High quality grass silage (10·5 MJ metabolizable energy per kg dry matter (DM)) was offered ad libitum to three groups of autumn-calving dairy cattle, each group containing eight cows and eight heifers. In a 20-week period commencing at week 3 post partum each group received, on average, 1260 kg fresh weight of a concentrate containing 180 g crude protein per kg. Animals in treatment F each received a flat-rate of 9 kg concentrates per day throughout. In treatment D, a declining rate of 11, 10, 9, 8 and 7 kg/day was given in successive 4-week periods. Animals in treatment Y were each offered a fixed rate of concentrates (range 7 to 12 kg/day) based on their milk yield at 2 weeks post partum with a mean intake of 9 kg/day for the group. For treatments F, D and Y respectively, the mean daily milk yields were, 26·2, 26·7 and 26·9 kg for cows, and 19·5, 19·1 and 18·8 kg for heifers; mean live-weight gains were, 0·28, 0·30 and 0·22 kg/day for cows, and 0·41, 0·54 and 0·38 kg/day for heifers; and intakes of silage were, 10·1, 10·6 and 10·7 kg DM per day for cows, and 7·8, 7·7 and 7·3 kg DM per day for heifers. The differences between treatments were not significant but there were significant differences between cows and heifers. No significant differences were found between treatments in milk composition although heifers produced milk with significantly higher milk protein concentration (P < 0·05) and significantly greater milk lactose concentration (P < 0·01) than did cows. During the residual period (4 weeks indoors and 16 weeks grazing) all animals were treated as a single group and there were no significant differences in performance. The 305-day milk yields were not significantly different between treatments and averaged 6587 kg for cows, and 5124 kg for heifers.

In a 25-week experiment beginning at week 3 post partum, grass silages of 10·5 (H) and 8·9 (L) MJ metabolizable energy per kg dry matter (DM) were offered ad libitum to two groups of 24 autumn-calving dairy cows. Within each silage-quality group, two patterns of concentrate allocation were compared, a flat-rate (F) and a variable rate (V). All four treatment groups, HF, HV, LF and LV, received on average 1575 kg fresh weight per cow of a concentrate containing 170 g crude protein per kg during the 25 weeks. The cows on treatment F were all individually given 9 kg concentrate per day throughout. Individuals on the V treatments received different levels of concentrate, based initially on their 14-day milk yield and then reduced by 1 kg/day at 10, 15 and 20 weeks. For treatments HF, HV, LF and LV respectively, mean adjusted daily milk yields were, 24·4, 24·1, 21·6 and 22·1 kg; intakes of silage DM, 9·1, 8·7, 7·6 and 7·6 kg/day, and live-weight gains, 0·39, 0·31, 0·28 and 0·22 kg/day. The effects of silage quality were significant in each case, but the effects of pattern of concentrate allocation were not. Cows given the H silage produced milk with significantly greater lactose and solids-not-fat concentrations. During the residual period (2 weeks indoors and 14 weeks grazing) no significant differences in milk yield were observed. The 305-day yields of 6215, 6096, 5786 and 5824 kg for treatments HF, HV, LF and LV respectively, reflected the differences obtained during the indoor feeding period.

The purpose of the experiment was to investigate the possibility of using concentrations of hormones and metabolites in plasma of potential breeding bulls early in life as indirect selection criteria for butterfat production. Sixteen Red Danish bull calves were included in the experiment, 10 were offspring of parents selected for high butterfat production for two or three generations, and six were from parents selected for low butterfat yield. The average estimated relative breeding values of the calves in the two groups were 111 and 91.

At 3·5 and 7 months of age blood samples were collected every 6 h during 2 days of ad libitum feeding, 5 days of fasting and 2 days of refeeding. The samples were analysed for glucose, urea, free fatty acids, insulin and thyroxine. At 3·5 months plasma concentrations of free fatty acids were significantly correlated with breeding value under all feeding conditions examined. The increase in plasma glucose during refeeding at both ages was positively related to breeding value. Plasma insulin during the 1st day of fasting was positively correlated with genetic merit at 3·5 months of age and negatively correlated at 7 months. Plasma thyroxine was negatively correlated with breeding value at both ages, but the correlation was only significant at 7 months. Multiple regression analyses showed that a large part of the variation in breeding value for butterfat production could be described by plasma levels of hormones and metabolites when more than one variable was included in the model. With six variables in the model 0·67 and 0·73 of the variation could be accounted for at 3·5 and 7 months of age respectively.

The results of the experiment have to be considered with caution because only one sire was used per group, the parents were preselected, and the number of animals was small. The results, however, do indicate that plasma levels of hormones and metabolites in the early life of potential breeding bulls, measured after suitable physiological challenges, may be useful as selection criteria for butterfat production of their offspring.

Fourteen growing Belgian White Blue bulls were assigned to three groups: five controls (C); five bulls implanted with 140 mg trenbolone acetate and 36 mg Zeranol (TBA-Z); and four bulls implanted with 140 mg trenbolone acetate and 20 mg oestradiol-17β (TBA-E2). Testosterone (T) and luteinizing hormone (LH) levels in blood plasma were determined at day 0, 30 and 60. Mean plasma LH concentrations measured by repeated sampling over a 10-h period were similar at day 0, 30 and 60 in the three groups. At days 30 and 60, T levels were significantly lowered in treated bulls: namely 2·0 (s.d. 0·7) μg/1 v. 2·7 (s.d. 0·5) μg/1; 0·7 (s.d. 0·1) μg/1 v. 1·0 (s.d. 0·3) μg/1; 0·5 (s.d. 0·1) μg/l v. 0·4 (s.d. 0·2) μg/1 in the C, TBA-Z and TBA-E2 groups respectively. Moreover, anabolic compounds completely abolished pulsatile liberation of LH and T.

In control bulls intravenous injection of 0·5 ng/kg body weight of LH releasing hormone (LHRH) caused the release of a large quantity of LH (10 to 13 times the basal level after 10 min) followed by an increase in plasma T levels. On the other hand, LH and T responses to LHRH were reduced by TBA-E2 and TBA-Z treatments. A delay in LH response to LHRH was apparent 6 days after anabolic treatment. However, the total amount of LH liberated during the test was increased. The second effect was a quantitative reduction at days 20, 30 and 60 in LH and T secretion after LHRH. The modification of the hormonal pattern was quicker and more pronounced in TBA-E2 than in TBA-Z animals. Correlation was negative (r = −0·68; P < 0·05) between the mean daily gain during the experimental period and the total quantity of T liberated by the testis after LHRH stimulation at day 60. It was concluded that administration of trenbolone acetate plus Zeranol or trenbolone acetate plus oestradiol-17β in pubertal bulls reduced the LH and T responses to LHRH and abolished the pulsatile LH and T secretions.

Post-weaning growth, dry-matter intake, carcass characteristics, chemical composition of the 9th to 11th rib section and food conversion efficiency were evaluated for Simmental bulls (15) and heifers (18) and Hereford bulls (17) and heifers (14) from approx. 240 days of age to 470 days of age. Within each breed × sex sub-class, animals were assigned to one of three energy intake levels: (1) ad libitum, (2) 795 kJ metabolizable energy (ME) per kg0·75 per day and (3) 544 kj ME per kg0·75 per day.

Simmentals tended to exhibit higher post-weaning growth rate and consumed more dry matter than Herefords. At ad libitum intakes, efficiency estimates (gain/food) were greater initially but decreased more rapidly for Herefords than for Simmentals. No differences were observed in efficiency estimates between Herefords and Simmentals fed at 795 kJ ME per kg0·75 per day and both breeds fed at this level improved in efficiency as time on test increased.

Bulls tended to have greater growth rate, and consume more dry matter than heifers. At ad libitum food intake, bulls were more efficient than heifers and the decrease in efficiency of the two sexes was parallel. Heifers fed at 795 kJ ME per kg0·75 per day had a constant efficiency throughout the test while bulls improved in efficiency.

Body-composition data from 73 non-pregnant, non-lactating cows of five genotypes were used to calculate the composition of empty body-weight change in mature cattle. The composition of empty body-weight change was shown to be dependent on empty body weight, containing more fat and less water, protein and ash at higher empty body weights. There were no differences between the genotypes. Between 300 and 600 kg empty body weight the protein concentration in empty body-weight change ranged from 125 to 40 g/kg, whilst application of standard energy values for fat and protein gave equivalent figures for body energy of 22·5 to 32·7 MJ/kg.

Four central performance tests of growth in Hereford bulls from about 10 to 19 months of age on pasture were conducted in New Zealand. From the 100 bulls performance tested 63 were representatively sampled, including bulls with high and low performance test rankings, and progeny tested in dairy herds. Crossbred progeny were purchased from the dairy herds at 3 to 4 months of age, assembled in one location and reared together on pasture for 14 to 15 months prior to slaughter. Regressions of progeny growth and carcass traits on a number of different performance traits for growth of their sires were in almost all cases not statistically significant. The effective heritability, from offspring-sire regression, was 0·07 (s.e. 0·05) for final live weight and 009 (s.e. 0·06) for post weaning gain from about 200 to 550 days of age. It is concluded that central performance tests, as presently conducted in New Zealand, are of limited value for ranking breeding values of bulls for growth. Possible reasons for these results are discussed. It is suggested that pre-test environmental effects and age at the start of the central test are critical factors.

Lifetime maternal records were collected from 116 Red Poll cows born over a 12-year period. Estimates of mature cow weight (A), maturation rate (K) and lifetime maternal performance characters (years in herd, YH; number of calves weaned, NC; total calf weight weaned, TW; total calf weight plus mature cow weight produced, TW + A; average calf weaning weight, AW; calf weight weaned per year in the herd, TWIYH and predicted cow metabolizable energy (ME) required per kg beef produced, MEITW + A) were calculated to study the relationship between cow growth characters and maternal performance. Calf weights were adjusted to a steer basis. Reproductive management practices consisted of breeding heifers to calve as 2-year-olds; cows failing to calve in two successive seasons were culled. Mean mature cow weight was 554 (s.e. 6) kg with a mean maturation rate of 0·059 (s.e. 0·001) per month. The correlation between A and K was −0·69. Means for lifetime maternal characters were: YH, 5·1 (s.e. 0·2); NC, 4·7 (s.e. 0·2); TW, 1187 (s.e. 54) kg; TW + A, 1741 (s.e. 55) kg; AW, 252 (s.e. 1·7) kg; TWIYH, 228 (s.e. 4·5) kg/year; and MEITW + A, 72 (s.e. 1·2) MJ ME per kg beef. The regression of maternal lifetime productivity measures on mature cow weight was quadratic for YH, NC, TW and TW + A with optimal cow weight being 606, 600, 605 and 628 kg, respectively. AW and MEITW + A were positive linear functions of cow mature weight. Regressions of YH, NC, TW, TWIYH and TW + A on K were negative linear functions. AW and MEITW + A were not significantly related to K.

A study was made of the behaviour of young calves at two Scottish auction markets, Lanark and Stirling, and an experiment was conducted to assess the effect of an auction market on the behaviour of calves less than 1 week old.

Several features of the marketing procedure were identified as causing the calves distress, mainly because the calves were unable to lie down and rest. Crowding of calves in the pens, movement to different pens, and penning of very young calves with older calves were the three main reasons why calves could not rest. The older calves (approx. > 10 weeks) were more active, running and jumping around the pens and disturbing the very young animals which stood up in response to being trodden on.

Crowding was severe in some pens although there was no clear evidence to show that small groups of calves (6 to 10 calves) in small pens rested more than calves in large groups (20 to 50 calves) in larger pens.

Calves showed their distress initially by calling loudly, looking wildly around their new environment and sometimes by running around the pen and calling. As time passed behavioural signs of distress were less prominent and calves assumed a ‘depressed’ posture with their heads low, ears held back, tails clamped down and with their weight distributed more on their hindlegs than on their forelegs.

Calves subjected to an experimental market showed similar signs of distress to those calves in the real markets, whereas control calves rested for more than 0·74 of the same time. Experimental calves which were subjected to a journey of 2.5 h were less easily disturbed from the lying posture at the experimental market than calves which had undergone a journey of 15 min only.

Data were collected from 600 newborn lambs, offspring of 354 Western crossbred ewes and 26 rams, to determine heritability estimates as well as phenotypic and genetic correlations between wool follicle variables using histological techniques. Breed of sire and sire within breed were significant sources of variation in total and secondary wool follicle populations and secondary:primary (S:P) ratio. Heritability estimates calculated by regression of offspring on dam were slightly higher than by paternal half-sib correlation or regression of offspring on sire. Expressed as an average of the three methods of calculation, the heritability estimate for S:P ratio was highest (0·69), followed by estimates for secondary, total and primary wool follicles (0·52, 0·46 and 0·36, respectively). These estimates are similar to the heritabilities of fleece weight, staple length and fibre diameter. Selection for increased density, provided an accurate measure is used, is suggested as an effective means for increasing fleece weight within grade.

The growth of Southdown and Clun lambs was studied over the period birth to 415 days of age.

At birth, 50, 100, 150 and 200 days of age five lambs of each breed, and at 415 days three lambs of each breed, were slaughtered and their body composition determined by dissection.

The relative growth of lean, bone and total body fat was not influenced by breed. At each age both Cluns and Southdowns had similar proportions of total body fat, and were considered to be at the same stage of maturity.

There was a breed difference in fat partitioning, with the Clun depositing proportionately more of its total body fat intra-abdominally, compared with the Southdown. However, there was no significant effect of breed on the growth of individual fat depots relative to total fat. From earliest to latest the order of maturity was pericardial, intermuscular, perirenal-retroperitoneal, mesenteric, subcutaneous and lastly, omental fat.

Six weaned lambs were allocated to each of eight restricted feeding treatments with 1·00, 0·85, 0·71, 0·57, 0·43, 0·29, 0·15 or 0 of the diet as perennial ryegrass and the remainder as white clover, and to one ad libitum treatment with perennial ryegrass offered alone. A further six lambs were offered white clover ad libitum starting on day 15. Lambs on the restricted treatments received the same daily allowance of dry matter relative to live weight, adjusted at weekly intervals to allow the greatest possible intake without any rejection of herbage. Fresh cut herbage was offered daily and measurements were made over 69 days. Twelve additional lambs were slaughtered at the beginning of the experiment, and all lambs on restricted treatments were slaughtered at the end.

Increasing the proportion of clover in the diet increased the intake of nitrogen, empty-body-weight gain, carcass weight gain and nitrogen retention. When herbage was offered ad libitum, lambs ate significantly more clover than ryegrass and gained weight faster.

The weight of gut contents decreased as the proportion of clover in the diet increased. The digestibility of the organic matter, energy and nitrogen of the mixed diets simply reflected the digestibilities of the two herbages and their proportions in the mixture.

The rate of incisor, pre-molar and molar tooth loss was studied in two groups of Masham ewes, one from 8·75 to 12·25 years of age, and the other from 7·25 to 9·25 years of age. Incisors were lost at the rate of 0·93 per year in group 1 and pre-molars from the lower jaw at the rate of 1·04 per year. The rate of loss of molars from the lower jaw and pre-molars from the upper jaw was much slower, whilst there was virtually no loss of molars from the upper jaw.

Mean litter size declined gradually from age 7 in group 1, but there was no decline up to age 9 years in group 2. Lambing percentage declined gradually from age 6 years, with a marked drop after age 10 years caused by an increase in barrenness and lamb mortality. Selling percentage also began to decline from age 6 years but dropped sharply after age 9 years following an increase in the number of lambs having to be reared by hand. Ewe live weight, lamb birth weight and lamb growth to 4 weeks of age showed no decline up to 12 years of age.

The effect of prolonged intake of saline well waters on the productive performance of 56 mature ewes and their lambs of the Magra and Marwari breed of the Rajasthan desert was studied for a period of 44 months. The sheep were maintained at pasture and given drinking water containing 0·3, 2·0 and 3·5 g/1 of total soluble salts. Body-weight changes during pregnancy and lactation, milk yields, greasy-fleece yields of the ewes, lamb birth weights and subsequent body-weight gains, up to weaning and post weaning, and greasy-fleece yield and pre-weaning and post-weaning survival rates of the lambs remained unaffected by the salinity levels in the waters tested.

A total of 219 lambs of the Welsh Mountain (W) and Scottish Blackface (B) breeds, and six types of crossbred with varying proportions of the two breeds from a cyclical crossbreeding experiment, were slaughtered in six groups at fortnightly intervals from 6 to 8 months of age. Each group had balanced numbers of each genotype and each sex. Genotype differences and effects of heterosis were estimated. Fat grades were assessed by farm staff before slaughter and Meat and Livestock Commission fat and conformation scores and external linear hindquarter measurements of each carcass were recorded.

At the same age, W carcasses were lighter (W: B = 0·86, W = 11·7 kg, B = 13·4 kg) but were more mature and had more kidney fat (W: B = 1·73) and higher fat and conformation scores especially in the loin region, but relatively shorter, thinner legs. At the same degree of maturity (carcass weight/estimated mature carcass weight), the Welsh carcasses had more kidney fat but the difference in leg measurements was reduced, and the differences for fat and conformation scores disappeared. When compared at the same grade, the Welsh lambs were 2 kg lighter and had higher conformation scores suggesting comparative undergrading, especially by the farm assessors. Results for crossbred lambs were as predicted from their breed composition and there was no evidence of heterosis.

The results suggest that at the same estimated carcass fatness, the Blackface has the potential to produce a heavier carcass but is later maturing, taking approx. 12 days longer to reach this degree of fatness.

Nitrogen balance was measured in a series of experiments to determine the optimum balance between lysine, threonine and methionine plus cystine by successive additions of the free amino acids to a basal diet of barley, soya bean meal and tallow. The basal diet had a calculated digestible energy (DE) value of 14·5 MJ/kg and a crude protein content of 146 g/kg. The ranges of total lysine; threonine and methionine plus cystine tested were (g/kg) 6·6 to 11·8, 4·9 to 6·9 and 4·3 to 71, respectively. Latin-square designs were used involving a total of 33 pigs. Nitrogen utilization was optimized in pigs of 3 to 9 weeks of age when each kg of diet contained 10·5 g lysine, 6·4 g threonine and 5·0 g methionine plus cystine, corresponding to a ratio of 100: 61: 48. Thereafter, five diets were formulated in which the same ratio was maintained, but at different protein levels (129 to 192 g/kg). Again the diets were based on barley, soya bean meal and tallow supplemented with free amino acids. These diets were compared, in both nitrogen balance and performance experiments, with a conventional early-weaning diet with a protein content of 240 g/kg. All six diets had the same calculated DE value (14·5 MJ/kg). The N balance experiment was of Latin-square design and involved 18 pigs, and the performance experiment used 36 pigs fed individually from 3 to 9 weeks of age. A diet containing 0·99 g lysine per MJ DE (14·4 g lysine and 192 g balanced protein per kg) was considered to be adequate on the basis of the growth rate and food conversion efficiency results obtained.

Eight diets based on barley and soya bean meal were formulated. Two basal diets, one of which included fish meal, were formulated to conform to the recommendations of the Agricultural Research Council (1981) for all amino acids except lysine. Four further diets were made by adding L-lysine to these diets, in two increments; the highest concentrations of lysine were also supplied in two further diets by the inclusion of a higher proportion of soya bean meal. Each diet was given ad libitum to 10 growing pigs, five castrated males and five females, which were housed and fed individually.

Measurements of performance were made over the weight range 22 to 55 kg. Carcasses were appraised after slaughter at a mean weight of 75 kg.

Addition of lysine, but not of soya bean meal, significantly increased daily food intake and carcass fatness. Daily growth and food conversion efficiency were not significantly affected. Because of the high food intake the daily lysine intakes on the basal diets greatly exceeded the suggested daily requirement and the results indicate that in such circumstances the response to the amino acid supplementation of an apparently inadequate protein may be negligible.

Data for 15 487 pigs taken from the first 8 years (1973–81) of the Meat and Livestock Commission's Commercial Pig Evaluation were used to examine the effects of sex, feeding regimen, slaughter weight and day of slaughter on muscle quality characteristics in 20 populations (pigs from different commercial breeding companies and control populations). The characteristics examined included pH measurements both at 45 min post mortem (pH,) and after overnight cooling (pH2), in the m. longissimus and m. semimembranosus. Visual assessments of m. longissimus colour and condition were also made.

The overall mean for pH, in the m. longissimus was 6·34; 0·12 of pH, values were less than 6·0. The proportion of carcasses visually assessed as either pale or wet was 0·116, and 0·027 were assessed as both pale and wet.

The populations were compared separately within each of three time periods (covering the full 8 years) since significant population × time period interactions were recorded for several characteristics. Within each period the populations differed significantly for all characteristics examined (P < 0·05); but with the exception of two extreme populations, the differences were relatively unimportant.

The effects of sex, feeding regimen and slaughter weight were negligible but the effect of day of slaughter was very important: the s.d. of pH1 was reduced by 0·15 when calculated within day but by only 0·01 when adjusted for all other factors.

Muscle quality characteristics were poorly correlated with carcass characteristics: the highest correlation within day of slaughter was −0·23, recorded between pH, and ham conformation score.

Four groups of does (16 per group) were remated either 1, 7, 14 or 21 days after parturition over a 1-year production cycle. Doe mortality rate was independent of treatment and overall was 0·27. The remating interval after parturition had no effect on conception rate, which was high on all treatments (0·86 to 0·93). The high overall conception rate resulted in more litters being born as the parturition to remating interval decreased. Expressed on a common 365-day experimental period the number of litters per doe was 8·9, 8·5, 7·8 and 6·7 (average s.e. of difference 0·33) for treatments 1, 7, 14 and 21 respectively. Litter size was not significantly affected by treatment and consequently the number of pups born per doe per year increased as remating interval decreased: 75·0, 73·4, 67·4 and 591 respectively. Pup mortality rate at birth and subsequently was high (0·42) on all treatments and the number of pups weaned per doe per year for treatments 1, 7, 14 and 21 was 48·3, 43·5, 40·0 and 33·3 respectively. Pup birth weight, 21-day litter weight and weaning (25-day) weight were all unaffected by treatment, as was doe body-weight change.

Problems of making selection decisions among animals from several environmental groups with heterogeneous variance are discussed. Unless correction for heterogeneity of variance is made, animals will tend to be selected from the more variable groups, especially if selection is intense. This is an accurate and fair procedure only when the heterogeneity reflects real differences in heritability. It is shown that, if observations are expressed as deviations relative to the estimate of standard deviation from the group, the accuracy is high unless groups are very small.