambs may be concentrate-finished, we investigated the effect of concentrate finishing after grazing on the carotenoid concentration of fat in sheep, and its significance for discriminating lamb production systems. In experiment 1 with 32 lambs, four feeding treatments were compared: G = grazing, C = feeding a concentrate-based diet, GSC = short concentrate-finishing period after grazing, and GLC = long concentrate-finishing period after grazing. The concentrate supply was regulated to have similar average daily gain for all treatments. In experiment 2, 42 ewes were given a low carotenoid diet after pasture feeding, for 0, 8, 22, 42, 84 or 126 days. The feeding level was adjusted to maintain body weight and body condition score. The nature and concentration of carotenoids was analysed by HPLC on diets and lambs’ perirenal fat. The reflectance spectrum of perirenal fat was measured at slaughter. Lutein was the only carotenoid in lamb fat. In experiment 1, the intensity of light absorption by lutein was linearly related with its concentration in the fat (P < 0·001) and was negatively correlated with the duration of the finishing period. The design of experiment 2 avoided the confounding effect of fat gain during the finishing period and examined the effect of the duration of this period by itself. There was no effect of stall-feeding duration on the intensity of light absorption by carotenoids in the fat in experiment 2, demonstrating that the effect of stall-feeding duration in fattening lambs was mediated via a dilution of existing fat with whiter fat rather than through pigments coming out of the fat. The concentration of lutein and the intensity of its light absorption in the fat decreased with lamb body-weight gain during the finishing period (P < 0·01 and P < 0·05 respectively) and increased with plasma carotenoid content at the end of the grazing period (P < 0·001). Because of the inter-individual variability in carotenoid absorption, the use of the reflectance spectrum of the fat alone may cause some concentrate finished grazing lambs to be classified as C lambs shortly after the beginning of the stall-feeding period, whereas others may be considered as G lambs for a long period of time. However, the combined use of plasma carotenoid content at slaughter together with the reflectance spectrum of the fat improves reliability in the discrimination of grass-fed, concentrate-fed and concentrate-finished grazing lambs, by taking advantage of the differences in the rate of reduction in carotenoid concentration in blood and fat.

An experiment was undertaken to compare the carcass characteristics and meat quality of lambs from crossbred ewes produced by crossing Texel sires with Rouge de l’Ouest dams and Rouge sires with Texel dams, relative to lambs from purebred Texel and Rouge ewes. The ewes were crossed with Texel or Rouge sires and the relative performance of the sires assessed in terms of lamb carcass quality. Ewe and ram genotype had a significant effect on conformation classification. Lambs from Texel ewes had a greater conformation classification (4·0) than lambs from Rouge ewes (3·4, s.e. 0·09) (P <0·001) and Texel-sired lambs had a greater conformation classification (4·0) than Rouge-sired lambs (3·6, s.e. 0·06) (P <0·001). Fat depth was significantly influenced by ewe genotype with lambs from Texel × Rouge ewes having greater fat depths compared with lambs from Texel ewes (longissimus dorsi 2·3 and 1·9 (s.e.0·12) mm respectively) (P <0·05). Chemical composition of the carcass and meat quality measurements were unaffected by ewe or ram genotype. Significant heterosis effects on lamb live-weight gain (21 g/day; 15%) (P <0·01) from birth to slaughter, age at slaughter (–37 days; –12%) (P <0·01), weight of perinephric and retroperitoneal fat (76 g; 38%) (P <0·01) and fat depth over the longissimus dorsi (0·3 mm; 16%) and gluteus medius (0·5 mm; 17%; P <0·05) were obtained. The results from this study demonstrate that significant heterosis effects, particularly in terms of lamb growth rate, can be achieved by crossing Rouge and Texel breeds. In addition lambs from hybrid ewes have similar conformation characteristics to the Texel breed which has been intensively selected for carcass characteristics.

A total of 74 pigs representing three commercially available crossbred types, Landrace (50%), Pietrain (50%) and Meishan (25%), were given food ad libitum over a 25- to 115-kg growth period and serially slaughtered for physical and chemical analysis in five groups at 32, 42, 63, 82 and 114 kg live weight (W). Results are presented in the order of pig type as above. Pig types grew at similar overall rates of live body gain, but the Meishan type ate more food and had greater back fat depth. The Pietrain type was least fat. Dissected fatty tissue grew substantially faster than the carcass as a whole; allometric exponents being 1·64, 1·34 and 1·52 (P < 0·05) for the Landrace, Pietrain and Meishan types respectively. Dissected lean tissue gains were 0·419, 0·427 and 0·308 kg daily (P < 0·01), and dissected fatty tissue gains were 0·251, 0·158 and 0·218 kg daily (P < 0·05); the Meishan type being slowest for lean gain and the Pietrain type slowest for fatty tissue gain. The Pietrain type had the largest cross-sectional area of the longissimus dorsi muscle, and the Meishan type the smallest. The pelvic limb of the Meishan type lost density (as measured by specific gravity) fastest, and that of the Pietrain slowest as the pigs grew. The Meishan type had a lower proportion of its carcass lean and a higher proportion of its carcass fat in the pelvic limb than did the other two types. For each kg of live-weight gain, 0·037, 0·041 and 0·032 kg (P < 0·05) of chemical protein was deposited in the pelvic limb of the three types respectively. Equivalent values for chemical lipid were 0·041, 0·035 and 0·041 (P < 0·05). The Meishan type retained protein at a relatively slower rate in the pelvic limb than in the body as a whole. The Pietrain type had the greatest ultimate protein mass in the pelvic limb. Estimation of whole body protein content as a linear function of pig live weight gives coefficients of 0·154, 0·178 and 0·168 kg (P < 0·05) for the three types respectively. Equivalent values for whole body lipid content were 0·269, 0·214 and 0·274 (P < 0·05). Best estimates of the daily rates of protein retention in the body of the whole live pig were 0·152, 0·197 and 0·142 kg/day for the Landrace, Pietrain and Meishan types respectively.

A deterministic bio-economic model was developed to evaluate the effects of changes in breeds and mating systems in a beef enterprise whilst keeping management constant. The model simulates all aspects of beef production including the transition of the breed composition, the biological performance and the overall economic performance of animals within the herd, over time. Breed performance parameters are based on a synthesis of results from published beef breed comparison experiments. In order to illustrate how the model is implemented an example is given based on UK economic information. The model predicts physical and financial performance over a planning horizon of 20 years. For a hypothetical enterprise, changing from buying in surplus dairy cross heifers to a situation of self-replacing beef cows, the model demonstrated a financial advantage, due largely to a reduction in production costs.

The objective of this study was to evaluate the ability of the plant extracts Yucca shidigera, Quillaja saponaria and a combination (a blend of capsicum, carvacrol and cinnamaldehyde) to stimulate piglet and sow performance when used as supplements in the diets of lactating sows. These extracts were selected for their potential benefits to health, appetite and digestion. Eighty hybrid sows were housed in conventional indoor farrowing crates from day 107 of gestation until weaning. Sows were allocated according to parity, live weight, fatness and past reproductive performance, to one of four dietary treatments: control (C), combination (COM, 100 g/t food), yucca (Y, 200 g/t), quillaja (Q, 250 g/t). Between days 107 to 114 of gestation, sows received 2·5 kg food per day of their respective diet. During lactation food was offered ad libitum with sow food intake (FI) recorded daily. Faecal samples were obtained from sows daily in order to measure diet digestibility using titanium dioxide as an external marker. Piglet live weight and sow P2 backfat were recorded on days 1, 7, 14 and 21 and at weaning on day 23 (s.e.2·5). Piglet live weight and rectal temperature were measured at birth and 24 h of age. Piglet growth between birth and 24 h was significantly affected by sow treatment. Litters from COM sows held the greatest advantage (117 v. C 99, Q 77, Y 107 g per pig per day, P < 0·01, s.e. = 7·9). Piglet body temperature at birth was also higher in COM litters when compared with treatment C (38·58 v. 37·95oC, P < 0·05)). Q and Y piglets were intermediate between the two. Sow treatment had no effect on piglet performance between day 1 and 14 of lactation. However, between days 15 and 21, piglets from COM sows again significantly outperformed all other treatments (COM 290, C 246, Q 235, Y 255 g per pig per day, P < 0·001, s.e. = 9·3). Piglet weights on day 21 were also significantly greater for the COM sows (6878 g v. C 6584 g, Q 6330 g, Y 6498 g, P < 0·05 s.e. = 132). No benefit was seen from supplementation with either yucca or quillaja extracts on piglet growth. Sow FI and P2 backfat loss between parturition and weaning were unaffected by treatment. However, diet digestibility was enhanced by all supplements during week 1 of lactation in terms of dry matter, organic matter and crude protein. It is concluded that some plant extracts may enhance piglet and sow performance prior to weaning.

Sixty crossbred (Large White × Landrace × Duroc) pigs were used to compare the growth performance, carcass and pork quality characteristics of entire, surgically castrated and immunologically castrated male pigs from two Western Australian commercial genotypes (genotype A : ‘lean’ genotype and genotype B : propensity for increased subcutaneous fat deposition). Pigs from genotype B had a higher average daily gain and a superior food conversion ratio compared with pigs from genotype A. Entire males had lower backfat compared with surgically and immunologically castrated male pigs. Pork from entire males was drier, tougher and had lower overall acceptability scores compared with surgically or immunologically castrated male pigs. Pork from genotype A pigs had a lower m. longissimus thoracis (LT) ultimate pH and higher drip loss compared with pork from genotype B pigs. However, consumer taste panel assessment indicated that pork from genotype A pigs was more tender, had higher juiciness and overall acceptability scores compared with pork from genotype B pigs. Within genotype A, the consumer taste panel preferred pork from surgically castrated pigs compared with either entire or immunologically castrated pigs. Within genotype B, the consumer taste panel preferred pork from immunologically castrated pigs compared with either entire or surgically castrated male pigs. These results indicate that interactions between genotype and castration method can significantly influence eating quality of pork.