Twenty-two triplet or small twin lambs were reared in two ways. One group received cow's milk and the other a synthetic milk designed to approximate in composition to ewe's milk.

The group fed synthetic milk made significantly better live-weight gains to weaning. This difference was not maintained after weaning. Possible reasons for this are discussed.

Two 2 × 4 factorial experiments each involved 8 litters of 8 pigs, one pig from each litter being allocated to each treatment. Diets containing supplements of a commercial grade of copper sulphate were compared with others containing Analar (Experiment 1) or micro-analytical reagent grade copper sulphate (Experiment 2). Four levels of each of two grades of CuSO4.5H2O, providing 16, 62, 125 or 250 p.p.m. Cu in the diets, were given in each experiment.

The pigs were put on experiment at 8—9 weeks of age and most were slaughtered as their individual weights reached about 200 lb. The exceptions were 4 litters in Experiment 1 which were taken off experiment at that weight but not slaughtered. The pigs were fed in individual compartments, meal allowances being determined from a fixed scale based on live-weight.

Purity of copper sulphate did not affect growth rate, feed conversion efficiency or carcass measurements in either experiment.

Response to level of copper sulphate between about 45 and 100 lb. liveweight differed somewhat between experiments. In Experiment 1 pigs receiving 125 or 250 p.p.m. in the diet grew 4 or 9% faster and had better feed conversion efficiencies than those receiving 16 or 62 p.p.m. Cu. In Experiment 2, pigs receiving 62, 125 or 250 p.p.m. Cu all grew about 4–5% faster and had 1–5 % better feed conversion efficiencies than those receiving 16 p.p.m. Cu, but the effect on feed conversion efficiency was not statistically significant.

Increase in copper sulphate above the trace level supplying 16 p.p.m. Cu in the diet had no effect on growth rate or feed conversion efficiency between 100 and 202 lb. live-weight or on killing-out percentage or carcass measurements.

Comparison of the results with those from a previous experiment showed that in pigs fed according to a fixed scale the greatest consistent increases in growth rate and feed conversion efficiency have occurred with copper sulphate as 0·1% of the diet, giving 250 p.p.m. Cu. This supplement has only improved performance between 100 and 200 lb. live-weight in one experiment out of five.

1. Nitrogen balance studies were made on eight early weaned calves given diets varying in crude protein content from 11·6% to 22·6% in dry matter.

2. Nitrogen retention increased significantly as the level of crude protein increased to 19·20%; there was no further increase in nitrogen retention when the level of protein was increased to 22·6%.

3. Dry matter digestibility and apparent digestibility of dietary nitrogen rose progressively as the level of crude protein increased.

4. The nitrogen retention of calves fed diets adequate in protein was calculated to be 2·88 g. per 100 g. gain in body weight.

1. Nitrogen balance studies were conducted on 6 early-weaned calves fed three diets containing respectively commercial groundnut meal, heattreated groundnut meal and fish meal as the major protein sources.

2. Nitrogen retention and live-weight gain differed significantly between diets, being highest on the fish meal diet and least on the commercial groundnut diet.

3. Blood urea concentration was significantly lower on the fish meal diet than on either of the groundnut diets but differences between the groundnuts were not significant.

4. Differences between diets in nitrogen utilisation were due almost entirely to differential urinary nitrogen losses.

The transferrins in Swedish cattle were studied with the starch gel method. A continuous tris buffer system was used. With sera from young calves each transferrin allele appeared to determine four fractions. Among some animals from Norway two seemed to have a transferrin type not earlier described for the European cattle breeds. The frequencies of the transferrin alleles found in a bull sample from the Swedish Red-and-White breed were TfA = 0·53, TfD = 0·18 and TfE = 0·29. Family data were in good agreement with the theory of inheritance. The transferrin types were used in parentage testing and a formula is given for the possibility of making exclusions. The value of the transferrin types in diagnosis of zygosity in cattle twins is shown. The transferrins seem to occur in bovine milk also.

1. Three groups, each comprising four Hereford-cross and four Friesian half-sib male calves, were fed milk substitute and offered grass cut from autumn pastures. Two of the groups received meal supplements of similar energy value but differing in protein content. The third group received no meal supplement.

2. As the consumption of meal rose the intake of herbage dry matter decreased but total dry matter intake increased.

3. The effects of the two meals on the progress of the calves were similar but not apparent until after the first 6 weeks. The lack of response to the high protein content of one meal suggests that energy may be the limiting factor to growth of calves reared on autumn pasture.

4. Hereford-cross calves which did not receive a meal supplement tended to make the best live-weight gains during the subsequent grazing season, but no such recovery was made by the Friesians.

Forty-eight sows were inseminated into the uterus with semen (sperm fraction) diluted to 20 ml. with an egg-yolk glucose phosphate (YPG) diluent to contain 10·0 × 109, 1·0 × 109 and 0·1 × 109 spermatozoa. In 24 sows (120 ml. group) insemination of the 20 ml. diluted semen was followed by the intra-uterine insemination of 100 ml. YPG diluent, alone. The success of insemination was judged at autopsy from ova recovered 2-4 days after insemination (Experiment A) or from counts of foetuses present 25 days after insemination (Experiments B and C). In Experiment A the numbers of ‘cleaved’ ova were recorded before fixation: the numbers of ova judged to be ‘fertilised’ were counted in preparations of fixed and stained ova. For 24 sows inseminated with 20 ml. semen alone at the three dosage levels (10·0 × 109, 1·0 × 109 and 0·1 × 109 spermatozoa) the percentages of ‘cleaved’ and ‘fertilised’ ova were 78·5 and 80·9; 83·5 and 81·2; 24·6 and 19·8. For sows inseminated with the same sperm numbers in 20 ml. semen followed by 100 ml. diluent, the percentages were 41·5 and 43·9; 44·2 and 36·2; 24·6 and 6·7. Comparison of numbers of sows with some ova cleaved (or ‘fertilised’) and sows with none cleaved (or ‘fertilised’) showed no significant differences in sow fertility between treatments.

Comparison of numbers of sows with all ova cleaved (or ‘fertilised’) and sows with none cleaved (or ‘fertilised’) shows that inseminations with the 20 ml. volume, alone, were of significantly higher fertility than those inseminated with 120 ml.

Estimates of fertility based on the examination of unfixed ova differed in 9 sows from estimates based on the examination of fixed and stained ova. In one sow some uncleaved ova were shown to be pronucleate after fixation and staining. Morphologically abnormal ova were identified in 6 sows; most of these abnormal ova showed multinucleate blastomeres. These abnormal ova were found only in sows inseminated with not more than 1·0 × 109 spermatozoa.

Counts of the numbers of spermatozoa on fixed ova showed that these tended to decline as the number of spermatozoa inseminated declined. Comparing sows inseminated with the same number of spermatozoa there tended to be fewer spermatozoa on ova from sows inseminated with 120 ml. than on ova from sows inseminated with 20 ml.

Of 13 sows in Experiment B inseminated with 20 ml. semen containing 10·0 × 109 spermatozoa, 9 had foetuses present at autopsy 25 days later (11·6 foetuses per sow).

Of 17 sows in Experiment C inseminated with 20 ml. semen containing 1·0 × 109 spermatozoa, 7 had foetuses present at autopsy 25 days later (7·1 foetuses per sow).

The difference in pregnancy rate for the two groups is not statistically significant.

Differences in litter size between the two groups of sows are explainable by differences in ovulation rate between the two groups (group B, 18·2 corpora lutea per sow, group C, 13·4 corpora lutea per sow).

1. Judges' scores for the ‘proportion of cuts’ of bacon sides were related to the length and to the ratio of the length and depth of the sides, but not to the weight of the fore-end.

2. In two investigations involving six hundred and eighty sides of bacon, length showed little relation to the yields of the major wholesale cuts or to measures of value based upon them, although in one analysis longer sides tended to have lighter fore-ends. Fatter sides tended to be heavier in the back and lighter in the fore-end and gammons than leaner sides of the same weight.

During a survey of beef production in East Anglia carcasses of 163 Friesian, 87 Dairy Shorthorn and 45 Aberdeen-Angus × Friesian steers and 44 Aberdeen-Angus × Friesian heifers were measured and scored by visual assessment for fat development. They were also graded by the Ministry of Agriculture, Fisheries and Food.

Age data indicated that the Friesian steers were, on average, younger at slaughter than the other groups, but they were incomplete and comparison was based on carcasses of the same weight. The Dairy Shorthorn steers had higher mean values than Friesians in three of the carcass measurements taken. The Dairy Shorthorns had a higher average fatness score and a higher proportion of Grade A carcasses. Aberdeen-Angus × Friesian steers had lower mean values for measurements of the hind leg, higher fatness scores and a higher proportion of Grade A carcasses than either of the two pure breeds. Aberdeen-Angus × Friesian heifers had lower mean values for measurements of both fore and hind legs, higher fatness scores and a slightly higher proportion of Grade A carcasses than the steers.

The information gained by use of measurements and fatness scores explained, but did not materially add to, the assessment of the relative value of the groups of carcasses given by grade.

A comparison has been made in five flocks with a total of 473 sheep of the effect of 15 mg. diethylstilboestrol (DES.) as a paste, 15 mg. hexoestrol as an implant, and 5·0 mg. oestradiol benzoate plus 50 mg. progesterone (O.+P.) as two implants, on the growth rate and slaughter characteristics and carcass grading of fattening male hoggets.

In those flocks where the plane of nutrition was adequate, all hormone treatments resulted in a significant increase in live-weight gain. During the first 24–40 days, DES. paste resulted in significantly greater daily live-weight gain compared to hexoestrol or O.+P. in two out of five flocks, but over the whole period there were no significant differences between these treatments. In one flock which was on a lower plane of nutrition there were no significant effects of hormone treatment.

The hormone treatments resulted in extra carcass weight, extra pelt weight but no change in killing-out percentage or in carcass grade. There were no significant differences between treatments in the slaughter characteristics studied.

Data on carcasses of 352 Large White baconers by 44 boars were taken from reports of Progeny Testing Stations to estimate the heritability of chemical fat in the loin muscle and of fatty tissue content in the carcass, and their phenotypic and genetic correlations.

The heritability of the chemical fat content in the loin muscle was found to be 0·50, that of the fatty tissue content in the carcass 0·69. The genetic correlation between the characteristics under study seems to be very low (rA = 0·11), and their phenotypic correlation, though significant statistically, was also found to be low (about 0·2).

A feeding trial is described in which 32 individually-fed Large White pigs were used to investigate the effects of variations in the protein and energy status of the diet on growth, efficiency of food utilisation and carcass characteristics. The salient features of the finding were:

1. Over the weight interval 50–100 lb., it appeared that 1·0% was a more appropriate level of dietary lysine than one of the order of 0·75%; the former figure corresponded to a level of 5·8% of dietary protein.

2. In the ‘finishing phase’ of growth from 100–200 lb. the pig clearly tolerates wider energy : protein ratios than is the case in earlier life, with advantageous results in terms of growth performance but deleterious effects on carcass suitability.

3. An increase in dietary energy status in the ‘finishing phase’ yields growth responses only if protein level is appropriately adjusted.

4. It is suggested that Large White pigs require a level of 0·5–0·6% of dietary lysine in the ‘finishing’ period.

A series of trials were designed to determine the slaughter weight of cutting pigs at which lean meat production is most economical, and to investigate nutritional factors which affect lean meat onput in cutting pigs of about 260 lb. live-weight. The trials involved about 1100 pigs and ad lib. feeding was adopted from weaning to slaughter.

In the first trial, pigs were fed on various diets to 300 lb. live-weight. The diets differed in the amount of protein fed during the 90–180 lb. growth period, and the most economic growth was made by feeding a high protein (17 %) diet to 140 lb., or a medium protein (14 %) diet to 180 lb. followed by a cereal-mineral diet thereafter to 300 lb.

Animals were slaughtered and dissected at various live-weights between 90 and 300 lb. and it was found that killing-our percentage, the percentages of usable meat (lean plus fat) and of fat, increased with carcass weight. The increase in fat deposition was mainly at the expense of the non-edible parts of the carcass. Onput of lean and increase in area of eye muscle occurred throughout the range.

Total food requirements, expressed as pounds of food, calories of gross energy or pounds of protein, per pound of usable meat produced decreased as slaughter weight increased. The cost of food required to produce a given quantity of lean meat was least when pigs were slaughtered between 240 and 260 lb. when the commercial value of the remainder of the carcass was taken into account.

The second trial investigated the effect of two levels of protein and mineral supplementation of cereals during the 140–260 lb. growth period of heavy pigs. Correct mineral supplementation of cereals was essential because, although lean meat production was not increased, the cost of food required to produce it was less. The lower protein diet had no effect on growth or carcass composition, but the higher protein diet increased the lean meat content of carcasses and decreased the amount of food required to produce it. The production of the extra lean meat, however, was not economical because of the cost of the high protein diet.

The third trial showed that replacement of barley by wheat during the 140–260 lb. growth period led to carcasses having less lean meat and to higher feed requirements. This is probably connected with the high energy content of wheat as compared to barley.