In three experiments, four grass silages and four grass hays were offeredad libitum to a total of 164 Finn Dorset ewes rearing twins in the 1st month of lactation. In addition, one of three constant daily levels (300, 650 or 1000 g fresh weight per ewe) of a barley-based concentrate was offered. In the first experiment, replacement rate of silage with in vitro organic matter digestibility (OMD) of 0·65 was less than for hay (OMD 0·59), at –0·09 v. –0·62 g forage OM per g concentrates OM. Consequently, lamb growth rate was greater and ewe weight loss was less with increased concentrate level for the silage than for the hay. In the second experiment, the replacement rates of three silages (OMD 0·56, 0·60 and 0·67) were not significantly different (mean –0·29) and, once again, increased concentrate level gave significantly better ewe and lamb performance. Finally, the replacement rates for three hays (OMD 0·51, 0·59 and 0·72) were also not significantly different (mean –0·30). Equations are presented to predict the intakes of hays and silages by ewes in early lactation.

Twelve Large White × Landrace boars, initial mean live weight (kg) 5·51 (s.e. 0·8) were offered cereal-based diets containing 0 (diet C) or 150 g sugar-beet pulp per kg (containing no molasses or other additive) (diet 15SB) and the indigestible marker titanium dioxide from 21 to 57 days of age. The daily intakes, live-weight gains and food conversion ratios of the piglets were monitored from day 28. The apparent digestibilities of nitrogen (N), gross energy (GE) and non-starch polysaccharides (NSP) were measured on days 32 and 56. There were no significant differences either in voluntary intakes, or in the daily live-weight gains and food conversion ratios between the two diets. Likewise, there were no significant differences in the apparent digestibility of N and GE of the two diets. However, the capacity at 56 days of age to digest N from diet 15SB was greater than at 32 days of age. The apparent digestibility of total NSP at both 32 and 56 days of age was significantly greater for diet 15SB (averaging 0·75) than for diet C (averaging 0·54) (P < 0·001). The major NSP components of diet 15SB were arabinose, glucose and uronic acids, but the predominant NSP constituents of diet C were arabinose, xylose and glucose. The apparent digestibilities of arabinose (P < 0·05), mannose (P < 0·05), glucose (P < 0·05) and uronic acids (P < 0·001) were significantly greater from diet 15SB than from diet C. The apparent digestibility of NSP components from both diets tended to increase with age of piglet. These results are discussed in relation to the early establishment of an efficient gut microflora and indicate that the fermentative capacity of very young pigs may be higher than previously thought.

Three experiments were conducted to investigate the effect of genotype on the morphological characteristics, chemical composition and feeding value of nine chopped barley straws, and responses of the feeding value to a supplement of soya-bean meal (SBM). In experiment 1, the straws were offered ad libitum to 12 wethers and measurements were made of straw intake and dry (DMD) and organic (OMD) matter digestibility using a balanced lattice design with three periods. Experiment 2 used the same experimental design but the straws were offered ad libitum with 200 g SBM. Experiment 3 measured the dry matter losses (DML) of ground straws from nylon bags placed in the rumen of three wethers. The extent (b) and rate (c) of DML were estimated using the equation DML = a + b(l – ect).

There were significant differences in the stem height (P < 0·001), leaf proportion (P < 0·001), and protein (P < 0·001) and modified acid detergent fibre (P < 0·01) concentrations between the straws. Significant (P < 0·05) effects of genotype on intake were seen but the variation in intake between them decreased when the protein supplement was added. Effects of genotype on DMD (P < 0·05) and OMD (P < 0·05) were seen in unsupplemented straws and differences of OMD (P < 0·05) were still apparent when SBM was given with straw. Although there were significant (P < 0·05) differences in DML after 48 h incubation, the constants b and c were similar (P > 0·05) across the genotypes. Protein concentration in the straw, although closely correlated with intake, appears to have less value as a predictor of feeding value than previously thought.

The effect of degree of saturation (ratio of unsaturated to saturated fatty acids, U/S) and free fatty acid (FFA) content of fats upon their digestible energy (DE) values was investigated in post-weaning pigs. The two fats evaluated were soya-bean oil (SO) and tallow (T) (representing extremes of saturation) together with their acid oils (SAO and TAO respectively) providing high FFA levels). Blends of the four fats provided treatments with varying FFA content and U/S ratios. The experimental fats were evaluated by substitution, at 40, 80 and 120 g/kg into a basal diet, in a randomized-block design, with 98 gilts and 98 boars of approximately 12 kg live weight. Pigs had been weaned at 28 days of age and experimental diets were given 7 days after weaning. When pigs obtained a weight of 10 kg the inert marker titanium dioxide was added to the diets as a reference substance. A 5-day adjustment period was allowed followed by a 5-day collection period of faeces by grab sampling. Fat content of food and faeces, with methodology based on acid hydrolysis, allowed calculation of apparent digestible fat (AFD) of experimental diets. Analysis of variance demonstrated effects of fats, rates of inclusion, and fats × rates (P < 0·001 in all cases). There was no effect of sex. Extrapolation of the function obtained by regressing AFD of diets (y) on rate of inclusion of fat (x) to × = 1000 generated values for the fats. The product of the coefficient of fat apparent digestibility of fats and their respective gross energies gave DE values for fats which were: SO = 37·2 MJ/kg, SAO = 35·0 MJ/kg, T = 34·3 MJ/kg and TAO = 27·4 MJ/kg. Data for fat blends intermediary between these fats showed that DE improved as a function of U/S and that DE declined linearly with increasing FFA content.

A 2 X 3 factorial experiment was designed to study the consequences of feeding strategy during rearing and pregnancy over eight parities on sow growth and body condition. Two hundred and fifty-four gilts were group-fed on a restricted scale rising to either 2·25 (L) or 2·70 (H) kg/day (12·5 MJ/kg digestible energy (DE), 193 g/kg crude protein (CP) diet) from 70 to 175 days of age. A total of 156 of the L and H gilts were then given either 1·8 (l), 2·1 (m) or 2·4 (h) kg/day during subsequent pregnancies (12·9 MJ/kg DE; 177 g/kg CP diet). The same diet was offered to a standard scale during lactation. Sows were group-housed in pregnancy and given straw bedding. Losses of sows in rearing and each parity were not associated with treatment. After rearing, data have been presented only for those sows which completed eight parities. At 175 days of age, H gilts had grown faster (P < 0·001). From 175 days to service all gilts were given the same feeding regime but L gilts put on significantly more weight than H gilts, exhibiting more efficient utilization of food. There were no statistically significant differences in weights between L and H sows after the third pregnancy but L sows gained more weight than H sows in most pregnancies. The sows grew in each parity, indicating mature body size was not achieved. The pregnancy regimes had a significant (P < 0·05) effect on live weight, P2 backfat measurement, body length, neck circumference and condition score. Pregnancy treatment h produced the heavier and fatter animals but not all treatment l sows maintained adequate backfat levels for six parities. When housed in groups and given a generous supply of straw, the nutritional requirements of sows to sustain growth and body condition suitable for a long life may be less than has been previously identified for sows housed on concrete and slats without bedding.

Two experiments were performed to evaluate the influence of relaxin on the fertility of gilts inseminated with aged boar semen. For experiment 1, oestrus was induced in 43 Yorkshire × Landrace gilts by injection of 400 i.u. PMSG plus 200 i.u. hCG. At 24 h after oestrus detection, gilts were inseminated with fresh semen (1 to 2 day old; no. = 15), aged semen (5 to 6 days old; no. = 15) or aged semen containing 400 fig/l of relaxin added at the time of semen extension (no. = 13). Pregnancy rates 24 days after insemination were lower in gilts receiving aged semen (P < 0·05), an effect not prevented by added relaxin. There was no effect of either semen age or relaxin on numbers of embryos. In experiment 2, the ejaculates of eight boars were extended with or without the addition of 400 fig/I relaxin and motility monitored for 7 days. Fresh sperm motility decreased from 87-5 (s.e. 2·5)% at collection to 71-2 (s.e. 3·3)% after 7 days. The attenuation of sperm motility was not affected by relaxin.

Experiments were carried out to establish the suitability of full fat neem seed meal (FFNSM) in broiler and growing rabbit diets. In the broiler experiment, 200-day-old (Babcock) broiler chicks were used in a 10-week trial, with the FFNSM fixed at 0 (control), 25, 50, 75 and 100 g/kg diet. In the rabbit experiment 24 rabbits of three different breeds were used in an 8-week trial, with the FFNSM fixed at 0 (control), 100, 200 and 300 g/kg diet. The criteria of response were food intake, weight gain, food conversion and protein efficiency ratio and mortality. There was a significant (P < 0·05) negative correlation between the dietary inclusion of FFNSM, weight gain and food conversion efficiency of the birds in the starter phase. In the finisher phase from 5 to 10 weeks, food intake, weight gain, food conversion and protein efficiency ratio did not differ significantly (P > 0·05) between the birds on the control diet and diets containing up to 75 g FFNSM per kg. For all the measurements, rabbits on the diet with 100 g FFNSM per kg gave better results than the control. Food intake, weight gain, food conversion efficiency and protein efficiency ratio did not differ significantly (P > 0·05) between rabbits on control diet and the diet containing 200 g FFNSM per kg. Performance on the diet with 300 g FFNSM per kg was poorest.

Eight non-pregnant, non-lactating adult ewes weighing 56 kg were fed for 26 days on a meadow hay (organic matter 937 g, crude protein 107 g, metabolizable energy (ME) 8·3 MJ per kg dry matter) to satisfy half of their daily energy and protein maintenance requirements i.e. 200 kj ME and 1·3 g truly digestible protein per kg M0·75. They were then allotted to two groups of four each. Control ewes continued to receive the initial diet for another 74 days while the others were supplemented with 60 g/day fish meal to receive 200 kj ME and 2·7 g truly digestible protein per kg initial M0·75 per day.

In spite of its high nitrogen content, the digestibility of the hay was increased by the protein supplementation, e.g. from 0·56 to 0·60 for neutral-detergent fibre and from 0·54 to 0·59 for energy.

The supplemented ewes lost significantly less body weight than the controls (96 v. 134 g/day) essentially because of their higher ME intake (272 v. 252 kj/kg average M0·75 during the experimental period). The measurements of blood metabolites suggest that the daily amounts of mobilized body protein increased with duration of underfeeding. The additional amino acids provided by fish meal were principally used as a source of energy and for wool growth.

Four groups of 10 indigenous goats, suckling indigenous or crossbred, single or twin kids, were used to study the effect of sucking stimulus on milk yield and composition during a 12-week suckling period and over the first 20 weeks of the subsequent milking period. During the suckling period, goats with twins produced more milk (F < 0·001) than those with singles. There was no effect of kid genotype in goats rearing twins but single crossbreds took 1·11 times more milk than indigenous. Goats with single kids had higher concentrations of fat (F < 0·001), protein (F < 0·05) and lactose (F < 0·05) in milk than did those with twins. Growth rate of kids was related to differences in milk intake, with singles higher than twins (F < 0·001) and crossbred singles higher than indigenous singles (F < 0·05). It is concluded that the indigenous breed can respond to the increased sucking demand of twins but not sufficiently to meet their needs. During the milking period the mean yield was reduced to about one-third and was not dependent on the corresponding yield in the suckling period. There were minor differences of milk composition associated with number or genotype of kids suckled.

Cashmere production was evaluated on Scottish feral (F) goats, on goats imported from Iceland (I), Tasmania (T), New Zealand (N) and Siberia (S), and on two- and three-way crosses between feral and imported lines. Evaluations were based on the weight of cashmere in 10 cm2 mid-side patch samples taken at 5 months of age, with annual cashmere production being predicted from sample cashmere and body weights. Data were collected on 121 purebred and 706 crossbred kids of both sexes. Mean fibre diameter for the F, I, T, N and S lines was 13-75 (s.e. = 0.82), 14·04 (s.e. 0·41), 16·13 (s.e. 0·35), 16·63 (s.e. 0·49) and 17·97 (s.e. 0·50) μm, mean estimated annual cashmere production was 37·3 (s.e. 71·3), 914 (s.e. 31·7), 227·1 (s.e. 28·1), 275·1 (s.e. 42·5) and 579·8 (s.e. 44·7) g, and mean live weight was 15·71 (s.e. 2·16), 17·65 (s.e. 0·93), 16·39 (s.e. 0·83), 16·53 (s.e. 1·28) and 21·9 (s.e. 1·28) kg, respectively. Significant positive heterosis existed between some lines for body weight and cashmere production, with the I line goats consistently showing the largest effects. Combining fibre diameter and cashmere production by their relative economic importance into an index designed to indicate the total value of the fibre produced by each genotype, the cashmere production index, reduced the large production differences between the lines, although the S line was still superior to all other lines. When the cashmere production index was adjusted to account for the economic importance of fibre colour, however, the T and N lines, the only lines which produced white fibre, were comparable to the S line. The cashmere production index for the S line was very sensitive to changes in the relative economic weight for fibre diameter, and if the price differential for high quality (i.e. fine) fibre was increased by a factor of 1·36, or greater, then the T and N lines were superior to the S line. Three-way cross means were estimated from line means and heterosis effects. No cross was consistently superior to all other genotypes, but several of the crosses showed the advantages of potentially producing white fibre as well as having high cashmere production indexes, with their indexes being insensitive to changes in the relative economic weights. Future selection for cashmere production in this population should concentrate on individuals of outstanding genetic merit, regardless of their line or cross.

In a study of the growth of various body parts of the ostrich, only the growth of the head could be described with the Gompertz function. The growth of the ostrich head (y in g) with time (x in months) is described by the Gompertz function y = 613 exp[−ln (613/133) exp(−0·26x)]. This information could be used in the design of carcass classification systems.

Electronic feeding systems for progeny testing pigs, allow selection to occur under conditions found on commercial farms. This paper reports on the feeding behaviour of six groups of 10 pigs, balanced for sex and initial body weight (mean starting and finishing weight: 32·1 kg v. 68·5 kg), monitored on such a system, for an average of 38 days. These data represent 26 542 feeder visits for which the pen, identity of the pig, feeder entry and exit times, and the amount of food consumed are known. The results show significant time-of-day effects for frequency of feeder visits, feeding rates, mean feeder occupation time, mean food intake per feeder visit, total food intake and total feeder duration (all P < 0·001). A single peak in feeding behaviour was observed between 13·00 and 16·00 h. Significant pen effects were observed on all feeding variables (e.g. feeder occupation times P < 0·05) with the exception of total food intake (P > 0·05). Individual pigs were found to possess different types of meal regulation, as measured by prandial correlations. Pens were found to have significantly non-random sequences of feeder entries (e.g. yen 1, P < 0·001). The range of feeder visits (three to 69) observed, was higher than reported in any previous study. Physical performance on the system, in terms of gain in body weight and total food intake was best predicted by total feeder occupation time, suggesting that individual pigs could adapt to the physical and social constraints imposed by the system, by altering aspects of their feeding behaviour. The results suggest that feeder access competition resulting from social synchrony and facilitation strongly influenced the feeding behaviour of pigs on this computerized food intake recording system.

The present study was carried out on the pure Bauscat (Bau), pure New Zealand (NZW) and pure Californian (Cal) strains of rabbit. Overall reproductive performance for overdue does of the three breeds was determined and compared with that of does delivering at the normal time. Overdue does of the Bau and NZW breeds had a significantly (P < 0·05) higher annual mean number of pups weaned than overdue Cal does. There was a high incidence of pup mortality in post-mature litters, and the causes of this high mortality were crushing of the skull followed by subsequent stillborn-birth difficulties and intra-uterine death in all three breeds. Obliteration of the anterior fontanelle of pups from post-mature litters occurred in 71%, 75% and 69 % of the deaths diagnosed at birth in the Bau, NZW and Cal breeds, respectively. Induction of parturition with either PGF2α or oxytocin reduced pup mortality in overdue does. The birth-to-remating interval was significantly (P < 0·01) lower in overdue does in which parturition was induced with PGF2∞ but significantly longer when parturition was induced with oxytocin.

Forty-five New Zealand White and 35 Californian doe rabbits, 8 months old and in the third parity of their 1st year of production were used in this study. Thirty-five does were concurrently pregnant and lactating, the remaining 45 does were non-pregnant. Milk samples were collected in colostrum and at the 7th, 14th, 21st, 28th and 35th days of lactation. Neither breed nor pregnancy status affected the does milk composition except for total phosphorus which was significantly lower (P < 0·05) in the pregnant does' milk. However the major components of milk except lactose, were significantly affected by stage of lactation. Both moisture: total solids and calcium: phosphorus ratios were the same (2:1) throughout the lactation. The ratio between retinol concentration in colostrum and in the 5th week was about 10:1. Specific gravity was significantly (P < 0·05) correlated with protein, lactose (positive) and fat (negative).

Pigs with inbreeding coefficients, ranging from 0·125 to 0·375 were analysed for effect of inbreeding on daily carcass gain, body length and meat proportion in the carcass. The foundation animals were back crosses of a Landrace boar of his daughters which were Yorkshire Landrace hybrids. The statistical model included effect of sex and slaughter weight in addition to the effect of inbreeding. A statistically significant effect of inbreeding on daily carcass gain was found with a linear decline of 1·6 g for 0·1 increase in inbreeding coefficient. There was no effect of inbreeding on body length and meat proportion. Carcass weight had a highly significant effect on body length and daily carcass gain. Effect of sex was statistically significant for meat proportion only.