Using a pedigreed population of Drosophila melanogaster, various indices of individual and full-sib family information were compared for predicting progeny performance for bristle score. On average, the indices were 14% more accurate than individual performance or family mean taken separately. Index weights computed a priori from data solely on the parent's generation gave an index almost as accurate as that computed a posteriori by multiple regression of performance of progeny on parents and parent's full sibs. The value of the index was therefore as predicted from theory.

1. The primary growth of perennial ryegrass (Lolium perenne cultivar Endura) was cut on 23 May (high digestibility) and 23 June (low digestibility) and ensiled with an additive consisting of equal volumes of formic acid and formalin to supply 30 g formaldehyde per kg crude protein. The silages were given ad libitum, together with 6·3 kg dry matter per day of a barley/soya bean supplement, to 24 British Friesian cows over weeks 4 to 18 of lactation.

2. The delay in cutting the primary growth led to an increase in grass yield from 3·78 to 6·94t dry matter per ha but a depression in the content of digestible organic matter in the silage dry matter from 748 to 639 g/kg. However, the effect of the digestibility of the silage on the digestibility of the total diet by the cows was small. The silages contained low levels of fermentation acids and ammonia-nitrogen.

3. The digestibility of silage did not influence silage dry-matter intake in early lactation but in mid lactation the intake of the low-digestibility silage declined whilst that of the high-digestibility silage increased slightly.

4. Cows given silage of high rather than low digestibility produced significantly more milk (high, 28·0 v. low, 24·7kg/day, P < 0·01 ) of lower fat content (high, 36·1 v. low, 41·0 g/kg, P < 0·01 ) but higher protein content (high, 31·5 v. low, 29·4g/kg, P < 0·05). Cows given silage of low digestibility lost more live weight than cows given silage of high digestibility but the effect was not significant.

Sixteen Hereford-cross cattle (mean live weight 263 kg) in groups of four were individually given 1·5 kg cubed barley per day with ad libitum access to oat straw. In a 4 × 4 Latin square design (21-day feeding periods) they were additionally given either no supplement (diet A) or 100g/day of a fully soluble liquid supplement containing urea (equivalent to 1090 g crude protein per kg), calcium, phosphorus, sodium, trace elements and vitamins, presented either in the cubed barley (diet B), in the drinking water (diet C) or in a molasses lick (3 parts molasses:2 parts liquid supplement:1 part water) (diet D). Each method of supplementation significantly increased the mean voluntary straw dry-matter intake from approximately 2·9 to approximately 3·25 kg. Mean blood urea concentrations were significantly increased from approximately 1·0 to approximately 1·9 mmol/1 by all three treatments. The coefficients of variation for the individual blood-urea values of the cattle when given each of the three treatments were very comparable, indicating that there was a reasonable individual uniformity of intake of liquid supplement irrespective of method of presentation.

Cassava is increasingly available in the United Kingdom for use in compound feeds. The trial reported here was a 2 × 4 factorial and compared dairy cow compound feeds containing nil or 400 g of cassava per kg, and crude protein levels of 100, 120, 140 and 160 g/kg, given in conjunction with grass silage.

Forty-eight Friesian cows were used in a change-over design with four periods each of 4 weeks. The trial, therefore, compared six blocks of four cows on each of the non-cassava and cassava treatments, with each cow in a block receiving a different protein level. Compound feeds without cassava had a mean barley content of 600g/kg whereas feeds with cassava had a mean barley content of 103g/kg.

There were no significant differences in milk yield (21 14 and 22·27 kg/day) or milk fat level (41·4 and 40·4g/kg milk) on the non-cassava and cassava treatments respectively (P ≤ 0·05). Differences in solids-not-fat concentration were also not significant.

Average intakes of silage were similar on each type of diet. Daily intakes of the compound feed per cow varied from 6·95kg on the non-cassava treatment to 7·08kg on the cassava treatment. This difference in compound intake was not significant. The results indicated that compound feed containing 400 g of cassava per kg perform as well as cereal-based feeds and, therefore, cassava can be considered as a satisfactory replacement for cereals up to a level of 400 g/kg in compound feeds for dairy cows.

A trial compared the voluntary water intake of 72 purchased British Friesian bull calves fed at different nutrient intake levels by varying the type and strength of the milk replacer given to 5 weeks of age. There was no control group without water on offer. Water was offered from the 1st day the animals entered the unit. All calves received 4 1/day of either cows' milk (12 calves), milk replacer with 100 g fat per kg (24 calves), milk replacer with 170 g fat per kg (24 calves) or milk replacer with 200 g fat per kg (12 calves). Standard early-weaning pellets containing 190 g crude protein per kg and hay ad libitum were on offer from the 2nd day on the unit. Results indicated that voluntary intakes of water were highest with calves fed on cows' milk and lowest on the milk replacer with 100 g fat per kg given at the lowest mixing strength, although differences were only significant in week 5 (P ≤ 0·05). By covariance analysis, the effects of water intakes on live-weight gain and on pellet intake were examined. The regression coefficient of live-weight gain (weeks 0 to 5) (kg) on water intake (weeks 1 to 5) (1) was b= 0·056 (s.e. 0·021, P ≤ 0·01). The regression coefficient of pellet intake (weeks 0 to 5) (kg) on water consumption was: b= 0·082 (s.e. 0·031, P ≤ 0·01). There was thus a significant correlation of both live-weight gain and pellet intake with water intake. For each extra litre of water consumed per day, there was an extra pellet intake of 0·082 kg and an increase in live-weight gain of 0·056 kg. There was a significant difference in total water intake according to the initial live weight of the calf.

1. An anatomical explanation of the observed differences between double-muscled and phenotypically normal cattle was sought by detailed dissection of the sides of six double-muscled Santa Gertrudis steers and six Brangus steers.

2. Relative to carcass weight the double-muscled steers had a significantly greater proportion of muscle and a significantly lower proportion of bone and fat than the Brangus steers. Relative to muscle plus bone weight the muscle proportion was greater and the bone proportion lower in the double-muscled steers.

3. The musculature of the double-muscled steers exhibited a gradient of hypertrophy: 12 muscles (234g/kg of total muscle weight) were grossly hypertrophied, 56 muscles (565g/kg) were hypertrophied to a lesser degree and 28 muscles (195g/kg) showed either a minor degree of hypertrophy or no hypertrophy.

4. The grossly hypertrophied muscles were generally the larger, superficial muscles of the proximal pelvic limb and shoulder area. The muscles showing least hypertrophy were mostly small muscles located in the deeper areas of the carcass, particularly around the spine and in the proximal hindlimb, and in the proximal and distal forelimb.

5. Abnormalities of shape in double-muscled cattle may be attributed largely to altered proportions of total muscle and total fat, and to changes in weight distribution within the musculature.

Carcass evaluation data from two breed-comparison trials were used to examine the value of conformation as an indicator of carcass composition when used in addition to carcass weight and different measures of fatness. One trial involved 1478 crossbred lambs out of three ewe types by Border Leicester, Dorset Down, Ile-de-France, North Country Cheviot, Oxford Down, Southdown, Suffolk, Texel and Wensleydale sires. The other trial involved 920 crossbred lambs out of two dam types by Dorset Down, Ile-de-France, Oldenburg, Oxford Down, Suffolk and Texel sires. Each trial extended over 3 years.

Conformation contributed little to the prediction of carcass lean percentage or proportion of lean in the higher-priced joints, although the additional precision was often significant at P<0·01. When conformation was used in association with dissected subcutaneous fat percentage, it was positively associated with carcass lean content; used with a visual assessment of external fat cover on a five-point scale, which provided a less effective control of fatness variation, it tended to be negatively related to carcass lean content.

Conformation was slightly more valuable for the prediction of lean to bone ratio and m. longissimus depth. The addition of sire-breed effect to weight and fat class provided an important increase in the precision of prediction of percentage lean in carcass and lean to bone ratio. Texel progeny had higher lean to bone ratios and more lean in the carcass than progeny of other sire breeds, but they did not have sufficiently high conformation scores to clearly identify this advantage.

A series of trials was conducted to measure the extent of individual variation in feedblock intake for ewes on upland/hill farms. From 15 flocks on nine farms 4284 ewes were selected with a range of environmental conditions and levels of performance. Ewes were given either Rumevite, Norbloc or Wintawell feedblocks containing chromic oxide. Faecal grab samples were taken per rectum from individual ewes and analysed for their chromium content to obtain estimates of feedblock consumption.

The results showed that provision of feedblocks does not ensure a uniform intake of supplementary nutrients by sheep in upland/hill situations. On average, 19% of the 2931 ewes sampled had not eaten the feedblock on offer. The proportion of ewes not consuming feedblock varied from flock to flock (0 to 67%). The coefficient of variation of faecal chromium concentrations varied between flocks (46 to 231%). The reasons for the large variation in intakes observed are discussed. Feedblock intake was significantly affected by the grazing area per ewe (P<0·01) and the age of ewes (P<0·05 to P< 0·001).

1. The ability to resist hypothermia was measured in 265 lambs of 10 breeds immersed in a progressively cooling water bath.

2. Cold resistance varied significantly between breeds, with hill lambs showing the highest resistance. Hill breeds and feral breeds together had the highest weight-specific cold resistance.

3. Cold resistance was positively correlated with birth weight and skinfold thickness.

4. Age at test varying from 1 to 60 h did not significantly affect cold resistance.

5. Rate of recovery from hypothermia varied slightly between breeds. The feral lambs tended to recover fastest.

The follicle population of 44 purebred 20-month-old Corriedale ewes and rams was examined for effects due to sex and birth status. Twin birth resulted in a lower ratio of secondary to primary follicles at 20 months of age in these medium follicle-density animals. This effect is similar to that reported for the high follicle-density Australian Merino. Similarly, the ewes had a lower ratio of secondary to primary follicles than the rams.

The postural behaviour of a group of 12 pigs in a pen was studied whilst the air temperature was varied, all physical variables except pig weight being held constant. The air temperature was varied between −4°C and + 5°C of the theoretical lower critical temperature. The range of live weight was from 30kg to 75 kg. An indication of whether the pigs were above or below their lower critical temperature was obtained from the amount of huddling. Pigs of less than 45 kg live weight had a greater tendency to modify their environment by altering their posture. Measurements of floor-area covered showed that pigs over 50 kg live weight occupied an area approximately equal to the recommended minimum whilst smaller pigs occupied up to 20% less area than that recommended, depending upon the temperature: this was due to the tendency of smaller pigs to lie on top of each other when cold.

1. Two trials were carried out to investigate the effects of high-copper supplementation of isonitrogenous diets containing either white-fish meal or soya bean meal as the sole protein supplement.

2. There was no difference in performance between the two diets when they were fed unsupplemented with copper in trial 1. The addition of 250 mg copper per kg diet significantly and similarly improved performance on both diets.

3. Liver-copper stores, but not kidney-copper stores, were significantly increased when the copper-supplemented diets were fed. The level of the liver-copper stores on the soya bean meal supplemented diet was, however, some 400g/kg less than that on the white-fish meal supplemented diet. The significance of this clearly established finding is discussed.

A basal diet containing 120 g crude protein per kg and 9g lysine per kg, and previously shown to be limiting in one or more essential amino acids and/or non-essential nitrogen, was examined. It was fed either alone to growing female pigs from 25 kg to 55 kg live weight or in combination with four supplements of synthetic amino acids each containing three out of isoleucine, methionine, threonine and tryptophan. A control diet containing 140 g crude protein per kg and 9g lysine per kg was also included. Blood samples were collected at 40 kg live weight in order to examine the influence of dietary treatments on blood metabolites. Results for growth performance, carcass composition and blood urea indicated that threonine was the first limiting amino acid in the basal diet. Plasma free amino acids gave no clear trend. Growth performance and carcass composition were unaffected by supplementation of the diet with glycine indicating that the dietary supply of non-essential nitrogen was adequate.

Twenty sows and their litters were observed at regular intervals over the 1st week post partum to determine piglet-teat relationships. At 7 days of age, three piglets were exchanged between five pairs of litters, the other 10 litters remaining intact as controls. Observations of sucking were continued for another week. All piglets were weighed at 3, 7 and 14 days of age. Cross-fostering disrupted the teat sucking relationships of the whole litter compared with those of control litters, but the probability of sucking at the same teat in the 2nd week as in the 1st was less in fostered piglets than in their non-fostered littermates. The weight gain of fostered piglets during the 2nd week was reduced to 79% of that in their non-fostered littermates. Both disruption of sucking and reduction in weight gain were greater in those piglets that had to compete, on their foster mother, for the teat they preferred during the 1st week than for those whose teat was free.

The behaviour of eight litters of Large White × Landrace piglets aged 3 weeks was scored in flat-deck cages every 2min for 12 h during the day, noting the frequences of 11 behaviour patterns. Similar observations were made at 6 weeks of age, and five main activities at the two ages were compared. There was a significant decrease in the frequency of aggressive encounters between the two ages, while the other activities remained at the same frequencies. The proportion of scores devoted to the main activities is given.