The objective of this study was to investigate the effects of silage characteristics on water intake of lactating dairy cows and to examine the prediction of water intake. Sixteen grass silages, differing in fermentation and intake characteristics, were offered ad libitum to dairy cows in early lactation supplemented with 7 kg/day of concentrate (13·3 MJ metabolizable energy per kg dry matter (DM) and 216 g crude protein per kg DM). Four silages were offered in each of four incomplete change-over design experiments, consisting of three 3-week periods. Water intakes were recorded through individual Kent water meters and press water bowls over the final week of each period. Tree (drinking) water intake ranged from 20·1 to 89·9 (mean = 45·2; s.d. = 12·96) I/day whilst total water intake (also including food water) ranged from 48·4 to 123·8 (mean = 87·3; s.d. = 14·12) I/day. Water intake increased with increasing silage DM concentration, however free water replaced silage water at a rate less than 1. Milk yield and silage D value (digestible organic matter, g/kg DM) were strongly positively correlated with free water intake (r = 0·751 and 0·595 respectively), though fermentation indices were not good single predictors of water intake. Further analysis revealed problems owing to collinearity within the predictors of water intake: DM intake, silage D value and milk yields being significantly correlated, as were pH and volatile fatty acids as a proportion of total fermentation acids. The ridge regression technique was used to reduce collinearity problems and produce stable equations. The best prediction equations for water intake involved a combination of both animal and analytical information: diet DM concentration, milk yield and silage pH. The use of fermentation information, whether from titration or high-performance liquid chromatography did not describe real variation in water intake beyond that described by silage pH. Free water intake was higher with higher diet DM concentrations, higher milk yields and higher silage pH.

Dose-response experiments were designed to determine the dosage of somatostatin (SRIF) necessary to alter serum growth hormone (GH) response to administration of GH-releasing factor (1·44; GRF) in cattle. The objective of this experimentation was to develop a GRF/SRIF challenge model that might be useful in early identification of animals which are genetically superior for milk production traits. In experiment 1, calves received either 0, 5 or 10 /JLg GRF per 100 kg body weight (BW) or GRF 1·29 at 1 ug per 100 kg BW. Both the 5 and 10 ug GRF per 100 kg BW dosages increased GH concentrations (P < 0·05). In experiment 2, animals received 3 ug GRF per 100 kg BW concurrent with administration of 0, 0·5, 1 or 2 ug SRIF per 100 kg BW at 0 min, with second dosage of GRF at +120 min. Administration of SRIF in those dosages did not alter GH response to GRF. In experiment 3, animals received 5 ug SRIF per 100 kg BW at -2, -1, 0 or +1 min relative to 3 ug GRF per 100 kg BW, with a second GRF injection at +120 min. No differences (P < 0·05) were found in response due to timing of SRIF administration. In experiment 4, animals were administered 0, 5, 10 or 20 Xg SRIF per 100 kg BW concurrent with 3 ug GRF per 100 kg BW. SRIF delayed (P < 0·05) the occurrence of maximum GH concentrations but did not affect the maximum concentration nor the area under the GH response curve (AUC) following either the first or second GRF injection. Utilizing data from experiment 4, individual animal response to GRF was reasonably consistent, as repeatabilities of AUCs for 1 h following first and second GRF injections were 0·80 and 0·65, respectively. Furthermore, sufficient among-animal variation existed so that animals could be distinguished from each other. Thus we conclude the method described herein might be useful in identifying superior dairy calves but accuracy would potentially be enhanced by collecting blood samples more frequently during the 20 min immediately after GRF injection.

The potential of the spot urine sampling technique as an alternative to performing a total urine collection was evaluated. Twelve multiparous Holstein-Friesian cows were given two experimental diets in a complete change-over design using two 14-day experimental periods. Experimental diets were either silage offered ad libitum with 7 kg fresh weight concentrate supplement as a single meal (SF), or a complete diet formulated from the same ingredients with a similar foragexoncentrate ratio (CD). Total urine collections were performed every 2 h on days 11 and 14 of each experimental period. Subsamples of urine were stored at 20°C and subsequently analysed by high-performace liquid chromatography. Daily allantoin and purine derivative (PD) excretion were highly correlated (r = 0·995, no. = 48, P < 0·001). PD and creatinine excretion during each 2-h interval depended on time of collection (PD, P < 0·001 and creatinine, P < 0·05) and on cow (P < 0·01) but were unaffected by sampling day or treatment. Diurnal variations in the molar ratio ofPD or allantoin to creatinine (PD/c and Ale, respectively) followed similar diurnal patterns as observed for PD and allantoin excretion. The data were used to assess the error of prediction of daily mean PD/c or Ale ratios. Three spot sampling regimens (based on the collection of four 4-h samples, three 8-h samples or two 12-h samples) and also on either single or 2-day urine collections were evaluated. Collection of multiple samples within a day was more reliable than collecting fewer samples over several days. Prediction errors were greater for SF compared with CD. Even the most intensive sampling regimen did not allow an acceptable prediction of daily mean PDIc or Ale ratio, minimum r values for PDIc and Ale ratios were 0·098, 0·136 and 0·547, 0·579 for SF and CD, respectively. Furthermore, daily mean PDIc and Ale ratios proved poor predictors of daily PD and allantoin excretion (r values of 0·69 and 0·72, respectively). Total urine collection appears necessary to assess accurately daily PD excretion in dairy cows.

Somatic cell count (SCO data collected on individual cows since 1991 were obtained from National Milk Records. Following validation genetic and phenotypic parameters were estimated from the lactation average SCCfor 63 424 Holstein/Friesian (HOD, 7966 Ayrshire (AYR) and 14 509 Jersey (JER) animals. The first three lactations were included in the analyses. The heritabilities (h2) for first lactation log SCC (LSCC) were 0·11 (s.e. 0·01), 0·12 (s.e. 0·02) and 0·09 (s.e. 0·03) for the HOL, JER and AYR breeds respectively. Estimates for herd sire interaction (c2) effects ranged from 0·01 to 0·02. Analysis of the first three lactations with a repeatability model produced similar h2 and c2 estimates. Permanent environment estimates ranged from 0·21 to 0·25. Heritabilities of individual test day LSCC ranged from 0·04 (s.e. 0·02) to 0·10 (s.e. 0·03). Genetic correlations between SCC and milk, fat and protein yield for the HOL breed were 0·06 (s.e. 0·05), 0·14 (s.e. 0·06) and 0·09 (s.e. 0·06) respectively. Genetic evaluations were obtained for 666 595 and 9136 animals for Holsteins and Ayrshires, providing evaluations on 13 525 and 1713 bulls respectively in each breed. The range of LSCC predicted transmitting abilities (PTA) was ±25% although the proportion of bulls with reliability > 0·50 was low at 0·17 and 0-05 for HOL and AYR respectively. The correlations between the LSCC PTAs for HOL bulls with at least 50 daughters and their genetic evaluations for linear type were essentially zero for body and some udder traits. Significant negative correlations were obtained for a number of traits including foot angle (0·14), fore-udder attachment (0·19) and udder depth (0·19) and a positive correlation for teat length (0·15). SCC evaluations will be implemented by the Animal Data Centre. Reliabilities will be lower than production because of the lower h2 for SCC and the lower progeny group size since only 0·80 of recorded cows have SCC records.

The Dairy Information System (DAISY) was developed to record fertility and health information for use in research and to help farmers manage their farms. Data from 33 herds recording health and fertility over a 6-year period were used to study genetic relationships of several health, fertility and production traits. There were 10 569 records from 4642 cows of all parities. These were used to estimate genetic parameters for health: mastitis, lameness and somatic cell score (SCS), for fertility: calving interval, days to first service, conception to first service and for production: 305-day milk, butterfat and protein yields. Heritabilities for these traits were also estimated for the first three lactations. (Co)variances were estimated using linear, multitrait restricted maximum likelihood (REML) with an animal model. Mastitis and lameness were treated as all-or-none traits. The incidence of these diseases increased with lactation number, which may lead to variance component estimation problems, as the mean is linked to the variance in binomial distributions. Therefore, a method was used to fix the within-lactation variance to one in all lactations while maintaining the same mean. The heritability for SCS across lactations was 0·15. Heritabilities for other health and fertility traits were low and ranged between 0·013 and 0·047. All genetic correlations with the production traits were antagonistic implying that selection for yield may have led to a deterioration in health and fertility. The genetic correlation between SCS and mastitis was 0·65 indicating that indirect selection for improvements in mastitis may be achieved using somatic cell counts as a selection criterion. The potential use of linear type scores as predictors of the health traits was investigated by regressing health traits on sire predicted transmitting abilities for type. The results indicate that some type traits may be useful as future selection criteria.

The size and composition of three herds belonging to Maasai pastoralists were monitored for more than 5 years (1990 to 1996). Animals were categorized as either suckling calves, weaned heifers, weaned males or breeding females. The dates of entries and exits were used to estimate the total number of observed animal days for each category. Fertility rates of breeding females and mortality and disposal rates for each category were estimated using animal days as the denominator. Herd differences were tested using contingency tables. Age to first calving and calving intervals were estimated and examined using analysis of variance tests.

The patterns of births and deaths were seasonally influenced. The mean annual calving rate of all breeding females was 65·6% and for females excluding first calvers was 46·9%. No herd effects were observed. The mean observed interval between calvings was 609 days and the calving interval, calculated from the parturition rate, was 649 days with no herd differences. Mean age at first calving was approximately 4 years with no herd differences. Mean annual mortality rates were 8·9% for breeding cows, 7·8% for weaned males, 6·7% for weaned heifers and 22·1% for calves. The mean annual culling rate of cows was 10·8% and the sale rate of heifers and weaned males was 12·9% and 41·5% respectively. The mean age at disposal of heifers was 655 days and of steers was 801 days. Herd sizes were shown to fluctuate annually with no obvious trend between herds. The main determinants of production identified were the effect of seasonally poor nutrition on the rate of reproduction and the effect of season, herd mobility and disease on mortality.

The study describes production levels that can be used to predict future changes to the system. The results are discussed in terms of the factors influencing and their relevance to pastoral development. The findings are compared with those observed in other, similar areas.

Thirty-two N'Dama bulls aged 3 to 4 years were used to study the interactions between work, trypanosomosis and nutrition. The bulls were randomly allocated to two treatments, working (W) and non-working (N). Half in each treatment were placed on an andropogon hay basal diet (B), the other half on a better quality groundnut hay diet (H). Five days a week, four pairs of animals in the BW group and and four pairs in the HW group pulled weighted sledges four times around a 2056-m track. Loads were set to ensure energy expenditure was equivalent to 1·4 times maintenance. After 4 weeks all 32 bulls were injected intradermally with 104 Trypanosoma congolense organisms. The trial continued for a further 8 weeks.

Trypanosome infection caused a significant (P < 0·001) decline in packed cell volume (PCV), and the anaemia was more severe (P < 0·05) in working animals; three pairs in the HW group and two pairs in the BW group were withdrawn because PCV fell below 17%. Diet had no effect on PCV or parasitaemia. Infection caused a decline in food intake (P < 0·001) but with significant interactions between diet and work. Intake patterns were similar in the BN and BW groups whilst the HW animals consumed significantly more groundnut hay compared with the HN group (P < 0·01). However, nutrition had no significant effect on lap times or the team's ability to work under trypanosomosis challenge. Post-infection, diet was the dominant factor determining weight change, HN and HW animals weighed significantly more than BN and BW animals (P < 0·01) and the interaction between period, diet and work demonstrated that BWhad the lowest weights in the latter stages of the trial (P < 0·05).

The results suggest that supplementation with better quality forages confers no benefit to an animal infected with trypanosomes. Nor can trypanotolerant cattle sustain long periods of work if subiected to a primary challenge of trypanosomes.

A deterministic simulation model was constructed to develop breeding objectives and estimate biological and economic values. The model simulates life-cycle production of a breeding cow and growth performance of her offspring. Input variables are divided into four categories: animal traits, nutritional variables, management variables and economic variables. The economic variables assume typical beef cattle production in Japan. The outputs from the model include cow-calf performance, feedlot performance and biological and economic efficiency. The model's ability to simulate herd composition, food intake of cow and calves, cow body-weight changes, empty body and carcass composition of feedlot animals and production efficiencies is illustrated.

A deterministic bio-economic model simulating beef production during the life cycle of a cow and her offspring was used to estimate biological and economic values of daily gain, marbling score, birth weight, weaning weight and mature weight for three production systems (cow-calf, feedlot and integrated) and alternative production circumstances in Japan. Biological efficiency (live-weight basis and lean-weight basis) and economic efficiency (returns over costs) were regarded as breeding objectives. Alternatives included reducing the maximum number of reproductive cycles, marketing by constant slaughter weight (BASE), constant age or constant carcass fat content, lighter slaughter weight and doubling food prices. Biological efficiency on a live-weight basis for the cow-calf system was most influenced by increasing weaning weight; for the feedlot and integrated system, increasing daily gain had the largest influence. For biological efficiency of lean production, increasing daily gain and mature weight had the largest influence in the feedlot and integrated systems, respectively. For economic efficiency, increasing weaning weight was most beneficial in the cow-calf system and increasing marbling score was most beneficial in the feedlot and integrated systems. Economic values of daily gain and weaning weight decreased markedly with increasing genetic levels of these traits. Marketing by age decreased the biological values of daily gain but increased the economic value of daily gain. Marketing at a constant carcass fat content decreased biological values of mature weight but increased the economic value of mature weight. Decreasing slaughter weight provided negative economic values of daily gain and weaning weight. Economic values were reduced when food prices were doubled.

Thirty crossbreed steer calves were randomly assigned to one of three feedlot treatment groups to evaluate the effectiveness of diatomaceous earth (DE) as an anthelmintic treatment and its effect on subsequent growth performance. Steers were adapted to a cereal-based diet for 15 days on the farm of origin and given an additional 21 days to adjust to the feedlot diet. Calves had not been dewormed prior to starting the study. On day 0 (2 January 1996) the positive control group of steers (CONV; no. = 11) was given 10 mg/kg of albendazole, a second group began receiving (on day 2) 0·3 kg of diatomaceous earth (DE; no. = 9) mixed daily with their food for 46 days and the negative control group (CTRL, no. = 9) received no anthelmintic treatment. Rectal faecal samples were collected upon arrival at the feedlot and the resulting egg counts showed that all steers were positive for nematodes and coccidia. Faecal samples were collected on days 0, 15, 28 and every 28 days thereafter to determine faecal egg counts. The last sample was taken on the day of slaughter. On day 0, the average count for all calves was over 70 eggs per g faeces (epg) for trichostrongyle type eggs; counts for Nematodirus sp., Strongyloides sp., Trichuris sp. and Capillaria sp. were negligible. CTRL and DE steers had higher parasite levels than CONV steers during the 1st (P < 0·01) and 2nd months (P < 0·05) after treatment. Egg counts for CTRL and DE groups decreased in March and none of the groups differed (P > 0·05) significantly for the remainder of the study. Coccidia levels decreased over time similarly for all groups. Offering 20 g DE per kg food intake for 46 days to beef steers on a high cereal -based diet had no effect (P > 0·05) on body weight, average daily gain, dry-matter intake, food conversion or days on food compared with the untreated control steers. Cumulative food conversion during the first 2 months was better for CONV than for DE and CTRL steers (P < 0·01) but did not differ between the latter two groups (P > 0·05). Cumulative food conversion for the rest of the study remained the same for all groups (P > 0·05). CONV calves required fewer days on food than DE calves (P < 0·05) but about the same number as CTRL calves (P > 0·10). Steers in the DE group required a similar number of days on food (230·22 ± 7·86 days) to reach target end points as CTRL steers (218·75 ± 8·34 days; P > 0·05) but more days than CONV calves (201·64 ± 7·11 days; P > 0·05).

The accumulative effects of different levels of annual energy intake over the first two parities on four breeds of beef cow (small size and low milk potential, Aberdeen Angus; small size and high milk potential, Welsh Black; large size and low milk potential, Charolais; and large size and high milk potential, Simmental) were assessed for various production traits and calf performance. Heifers were allocated to each of two levels of annual energy intake relative to metabolic body weight (M0·75) (mean daily intakes equivalent to 705 and 820 kj M0·75) and for the next 2 years these animals (10 per breed) were continuously housed and given diets designed to represent energy intakes while grazing during the summer and conserved forage feeding during the winter. Changes in live weight and body composition were measured throughout both years and milk yield, milk composition and calf performance during both lactations.

Animals from each of the four breeds gained weight but lost body condition during their first two parities in a manner that was dependent on their annual level of dietary energy intake. Welsh Black cows grew more than Aberdeen Angus cows and Charolais cows more than Simmental cows so that, by weaning during the second parity, the rank order of live weights between breeds was Charolais > Simmental > Welsh Black > Aberdeen Angus. Welsh Black and Simmental cows produced higher yields of milk (7·9 and 8·7 kg respectively) than Aberdeen Angus and Charolais cows (6·5 and 5·7 kg respectively; P < 0·001). Calves from the two large breeds grew more quickly than those from the two small breeds (1·13 v. 0·99 kg/day; P < 0·01) and calf performance was influenced by milk consumption. Biological efficiency, defined as weight of calf at weaning per GJ metabolizable energy (ME) on an annual basis, increased as annual energy intake decreased and tended to be higher for large breeds on 33 GJ ME per year than for small breeds on the same level of annual energy intake (7·19 v. 6·75). The complex means by which the different breed types interacted with their nutritional environment is discussed.

The metabolic status and reproductive performance of four pure breeds of beef cow (small size and low milk potential, Aberdeen Angus; small size and high milk potential, Welsh Black; large size and low milk potential, Charolais; and large size and high milk potential, Simmental) were monitored during their first two parities. Heifers from each breed were allocated to one of two levels of annual energy intake relative to metabolic body weight (M075) (mean daily intakes equivalent to 705 and 820 kj/kg M0·75) in a factorial design. In the 1st year 64 heifers (eight per treatment) which had calved as a consequence of first or second service were selected for the experiment. In the 2nd year 40 of these animals (five per treatment) which held to first or second service remained on experiment. Animals were housed all year round and given diets designed to represent energy intakes while grazing during the summer and conserved feeding during the winter. Pregnancy was established in late July of each year using a combination of oestrous synchronization and artificial insemination. Blood samples were collected at monthly intervals from weaning in November until calving in May; three times weekly from calving until oestrous synchronization (11 weeks later); and fortnightly thereafter until weaning.

For the annual levels of dietary energy intake offered, two breeds (Welsh Black and Charolais) exhibited relatively high growth rates and had the longest post-partum anovulatory periods; and Charolais cows also had the poorest conception rates of all breeds. Relatively lean cows at calving (body condition score < 2·5 units) were sensitive, in terms of the duration of the anovulatory period, to live-weight loss during the early post-partum period, particularly when blood glucose levels were low, whereas relatively fat cows at calving (body condition score > 2·5 units) were not. The data suggest: (i) that mechanisms controlling the anabolic processes governing maternal growth are antagonistic towards those that control reproduction; and (ii) the catabolism of lean tissue rather than fat tissue during the early post-partum period is also antagonistic towards the mechanisms that govern reproductive function in cows.

Thirty single-bearing Merino ewes were used to examine the effect of feeding supplement, from 91 to 140 days of gestation, on changes in chemical composition of the ewes, on the relationships with live weight and body condition score and on the foetus. Ewes grazed a perennial ryegrass pasture and were offered either no supplement or 500 g per head per day of a concentrate supplement from days 30 to 90 and (or) from days 91 to 140 of pregnancy. Maternal carcass and non-carcass components, uterine wall, foetus and placenta plus cotyledons were chemically analysed. Live weight (LW) and body condition score (BCS) on day 140 were both affected by supplementation during late pregnancy, mobilization of protein and fat being lower in animals receiving supplement. BCS accounted for more variation than LW in the carcass fat depot. Because this depot was the most important source of energy from days 91 to 140 of gestation, this suggests that BCS is a useful estimator of mobilization of maternal fat reserves during this stage of pregnancy. The ability to mobilize reserves and protect foetal growth by Merino ewes in southern Europe, where large fluctuations in grass growth rate exposes them to considerable undernutrition as pregnancy proceeds, was confirmed in this experiment. However, when the nutritional regime is extreme, supplementary feeding to the ewes is recommended, in order to make the whole system economically profitable.

In a feeding experiment β-hydroxybutyrate (BHB), glucose, albumin, total protein, globulin and urea concentrations in the plasma of twin-bearing ewes were analysed. Mature Suffolk cross ewes were given either formic acid (FA)-treated grass silage or grasslmolassed sugar-beet pulp (MSBP) silage in late pregnancy. The experiment commenced on day 91 of pregnancy and the dietary treatments were FA-treated silage (Tl), FA-treated silage + soya-bean meal (SBM) (T2), MSBP silage (T3), MSBP silage + SBM (T4), FA-treated silage + MSBP (T5), FA-treated silage + MSBP + SBM (T6) or FA-treated silage + 150 g crude protein (CP) per kg concentrate (T7). SBM was given only in the last 22 days of pregnancy aiming for a total CP intake of 220 g per ewe per day. Blood samples were collected by jugular venipuncture from each ewe 3 h following consumption of the morning dietary allowance on days 121, 128, 135 and 142 of pregnancy. Daily metabolizable energy (ME) intakes of 6·8, 11·4, 9·6, 12·8, 10·5, 13·7 and 14·7 (s.e. 0·58) MJ per ewe were recorded for Tl to T7 respectively over the last 3 weeks of pregnancy. Respective CP intakes of 72, 213, 110, 225, 109, 215 and 175 (s.e. 5·64) g per ewe were recorded for Tl to T7 respectively over the last 3 weeks of pregnancy. BHB concentrations (mmol/l) on day 121 of pregnancy of 1·18, 1·25, 0·52, 0·52, 0·56, 0·39 and 0·45 (s.e. 0·17), on day 128 of pregnancy of 1·17, 0·94, 0·52, 0·51, 0·72, 0·62 and 0·39 (s.e. 0·20), on day 135 of pregnancy of 1·53, 0·68, 0·68, 0·66, 0·71, 0·62 and 0·46 (s.e. 0·20) and on day 142 of pregnancy of 1·43, 0·60, 0·62, 0·56, 0·62, 0·56 and 0·63 (s.e. 0·20) were recorded for Tl to T7 respectively. There was a quadratic relationship between plasma BHB concentration and ME intake on days 121 (R2 = 0·538, P < 0·001), 128 (R2 = 0·324, P < 0·001), 135 (R2 = 0·429, P < 0·001)) and 142 (R2 = 0·344, P < 0·002) of pregnancy. There was a positive relationship between plasma glucose concentration and ME intake on day 222 (R2 = 0·208, P < 0·002), 228 (R2 = 0·203, P < 0·05), and 135 (R2 = 0·160, P < 0·02) of pregnancy. Albumin concentrations (gll) on day 128 of pregnancy of 21·8, 21·7, 23·6, 22·9, 22·5, 22·9 and 24·3 (s.e. 0-75), on day 135 of 20·9, 23·6, 24·2, 24·1, 22·4, 24·1 and 23·8 (s.e. 0·75), and on day 142 of 16·9, 22·6, 20·7, 22·2, 20·4, 22·7 and 21·1 (s.e. 1·05) were recorded for Tl to T7 respectively. Plasma albumin concentrations were significantly affected by SBM supplementation (P < 0·05). Despite the lower than generally recommended energy concentrations in T2 to T7, the concentrations of plasma BHB were within the normal range for healthy sheep.

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.

An experiment was conducted to evaluate the feeding characteristics and the productive responses of lamb diets containing increasing levels of dried brewers' grains (DBG). Five groups of six 70-day-old Bergamasca lambs were housed in individual pens and given ad libitum for 9 weeks pelleted diets containing 200 g/kg of concentrate and 800 g/kg of a mixture of DBG and lucerne hay in the ratios of 0:80 (DBG0), 20:60 (DBG20), 40:40 (DBG40) 60:20 (DBG60) and 80:0 (DBG80). During the last 12 days of the experimental period, a digestibility trial was carried out for each diet. After this, all the lambs were slaughtered and the composition of the empty body weight was determined. The initial composition of the empty body was estimated from the composition of a sixth group of lambs slaughtered at the beginning of the trial.

The apparent digestibility of dry matter (DM), organic matter, crude protein, ether extract, neutral-detergent fibre and energy increased with the proportion of DBG. The daily DM intake relative to metabolic body weight (M0·75) diminished significantly with the increasing proportion of DBG in the diet, from 127 g/kg M0·75 for diet DBG0 to 83 g/kg M0·75 for diet DBG60. The daily live-weight gain and food DM conversion efficiency were highest with the intermediate diets (414 g/day with diet DBG40 and 240 g/kg DM with DBG60), showing a quadratic trend, an indication of a positive interaction between DBG and lucerne hay. The fat content of the live-weight gain was particularly high in the lambs given the diet with the highest proportion of DBG. It was concluded that DBG may be profitably used in growing-fattening diets for lambs in a proportion not exceeding about 400 g/kg DM.

Two experiments were carried out with Scottish Blackface lambs to investigate the effects of restricted nutrition during pregnancy and lactation on voluntary food intakes (VFI) between weaning and 2 years of age. Ewes were given diets providing 0·7 (LP) or 10 (HP) of their estimated metabolizable energy requirements during the last 6 weeks of pregnancy and subsequently grazed swards with mean sward surface heights of approximately 3 cm (LL) or 6 cm (HL) during lactation. All lambs were weaned at 17 weeks of age. In experiment 1, four treatment combinations (LP-LL, LP-HL, HP-LL and HP-HL) were applied and female lambs were studied. In experiment 2, two treatment combinations (LP-LL and HP-HL) were applied and male lambs were studied. In both experiments the lambs received a common level of nutrition between weaning and 2 years of age.

In both experiments, mean live weights were proportionately 0·2 higher for HP-HL than for LP-LL lambs at weaning (P < 0·001) and in experiment 2 mean live weights and body condition scores were still higher in HP-HL than in LP-LL lambs at 2 years of age (P < 0·05). Abomasum weights were higher in HP than in LP lambs at birth and higher in HP-HL than in LP-LL lambs at weaning in experiment 1 and the weights of the rumen and dimensions of the rumen villi were greater in HP-HL than in LP-LL lambs at weaning in both experiments (P < 0·05). The treatments had no effect on lipid content or mean adipocyte diameter in the main fat depots at birth or weaning. There were no treatment effects on VFI in either experiment. It was concluded that restricted nutrition during late pregnancy and early lactation does not affect VFI between weaning and 2 years of age in sheep, even though there are differences in live weight and the development of the gastrointestinal tract at weaning and there may be long-term effects on live weight and body condition, particularly in male animals.

Previous results have shown that certain phenotypes of Angora goat differ in respect of glucose metabolism and it has been proposed that this is linked to the high incidence of abortions in this breed. The aim of this experiment was to investigate adrenal function, food digestion and nutrient partitioning as possible causes of differences in glucose metabolism between a phenotype which produces a relatively large amount of mohair of a large fibre diameter (high producers) and a phenotype which produces less mohair of a smaller fibre diameter (low producers). Two groups consisting of 15 3-year-old Angora bucks each and representing two different phenotypes were given a maintenance diet for the duration of the trial. Plasma glucose concentrations during a 4-day fast were lower (P < 0·01) in high producers than in low producers and plasma glucose concentrations following insulin injection also fell to a greater extent in high producers than in low producers (P < 0·05), indicating that high producers were less able to mantain plasma glucose concentrations during periods of increased demand than low producers. The decrease in glucose concentration following insulin injection was accompanied by a rise in plasma cortisol concentrations until 60 min after the insulin injection but there were no differences between phenotypes (P > 0·05). Similarly, cortisol concentrations rose to a peak 60 min after ACTH injection and there were no differences between phenotypes (P > 0·05). In both instances, the pattern of cortisol concentrations was consistent with normal adrenal function and there were no indications of adrenal insufficiency. Although differences in digestion were observed between phenotypes (P < 0·01), these were small. There were no differences in nitrogen (N) intake or retention (P > 0·05). High producers deposited substantially more (proportionately 0·56) N as fleece than low producers (P < 0·01), and partitioned a greater proportion of N intake to fleece production (P < 0·01). It was concluded that adrenal insufficiency was not implicated in the observed differences in glucose metabolism between phenotypes but differences in digestibility and nutrient partitioning may play a role.

An experiment was carried out to investigate the proposal that the voluntary food intake of pigs, when given foods based on bulky materials, can be accurately predicted from the water-holding capacity (WHC, g water per g dry food) values of the foods. A basal food (B), with 12·9 MJ digestible energy and 249 g crude protein per kg dry matter, was diluted to two extents by either sugar-beet pulp (S), grass meal (G) or soya hulls (H). The contents of the bulky materials in the total diets were either 320 g/kg (foods BS, BG and BH) or 800 g/kg (foods S, G and H). Each of these six foods was given ad libitum to six pigs in period I, which lasted for 21 days, with a further four given B. In period II, which lasted for 14 days and followed period I immediately, the pigs were also given their food ad libitum. Only the 36 pigs from the six ‘bulky“treatments (i.e. on treatments other than B) continued in a change-over design. Two pigs from each of the six ‘bulky’ treatments were allocated to the three foods of the same level of dilution (e.g. the six pigs from BS were changed to BS, BG and BH). Of the ‘bulk’ characteristics measured (crude fibre, acid-detergent fibre, neutral-detergent fibre, apparent digestibility of the organic matter, density and WHC) only WHC accounted sufficiently for the effects of the foods on the voluntary food intake of the pigs. The two methods of centrifugation and filtration that were used for the WHC determination were very highly correlated (r = 0·978), with food B having the lowest value, 3·86 g water per g dry food, and food S having the highest value, 8·48 g water per g dry food, when measured by centrifugation. In both periods the rate of intake was calculated as g/kg live weight per day, scaled intake (SFI). Live-weight gain and food conversion efficiency both decreased significantly (P < 0·001) as B was diluted with S, G and H. For the six ‘bulky’ feeding treatments SFI in the last 14 days of period I was proportional to the reciprocal of the WHC of the foods: SFI (g/kg per day) = 235 (s.e. 6·3). No effects of previous feeding treatment on site were observed in period II as a whole; however, intake initially increased when the food had lower WHC than the one previously offered and decreased when it had higher WHC. It was concluded that: (a) the WHC of a food is a sufficient descriptor of its ‘bulk’ and that it accounts for the effects on the voluntary food intake of pigs; (b) the detailed methods used for measuring WHC need to be standardized; (c) pigs can adapt more rapidly to bulky foods when they have had prior experience of such foods; (d) the length of time needed to observe an intake, which will be characteristic of the bulky food on offer, depends on the prior experience of the pig.

In order to evaluate the effect of exercise training and spontaneous physical activity on growth performance, carcass composition, and locomotory ability 48 female and 48 entire male pigs were subjected to one of three treatments: individual housing in pens of 2-5 m2 (confined; C), individual housing and treadmill training for 15 minlday at a speed of 4 km/h, 5 days/week for a period of 70 days (trained; T) and group-housing equal to 0·9 m2 per animal (free; F). Pigs in treatment C and T did not differ with regard to daily gain, food intake, kg food per kg gain and carcass lean content. Training did, however, induce significant cardiac hypertrophy (by a proportion of 0·06). In treatment F (i.e. large pens), daily gain was 135 g lower than in treatment C. Dissection of the carcasses showed that treatment F increased the weight of m. psoas major (by 30 g) and the total carcass bone mass (by 130 g) when compared with treatment C. Proportions of carcass lean and intramuscular fat were unaffected by treatment F. Likewise, leg weakness and osteochondrosis did not differ between treatments, whereas the locomotory ability was positively affected by rearing in large pens (treatment F) but not by treadmill training (treatment T). Thus, physical activity in large pens induced various adaptations throughout the body.