Two experiments, involving 144 and 168 pigs weaned at 22 to 31 days, to investigate the response to inclusion of copper (CuSO4.5H2O), copper plus carbadox/sulphadimidine or copper plus avoparcin supplements in starter and grower diets were made. The carbadox and sulphadimidine levels were 50 and 100 mg/kg diet respectively in both diets. Avoparcin was included at 40 mg/kg in the starter diets and 20 mg/kg in the grower diets. In the first experiment the levels of copper were either 180 or 340 mg/kg in the starter diets and either 90 or 270 mg/kg in the grower diets. In the second experiment the levels were either 20 or 180 mg/kg in the starter diets and either 10 or 180 mg/kg in the grower diets.

In the starter period of the first experiment, supplementation with carbadox/sulphadimidine or avoparcin proportionately increased the rate of growth by 0·41 and 0·07 respectively in relation to supplementation with 340 mg copper per kg diet (P < 0·05). Neither supplement improved growth rate in the grower period. In the second experiment there were no significant differences in growth rate. However the rates of growth in both the starter and grower periods were higher in pigs receiving carbadox/sulphadimidine than in those receiving avoparcin, while these in turn grew slightly faster than those receiving copper only.

Taking into account the costs of the supplements the inclusion of the carbadox/sulphadimidine supplement produced an economic benefit compared with the other treatments.

Pre-weaning growth data from 3822 calves reared in 11 Victorian herds were analysed. The results suggested that the superiority of males (bulls) over castrated males (steers) in pre-weaning growth was due, at least partly, to the early castration of poorly growing male calves, i.e. to the effects of early selection. The extent of this selection bias was further examined using results from similar studies and from experiments in which bulls and steers were selected without bias. These studies strongly supported the view that the superiority of bulls over steers was primarily due to selection and not to sex effects. If sex did influence the bull-steer difference it was of no statistical or practical importance.

In the Victorian data, the ratio of bulls to steers was higher in subclasses in which average growth rates were higher. When selection effects are correlated in this way with other environmental effects such as age of dam effects further biases may arise in estimation of those effects and hence in individual or mass selection.

The results indicated, therefore, that unless bulls and steers are treated as one sex biases can arise in both individual selection and progeny selection.

The mean daily water intakes of individually penned wether sheep were determined over consecutive 7-day periods. Increased intakes of dry matter and/or crude protein resulted in higher intakes of water. The drinking pattern throughout the day was directly related to the type of food offered and its distribution during the day.

The first paper of this series (Alder, Tayler and Rudman, 1964) described experiments carried out over 4 years on the effects of hexoestrol on live-weight gain and herbage intake in grazing steers. The 52 steers used weighed between 750 and 1,100 lb. initially and included four pairs of twins. The experiments lasted between 55 and 124 days and involved both summer and winter grazing. This paper is concerned with observations made on the animals after slaughter.

Two trials were conducted with two complete fattening diets contain- ing 25 and 45 % fibrous roughage, to examine the effects of three moisture levels and five soaking conditions on the performance and ruminal fermentation of fattening cattle.

Differences between treatments in live-weight gain and carcass-weight gain were not significant but there were differences in the efficiency of conversion of metabolizable energy into live weight and into carcass weight and in some instances these were significant. There was a trend towards increased weight of kidney, pelvic and cod fats and a slight decrease in weight of other fat trim of the carcass (subcutaneous and intermuscular) on the treated diets, as compared with the dry control diet.

The pH of the rumen liquor of animals given the soaked rations was lower and the total volatile fatty acid concentration higher than that of animals receiving the dry control diet. The propionic acid concentration in rumen liquor was significantly higher in animals receiving moistened diets.

In order to compare the digestibilities of amino acids in meat, skimmed-milk and fish meals, isonitrogenous, semi-purified diets containing these foodstuffs were given to five castrated male pigs, of 13 kg live weight, with ileo-rectal anastomoses. Apparent digestibilities were calculated as (amino acid consumption —Heal digesta amino acids)Iamino acid consumption. In the order, meat, milk and fish meal, digestibilities were: of N, 0·80, 0·84, 0·88 (s.e.d. 0·021); of lysine, 0·84, 0·94, 0·94 (s.e.d. 0·011); of threonine, 0·81, 0·86, 0·91 (s.e.d. 0·017); of methionine, 0-86, 0·94, 0·94 (s.e.d. 0·006). In vitro solubility of N in 0·2 gll solution of pepsin and hydrochloric acid was 0·93 (s.e. 0·003) for meat, 0·97 (s.e. 0·001) for milk, and 0·95 (s.e. 0·001) for fish meal. In conclusion, the digestibilities of essential amino acids were greater in the milk and fish meals, than in the meat meal.

The LDH values in blood plasma of Pietrains and Large Whites are significantly different during moderate stress (sampling of blood), being higher in the Pietrains. The difference is largest in the LDH-5, the muscle iso-enzyme. Not only are the values higher, but the isoenzyme is also demonstrable in more individual animals.

More stressful situations (forced muscular exercise) result in a rise in plasma LDH-5 in both breeds; the rise is larger in the Pietrains. Two possible causes for the higher LDH-5 values in Pietrain blood plasma are suggested.

Comparisons have been made of a calf early-weaning concentrate mixture in which 50% of the total nitrogen was derived from groundnut meal and a similar mixture having 33% of the nitrogen from groundnut and 19% from white-fish meal.

In a feeding trial with 9 pairs of Aberdeen-Angus crossbred calves which were weaned at 3 weeks and then fed ad libitum, those given the ‘groundnut plus fish meal’ ration ate 4% less concentrate and gained 6 lb. more in weight over an 81-day period than their pair mates fed the ‘groundnut’ ration. Neither effect was significant.

There were no differences between the two rations in their digestibility or their ability to promote nitrogen retention when food intake was equalised.

In mammals ‘maleness’, i.e. the presence of testes, is thought to be controlled by a single gene on the Y chromosome. Recently, a candidate gene termed the SRY (sex-determining region Y) gene has been located. If the SRY gene is the gene causing maleness then a transgenic male with the SRY gene on an autosome would produce a greater proportion of male offspring than a normal male. This would be advantageous in situations where male offspring are more valuable than females. Such transgenic males have a reduced probability of propagating their genotype and an effort has to be made to avoid their extinction. This is at the cost of genetic progress which must be made to enable the transgenics to remain competitive with normal males.

In a simulated beef cattle breeding scheme if half of the annual matings were made to transgenics then after 15 years of selection the transgenic males fell the equivalent of 2·6 years of selection behind males in a traditional herd. If all matings were made to transgenics they fell over 9 years behind. Selection for lean food conversion ratio was considered as an example. After 15 years of selection the gain in biological efficiency from more male offspring outweighed the loss from reduced genetic progress only when more than 0·5 of the bulls used in the breeding scheme were normal males. In practice, the difficulty of maintaining a small population of transgenic males along with other costs not included in the calculations suggest that breeding schemes in beef cattle with an SRY transgene would not be practicable without further technology.

1. A field investigation to estimate the mean weight and chest girth of unserved Friesian, Ayrshire and Dairy Shorthorn heifers of between 3 and 24 months of age was carried out.

2. Data from 1,620 Friesians, 725 Ayrshires and 455 Dairy Shorthorns in the North of England were obtained, with a mobile weighbridge and a. spring-loaded steel tape in the winter 1958–59.

3. It was found that on average the Friesians were heavier and had a greater chest girth than the Ayrshires and Dairy Shorthorns, which did not differ significantly.

4. These heifers were apparently reared on planes of nutrition which, judged by conventional feeding standards, may be described as ‘low’.

5. After eliminating the linear effect of age by covariance analysis, highly significant differences between herds and between sires in weight and chest girth were found.

6. The investigation demonstrated the feasibility and value of collecting field data on body size.

An experiment was carried out to investigate the performance of young steers given either ammoniated hay alone (TA), or supplemented daily with either 112 g fish meal (TF) or 2 kg barley (TB) or 2 kg barley-based concentrate (TC), compared with untreated hay supplemented with either urea (UU), to raise the nitrogen content of the diet to that of the ammoniated hay, or with 2 kg concentrate (UC). Serial slaughter of animals was carried out to examine the effects on body composition during the winter feeding period and subsequent grazing season.

Ammoniation of the hay significantly increased the in vivo digestibility of organic matter, acid-detergent fibre, neutral-detergent fibre and cellulose fractions (0·672 v. 0·643, 0·740 v. 0·670, 0·758 v. 0·638 and 0·826 v. 0·741, respectively). When offered with 2 kg concentrate, intake of ammoniated hay was higher than that of the untreated hay. Empty body weight gains (EBWG) during the winter period were affected by treatment (174, 225, 293, 590, 631 and 692 g/day for treatments UU, TA, TF, UC, TB and TC, respectively), and were highly correlated with total gross energy intakes (56·0, 61·0, 62·9, 74·5, 73·2 and 83·1 MJ/day, respectively). As the rate of EBWG increased, the fat proportion (g/kg EBW) at turn-out also increased. During the grazing season animals which had been on treatments UU, TA and TF showed a marked degree of compensatory growth (759, 686 and 640 g/day EBWG, respectively) compared with treatments UC, TB and TC (623, 572 and 601 g/day EBWG, respectively), and differential rates of tissue gain. This resulted in reduced, though still significant, differences in EBW, although body composition (g/kg EBW) at final slaughter was similar for all treatments. Thus, whilst short-term advantages in intake and performance can be obtained by ammoniation of hay, the benefits so achieved may not persist due to subsequent compensatory growth at pasture.

There have been suggestions that positive feedback from the meal may stimulate the performance of undesirable behaviour, such as stereotypies, in the post-feeding period. The aim of this work was to measure the short-term effects of a meal on the post-feeding behaviour of the pig.

Pigs (70 kg live weight) were offered food ad libitum for 7 days and then given a restricted food allowance for 23 days (experiment 1) or 14 days (experiment 2). In experiment 1, the food allowance was given in one, two or three meals per day. In experiment 2, the food allowance was given in two meals per day and comprised ingredients which supplied glucose at different rates (starch, glucose/starch, starch/guar gum). The pigs' posture and behaviour were recorded in three 1-h periods during the day on 2 days consecutively during the ad libitum feeding period (time period 1) and on pairs of days on three (periods 2, 3 and 4: experiment 1) or two (periods 2 and 3: experiment 2) subsequent occasions during food restriction. The meal frequency or estimated rate of glucose supply had no significant effects on posture or behaviour. In both experiments activity increased with the duration of food restriction. In periods 1, 2, 3 and 4 of experiment 1 the proportions of observations spent were: standing 0·244, 0·260, 0·706 and 0·728 (s.e.d. 0·0346); nosing 0·073, 0·094, 0·229 and 0·253 (s.e.d. 0·0169); rooting 0·032, 0·037, 0·108 and 0·133 (s.e.d. 0·0133). In periods 1, 2 and 3 of experiment 2 the proportions were: standing 0·247, 0·302 and 0·446 (s.e.d. 0·0240); nosing 0·045, 0·075 and 0·138 (s.e.d. 0·0113); chewing 0·101, 0·126, 0·155 (s.e.d. 0·0121). In experiment 1 feeding rate increased with duration of restriction (P < 0·001), but was unaffected by treatment. It is concluded that post-feeding behaviour was influenced more by long-term changes in state (i.e. prolonged food restriction) than by short-term effects of the meal.

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.

Daily partial milk yield of Sanga cows in 13 smallholder agropastoralist herds at two locations on the Accra Plains was recorded through monthly sampling. Estimates of mean daily partial milk yield and milk composition were computed from 1266 observations. The unadjusted mean daily partial milk yield was 875 (s.e. 11) g. The composition of milk: total solids (TS), fat (F) and solid-not-fat (SNF) were 131 (s.e. 14), 41 (s.e. 11) and 90 (s.e. 7) g/kg respectively. Least squares estimate of mean daily partial milk yield were 808·2 and 462·4 g with average s.e. of 41·8 for wet and dry season respectively. The wet and dry season differences in daily partial milk yield, TS and F were highly significant (P < 0·01). Seasonal difference in SNF was not significant.

Herd difference in partial milk yield, TS, F and SNF were highly significant (P < 0·02). There were no significant effects of location on daily partial milk yield and SNF, although location effects on F and TS were significant (P < 0·05). The highest milk yield was observed in cows in third lactation and the lowest in cows in seventh lactation (P < 0·01). Daily partial milk yield peaked in the 3rd month of lactation. On average, lactation length was 210 to 240 days. Both linear and quadratic effects of stage of lactation were highly significant (P < 0·01). Lactation curve parameters for partially milked cows were also estimated. The implications of the results for milk production in sub-Saharan Africa were discussed.

In three experiments, seven grass silages, four grass hays and winter barley straw, with and without anhydrous ammonia treatment, were offered ad libitum to a total of 134 Finn Dorset ewes in weeks 11 to 15 of pregnancy and intakes were measured. The untreated straw diet was supplemented with 300 g fresh weight of concentrates per ewe. Number of foetuses carried did not affect intakes in mid pregnancy. Organic matter digestibilities measured in vivo in week 15, ranged from 0·39 to 0·69 for hays and 0·53 to 0·79 for silages. Generally, between weeks 11 to 15 of pregnancy, hay intakes showed either little change or slight increases whereas intakes of silages or straws showed little change or slight decreases. Forage intake was higher on the better quality hays and silages and ewes gained weight and body condition, compared with losses for the poorer diets. In late pregnancy, the ewes were offered grass silage ad libitum and rations of concentrates according to a rationing programme. There were no residual effects of the mid-pregnancy treatments on lamb birth weights but ewes offered the poorer diets in mid pregnancy still tended to be lighter and thinner post partum. Equations are presented to predict the intakes of hays and silages from food and animal factors.

Fifty-four multiparous Yorkshire × Landrace sows were allocated equally to receive an intramuscular (i.m.) injection of 3 ing oestradiol-17β (E2) or no injection at 112 days of gestationto determine the effect of E2 on the timing and duration offarrowing. All sows received an injection (i.m.) of 10 mg prostaglandin F2x af 113 days of gestation. Of the soivs allocated to treatment, 21 oestrogen-treated and 19 control sows were assigned to be observed for the onset of parturition. A further six oestrogen-treated and eight control sows were included to increase the data base for litter production. The time of piglet delivery was monitored between 08·00 and 18·00 h on day 114 of gestation. Blood samples were obtained from each offour piglets from four E2-treated and five control litters. More E2-treated (8/21) than control sows (1/19) farrowed before 08.00 h of day 114 (P < 0·05) although, for those sows farrowing during the observation period, there was no effect on the time to onset or duration of parturition. Plasma oestradiol concentrations were higher (P < 0·06) in piglets delivered by E2-treated sows. However,this was not associated with any effect on piglet pre-weaning survival. It is concluded that exogenous oestradiol can influence the timing of onset offarrowing in some sows. Although further refinement in terms of timing of E2 injections is required, it seems likely that exogenous E2 may have a useful role to play in hastening the induction of parturition in sows.

A 2 ✕ 2 ✕ 3 factorial arrangement of treatments used 522 boars to examine the main effects and interactions of season (spring v. summer), number of pigs per pen with a single-space feeder (13 or 16 pigs per pen with a singlespace feeder; 0·78 m2 per pig v. 0·65 m2 floor space per pig) and nutrient density of the diet (12·5 g lysine per kg and 14·0 MJ digestible energy (DE) per kg from 38 kg to slaughter (high), 12·5 g lysine per kg and 14·0 MJ DE per kg during the growing phase and 10·0 g lysine per kg and 13·6 MJ DE per kg during the finishing phase (split) and 10 g lysine per kg and 13·6 MJ DE per kg from 38 kg to slaughter (low)) on the performance and carcass characteristics of growing and finishing pigs. The smaller group of pigs had a higher food intake during the grower-finisher period than the high stocked pigs (P < 0·01). The pigs had a higher lysine intake in the spring than in the summer months (P < 0·05). Differences in daily food intake for the smaller group of pigs were reflected in increased growth rate during the grower-finisher period (P < 0·001). However these pigs had a poorer food conversion ratio during the grower-finisher period (P < 0·05) than the bigger group of pigs. The pigs offered the high specification and split-fed diets had better growth rate (P < 0·05) than the pigs given the low specification diet during the grower and finisher period. There was a significant two-way interaction in growth rate between dietary treatment and season during the finisher period (P < 0·01). The pigs given the high specification diet had a better growth rate (P < 0·001) than the pigs given the low diets during the summer months. However, the high specification diet depressed growth rate during the spring months (P < 0·05). The pigs had a lower backfat and higher lean meat in the summer than in the spring months (P < 0·05).

Commercial application of multiple ovulation and embryo transfer (MOET) technology will be subject to practical constraints and economic rationalism. This study examines use of MOET in its most profitable arena: to breed stud rams which will disseminate genetic improvement widely through multiplier studs to commercial flocks. A deterministic prediction is used to evaluate schemes based on an open nucleus MOET group within a Merino parent stud, taking account of genetic merit and inbreeding. Selection is based on clean fleece weight with an assumed heritability of 0·4. Embryos are collected at a rate equivalent to 3·45 live lambs per donor. Benefits of MOET were calculated from the discounted expressions of rams sold, and compared with the costs incurred.

As the proportion of the flock born from MOET increases, the rate of genetic gain increases rapidly at first, but diminishing returns are observed. The costs ofMOET increase linearly with the number of lambs produced, so the optimum proportion ofMOET lambs is for practical purposes always less than 100%.

Some use of MOET was profitable provided the stud sells sufficient stud rams each year. Sensitivity tests found that other parameters had only a small impact on the optimum level ofMOET. In general however, changes which increased the rate of genetic gain (heritability, flock size) or increased its value (wool price, lower discount rate) increased the optimum number ofMOET lambs.

The results should provide guidelines to optimum investment in MOET for the wool industry. An across flock genetic evaluation scheme is probably necessary to motivate this investment.

Thirty entire male piglets weaned at 21 days of age were used to study the effects of two levels of dietary protein (178 and 194g/kg), each in combination with five levels of supplemental lysine (0, 1·5, 3·0, 4·5 and 6·0g/kg), in diets given ad libitum and containing 14 MJ digestible energy per kg, on performance from 6 to 20 kg live weight.

Raising total lysine from 7·2 to 8·7 g/kg diet with 178 g crude protein per kg promoted significant increases in average daily gain, efficiency of food conversion and voluntary food intake, and raised all these parameters to levels exhibited by piglets receiving the basal diet containing 194 g crude protein per kg (8·7 g total lysine per kg).

Lysine supplementation of the diet containing 194g crude protein per kg had no effect on growth performance or food intake.

Carcass characteristics at 20 kg live weight were not significantly affected by either dietary crude protein or total lysine (P> 005).

Data were available from 11 474 gilts performance-tested on 137 farms. The data were analysed to provide pooled within-farm sire component estimates of h2 and genetic correlations.

Estimates of h2 of 0·43 ± 0·10, 0·44 + 0·09 and 0·49 ±009 were obtained for weight for age, C + K and shoulder fat depths respectively in 3583 gilts in 49 Large White herds. Comparable Landrace values derived from 2810 gilts in 43 herds were 0·44 + 0·11, 0·40 ±0·10 and 0·51 ±0·12 respectively. Estimates were consistent from herd to herd.

Estimates of h2 made on data from 5081 crossbred pigs, of mainly Large White and Landrace parentage, varied with herd from 0·10 to 0·40 for weight for age and from 0·08 to 0·96 for shoulder fat depth. Significant differences between breeds were found for the genetic correlations between weight for age and the fat depths, and between shoulder and mid-backfat depths. The variance was partitioned into various components. For index score, the within-herd variance averaged 73% of the total variance.