Masham ewes were mated at three stages of the breeding season, early (15 September to 20 October), mid (20 October to 24 November) and late (15 December to 19 January), at two different body condition scores, 4 and 2, for 3 successive years. The mean scores achieved for body condition 4 were 3·6, 3·7 and 3·9 for early, mid and late respectively and for body condition 2 were 2·4, 2·3 and 2·2. In the late lambing flock more ewes were marked by vasectomized rams and less ewes were barren than in the early and mid flocks. The ewes in higher body condition at mating had significantly more triplets and fewer singles, and a higher lambing percentage (183 versus 165). This effect of body condition on litter size distribution was significant at each time of mating, with the ewes at the late mating producing significantly fewer triplets and more singles; this difference was caused by a reduction in the performance of the body condition 4 ewes in the late group.

Young ewes in the body condition 4 group produced significantly fewer triplets and more singles than the mature ewes in the same body condition group, but at the lower body condition age had no effect on litter size distribution.

Genetic parameters for pre-weaning live weights and ultrasonic scanning measurements were estimated from a flock of Scottish Blackface sheep undergoing an embryo transfer programme. Maternal environmental effects could be evaluated without confounding with maternal genetic effects because embryos were transferred to unrelated recipient ewes. The data for the study were collected over a 7-year period (1993-1999) and related to a conventional hill farming system. The data were from 1465 lambs, the progeny of 60 sires, 263 donors and 784 recipient ewes. The only exception to the conventional farming system was at mating time when embryos were collected from selected donor ewes, following superovulation, and transferred to unrelated recipient ewes. Maternal environmental effects were important for birth weight (BW), 4-week weight (W4) and weaning weight (WW) but of less importance for ultrasonic fat depth (UFD), muscle depth (UMD) and muscle width (UMW). The heritabilities of the pre-weaning weights were moderate (0·17 to 0·23). The heritabilities of UFD and UMD were 0·44 and 0·27 respectively and were higher than found in previous similar studies. The heritability of UMW was low, 0·06. The genetic and phenotypic correlations among the pre-weaning weight traits were positive and moderate. There was a positive genetic ( + 0·25) and phenotypic ( + 0·24) correlation between UFD and UMD. The phenotypic and genetic correlations between BW and W4 and the scanning traits (UFD, UMD and UMW) were close to zero, and the correlations of WW with UFD, UMD and UMW were positive. The results of this study clearly demonstrate the importance of maternal environmental effects for lamb weights up to weaning and also suggest that genetic improvement for carcass composition in some populations of extensively reared hill sheep could be achieved more rapidly than previously thought possible.

Native chicory inulin is one of the promising alternatives to replace antibiotic growth promoters in young animals. Several potential mechanisms of prebiotic action have been proposed, such as modification of the intestinal microbiota composition leading to improved epithelial integrity and gut mucosal immunity of the host. The current study was focused on inulin effect on the large intestinal proteome and its implications for gut barrier functions. Therefore, we used proteomic techniques to determine changes in the large intestinal mucosa proteome of growing pigs after 40-day supplementation with native chicory inulin. The experiment was performed on 24 piglets fed from the 10th day of life an unsupplemented cereal-based diet or inulin-enriched diets (1% or 3%) with an average degree of polymerisation ≥ 10. At the age of 50 days, animals were sacrificed and tissue samples were collected from the cecum, and proximal and distal colon. Feeding diets supplemented with both levels of native inulin increased cecal and colonic expression of molecular chaperones, protein foldases and antioxidant proteins, which are collectively responsible for maintaining mucosal cell integrity as well as protecting against endotoxins and reactive oxygen species. This may confirm the beneficial effect of inulin on the gut health in growing pigs.

Two experiments were designed to study the effect of rearing method, female company, and repeated libido and semen tests on the pattern of sexual development of ram lambs. Four artificial rearing treatments (AR) were compared with natural rearing (NR) in one experiment and four artificial compared with three natural rearing treatments in a second experiment. Lambs on AR treatments in both experiments, as well as naturally reared lambs in the second experiment, were reared with or without females either before and/or after weaning. Half the lambs in the second experiment were libido and semen tested, and their mean plasma testosterone level was also measured, while the rest were only tested at the end of the experiment. The effect of method of rearing and female company on body growth, testes diameter, libido and semen quality were also investigated.

A close relationship was found between body weight and sexual characteristics (for example, testis diameter, semen traits, libido, testosterone level and age at the onset of sexual maturity). NR resulted in faster growth than AR but was not appreciably different from early weaned-naturally reared treatments. It was also observed that mating performance improved steadily with advancement in age and increase in body weight. The onset of sexual maturity was attained at a minimum of 23 kg body weight and a minimum of 198 days of age. However, the heavier the lamb when sexually mature, the better its mating performance.

Previous libido tests of ram lambs improved their subsequent mating performance, but had no effect on semen quality. However, libido tests did not improve the performance of those ram lambs which did not exhibit initial libido.

It is suggested that early weaning at 2 months of age could be a suitable system for ram lambs weaned off their mothers for breeding purposes. These lambs should be reared as an all-male group but libido tested at monthly intervals commencing at 3 months of age. The criteria for selecting these lambs at an earlier age should be body weight and testis diameter.

Estimates of dam reproductive performance are reported for purebred Africander, Angoni, Barotse and Boran dams, and the reciprocal crossbreds of the latter three breeds, under ranching conditions in Zambia.

Mean performances based on a maximum of 1996 records collected over six parities were: calving rate, 65·6%; weaning rate, 62·8%; calf birth weight, 26·6kg; calf weaning weight, 163·6kg; and dam live weight at weaning, 363 0 kg.

Purebred Africander and Barotse dams had significantly poorer calving rates, 542 and 57·6% respectively, than the purebred dams of the Angoni and Boran breeds, 69·1 and 66·0% respectively. Reciprocal crossbred dams of the latter two breeds had the highest calving rates, 71·2 and 74·4%. Heterosis estimates for calving rate were 0·8% for Angoni/Barotse crosses, 7·8% for Angoni/Boran crosses and 10·3% for Barotse/Boran crosses and, for weaning rate, 3·7, 6·7 and 11·5% respectively. There were no differences between reciprocal crossbred dams for calving and weaning percentages. The mortality rate of calves born to crossbred dams was 40% and that of the calves born to purebred dams of the same breeds 4·7%. Dam status at mating had an important effect on fertility with the calving rate of dams dry at mating, 89·1%, contrasting with a rate of 39·8% for those dams that were lactating at mating and that had calved late in the season.

There were large differences between breeds for calf weights but heterosis estimates were small and nonsignificant. There were no differences between the progeny weights of reciprocal crossbred dams. Sex, date and period of birth, and dam status had significant effects on calf weights.

Africander dams had the heaviest, and Angoni dams the lightest, live weights at weaning, 421·1 and 320·7 kg respectively. Heterosis estimates for dam live weights were small and non-significant, and reciprocal crossbred differences were unimportant. Dams which lost most live weight during the dry season, that had extremely light live weights at the beginning of the breeding season or that gained little weight during the breeding season had significantly poorer fertility than other dams.

Overall estimates of heritability derived by dam/daughter regression were 0·20 for calving percentage, 0·76 for calf birth weight and 0·72 for calf weaning weight.

In three experiments pregnant ewes (mean weight 72·5 kg) were subjected to different planes of nutrition on grass silage-based diets during mid pregnancy and, in factorial designed trials with ad libitum silage or ad libitum silage + concentrates in late pregnancy. The high plane of mid-pregnancy nutrition resulted in an average gain of 11·5 kg between weeks 7 and 14 of pregnancy while the low plane gave an average loss of 3·5 kg during this period. These differences did not affect lamb birth weight but ewes on the high plane were 7·2 kg heavier after lambing than those on the low plane. The effect of plane of nutrition during mid pregnancy on silage intake during late pregnancy was variable but there was some evidence of a greater reduction in intake during the last few weeks of pregnancy following the high plane of mid-pregnancy nutrition. The higher plane of nutrition in late pregnancy resulted in higher ewe live weights as well as higher lamb birth weights and highest lamb birth weights occurred following restriction in mid pregnancy and a high plane of nutrition in late pregnancy.

Plasma 3-hydroxybutyrate levels were variable but there was little evidence of an effect of mid-pregnancy nutrition although levels appeared to be increased by the low plane of nutrition in late pregnancy.

This experiment evaluated production and health parameters among cattle offered concentrates containing inorganic or organic complexed sources of supplemental Cu, Co, Mn and Zn during a 45-day preconditioning period. In total, 90 Angus×Hereford calves were weaned at 7 months (day −1), sorted by sex, weaning BW and age (261±2 kg; 224±2 days), and allocated to 18 drylot pens (one heifer and four steers per pen) on day 0; thus, all pens had equivalent initial BW and age. Pens were randomly assigned to receive a corn-based preconditioning concentrate containing: (1) Cu, Co, Mn and Zn sulfate sources (INR), (2) Cu, Mn, Co and Zn complexed organic source (AAC) or (3) no Cu, Co, Mn and Zn supplementation (CON). From day 0 to 45, cattle received concentrate treatments (2.7 kg/animal daily, as-fed basis) and had free-choice access to orchardgrass (Dactylis glomerata L.), long-stem hay and water. The INR and AAC treatments were formulated to provide the same daily amount of Co, Cu, Mn and Zn at a 50-, 16-, 8- and ninefold increase, respectively, compared with the CON treatment. On day 46, cattle were transported to a commercial feedlot, maintained as a single pen, and offered a free-choice receiving diet until day 103. Calf full BW was recorded on days −1 and 0, 45 and 46, and 102 and 103 for average daily gain (ADG) calculation. Liver biopsy was performed on days 0 (used as covariate), 22 and 45. Cattle were vaccinated against respiratory pathogens on days 15, 29 and 46. Blood samples were collected on days 15, 29, 45, 47, 49, 53 and 60. During preconditioning, mean liver concentrations of Co, Zn and Cu were greater (P⩽0.03) in AAC and INR compared with CON. No treatment effects were detected (P⩾0.17) for preconditioning feed intake, ADG or feed efficiency. No treatment effects were detected (P⩾0.48) for plasma concentrations of antibodies against Mannheimia haemolytica, bovine viral diarrhea types 1 and 2 viruses. Plasma haptoglobin concentrations were similar among treatments (P=0.98). Mean plasma cortisol concentration was greater (P⩽0.04) in CON compared with INR and AAC. No treatment effects were detected (P⩾0.37) for cattle ADG during feedlot receiving. Hence, INR and AAC increased liver concentrations of Co, Zn and Cu through preconditioning, but did not impact cattle performance and immunity responses during preconditioning and feedlot receiving.

Ghrelin, the ‘hunger’ hormone, is an endogenous growth hormone secretagogue that exerts a wide range of physiological functions. Its perinatal presence suggests that ghrelin might be involved in growth and metabolism processes during intrauterine and postnatal life. Intrauterine growth-restricted (IUGR) neonates have altered endocrine and metabolic pathways because of malnutrition during foetal development. These changes might include an altered gastrointestinal presence of ghrelin cells (GCs). As ghrelin is mainly secreted by the stomach, this altered presence might be reflected in its serum concentrations. Small-for-gestational age (SGA) pigs appear to be a natural occurring model for IUGR children. Therefore, the first aim of this study was to investigate the presence of gastrointestinal GCs expressing active ghrelin in normal weight (NW) foetal and postnatal piglets compared with their SGA littermates using immunohistochemical analysis in combination with stereological methods. Second, total ghrelin serum concentrations of these piglets were analysed with a porcine radioactive immunoassay. In addition, the growth of the gastric pars fundica in the NW and SGA piglets was analysed stereologically. Corresponding with humans and rats, it was shown that opened- and closed-type immunoreactive GCs are distributed along the entire gastrointestinal tract of the perinatal NW and SGA piglets. However, in contrast to the rat’s stomach, the porcine GCs do not disperse from the glandular base to the glandular neck during perinatal development. Furthermore, stereological analysis demonstrated that the NW neonates have a higher amount of gastric cells expressing active ghrelin compared with the SGA piglets that could result in higher milk consumption during the neonatal period. This finding is, however, not reflected in total serum ghrelin levels, which showed no difference between the NW and SGA piglets. Moreover, the stereological volume densities of the fundic layers demonstrate a similar growth pattern in the SGA and NW piglets.

Three experiments investigated differences between sheep breeds in response to supplementary feeding and very close confinement with familiar and unfamiliar sheep; and differences between individuals in response to a taming procedure prior to transport in a trailer. The first two experiments were with a mixed flock of Clun Forest lambs and crossbred lambs from Orkney. An initial tendency to feed with others of the same breed diminished over 3 weeks. Responses of heart rate and salivary cortisol concentration when one sheep (the visitor) was penned in an enclosure of 1 m2 with three other sheep of the same or the other breed (the trio group), did not depend on whether the visitor and the trio group were of the same or different breed. Clun Forest sheep showed little response while Orkney sheep showed increased heart rate and some elevation of salivary cortisol concentration. In the third experiment, 34 Beulah Speckled Face ewes were divided into two groups one of which was subjected to a taming procedure over a period of 3 weeks. Response of salivary cortisol concentration to subsequent journeys of 2h in a livestock trailer did not differ between tamed and untamed sheep. There were individual differences in the response to taming and this was correlated with the cortisol response during transport, in that those sheep which responded most to taming showed the least elevation during transport.

An experiment was carried out with 123 pairs of cows located at 11 centres and extending over 3 years, to compare the performance of cows fed at a fixed rate of starch equivalent per gallon with similar cows fed according to an experimental scale, in which the rate of feeding per gallon increased with increasing milk yield.

Records of milk yields and concentrate consumption were made. Feeding according to the experimental scale produced significantly more milk during the first 14 weeks of the lactation. The increase in milk yield for 52 pairs observed over 28 weeks was not significant in either the first 14 or first 28 weeks.

The economic response (lb. milk for each addition lb. starch equivalent for all pairs over 14 weeks was 1·42 and was very near the predicted value. A slightly larger response of 1·64 was obtained from the highest yielding cows. The response over 28 weeks (for 52 pairs only) was 1·30. Considerable variation in this response was found between seasons and between centres.

These results are discussed in terms of the practical application of the feeding scales used and the responses obtained.

The assumption that observed values for litter size result from a set of thresholds which impose a discontinuity to the visible expression of a continuous underlying variate has been tested using data from the French sheep recording scheme: 629 724 natural lambings for 32 different pure breeds and 66 379 litters obtained after synchronization treatment in 15 breeds. Frequencies of single, twin, triplet and higher-order births varied regularly with litter size within each fecundation type. The coefficient of variation of litter size was remarkably constant from breed to breed under both natural (0·35 to 0·40) and induced lambings for which it was higher (0·40 to 0·45). The regression of the difference between the first two thresholds of an underlying normally distributed variate on prolificacy was slowly negative for natural fecundation, but not significant for induced fecundation. A significant effect of fecundation type was found, resulting in a lower incidence of induced than of natural twin litters for the same level of prolificacy. Multivariate polynomial regression of frequencies on natural and induced prolificacy was used to predict expected frequencies of litter size and the proportion of lambs of each birth type.

The work described was carried out to study the expression of insulin-like growth factor 1 (IGF-1) and growth hormone-receptor (GHR) mRNA in liver, skeletal muscle and adipose tissue from three breeds of pig with varying growth characteristics. The three breeds studied were the Large Wlrite, noted for its lean tissue; the Duroc, characterized by its high intramuscular fat content; and the Meishan × Landrace (0·5 Meishan), noted for its fat, poorly conformed carcass and slower growth rate. The probes used were designed to monitor promoter usage for IGF-1 expression and also expression of the extra-cellular domain of the GHR. Eighteen gilts, six of each breed, were given a barley/wheat diet (158 g crude protein, 10·7 g lysine and 13·9 MJ energy per kg), to appetite, for 1 to 2 weeks until they reached about 85 kg. Samples of liver, longissimu s dorsi (LD) muscle and three adipose tissue depots (subcutaneous (SC), perirenal (PR) and omental (OM)) were collected immediately after slaughter and frozen in liquid nitrogen (total time of sample collection to plunging of sample into liquid nitrogen was <3 min), prior to extraction of total RNA and ribonuclease protection assays. Individual serum samples collected at exsanguination were frozen prior to IGF-1 radioimmunoassay. There were no breed differences in the serum IGF-1 concentrations (range 49 to 134 μg/l), or in expression of the GHR gene or either class of IGF-1 transcript in the liver. However, there was a significant difference between the breeds in expression of IGF-1 mRNA in the LD muscle (P < 0·001), the order being Duroc > Wliite > Meishan, with only class 1 transcripts of IGF-1 being found. GHR expression in LD muscle was lower in White than in the other tivo breeds (P = 0·022). There was a significant difference between the breeds in expression of IGF-1 mRNA (only class 1 transcripts present) in the adipose tissue (P = 0-006), the order being Wliite · Duroc · Meishan, and also a significant depot difference, with expression being highest in the SC depot (P < 0·001). There were no differences between the breeds or depots in expression of GHR mRNA in adipose tissue. The observed differences in muscle and adipose tissue IGF-1 expression may relate to the overall growth of the animal.

Lysine (Lys) availability in three different soya-bean meal (SBM) products was determined using the following techniques: whole body (WB) net flux of Lys, digestible Lys (duodenal flow × intestinal digestibility) and the plasma Lys response curve method of Rulquin and Kowalczyk (2003). Four multiparous Holstein cows (173 days in milk) were equipped with ruminal and duodenal cannulas and used in a 4 × 4 Latin square experiment with 14-day periods. The animals were fed either solvent-extracted SBM (SE), expeller-processed SBM (EP) or lignosulphonate-treated SBM (LS) at 23% of the diet dry matter (DM). The fourth treatment (SE70) consisted of a continuous infusion of Lys (70 g/day) into the omasum of cows fed the SE diet. Chromium(III) oxide was included as a digesta marker in order to determine the duodenal flow of amino acids (AA). On day 12 of each experimental period, six blood samples were collected to determine plasma Lys concentrations. Immediately after that, a pulse dose of L-[2–15N] Lys was administered in the jugular vein. Jugular blood samples were then collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 16, 19, 25 and 31 min after the injection to determine 15N Lys enrichment. On each of days 13 and 14, eight digesta samples were collected and pooled by period. Amongst the diets of SBM (SE, EP, LS), no differences were observed for duodenal Lys flow or digestible Lys. Duodenal flow of microbial N with SE was numerically higher, compared with EP and LS, indicating enhanced duodenal supply of microbial Lys for this diet, and this may have compensated for the additional Lys derived from undegradable protein in rumen-protected SBM products (EP and LS). The use of the plasma response curve method as well as the measurement of WB Lys flux also revealed no differences in Lys availability among the SBM products. The WB flux method resulted in 100% post-ruminal recovery of the Lys infused with diet SE70 compared with the control diet SE, which indicates that the method is reliable for determining Lys availability. The Lys flux approach not only allows for the estimation of intestinally available essential AA but also it avoids the use of cannulated animals.

The aim of this study was to determine the effects of restricted feeding before puberty on growth performance and mammary gland development in replacement ewe lambs. At weaning, 72 Dorset ewe lambs were assigned to one of the three diets: an ad libitum control diet with medium-quality forage (MQF; diet A-MQF); a restricted diet with the same forage as A, but less feed concentrate (diet R-MQF); or a high-quality forage (HQF) diet (diet F-HQF). The quantity of concentrate offered to the group R-MQF and F-HQF ewe lambs was adjusted to obtain 70% of the control ewe lambs’ growth rate. The diets were offered for 75 days after weaning to cover the allometric phase of mammary gland development. During this period, average daily gain (ADG) was 223 and 229 g/day for groups R-MQF and F-HQF, respectively, compared to 305 g/day for group A-MQF (P < 0.0001). At the end of this period, 28 ewe lambs were slaughtered and their mammary gland was collected. Parenchymal fresh tissue weight tended to be higher for groups R-MQF and F-HQF compared to group A-MQF (P = 0.09). Stroma weight was greater (P < 0.05) for the group A-MQF ewe lambs than for those in the other treatments. Total DNA and total protein in parenchymal tissue tended to be greater for groups R-MQF and F-HQF (P = 0.09 and P = 0.07, respectively). Dry fat-free tissue was greater for groups R-MQF and F-HQF (P < 0.05). The remaining ewe lambs were fed the same haylage and barley diet until their first lambing. During this period, compensatory growth was observed. ADG was greater (P < 0.01) for groups R-MQF and F-HQF than for group A-MQF, and feed conversion was improved (P < 0.01) for groups R-MQF and F-HQF compared with the control, whereas the dry matter intake was similar for all groups. Live body weight, loin eye depth and backfat depth at breeding and around lambing were similar for all groups. The results of this study suggest that restricted feeding before puberty improves mammary gland development without compromising growth performance in ewe lambs.

The effects of live weight at weaning on carcass composition were studied with 104 Scottish Blackface lambs offered two diets differing in protein: energy ratio. Groups of lambs were slaughtered at initial live weights of 24·1 (s.e. 1·48) kg (LL) and 28·9 (s.e. 1·67) kg (IL) and at 33 kg, 38 kg, 43 kg, 53 kg and mature live weight.

Lambs were offered two diets — low protein: energy ratio (LP, 122 g crude protein (CP) per kg dry matter (DM): 10·4 MJ metabolizable energy (ME) per kg DM) and high protein: energy ratio (HP, 176 g CP per kg DM: 10·4 MJ ME per kg DM). The LP diet was offered ad libitum and the HP diet was restricted to a similar mean level. Muscle, fat and bone tissues in the carcass were separated and weighed and the carcass and non-carcass component tissues were analysed for chemical fat, protein and ash.

Daily live-weight gain (DLWG) of HP lambs (148 (s.e. 8·1) g/day) was significantly higher than that of LP lambs (118 (s.e. 8·1) g/day; P < 0·05) and food conversion ratios were lower up to a live weight of 43 kg (P < 0·05). There were no differences in intake or DLWG between LL and IL lambs. Mature live weight (73·3 (s.e. 1·79) kg) was not related to weaning weight or post-weaning diet.

There was no effect of diet on carcass composition at any slaughter weight but LL lambs had a higher fat proportion than IL lambs, which was significant (P < 0·05) at 33 kg only. During the feeding period, the increment of fat tissue per unit increase in live weight (348 (s.e. 15·8) g/kg LW) was not affected by live weight at the start of the diet. The difference between LL and IL lambs in fat proportion was directly related to the difference in weight gain required to reach slaughter weight. The difference was not a function of stage of maturity but only of weaning weight, itself largely determined by pre-weaning nutrition. At higher slaughter weights the relative difference decreased and became non-significant. Hence lambs lighter at weaning would be less suitable than heavier lambs for the production of light-weight lean carcasses.

Fat (and muscle) thickness measurements were carried out in five slaughterhouses on 174 selected carcasses to compare the Hennessy Grading Probe (HGP) with the Renco Lean-Meater (Renco) and Pie Medical ultrasonic devices for their ability to predict the lean meat proportion of pig carcasses. The day after selection, all left carcass sides were dissected according to the simplified European Union (EU) reference method. In addition 44 of these sides were further dissected according to the full EU reference method.

In a further set of slaughterhouses it was found impossible to measure fat thickness with the Renco and Pie Medical ultrasonic device due to extreme singeing of the carcasses. From the five slaughterhouses, between third and fourth from last rib, 6 cm off the dorsal mid line, observations on fat thickness with HGP and Pie Medical were similar but observations with Renco were significantly lower (F < 0·001). Correlations between fat thickness measurements taken with HGP, Renco and Pie Medical all exceeded 0·95.

In terms of residual standard deviations of prediction formulae, the HGP performed highly better than Renco or Pie Medical (23·7, 25·1 and 24·9 g/kg respectively). These results, together with practical problems, make the use of ultrasonic measurements under practical conditions at present less feasible than using the HGP.

Genetic parameters were estimated for litter size in two prolific sheep breeds, i.e. the Zwartbles and the synthetic breed Swifter. Genetic parameters and breeding values for litter size in different parities were estimated using both a repeatability and a multivariate animal model. The estimated heritability from the repeatability model was 0·10 for the Zwartbles and 0·12 for the Swifter. For the multivariate model, heritability of litter size in first, second and third parity was 0·05, 0·07 and 0·10 for the Zwartbles and 0·09, 0·12 and 0·09 for the Swifter. Genetic correlation for litter size in Swifter was 0·81 between parity 1 and 2 and 0·99 between parity 2 and 3. For the Zwartbles genetic correlations were all very close to unity. Environmental correlations between litter size in subsequent parities were not constant over parities. Phenotypic variance in litter size in both breeds was 0·309 in first parity and was almost 50% higher in later parities. Based on the results it is recommended to apply a multiple trait model.

Two experiments were conducted to measure the effects of a range of dietary lysine concentrations and environmental temperatures on the performance of pigs grown from 13 to 25 kg live weight. In both experiments 48 Large White x Landrace entire male pigs were assigned at 13 kg to one of six dietary lysine treatments (13·8 (L1), 11·8 (L2), 9·6 (L3), 7·6 (L4), 5·6 (L5) g/kg and L5 + supplemented lysine (L6)) and one of four temperature treatments (18, 22, 26 and 30°C). Animals were given ad libitum access to food until 25 kg live weight. There were significant differences in the rates of growth between dietary and temperature treatments with the highest gains on L2 (0·597 (s.e. 0·020) kg/day) and at 18°C (0·549 (s.e. 0·018) kg/day). Food intake (FI) increased significantly (P < 0·001) with decreasing lysine content, reached a maximum (L4) and then declined (L5). An increase in the supply of lysine in the diet resulted in significant increases (P < 0·001) in the gain per unit of food (FCE). There was an indication (P < 0·10) that the response in FCE to dietary lysine was dependent on the temperature, with maximum FCE being obtained at 22°C on LI (647 (s.e. 18·5) g gain per kg food). Dietary treatment had a significant effect (P < 0·001) on both the rate of protein (PR) and lipid deposition (LR) irrespective of the temperature. There was a 0·60 reduction in PR and a 1·36 increase in LR in pigs given L5 compared with those given L1. Similar trends occurred in the empty body protein and lipid contents at 25 kg live weight. Both temperature and dietary lysine levels had a significant (P < 0·05) effect on total heat loss (THL). The response in THL was similar to that observed in FI. The efficiency of lysine utilization at 22°C was significantly (P < 0·05) higher than at the remaining temperatures. The mean efficiency for pigs between 13 kg and 25 kg live weight was 0·64 (s.e. 0·05). In general, growth and food intake responses to dietary lysine level were independent of environmental temperature.

Three levels of soya bean meal (0%, 25% and 50% of the intake of hay dry matter) combined with three levels of pelleted barley (0%, 50% and 100% of the intake of hay dry matter) in a factorial arrangement of treatments were offered to Welsh Mountain ewe lambs receiving hay ad libitum for 14 weeks.

When barley was not given, soya bean meal added at 25% of the hay intake increased hay voluntary intake from 287 g/day to 412 g/day but hay intake was depressed to 339 g/day by a further increase in the level of soya bean meal. When barley was given, soya bean meal did not affect hay intake. With one exception, an increase in barley reduced hay intake, with the result that there were no differences between treatments in the digestible energy intakes of lambs receiving barley at each level of soya bean meal. In general, it was found that an increase in the concentrate allowance (barley + soya bean) reduced hay intake, whereas an increase in the crude protein content of the concentrate increased hay intake. The relationship between live-weight change, metabolizable energy intake and live weight was examined by regression analysis. Although live weight and voluntary intake were unrelated at the start of the experiment, a positive relationship emerged as the experiment progressed.

The possibility that restriction of pasture and controlled supplementation of the diet of milking cows with concentrates might improve the efficiency of utilisation of grazing was examined in a double reversal grazing experiment with 9 Ayrshire cows per treatment which extended over 4 months.

Cows received either pasture alone allocated daily by electric fence (treatment B), or half the pasture area plus one-third of their expected DOM intake offered as concentrates (treatment A).

In the first two periods, treatment A resulted in closer defoliation of the pasture.

Over the whole experiment there was no significant difference in yield of fat-corrected milk between treatments, although treatment A depressed butterfat percentage and raised milk yield significantly. Treatments did not influence live-weight gain significantly and toth groups gained over the season.

Feed intake estimated by chromic oxide-faecal index methods was similar for both treatments except in period 1. Intake estimates by clipping methods or by faecal index methods were in close agreement in period 1 for treatment B and in reasonable agreement in periods 2 and 3.

The results are discussed particularly with a view to the possibilities of replacing some grazing with barley or other concentrated feeds. On the available evidence this is economically feasible only where very profitable uses of the grassland saved are possible.