When testing facilities are limited and the number of breeds and/or crosses to be tested is potentially large, then multibreed designs which involve a large number of breeds with only a few animals per breed give the optimum allocation of animals within and between breeds for various objectives. Multibreed designs could therefore form a useful adjunct to existing breed testing and selection programmes. How far such designs should be introduced would depend, among other things, on the degree of confidence in existing information, on the success of existing testing schemes, and on the relevance of the selection criteria currently being used. In this, the first of a series of papers on multibreed designs, the general approach is outlined, and designs for measuring between-breed variation are considered.

To estimate the extent of between-breed variation, the best overall design is to have four unrelated animals per breed and as large a number of breeds as possible. Valuable experimental work on breed variation can therefore be done without vast facilities.

Optimal designs are given for estimating some of the genetic parameters needed to describe a population of breeds when testing facilities are limited and the number of breeds to be tested is potentially large. The best design for estimating the relative proportion of genetic variation within and between breeds is to have a large number of breeds, a few sires per breed, and a few offspring per sire, the total number of animals per breed being of the order of 10 to 20.

1. Weaned single-suckled calves (castrates) were housed at 260·7 kg live weight. Six genotypes, all two- or three-way crossbreds, were represented. A diet of bruised barley, wet distiller's grains, swedes and grass silage was offered until the required minimum live weight (363 kg) and body composition was reached. The cattle were then slaughtered (treatment A), or retained for 8 (treatment B) or 16 weeks (treatment C). During the period when treatment B and C animals were retained their diet was 53% bruised barley and 47% wet distiller's grains offered ad libitum.

2. Live weights at slaughter were 418·2, 458·6 and 496·1 kg (P < 0·001), carcass weights 240·5, 266·2 and 295·7 kg (P < 0·001), and killing-out percentages 57·5, 58·1 and 59·6 (P<0·01) for treatments A, B and C respectively. Daily live-weight gain did not decline during the 8 or 16 weeks cattle were retained on treatments B and C.

3. Retaining the cattle to slaughter points B and C caused increases in the percentage of low-value joints in the carcass, carcass fat percentage, dry matter and fat contents of the dissected m. longissimus dorsi; and decreases in the percentage of high-value joints, carcass lean and bone percentage, crude protein and ash contents of m. longissimus dorsi. The carcass composition was 55·6, 53·5 and 51·4% lean (P<0·001); 30·7, 33·3 and 36·2% fat (P<0·001); 13·7, 13·2 and 12·4% bone (P< 0·001) for treatments A, B and C respectively.

4. The results are discussed in relation to the choice made by beef producers between slaughter and retention of cattle which have reached suitable live weight and condition for marketing.

1. Fifty-four weaned single-suckled steer calves aged 11 to 14 mo were individually fed 2 kg wet distiller's grains, 10 kg swedes and an average of 11·5 kg grass silage daily. The quantity of silage offered was adjusted during the experiment in accordance with a live weight related scale. There were six treatments differing in the physical form, moisture content and level of barley grain offered. A nil barley supplement was compared with 2·5 kg barley dry matter daily offered either whole or bruised having been prepared for storage by drying (84·6% DM) and by treatment with propionic acid (79·9% DM); dried barley was also offered whole (at approximately 50% DM) after soaking in water for 24 hr. Each replicate of six cattle, one animal from each treatment, was slaughtered when all its members were subjectively estimated to have the required minimum body condition and minimum estimated carcass weight (186 kg) for marketing.

2. A supplement of barley grain caused increases in daily live-weight gain, slaughter weight, carcass weight and carcass fat content; and reduced carcass lean and bone content. These effects were increased if the barley grain was processed by bruising compared to being consumed unprocessed (whole). There was no indication that the method of preparation for storage or the moisture content of the barley grain when consumed affected the results of the experiment. It was concluded that the costs of processing barley grain by bruising for feeding to growing cattle for slaughter will be exceeded by the value of the additional animal performance obtained in comparison to feeding whole barley grain.

The effects of diets containing variable percentages of roughage and moisture on depot fats were studied. Treatments were 25 and 45% roughage in the complete fattening diet, and 10, 50 and 75% moisture content of the diets. Depot fats collected post-slaughter from kidney, pelvic, ruminal, cod and trim fats in the carcass (mostly subcutaneous and some intermuscular) were weighed and analysed for their fatty acid composition.

Increasing the quantity of roughage in the diet (from 25 to 45%) significantly decreased ruminal fat deposition. Moistening the feed significantly increased the deposition of kidney, pelvic and cod fat, and significantly reduced the deposition of fat trim in the carcass. The content of unsaturated triglyceride fatty acids was significantly greater in calves fed on the 25% roughage diet. Calves fed on the soaked diets had significantly higher contents of unsaturated fatty acids than the controls.

The content of unsaturated acids was greater in cod fat and carcass trim than in kidney, pelvic or ruminal fat.

Hydrogenation in vitro of fatty acids by ruminal micro-organisms decreased with increasing level of moisture in the diet.

It is suggested that the increased unsaturated fatty acid content of the depot fats of animals fed on soaked diets might be due to a reduction in the hydrogenation of dietary lipid by rumen micro-organisms.

Thirty-six British Friesian entire male calves were reared from 100 kg live weight (LW) to slaughter at 450 kg LW. They were offered maize silage ad libitum plus supplements of minerals and a protein concentrate or urea in three treatment diets: protein concentrate (P), urea (U) and (P/U) in which protein and urea each provided 50% of the supplementary N up to 200 kg LW followed by urea alone. Levels of N × 6·25 in the diet dry matter (DM) were 16% from 100 to 200 kg LW, 14% from 200 kg to 300 kg, and 12% thereafter. Barley was given to all the cattle over 12 mo of age at 1% of LW daily.

Live-weight gain in the 280-day period prior to the introduction of barley averaged 899, 684 and 580 (±31·0) g/day for P, P/U and U, respectively, and was greater for P than for the other two treatments (P<0·05). After the introduction of barley, gains were similar between treatments, averaging 1275, 1333 and 1270 (±43·2) g/day, resulting in mean ages at slaughter of 15, 16·5 and 17 mo for P, P/U and U, respectively.

Substitution of protein concentrate by urea was reflected in a reduced content of metabolizable energy (ME) in the diet and a reduced intake of DM and ME in period 1. Although the contents of ME in the diets were similar in period 2, when barley was given to the cattle, there was little evidence of compensatory growth in treatment P/U and U compared with treatment P. Live-weight gains predicted from ME intake showed good agreement with actual gains. However, reduced intakes and gains by treatments P/U and U compared with treatment P meant that the target weight and age at slaughter of 450 kg and 15 mo of age was met only by treatment P. For the complete system the cattle consumed an average of 2·3 t DM per head of which maize silage DM comprised 78%. Efficiency of feed use averaged 15·5 kg live-weight gain per 100 kg total DM eaten.

Thirty-nine British Friesian lactating cows were used to study the effects on milk production of supplementation of maize silage offered ad libitum during two 3-hr periods each day. During weeks 11 to 24 of lactation a comparison was made of (i) no supplement, (ii) 183 g/day of a mixture (2: 1) of urea: urea phosphate, (iii) 5 kg/day of barley plus 183 g/day of the urea: urea phosphate mixture, (iv) 7 kg/day of dried grass and (v) 10 kg/day of dried grass. The corresponding treatment mean values were: milk yield (kg/day), 10·0, 9·9, 13·4, 15·1, 16·8; fat content (%), 3·43, 3·80, 3·98, 3·92, 3·61; solids-not-fat content (%), 7·95, 8·03, 8·45, 8·51, 8·49; energy intake (MJ/day), 71·2, 76·9, 130·3, 132·7, 138·6; intake of dry matter as maize silage (kg/cow per day), 7·1, 7·7, 8·3, 7·7, 6·5. With the exception of fat content, the differences between treatments 1 and 2 were not significant but the values for these two treatments were significantly lower than those for the other three treatments.

1. Young adult and adult British Friesian female cattle (heifers and cows) which were lactating were individually fed on diets of grass silage ad libitum with supplements of dried grass, dried grass/barley or barley/groundnut in two randomized block experiments.

2. In Experiment I, equal quantities of dry matter (DM) as dried grass in the form of a wafer (W), cob (C) or pellet (P) were given with the silage during weeks 8 to 18 of lactation, to three groups of 12 heifers. Silage DM intakes were respectively 14·2, 14·3 and 15·8 ± 0·43 g/kg live weight per day (P<0·05). Milk yields were 14·0, 15·6, 16·7 ± 0·35 kg/day (P< 0·001). Milk composition and live-weight change did not differ significantly.

3. In Experiment II, five treatment groups of heifers and cows were offered silage with equal amounts of a supplement of either dried grass pellets (treatment 1) or dried grass/barley in the ratios of 2: 1 (treatment 2), 1: 2 (treatment 3), or a barley/groundnut supplement (treatment 4). In treatment 5 the cattle received the same supplement as in treatment 4, but at a 10% higher level. Silage DM intakes for treatments 1 to 5 during lactation weeks 6 to 22 were 8·64, 8·94, 7·96, 6·96, 7·63 kg/day (1, 2>4, P<0·01; 2>5, P<0·05). The intake of digestible organic matter, milk yields and live-weight changes over the whole experimental period were not influenced significantly by treatments 1 to 4, but in treatment 5 the milk was significantly higher in fat, protein and energy content than in treatments 1 to 4. Blood composition was normal and did not differ markedly between treatments.

1. Young adult and adult British Friesian female cattle (heifers and cows) which were lactating were individually fed ad libitum on ryegrass silage of high (HS) or low (LS) digestibility with one of two levels of a supplement of pellets of dried grass (H or L) in a 2 × 2 factorial experiment with three heifer and seven cow replicates.

2. The percentages of digestible organic matters in the dry matter (DM) in vitro were respectively 64·4, 57·5 and 69·0 for forages HS, LS and and the dried grass. The HS crop, however, was significantly lower in DM content, and after ensiling with formic acid additive had a higher lactic and total acid content than the LS crop.

3. The dry-matter intake of the less acid silage LS was greater than that of HS (P<0·05) although the dry-matter digestibility of the LS diets was on average 6 units lower than the HS diets. The intakes of digestible dry matter (DDM) and digestible organic matter were greater (P<0·05) in mid lactation when HS was fed. DM and DDM intakes were significantly increased by the higher level of feeding of the dried grass supplement.

4. The yield, composition and energy content of milk did not differ between silages but the yield and protein content of the milk increased significantly at the higher level of supplement feeding. The milk yields were respectively 19·35, 17·54, 19·49 and 17·97 ± 0·505 kg/head per day for treatments HSH, HSL, LSH and LSL on these all-grass diets over lactation weeks 4 to 20. Live-weight loss was greater (P<0·01) on the LS diets. Blood composition was normal and did not differ markedly between treatments.

Dissection data for 643 steer carcasses of 15 breed-type × feeding system groups were used to examine the distribution of intermuscular fat (IF) and subcutaneous fat (SF) depots between standardized commercial joints.

The increase in weight of IF and SF in each joint relative to the corresponding depot weight in the side was examined using the allometric equation. Pooled within-group growth coefficients for both IF and SF were lowest in the distal limb joints increasing inwards to the joints of the rib and loin regions. They were highest for the thin flank joint.

Group means for weight of IF and SF in each joint were adjusted to equal total IF and SF weight respectively using the pooled growth coefficients. Statistically significant but relatively unimportant differences were recorded between groups in the adjusted means for all joints tested. The largest differences occurred for the top piece and were 0·39 and 0·40 kg (in one side) for IF and SF respectively. The stability of regression equations between groups for predicting the percentages of IF and SF in the side from the respective percentage in each joint was also examined. Joints which gave the least precise predictions of IF (shin and leg) and SF (shin, leg and clod and sticking) had the most unstable prediction equations. The equations for the other joints differed little between groups.

1. The true availability of Cu in animal excreta and pasture dressed with excreta was assessed in three experiments from the responses in plasma Cu concentration of initially hypocupraemic ewes repleted with diets containing different Cu sources.

2. Herbage from a sward treated with Cu-rich pig slurry contained a larger proportion of available Cu than untreated herbage (0·058 v. 0·047; P<0·05, Experiment 1). Herbage Cu content was also increased from 7·3 to a maximum of 10·2 mg Cu/kg DM by slurry application.

3. Availability of Cu in dried pig slurry (DPS) and Cu sulphate was similar and lowered from 0·068 to 0·040 in both sources by increasing the sulphur content of the diet from 1 g/kg in Experiment 3 to 3 g/kg in Experiment 2. Availability of Cu in dried poultry waste (DPW) was greater than that in DPS (P < 0·05).

4. Treatment with ethylene diamine tetra-acetic acid extracted 64·3 % and 78·3% of the Cu in DPW and DPS, respectively.

5. The Cu toxicity hazard associated with the recycling of animal excreta of high Cu content is discussed.

Seventy-six pigs provided with indwelling venous catheters were exposed for 40 min to a temperature of 40°C and 100% relative humidity. Plasma 17-OHCS levels were determined during the period of stress and up to 24 hr thereafter. The results obtained were assessed in relation to backfat thickness, and eye-muscle area and appearance (Göfö value) in groups of 10 animals showing maximum and minimum values for these parameters. In all the animals the heat and humidity stress brought about an increase in the plasma levels of 17-OHCS. Significant differences were more often found in the induced 17-OHCS levels in those animals which appeared to be leaner on the basis of backfat thickness and eye-muscle area and produced poorer quality meat than in those with less lean of better quality. These results support the notion that there is increased activity of the adrenals of leaner types of pig which produce meat of poor quality.

Ventilation rates of 0·14, 0·42 and 0·71 m3/min per pig (2·3, 6·9 and 11·5 air changes per hour) were compared at weight ranges from 42 to 65 kg and from 69 to 88 kg and at optimum ambient temperature and at 8°C above optimal. A total of 96 pigs was used, housed so that gases from manure decomposition were present. Growth rate and food conversion were not affected by ventilation rates, but food intake was significantly lower at the lowest ventilation rate compared with the other two rates at the hotter temperature only. The odours and gases at the lowest ventilation rate were such that attendants strongly objected to them.

An investigation was carried out to determine whether teat order has any effect on metabolic rate in young pigs as determined by oxygen consumption in the thermoneutral zone. A total of six sows and their litters was examined. Metabolic rate was determined at 1 day old and thereafter at 7-day intervals up to 57 days of age. Teat order was determined by regular observations of the piglets suckling. There was considerable variation in metabolic rate both within and between litters but there was no detectable effect of teat order on metabolic rate expressed as ml O2/W0·75 per min.

Seven Soay rams were subjected to a short daylength from the middle of August until the end of October, and this hastened the onset of winter follicle inactivity which normally begins at the end of September. A reversion to long days until the middle of January slowed down the process, and in six animals the usual spring moult was inhibited.

Three aspects of body condition scoring in commercial sheep flocks were examined. Ewes in 44 flocks were condition scored when the rams were introduced to the flock and their subsequent lambing performance was recorded. The pooled regression coefficient obtained for the relationship between individual ewe condition score and litter size was 0·29±0·0243 with a squared correlation coefficient of 1·96%.

Between flock differences accounted for 57% of the variation in ewe condition score. Within the breeds recorded average flock condition score at mating was related to the number of live lambs born per 100 ewes mated. This relationship is shown for several breeds of ewe. A further 27 flocks were involved in a trial to evaluate the effectiveness of a specific use of condition scoring. Ewes were scored 6 to 8 weeks before mating and in 12 flocks the ewes in poor condition were given an improved plane of nutrition. These ewes showed an improvement of 12 lambs born per 100 ewes mated over ewes not given better nutrition.

It is proper, on the occasion of this lecture, to recall the man whose name it bears. John Hammond, the first president of our Society, was known to many of us, all of us have been influenced by his ideas, and the animal industries of this country, and indeed the world, have been transformed as a result of the work he and his small band of colleagues and students carried out at Cambridge, mostly before the Second World War. If anyone can be called the ‘onlie begetter’ of modern animal production it is John Hammond.