Twin lambs grazing with their dams at herbage allowances of 30 or 60 gdry matter per kg live weight per day (low and high, respectively) were weaned at 6, 8, 10 or 14 weeks of age. After weaning, the lambs were given a herbage allowance of 160 g dry matter per kg live weight per day.

Ewes on the low allowance ate less herbage, produced less milk and lost more weight than those on the high allowance. The lambs on the low allowance were lighter at weaning than those on the high allowance (137 v. 168, 16·2 v. 20·5, 17·9 v. 24·2 and 21·9 v. 30·4 kg at 6, 8, 10 and 14 weeks respectively).

Lambs weaned from ewes on the low allowance grew more slowly than the unweaned lambs when removed at 6 weeks, but not when weaned at 8 and 10 weeks of age. Weaning lambs from ewes on the high allowance reduced their growth rates at all weaning ages, despite the weaned lambs being grazed at an allowance which would not limit their intake of herbage. The intake of herbage per unit live weight by weaned lambs reached its maximum at approximately 8 weeks of age. After weaning, intake was higher for lambs from ewes on the low allowance than for those on the high allowance (38 v. 33 g organic matter per kg live weight per day). Lambs slaughtered at 17 weeks of age were heavier from the high allowance than from the low allowance. However, after 17 weeks of age the remaining lambs from the low allowance grew more rapidly than those from the high allowance, and when slaughtered at 25 weeks of age had similar weights. Treatments had no effect on the weights of the body components or carcass dimensions independent of their effect on empty-body weights at slaughter.

A new technique was used to analyse data from an experiment involving sequential measurements on the same experimental units. Results may be inconclusive if analysed in several univariate analyses of variance, one for each occasion, because the successive measurements contain the cumulative effect of treatments.

An experiment was carried out in which two pre-weaning herbage allowances and four ages of weaning were applied to 80 lambs and their live weights recorded twice-weekly until 25 weeks of age. The direct and residual treatment contrasts were evaluated over time using a response surface equation. The continuous variation of treatment effects over time was demonstrated simply by plotting the treatment contrasts and fitting the most appropriate equations to them. Treatment effects were tested by analyses of orthogonal regression coefficients over time, evaluated within each sex of each treatment group by multivariate analysis of variance.

Fitted equations of treatment contrasts were used to demonstrate the continuous variation of effects of pre-weaning herbage allowance on live weights of unweaned lambs, the residual effect of pre-weaning allowance on the weights of weaned lambs, and, separately, the effects of weaning and weaning age on live weights of the lambs.

All the live-weight data recorded in the experiment were used in the analyses. The assumptions made for the application of the method were satisfied and the results were much more informative than those of several univariate analyses of variance.

Scottish Blackface ewes in uniform, good, body condition at mating were differentially fed during pregnancy, such that two groups lost 0·15 to 0·20 (groups A and B) and one group gained 0·05 (group C) of maternal live weight by lambing time. The treatments had little effect on the number of lambs born per ewe lambing (1·39, 1·46 and 148 respectively).

Prior to parturition, group A was transferred to a poor hill pasture, and groups B and C to an improved upland reseeded pasture. Herbage intake by six single- and six twin-suckling ewes from each group was estimated in the 3rd, 6th and 8th week after parturition, and mean daily milk production was estimated on 1 day following each intake measurement period. Herbage intake by six dry ewes in each of groups A and B was also estimated.

There were significant differences amongst groups A, B and C, respectively, in mean organic matter digestibility of the herbage consumed (0·701, 0·771 and 0·773), mean daily digestible organic-matter intake (1·06, 1·46 and 1·46kg), mean live-weight change over the period ( –2·9, +5·4 and +l·3kg) and mean daily milk yield (0·64, 1·93 and 1·95 kg).

By the following mating time, after grazing the same pasture from weaning, there was still a difference in body condition score according to pasture type during lactation (2·08, 2·36 and 2·29, respectively). Ovulation rate measured after mating was consistent with the direct effect of body condition (1·34, 1·56 and 1·52, respectively).

A study was made of some aspects of reproduction in the Nungua Black Head and the Ghanian variety of the West African Dwarf sheep. The gestation period of the two breeds was similar: 150 and 148 days respectively. Ewes mated in August and September tended to have slightly longer gestation periods than those mated in March. The mean birth weights were 2·2 kg in the Nungua Black Head and 13 kg in the West African Dwarf. Type of birth affected the weight of lambs at birth. The Nungua Black Head had no triplets, 0·132 twins and 0·868 singles. The West African Dwarf was more prolific: 0·402 singles, 0·557 twins and 0·041 triplets. The weight advantage of the Nungua Black Head lambs at birth was maintained to weaning and they also had better survival rates. The adjusted 12-week weaning weights averaged 9·8 and 5·8 kg respectively for the Nungua Black Head and West African Dwarf. What the West African Dwarf lost in individual weight it appeared to make up in numbers so that, when the breeds were compared in terms of kg of lamb weaned per ewe mated, there was no significant difference between them.

Male crossbred lambs weighing 10 kg were given, by continuous abomasal infusion, one of a series of diets, equal in energy and nitrogen contents, which provided from 0·887 to 14·863 g lysine per 16 g nitrogen. Gross energy intake was l·38MJ/kg0·75 per day. Oxygen consumption and carbon dioxide production were measured using an open-circuit respirometer when the lambs weighed 12·5 kg. Neither heat production, as calculated from respiratory gas exchange and urinary nitrogen excretion, nor the gross efficiency of utilization of metabolizable energy were affected by the lysine content of the diets.

The linear growth rate of wool on three sites on each of six Wenslcydale × Blackface lambs was measured by wool fibre autoradiography following 11 injections of 35S-cystine. The first injection was given at 09.00 h, so that alternate 36h intervals between injections represented predominantly day (09.00 to 21.00h) or night (21.00 to 09.00 h). The overall mean growth rates on shoulder, mid-side and breech were 0·83, 0·96 and 0·95 mm/day. Differences between day and night growth rates were very small (proportionally<0·05) and inconsistent in 16 of the 18 samples; although breech samples from two sheep showed up to 0·14 faster growth in daytime, a circadian rhythm of wool growth seems unlikely on this evidence. Both linear wool growth rate and food intake increased steadily throughout the experiment.

Mid-side wool growth rates in a second group of three crossbred longwool lambs averaged 0·79, 100 and 1·14 mm/day and were relatively stable over a period of several months.

During the period 1974-77 six blocks of a perennial ryegrass/white clover sward were each divided into two for rotational paddock-grazing and silage cutting in alternate years. For each use an annual total of 360 kg nitrogen per ha was applied. Six livestock treatments of cattle only or cattle and sheep were grazed on the blocks. The stocking rates per ha and combinations of cattle (yearling steers) and sheep (ewes nursing twin lambs) respectively were low, 7·5 + 0; medium, 10 + 0, 7·5 + 5, and 5+10; and high, 7·5 + 10 and 5 + 15.

The annual quantities of herbage organic matter accumulated (6·6 to 7·2 t/ha) and consumed (5·6 to 6·7 t/ha) did not differ markedly according to grazing treatment during an individual year, nor was there an effect on organic matter accumulation in subsequent conservation years (11·3 to 12·0 t/ha). Between-year effects were significant. As judged by persistence of sown species there was no evidence of sward deterioration over the 4 years.

Total live-weight gain per ha increased with increasing stocking rate but with a decreasing increment. The ranges were 106 to 1·42 t/ha within treatments, 102 to 1/45 t/ha within years and 0·97 to 1·8t/ha within treatments × years. Individual gains of cattle (0·67 to 0·88 kg/day) and lambs (0·20 to 0·27 kg/day), and the proportion of lambs ready for slaughter (0·53 to 0·97), were lowest at the highest stocking rate. Mixed grazing compared with cattle-only led to improved cattle gains and improved total gains per ha. The benefits of mixed grazing for a species tended to increase as the proportion of that species in the mix decreased.

1. Four groups of British Friesian heifers born in April (no. = 30), July (no. = 29), October (no. = 30) 1977 and January 1978 (no. =27) were allocated to one of six treatments (planes of nutrition) at a mean age of 91 days. From 91 to 365 days of age heifers on treatments 1 to 5 were given individually, according to body weight, a proprietary pellet to 126 days of age, and thereafter a diet of dried lucerne and barley. Heifers on treatments 1 and 2 were fed at the same rate whereas heifers on treatments 3 to 5 were fed at successively higher rates. Heifers on treatment 6 were fed ad libitum the proprietary pellets to 126 days of age and thereafter a 'barley beef diet. Mean live-weight gains between 91 and 365 days of age for treatments 1 and 2 combined and 3 to 6, respectively, were 0·58, 0·68, 0·75, 0·82 and 1·06 kg/day.

2. Plasma progesterone concentrations were determined twice weekly in each animal. Puberty was assumed to have occurred 2 days before the start of the first period in which the progesterone concentration exceeded 1μg/1 for at least 10 days.

3. There was no significant difference between treatments in mean body weight at puberty (242 kg), but age at puberty (347, 305, 288, 301 and 239 days for treatments 1 and 2 combined and 3 to 6, respectively) was inversely related to rate of live-weight gain between 91 and 365 days of age. However, within each treatment group the fastest growing heifers reached puberty at the same age but at a heavier body weight than the slowest growing heifers.

4. There were significant seasonal effects on age and body weight at puberty. The most rapidly reared animals (treatment 6) born in January and April were, on average, 52 days younger and 54 kg lighter at puberty than those born in July and October, but the effects of season of birth in other treatments were different.

5. There was no significant difference between treatments in the number of conceptions (mean 0·67) achieved at first service by an Aberdeen Angus bull introduced when the heifers were 350 days of age.

The effects of the lactation, pregnancy and calendar month on monthly milk records of 1st and 3rd lactation Israeli-Friesian dairy cows were studied. The analyses involved 717 966 monthly records in 76 788 lactations of cows diagnosed as pregnant in herds providing 20 or above lactations per herd per year and lactation number. The records were grouped into 18 lactation classes according to yield post partum: high, medium and low cows within high, medium and low herds, separately for 1st and 3rd lactations.

The objects of the investigation were to estimate factors for relating persistency to peak yield, and to examine how interactions between peak yield and persistency should be taken account of in post partum breeding policies.

The major factor affecting yield was the number of months post partum; heifers dropped in yield by 0·173 from the 1st to the 10th month of lactation and cows by 0·46. The herd level affected the shape of the lactation curve. In high-yielding herds peak yields were achieved later than in low-yielding herds, but the rates of yield decline from the 2nd to the 10th month were similar in high- and low-yielding herds. Within herds, there were large differences in the rate of decline between cows with high and low peak yields. The monthly decline within herds from the 2nd to the 10th lactation month for animals of high and low peak yield were –0·0347 and –0·0217 for heifers and –0-0633 and –0·0520 for cows.

Effects of pregnancy on milk yields were observed from the 1st month post conception, but the effects were small. The effects of 7 months of pregnancy on test-day yields were 3 to 4 kg milk, independent of the yield level of the cow. It was suggested that the effect of herd level could be disregarded but that account should be taken oflactation number and the yield level of the cow within her herd. Heifers and cows in high-yielding herds may be mated later than cows in low-yielding herds. Since pregnancy had a similar effect on high- and low-producing cows, and within herds the higher yielding cows were less persistent in yields than the remainder, it might be a reasonable management policy to breed most of the cows in a herd of a particular lactation at approximately the same time post partum.

Data were extracted from Meat and Livestock Commission records from 44 herds with 392 progeny-tested sires in both farm and station environments. The farm data contained 4182 and 17 251 male and female progeny respectively, and the station data 2982 and 1490 male and female progeny respectively. Both sets of data were adjusted separately for the effects of month of test within sex. The farm data were also corrected to a constant end-of-test-weight corresponding to that at the station. Comparisons were made between both different and the same sexes in the two environments. Phenotypic correlations between a simple index measure in both environments ranged from +0·20 (farm females:station males) to +0·30 (farm females:station females). Genetic correlations between similar traits ranged from –018 (weight/age, farm males:station females) to +081 (simple index, farm males:station females). The correlations between female farm progeny and station male progeny were generally lower than for any other comparisons.

Total teat number in a Large White and a British Landrace population had a modal number of 14. The trait was highly leptokurtic, indicated by the fact that 086 of the population falls within one standard deviation of the mean. There was no sex difference in total teat number, although a small but significant breed difference existed. Heritability of the trait was low, of the order of 0·10 to 0·20 based on the sire component of variance. Larger dam terms suggested a maternal effect.

Severely inverted teats (nipple invisible) were observed in 0·17 of gilts. Mean number of inversions was 0·738 in the entire population but 4·01 in affected gilts. The heritability of the trait was of the order of 0·20 and a maternal component was possibly involved.

Inverted teats are not distributed at random. They occur most frequently in the umbilical and anterior regions and diminish sharply in frequency towards the rear. In this study 0·97 of all affected pigs had one or more inverted teats in the umbilical and anterior regions.

Forty-eight Large White × Landrace weanling pigs weighing initially 9·69 (s.e. 013) kg were used to evaluate the dietary methionine requirements of weanling European pigs reared under a humid, lowland, tropical environment. Response criteria used were growth rate, efficiency of food conversion, carcass quality, and the weights of some organs and individual muscles. The pigs (three male castrates and three females per treatment) were given a cassava flour-soya bean meal diet containing 202 g crude protein per kg dry matter and supplemented with increments of multiples of 0·8 g DL-methionine per kg diet. Total dietary methionine levels ranged from 2·3 to 7·9 g per kg diet dry matter. All diets contained 14·75 MJ digestible energy per kg dry matter. The experiment lasted 42 days, at the end of which the pigs were slaughtered at an average live weight of 17 kg.

Growth rate and feed efficiency were significantly improved when the basal diet was supplemented with DL-methionine (P< 0·001). No significant treatment differences in organ weight were found. Methionine requirement was significantly influenced by sex and age of the pigs, with castrates having lower requirements than females. Pooled estimated methionine requirements for optimum growth rate and efficiency of food conversion were 4·0 and 4·3 g/kg diet dry matter respectively. Maximum proportion of lean was recorded on the diet containing 3·1 g total methionine per kg dry matter.

Carcass data for a total of 1385 pigs from years 3 to 6 of the Meat and Livestock Commission's Commercial Pig Evaluation were used to examine the value of different shape assessments as predictors of carcass composition, when used in addition to carcass weight and fat thickness over the m. longissimus at the head of the last rib (P2). The sample comprised pigs from 13 breeding companies and a purebred Large White control.

The standard deviation of carcass lean proportion at equal weight and P2 was 24·5 g/kg. The addition of carcass length or visual conformation assessments (five-point scales) provided a small improvement in precision (minimum residual standard deviation = 24·2 g/kg). This improvement was associated with a reduction in the variation of lean to bone ratio.

The addition of an effect for breeding company to weight and P2 improved the precision substantially (residual standard deviation = 23·1 g/kg). The improvement was due mainly to the identification of differences in carcass fat content, there being a range of 30g/kg in carcass fat content between companies at equal weight and P2.

There was a further small improvement in precision from the addition of conformation assessments to weight, P2 and company (minimum residual standard deviation = 22·9 g/kg).

The study confirms earlier results which indicate that shape assessments are of limited value as predictors in the British pig population, due mainly to limited variation in lean to bone ratio. It also indicates that significant variation exists between companies in fat content at equal P2 and weight which is not explained by shape assessments.

The Hennessy and Chong Fat Depth Indicator and the Ulster Probe automatic recording instruments developed for measuring fat thickness were tested against the optical probe for use in pig carcass classification and grading.

Fat thickness measurements were taken using each probe 60 mm from the dorsal mid-line over the m. longissimus at the positions of the 3rd/4th lumbar vertebrae, 3rd/4th last ribs and last rib on a total of 110 hot carcasses covering the range of market weights in Great Britain. The standard deviation of carcass lean proportion at equal carcass weight was 35·4 g/kg.

The instruments differed little in the precision of carcass lean proportion prediction: residual standard deviation (g/kg) for the multiple regression with carcass weight and the best individual fat measurement for each probe were: last rib optical probe, 22·1; last rib Ulster Probe, 22·7; and 3rd/4th last rib Fat Depth Indicator, 21/6. Residual standard deviation (g/kg) for carcass lean proportion prediction from carcass weight and all three fat measurements in multiple regression were 21·3 optical probe, 21·3 Ulster Probe and 201 Fat Depth Indicator.

Similar mean fat measurements were obtained from the optical probe and Fat Depth Indicator, and for these instruments, but to a lesser extent for the Ulster Probe, the regression relationships with each other and with fat thickness measurements taken on the cut surface of the cold carcass were also similar.

The differences recorded in precision are unlikely to be sufficiently important to influence the choice of one probe rather than another.

Groups of pigs were observed from weaning to marketing for the incidence of tail and/or ear biting and persistent inguinal nose thrusting. The 16 groups included single and mixed litters, single or mixed-sex ratios, and comprised up to 12 pigs; 14 of the groups showed biting behaviour and 12 groups showed persistent inguinal nose thrusting behaviour. The onset of biting appeared from 0 to 44 days after weaning, and persistent inguinal nose thrusting was first observed 4 to 22 days after weaning.

There was a significant relationship between the number of pigs biting and being bitten in a group. The high ranks tend to bite middle and low ranks more than expected, the middle ranks bite other middle ranks more than expected, and low ranks bite the least. Within any rank there was no difference between male and females biting or being bitten. The most common situation was to have, in a group, some pigs which only tail bit, others that only ear bit, and others which both tail and ear bit. It is suggested that biting is a learned response spread by visual communication, so that visual barriers around affected groups may help to limit the spread of an outbreak.

In persistent inguinal nose thrusting behaviour, rank was important, as the top ranking pigs were the most most likely to show persistent inguinal nose thrusting. Persistent inguinal nose thrusting may have its origin in udder seeking, exploratory or rooting behaviour, but becomes used mainly by dominant pigs. The behaviour is halted by the pig which received the nose thrusts moving away.

Pigs weaned at 2 days of age were given a milk substitute until 28 days of age containing either 10 or 52 fig biotin per kg dry matter. During the last week of the experiment a slight deterioration in the ratio of feed: gain (0·1 > P > 0·05), but not in weight gain, was found in pigs given the low-biotin diet. No signs of biotin deficiency were observed, but pigs given the low-biotin diet had lower concentrations of biotin in the liver and carcass. Most of the biotin was in the liver. These results suggest that 10 fig biotin per kg dry matter may be adequate for pigs until at least 28 days of age.

Forty-eight castrate male and female Suffolk cross Mule lambs were used in a 2 × 2 factorial experiment to investigate the effect of autumn shearing and sex on growth performance over 46 days before slaughter. Lambs were penned individually outdoors and given pelleted lucerne ad libitum.

Shearing increased average food intake by 0·072 (P<0·05), live-weight gain by 0·149 (P<0·01) and carcass weight by 0·058 (P<0·05). It is concluded that shearing is financially worthwhile in climatic conditions such as the present experiment.

ANIMAL PRODUCTION, Volume 33, Part 1, pp. 81-86

COPPER SUPPLEMENTATION OF ISONITROGENOUS DIETS FOR GROWING PIGS CONTAINING WHITE-FISH MEAL OR SOYA BEAN MEAL AS THE PROTEIN SUPPLEMENT