1. The performance and profitability of growing-fattening bacon pigs on two diets, A and B, were compared in farm-scale trials at five centres involving a total of 94 pigs. Diet A contained normal amounts of white-fish meal, middlings and barley meal. Diet B was a cheap low-protein diet containing 90–95% barley meal and no wheat offals.

2. The average crude protein contents of the diets were: diet A, weaner meal 17·2%, fattener meal 14·1% and diet B 14·8% and 12·1% respectively.

3. The pigs on diet A had a daily live-weight gain 1·26 lb. and a food conversion ratio of 3·38 lb.; corresponding figures for the pigs on diet B were 1·22 lb. and 3·49 lb.

The food costs of the pigs on diet B were lower by 10s. 10d. per pig; although the grading of these pigs was slightly poorer, the ultimate profit was 7s. 10d. greater per pig than for diet A.

4. At a sixth centre, decorticated groundnut meal was used in diet B instead of soya bean meal; this had a marked adverse effect on the performance of the pigs and the profit was 18s. 3d. less per pig than for diet A.

1. An experiment to investigate the effect of dietary energy concentration on the voluntary intake and growth of pigs from 27·2 to 118·0 kg. (60 to 260 lb.) live-weight is described and the results discussed.

2. From 27·2 to 50·0 kg. live-weight energy intake was substantially restricted and growth retarded by diets of low energy concentration but from 50·0 to 118·0 kg. there was little difference between diets in either energy intake or growth because daily food intake of the low energy diets was increased.

3. Effects of diet on carcass quality as measured by full dissection were small except that killing-out percentage was lower on one of the low energy diets.

4. It is concluded that limited differences in the energy concentration and palatability of ingredients are unimportant in formulating pelleted diets for self-fed pigs.

Local cooling of the skin, produced by exposure to wind was shown to depress the rate of length growth of wool. The depression was associated with reductions in skin temperature and blood flow and with increases in heat transfer in the exposed regions. Fibre diameter did not appear to be affected and there were no indications of a systemic response of wool growth rate to exposure.

The aim of the investigation was to evaluate the specific effect, if any, of grass protein on the birth weight of lambs born to ewes wintered indoors. Grass meal was used as a substitute for fresh grass, and soya bean meal—representing a more conventional source of protein for winter diets—was compared with it. Both sources of protein were included at two levels, providing a high (90 g or 0·2 lb/day) and a low (45 g or 0·1 lb/day) intake of digestible crude protein.

The digestibility of dry matter was significantly higher for the diets containing soya bean meal (67·7%) than for those containing grass meal (58·2%). Dry-matter digestibility was not affected by level of protein intake. The digestibility of crude protein was significantly affected by protein source and level of intake.

Lamb birth weights were not significantly affected by source or level of dietary protein. There was a tendency for birth weights to be higher on the diet containing grass meal at low protein intakes. Ewe weight gains during the last eight weeks of gestation were significantly affected by level of dietary protein, and net body weight change was significantly affected by both source and level of protein. Gestation treatments had no effect on the performance of ewes or lambs during the first three weeks of lactation.

The retention of nitrogen during the 18th–20th weeks of gestation was affected by both source and level of dietary protein. Mean nitrogen retention was higher with diets containing soya bean meal (5·8 g per day) than with diets containing grass meal (3·6 g per day). There was no correlation between nitrogen retention and lamb birth weight.

Thirty-seven Blackface wether sheep, ranging from birth to eighteen months of age, were used to derive the allometric relationship between carcass muscle and carcass bone.

The equation

log10 muscle (g) = 1·36 log10 bone (g)—0·804

fitted the data well. (r = 0·995, b = 1·36±0·05, Sy.x = 0·0595.)

The deviations from this equation had a coefficient of variation of 14% indicating that other factors may influence the relationship of muscle to bone.

It is suggested that the variable

log10M—1·36 log10 5 + 0·804

is independent of differences due to different stages of natural development and can be used to examine the effects of different treatments on the muscle: bone ratio. The constant applies to sheep only.

1. Four experiments are described in which silages or kale were given to groups of ewes in the later stages of pregnancy and their voluntary intake recorded. A concentrate supplement was given in the last few weeks of pregnancy in each experiment. In experiments 1, 3 and 4 the ewes were housed in a semi-covered yard.

2. In the first experiment, three groups of 10 Scottish Halfbred ewes were offered one of three silages. A fourth group was offered all three in equal amounts. The silage with a low DM content, low crude-protein content, low pH and high crude-fibre content was eaten in smaller quantities than the other two silages. The ewes fed on this poor silage gained less weight during the latter half of pregnancy.

3. In a second experiment four groups of 15 ewes were offered either silage or kale and housed in a Dutch barn or left in a small paddock. There was no difference between the results from the two silage-fed groups in any respect. The ewes offered kale outside ate less than those offered it inside; they gained less weight and produced lighter lambs.

4. There were two groups of 13 ewes in experiment 3a, one group lambing 5 weeks before the other. Both were fed on the sanie silage; intake was higher in the late lambing group but there was no difference in lamb birth weights.

5. Experiment 3 was repeated with 15 ewes per group; the silage was of much poorer quality, intake being low and the ewes gaining very little weight. Lamb birth weights and growth rates were low.

6. Groups of 15 Scottish Halfbred (90 kg. live-weight) and 15 Speckle-faced Welsh (45 kg.) ewes were fed on yet another silage. The Specklefaced ewes ate more silage DM per unit weight than did the Halfbred ewes and gained in weight, whereas the Halfbreds did not gain.

7. In all experiments there was a decline in silage intake in the last few weeks of pregnancy. This decline did not always coincide with the start of concentrate feeding.

8. The results are discussed and comparisons made between experiments. Suggestions are made for the feeding and management of ewes fed on silage, including the recommendation that a silage for pregnant ewes should have at least 20% DM and 14% crude protein in the DM, but not more than 32% crude fibre in the DM.

Data were collected during 1961–2 on the live-weight, age and warm carcass weights of 83 lots of Israel-Friesian bull calves, 525 animals in all, the offspring of 26 sires. For varying numbers of these animals weight of various non-saleable fat components, including ruminal fat, kidney fat, inguinal fat and scapular fat were also obtained. Ruminal fat alone and ruminal fat plus kidney fat were found to be highly correlated with total non-saleable fat (r = 0·84 and 0·94, respectively). Heritability of dressing percentage was 0·20, of live-weight rate-of-gain 0·92, and of carcass rate-ofgain 0·49. The genetic correlation between live-weight and carcass weight was 0·7. Between-lot correlations indicated that increased rate-of-gain achieved through management will be accompanied by decreased dressing percentage and increased non-saleable fat content.

The body composition of four sows slaughtered on the 110th day of pregnancy was compared with that of four non-pregnant sows slaughtered after 110 days on the same feeding regime and with four sows slaughtered at the beginning of the 110-day period. Mean weight gains in 110 days of the pregnant and non-pregnant sows were 35·9 and 4·3 kg. respectively; the extra gain of pregnant sows over that of the non-pregnant was located in the carcass and reproductive organs. The extra carcass gain of pregnant sows was in muscle, fat and mammary tissue. The greatest proportion of the extra fat of the pregnant sows was in the back region while the greatest proportion of extra muscle was in the belly. There was considerable variation between individuals in moisture, nitrogen and fat contents of sample muscles and treatment differences were not significant.

In previous work the rumen microbiology of young animals fed on a high carbohydrate ration has been considered and has tended to be fairly consistent (Eadie, Hobson and Mann, 1959; Eadie, 1962). In this note a further controlled experiment on calves weaned on to a 50:50 mixture of roughage/high concentrate mixture and on to the high concentrate alone, is reported. In view of interest in the intensive feeding of cattle on barley these results from young animals are compared with a series of observations made more recently on older animals fed predominantly on barley, since it was obvious from the outset that the physical nature of the rumen contents was different in the two age groups. The sudden introduction of large amounts of carbohydrate into the diet of animals previously fed conventionally has been shown to create profound changes in the rumen microbial population (Krogh, 1961) and the microbiology of the young concentrate-fed calf was very different from the roughage-fed animal. However, the barley-fed steers used in this work had been early weaned on to a high concentrate ration and had clearly become adapted to the adult high carbohydrate diet.

1. A factorial split-plot experiment was conducted to investigate the growth of entire and castrate male pigs on conventional diets and diets containing higher levels of protein. Thirty-two Large White pigs were fed ad libitum from 50 lb to slaughter at 260 lb live weight. The carcasses were dissected.

2. The live-weight gain of entire males was the same as that of castrates on the conventional diet, but they grew non-significantly faster than castrates on the higher protein diet.

3. The entire males had a lower dressing percentage and less fat in the carcass than the castrates, but more lean, bone and rind, and a similar lean: bone ratio. The leanness of the entire males was increased on the higher level of dietary protein whereas the leanness of the castrates was unaffected except in the leg. The interactions were not significant.

4. The carcasses of the entire males were proportionately heavier in the head and shoulders and lighter in the middle than those of the castrates.

5. The majority of the entire males had flesh with a slightly tainted flavour.

Scotch grain distillers' solubles, known commercially as ‘Scotaferm’, are now available in Great Britain, and feeding trials were made to investigate the value of this material in the diet of the dairy cow. The solubles are a free-flowing light-brown powder produced by evaporating and then spray-drying the liquor (‘spent wash’) remaining in the whisky still after distilling the spirit. The analysis of a typical sample is 5% moisture, 29% protein (20% digestible protein as estimated by pepsin digestion), 9% fat, 5% crude fibre, 11% ash and 41% nitrogen-free extract. The food is a good source of B-vitamins and contains 3·8% calcium.

The data relating to twenty single location trials, involving the progeny of seven sires from one variety mated with random females from another, have been analysed to obtain estimates of sire × location (genotype–environment) interaction for egg production, 23- and 64-week body weights and 32-and 45-week egg weights. In no case was a significant interaction found, indicating genetic correlations not significantly different from unity.

The between- and within-sire components of variance have been calculated for each trait on each location separately. The regressions of these components on the mean levels at the locations have been obtained. Though low and non-significant, they tend to support the use of those locations giving maximum expression of a trait for comparisons involving that trait.

Many traits in farm animals, such as litter size or fleece weight, are the product or ratio of two or more component items. This note seeks to determine the circumstances in which selection directed at the component items is more effective in improvement than selection for the composite trait itself.

A change of one per cent in a product trait can be achieved by a change of one per cent in any of its components. The response expected on selection for a product trait or a component is proportional to h2C per cent, where h2 is the heritability and C is the coefficient of variation. Thus selection for a component trait (A) may possibly be more efficient than direct selection for the product trait (X) when is greater than . However, the correlated changes in other component traits would also have to be taken into account.

Total milk yield of sows is positively correlated with litter size (Bonsma and Oosthuizen, 1935; Wells, Beeson and Brady, 1940; Smith, 1952; Allen and Lasley, 1960) even though the amount of milk obtained by each pig decreases with increasing litter size. Positive correlations between sow milk yield and the creep feed consumption of her litter and between weaning weight and milk production have been reported by Bonsma and Oosthuizen (1935), and by Allen and Lasley (1960). Braude (1964) has comprehensively reviewed the literature on the associations between litter size, birth weight and weaning weight. Ward, Rempel and Enfield (1964) reported a positive correlation between weaning weight and post-weaning growth rate in swine.

A Number of controlled environment studies (reviewed by Blaxter, 1962 and 1964) have emphasised the necessity of providing shelter for out-wintered ruminants. The nature of suitable shelter requires definition and this may be sought by observing the use animals make of different forms of shelter. Direct observation of livestock may, however, sometimes be an inappropriate investigational method. In the work reported here, shelter usage by cattle was assessed from the occurrence of defaecations in various regions of a pasture. Evidence of increased sheltering activity under weather conditions encouraging greater body heat loss would suggest that this method of recording behaviour may be recommended for application in relevant situations.

Three trials with pregnant sows tied in stalls have been conducted to measure the effects on ration digestibility: (a) of a pelleted compound given once or twice per day, (b) of half the daily ration fed as barley at a separate time from the pelleted concentrate and (c) when the order during the day in which the barley and concentrate were fed was reversed.

Giving pelleted complete rations twice as opposed to once per day led to slight improvements in the apparent digestibility of dietary dry matter, grpss energy, crude fibre and phosphorus. When half the daily ration was given as crushed barley in the morning the apparent digestibility of phosphorus was slightly higher than it was when barley was given in the afternoon. Nevertheless the apparent digestibility of dry matter and crude protein was greater for the complete mixture given twice per day. All these effects were statistically significant.

The suggestion has been made (e.g. Anon, 1961; Brown, 1964; Spedding and Brown, 1961; Wixey, 1965) that a method of overcoming the inability of ewes to rear twin lambs well, may be to wean one lamb out of each pair at 2–4 weeks of age. The weaned lamb would be reared on concentrates and/or grass, and the remaining lamb, which would have access to the entire milk supply of the ewe, might then show a similar rate of growth to that of a lamb reared as a single from birth. Studies have also been made of the effect of the removal of one lamb out of twin pairs at 9 weeks of age (Cunningham and Maxwell, 1966) and at 12–16 weeks of age (Cunningham, 1964).

In experiments involving measurements on beef carcasses, the animals can be slaughtered at a given degree of fatness, at a prescribed live weight or at a prescribed age. The ultimate choice depends upon the purpose of the experiment but where comparisons are being made between different breeds receiving the same diet it is usual to slaughter animals at the same degree of fatness. This subjective assessment of the time at which the animals are to be slaughtered results in widely different slaughter weights and ages. In order to aid the interpretation of results, Pomeroy (1965) suggested that animals should be killed at at least three different live weights so that an estimate of the rate of change of various parameters can be derived.

Forage crops of the genus Brassica are known to contain goitrogens which under certain conditions can cause severe incidences of neonatal mortality in lambs and goitre in older sheep (Shand, 1952; Sinclair and Andrews, 1958, 1959, 1961; Andrews and Sinclair, 1962).

In the course of studies of certain aspects of lamb growth it was noted that lambs grazing rape (Brassica napus) had heavier thyroid glands than comparable lambs grazing grass. Pipes, Premachandra and Turner (1958) found that a degree of hypothyroidism increased the rate of fattening and influenced the carcass quality of cattle, and in view of this and other evidence it was decided to test the hypothesis that changes in the weight of the thyroid glands of lambs grazing rape were associated with changes in the rate of live-weight gain.

A Quality characteristic of the bacon side is the fat to lean ratio of the rashers obtained from it. Although this measurement has received attention in carcass evaluation (Pearson, Bratzler, Hoefer, Price, Magee and Deans, 1956; Lucas and Mitchell, 1962; Jonsson, 1963), unlike many others its accuracy as a predictor of lean content of the carcass has not been established. On this basis it was considered worth while to undertake an analysis of the method.