In two trials with 48 pigs it was found that when algae supplemented with certain B-vitamins replaced fish meal on an equal-nitrogen basis in a diet based on barley and fish meal there was no decrease in rate of gain or feed conversion efficiency. When vitamin B12 was omitted from the algal diet, there was a decrease in rate of gain. There were no consistent differences in carcass characteristics between pigs fed on the algal diets and those fed ondiets containing fish meal. Digestibility studies indicated that algae are low in digestible energy, but their protein is 70% digestible.

1. The voluntary feed intakes of pigs fed on diets having calculated digestible energy contents of 2,970, 3,356, 3,630 and 3,910 kcal/kg. dry matter were measured over four periods from 38 to 105 kg. live-weight.

2. The pigs achieved similar daily digestible energy intakes regardless of the digestible energy content of the diet.

3. When housed in metabolism crates pigs ate less than when housed in holding pens and the difference was greater than would be expected solely from the reduced exercise of the pigs in crates.

4. Daily digestible energy intake was 575 kcal/kg. live-weight 0.675 when the pigs were in holding pens. The daily digestible energy intake of pigs in metabolism crates increased less with live-weight.

5. The use of metabolism crates to obtain digestibility coefficients and values for nitrogen retention to be applied to animals housed under other conditions is discussed in relation to the differences found in apparent digestibility coefficients, feed intake and growth rates between pigs in crates and in holding pens.

1. Voluntary feed intake, performance and carcass quality were studied with 20 individually housed pigs given isocaloric diets (2,770 kcal/kg. DM) containing either 8·9 % or 12·9 % crude fibre in the dry matter over the period of growth from 45 to 91 kg. live-weight.

2. There were no significant differences between diets in voluntary feed intake, rate of gain or carcass quality.

3. Apparent digestibility coefficients and rates of passage of the diets were determined in eight castrated male pigs. Rates of passage were not significantly affected by diet or live-weight when determined at 57 and 82 kg. live-weight.

(1) Forty-five Ayrshire and Shorthorn bull calves were used in an experiment to study the ability of the calf weaned at 5 weeks on to concentrates, hay and water, to utilise urea added to a low-protein concentrate.

(2) Calves given the concentrate containing 20% crude protein gained weight significantly faster from 3 to 12 weeks than those given concentrates containing either 12% crude protein, or 18% crude protein of which 33% was in the form of urea. There was a tendency for calves given the urea supplement to gain weight at a slightly faster rate to 8 weeks than those given the low-protein diet, but this tendency was reversed between 8 and 12 weeks of age.

(3) At 15 weeks, the coefficients of apparent digestibility of dry matter, crude protein, crude fibre and nitrogen-free extract were significantly greater when an all-concentrate diet containing 19·6% crude protein was given, than with a concentrate containing 12·2% crude protein. When the lowprotein concentrate supplemented with urea was given (18·5% crude protein) the apparent digestibility of dry matter, crude protein and ether extract was significantly greater than on the low-protein concentrate. The digestibility of crude fibre in the urea-supplemented diet was intermediate between the values obtained on the high- and low-protein diets.

(4) Despite marked differences between treatments in the intakes of apparently digested nitrogen, similar amounts of nitrogen were retained, because of large differences in the amounts of nitrogen excreted in the urine. However, the amount of nitrogen stored per unit of body-weight gain was 27% higher in calves given the concentrate containing 19·6% crude protein than in those given either the low-protein concentrate or the urea-supplemented diet.

Some possible sources of error when sampling oesophageally fistulated sheep at pasture were examined in eleven trials. Samples collected from sheep asted for varying periods of up to 22 hours did not differ significantly in nitrogen content from samples collected from unfasted sheep. There was no significant difference between the nitrogen content of extrusa collected at the start of a 30-minute period and that of extrusa collected at the end of the period. Sheep transferred from a perennial ryegrass/clover pasture to a native pasture for three months ingested herbage containing 3·80% nitrogen when returned to the original pasture. Control sheep which had remained on the ryegrass/clover pasture selected material containing 3·33% nitrogen. In a further trial sheep transferred from a ryegrass/clover pasture to a Phalaris/ clover pasture consumed herbage with an organic matter digestibility of 70·8 % which contained 3·44 % nitrogen. The material consumed by similar sheep which had grazed the Phalaris/clover pasture for 18 months was 71·5% digestible and contained 3·63% nitrogen.

Diurnal changes in the digestibility and nitrogen content of the diet of free-grazing sheep were observed in two trials. Diurnal changes in nitrogen content were similar on different days but changes in digestibility were relatively smaller and less repeatable between days.

Consistent differences in the composition of the diet selected by individual sheep and selected on different days were observed in a further five trials. Variation between sheep and between days in the nitrogen content of the diet was ±5·6% and ±7·4% respectively, both estimates being expressed as coefficients of variation. Corresponding estimates for digestibility, calculated as standard deviations, were ±1·6 and ±1·3 units. The implications of these results when sampling oesophageally fistulated sheep at pasture are considered.

Female sheep of five breeds (Scottish Blackface (B), South Country Cheviot (C), Welsh Mountain (W), Lincoln Longwool (L), and Southdown (S)) were purchased as lambs of 5–6 months old and subsequently kept as a single flock on a grassland farm until they were 4½ years old (Southdowns to 3½ years). The sheep were used in a crossbreeding experiment with up to six breeds of ram.

The sheep were weighed and 8 body parts measured at frequent and regular intervals. The Blackfaces and Southdowns grew, relative to their mature size, a little faster initially than the Cheviots. Mature weights (lb.) were approximately B: 146, C: 145, W: 101, L: 197 and S: 129. The breeds differed in conformation but the order of maturity of the body parts was the same for each breed. Variances for body measurements decreased slightly with increasing age for early-maturing parts and increased a little for later parts. The coefficients of variation decreased slightly with increasing age. Variance in weight increased markedly with age (but not the C.V.) and showed the only large breed differences in variance.

Fleece weight, after the first shearing, was strongly affected by the amount of wool shed prior to shearing. Shedding differed significantly between the breeds, Cheviots shedding most. Shedding was also related to the number of lambs born per ewe. The total weights (lb.) of wool produced from four shearings were B: 23·2, C: 20·0, W: 15·6, L: 55·5 and S (estimated from 3 shearings): 20·8.

The numbers of lambs born per ewe totalled over three lamb crops were B: 5·81, C: 5·21, W: 4·53, L: 4·85 and S (estimated from two crops): 4·55. In survival to weaning, single-born lambs were no better than twins and crossbred lambs no better than purebred. Lambs born to Welsh mothers had the best survival; the other breeds did not differ significantly from each other. The breeds of ewe differed in the proportions of their twin lambs which had to be assisted at, or soon after, birth.

When each breed of ewe was mated to the same breeds of ram, the weights of lambs born to Blackface mothers did not differ significantly at birth from those of lambs born to Cheviots but were heavier at weaning. Lambs from Welsh mothers were the lightest at birth and weaning.

In relation to (live-weight)0·73 the maternal performance of the Welsh females was at least as good as that of the Blackfaces but the wool production was slightly poorer.

1. A growth trial and nitrogen balance studies were carried out on 32 early-weaned calves fed on a basal diet containing fish meal or diets in which the fish meal nitrogen was partially replaced by urea or ammonium acetate or totally replaced by urea.

2. Growth rate and feed conversion efficiency were highest on the fish meal diet and fell as urea replaced the fish meal.

3. Rumen ammonia levels and urinary nitrogen excretion were highest, and nitrogen retention lowest, in the calves receiving the diet in which fish meal nitrogen was completely replaced by urea nitrogen.

Three groups of eight yearling Friesian steers were fed on pelleted diets containing ground barley straw, maize and soya bean meal, the percentages of straw in the diets being 10, 30 and 50 (treatments 1, 2 and 3). The crude protein level was adjusted to 12% in all diets on an air-dried basis.

Daily live-weight gain for treatment 2 was 7% greater than for treatment 1, and 12% greater than for treatment 3. Voluntary feed intake was also greater in treatment 2, by 16% when compared with treatment 1 and 4% when compared with treatment 3. The efficiency of feed conversion decreased by 10% for each 20% increase in dietary straw level.

Weight loss during lairage was greater on treatment 3, as were total gut fill and omasum weight. The bone content of carcasses was similar for all treatments; carcass lean was increased in treatment 2. Carcass and channel fat was severely depressed in treatment 3.

The results are discussed in relation to dietary effects on carcass composition.

A trial designed to investigate the effects of two environmental temperatures, three feeding regimes and the interactions between them is described. A temperature of 72° F. was better than one of 54° F. for bacon pigs between 40 lb. and 200 lb. weight. The higher temperature resulted in faster growth, more efficient feed conversion and increased length of carcass. Other carcass characteristics were not significantly altered. Ad libitum feeding resulted in faster growth and fatter carcasses than restricted feeding, but did not have a significant effect on efficiency of feed conversion. When feed intake was restricted, feeding pigs once daily or twice daily resulted in similar performance and carcass composition.

There was a significant interaction between environmental temperature and feeding method for average daily gain in that pigs fed ad libitum grew faster at the low temperature and pigs fed restricted amounts of feed grew faster at the high temperature. No other interaction reached significant levels.

1. Sixteen foods, made up with differing proportions of roughage and concentrates and ranging in crude protein content from approximately 2·6% to 10·0%, were each offered ad libitum to Blackhead Persian wether sheep. The nitrogen balance of the sheep and the distribution of nitrogen in the urine were measured.

2. Urinary nitrogen excretion decreased with the digestible nitrogen intake. There was a highly significant (P < 0·01) positive correlation between either excretion of urea or of allantoin and digestible nitrogen intake.

3. The amount of creatinine excreted varied little with diet but was directly related to the body weight of the sheep.

4. For 8 diets, hippurate excretion by the sheep was directly related (P<0·01) to intake of digestible nitrogen, while a significant (P<0·05) positive correlation between the same measures was found for the other 8 diets.

5. It is suggested that with certain types of diets the excretion of either nitrogen, urea or allantoin in the urine may be useful indicators of digestible nitrogen intake of low-protein diets by sheep.

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.

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.

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 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.

Changes in prices of the basic cereals make it necessary to have a reliable assessment of their relative nutritive values if maximum economic efficiency of pig production is to be attained. As the primary role of cereals in pig feeds is as a source of energy, it is on this basis that comparison should be made but with due allowance for any major differences in nutrient content which may necessitate differential supplementation.

Sorghum, or milo, is a cereal imported into the United Kingdom which, at times, may be competitive with other cereals for price per ton but about whose nutritive value there is some confusion. Sorghum has not often been compared with barley as a cereal for pigs, but its value relative to that of maize seems to vary widely, between 80 and 100% (Braude, Mitchell and Robinson, 1950; Hillier, MacVicar and Pond, 1954; Aubel, 1956; Loeffel, 1957; Peo and Hudman, 1958; Schruben, 1959; Vanschoubroek, Spaendonk and Nauwynck, 1964). Estimates of relative digestible energy values (DE) are equally variable; the DE value of sorghum has been assessed as 94·5% (Diggs, Becker, Terrill and Jensen, 1959) and 96·2% (Robinson and Lewis, 1962) that of maize, whereas the TDN value given by Evans (1960) is greater than that of maize. Robinson and Lewis (1962) consider the DE value of sorghum to be 140% ofthat of barley, but Evans (1960) quotes a TDN value for sorghum which is 111% of that of barley. While variation in the type of sorghum used may account for some of this discrepancy, Dammers and Djikstra (1961) found little difference between the varieties milocorn, kaffir corn, granifero and white dari, and only guinea corn differed in having a lower energy value.

There is little published information on the seasonal distribution of ewe mortality in hill flocks. This note presents records relating to some 1,500 Blackface and 1,000 Cheviot breeding ewes on three hill farms over a 10-year period from 1955 to 1965. The farms are Sourhope, Roxburghshire, in the Cheviot Hills, with 1,000 Cheviot and 350 Blackface ewes on predominantly Festuca-Agrostis, Nardus and Molinia pastures, subject to intermittent snow cover; Glensaugh in the East Grampians in Kincardineshire, with 550 Blackface ewes on predominantly heather (Calluna) pasture on free draining ground, subject to prolonged periods of snow which necessitate regular supplementary feeding; Lephinmore on Loch Fyne in Argyll, with over 600 Blackface ewes on mixed pastures mostly overlying peat, not liable to prolonged periods of snow. Further details are given in the H.F.R.O. report (1958).