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.

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.

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. 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.

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 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.

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.

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.

Five years' records of unculled White Wyandotte flocks at Hillsborough, Northern Ireland, were analysed to give estimates of heritabilities and of genetic and environmental correlations by two methods. Pooling data for four years and eliminating hatch effects gave heritabilities of 0·28 for eggs laid by survivors to 500 days; 0·61 for weight of pullets at penning; 0·51 for weight of pullets at 8 weeks; 0·18 for days to first egg; and 0·71 for spring egg weight. These are in general agreement with most other published figures, as are most of the genetic correlations. A suggestion of sex-linkage in the genetic correlations between weight at 8 weeks and days to maturity was not supported by other figures from the data. The method of eliminating hatch effects, unexpectedly, gave higher heritability figures where heritability was already moderate or high. It gave numerically greater figures in most genetic correlations, but did not lead to an expected reduction in the environmental correlations. The data were probably inadequate for a rigorous test of the method.

A trial has been carried out to determine the effects of supplementing bacon pig diets with 125 and 250 ppm. copper (as copper sulphate) and/or aureomycin (14·4 ppm.). A total of 288 pigs were fed ad lib. from 40·100lb., and restricted-fed thereafter to bacon weight (200 1b.). Growth rate was increased by 125 ppm. copper, 250 ppm. copper, and aureomycin during the ad lib. feeding period. The magnitude of the responses was about the same in each case.

During the fattening stage from 100 1b. to bacon weight, 125 ppm. copper or aureomycin increased food conversion efficiency; 250 ppm. copper however improved growth rate also. There was probably some additive effect of 125 ppm. copper and aureomycin when fed together, but it is unlikely that such an effect occurred with the higher level of copper and aureomycin.

The liver copper content of pigs fed 125 ppm. copper was 3 times higher than that of the controls; 250 ppm. copper increased liver copper storage about 18·fold.

The similarity in response of copper and aureomycin feeding to pigs is discussed. It is concluded that, under the conditions of the trial, their mode of action is similar. Under similar conditions in general farm practice there is unlikely to be any economic advantage in supplementing pig diets containing 250 ppm copper with aureomycin; however, the bacterial environment may sometimes be such that additional benefit will be obtained by joint supplementation.

Two trials were completed using a total of 135 female hoggets from 5 to 7 months of age. The effect of implanting 15 or 30 mg. testosterone propionate or 2·5 mg. oestradiol benzoate plus 25 mg. testosterone propionate was assessed on average daily gain, slaughter characteristics and carcass yield. In the second trial some additional data were obtained on carcass quality.

No significant effect of testosterone with or without oestradiol could be demonstrated on average daily gain, carcass yield, carcass score or the proportion of retail cuts in the carcass. There was some indication that the treatment could yield carcasses with less subcutaneous fat without diminution of eye muscle size.

In the herd of Nganda cattle at the Government Livestock Experiment Station, Entebbe, Uganda, it was found that of the known environmental factors affecting milk production, the more important ones were age (in lactations) and length of the calving interval preceding the second and third lactations. The correlations between performance in different lactations of the same animal were high for lactation milk yield (0·73) and average daily milk yield (0·62) and low for calving interval (0·21) and dry period (0·15). The repeatability of lactation length was intermediate (0·42). The heritability values were around 0·3 for the weight measurements, around 0·2 for yield characteristics and around 0·1 for length of lactation and age at first calving.

The sires used in the breeding programme at Entebbe made little impact on production performance in the herd. The estimated genetic improvement in milk yield through selection of dams of cows was also low. It is argued from comparison with results from other parts of the tropics that superior genotypes for milk production are difficult to come by among indigenous cattle in these areas and that we should therefore look for other opportunities and methods to move ahead faster in the future.

1. A series of experiments with adult sheep were carried out in an attempt to place on a quantitative basis the generalisation that the voluntary food intake of ruminants increases with the quality of the fodder they are given.

2. Methods of determining voluntary intake free of subjective bias were developed. It was shown that voluntary intake varied with a fractional power of body weight close to 0·734. The length of time necessary to establish stable intakes was 12–15 days and the number of times fresh food was offered each day had no apparent effect on intake.

3. It was found that voluntary intake of long fodders was related to the apparent digestibility of their energy, increasing rapidly as digestibility increased from 38% to 70% and thereafter more slowly.

4. The giving of concentrated food resulted in a drop in the voluntary intake of fodder. With high quality hay 100 g. concentrates replaced 100 g. hay. With poor quality hay, 100 g. concentrates replaced 47 g. of hay.

5. The passage of three widely different hays through the gut was measured and the poorest passed most slowly. Calculations showed that the dry matter content of gut contents was the same for all three materials irrespective of their quality.

6. It was shown that an increase in digestibility of 10 units in the range 40–60% resulted in considerable increases in the total amount of energy apparently digested and in equivalent increases in daily gain.

7. The digested energy consumed/day/kg. W0·734 (E) can be related to voluntary intake (I) g./day/kg. W0·734 by the equation:—

E=4·(I—31)

which provides a rapid and easy method of assessing fodder quality under conditions of ad libitum supply.

8. The results are discussed and it is shown that under ad libitum feeding conditions an increase in the nutritive value of unit feed from 50 to 55, i.e. by 10%, increases body gain by 100%.

A Method of estimating grazing intake is essential for studies of feed utilisation in ewes under natural conditions. Since the ewe is a close and selective grazer, methods involving the cutting of comparable grazed and ungrazed areas of the pasture are unlikely to allow reliable estimation of pasture intake. It seems likely that only by a study of the faeces produced can reasonable estimation of individual intakes be made. The first requisite for such estimations is an accurate method of estimating faeces output. Sheep, with their relatively lower and drier faeces output, present fewer problems in total faeces collection than do cattle, which produce large quantities of faeces of a low dry-matter content. The collection of faeces, free from urine, presents a special difficulty in female animals.

1. Nine groups of 4 litter-mate Wessex Saddleback gilts were divided on a within-litter basis between 4 treatments so that they were reared from 8 weeks of age to 200 1b. live-weight according to different levels of total feed intake; (a) a high level rising to 8·0 1b. meal per day at 200 1b. live-weight, (b) a medium level approximately 80% of the high, (c) a low level approximately 60% of the high and (d) changing from the low to the medium level between 14 and 16 weeks of age. From 200 1b. live-weight to mating at first heat after reaching 300 1b. all were fed to the medium scale (6·5 1b. meal per day), and all were treated alike during each of 3 pregnancies and lactations.

2. Mean rate of growth from weaning to 100 1b. and from 100 to 200 1b. differed significantly between treatments (P<0·001), and mean efficiency of feed conversion of the low-plane group was significantly poorer than that of the high-plane group (P<0·05) from weaning to 100 1b. live-weight.

3. All gilts, regardless of treatment, reached puberty at approximately the same age (25 weeks), with the result that mean weight at puberty differed markedly between treatments (P<0·001); 116, 154, 189 and 147 1b. for treatments (a) to (d) respectively.

4. Gilts reared on medium and high planes of feeding exhibited oestrus less strongly than those reared on the low-plane, with the result that mean weight at successful mating was significantly greater in these two groups (P<0·05).

5. Four gilts in the low-plane group and one in the high-plane group failed to conceive after repeated matings, but numbers were insufficient to indicate the significance of this.

6. From the original 36 gilts, 27 first litters, 26 second litters and 25 third litters were produced and reared to 8 weeks of age. There was no significant difference between treatment groups in litter size at birth, mean weight of piglets at 3 or 8 weeks of age or total litter weight at weaning.

7. Trouble from temporary collapse of the legs was experienced in all but one gilt of the high-plane group between 6½ and 7½ months of age.

1. Paired lactation records of milk yield and fat percentage from experimental twins and commercial twins, full-sisters and half-sisters are used in a study of the influence of contemporaneity, genetic variation and herd differences.

2. The design of the investigation was such that members of a pair were alike in:

(i) both time of calving and lactation number,

(ii) time of calving only,

(iii) lactation number only, or

(iv) neither time of calving nor lactation number.

3. Intra-class correlations between pair members in respect both of yield and fat percentage were highest for contemporary records. Differences in time of calving and in lactation number produced, in aggregate, a decline in correlation of about 20%. However, the separate estimates varied considerably between the different types of pair.

4. The within-pair and between-pair variance components independently confirm these effects of contemporaneity. As the degree of contemporaneity of pair members declines the within-pair variance increases in size and the between-pair component decreases.

1. Twenty spring-born Friesian calves, housed indoors, were divided into two groups each of 10 calves. During their first three weeks all calves were fed alike on whole milk containing 3·5% butterfat. At three weeks of age calves in one group were changed to a diet consisting of reconstituted buttermilk powder which was made up to the same energy content as the milk. Up to the 30th day intake was gradually increased to 20% of body weight; thereafter till slaughter of the calves at approximately 200 1b. live-weight both groups were fed to appetite twice daily.

2. Calves in both groups grew well and differences between groups in growth rate, and age at slaughter, food consumption and food conversion, were all statistically non-significant.

1. Two groups of Friesian calves, one group of 10 reared on whole milk and the other group of 9 changed gradually from whole milk at 21 days of age to a full diet of reconstituted buttermilk powder at 29 days of age, were slaughtered at a live-weight of approximately 203 1b. Data obtained at slaughter showed a highly significantly heavier weight of omental fat from the calves of the whole milk group, and a significant difference in the weight of the unemptied intestinal tract in favour of the buttermilk group.

2. One side of each carcass was dissected by anatomical joints into the primary tissues; bone, muscle, fat, and tendon and waste. The absolute proportional weight of the dissectible fatty tissues and the weight of kidney and channel (pelvic) fat were statistically highly significantly heavier in the carcass sides of the calves reared on whole milk. The percentage of muscular tissue in the sides of the buttermilk reared calves was significantly higher than for the sides in the other group.

3. The chemical composition of the dissected muscular tissue revealed highly significant differences in fat (ether extract) and a significant difference in water percentage in favour of the carcass sides of the calves reared on whole milk.

4. The chemical composition of the dissected fatty tissue showed statistically highly significant differences in favour of the calves reared on whole milk for the items: water weight and percentage, fat weight and percentage, protein weight, and ash weight. The buttermilk group had in their dissectible fatty tissue a highly significantly greater proportion of water and protein.

5. The dissectible components of the individual joints showed: significantly heavier weight of fatty tissue from the leg, loin, pelvis, 9–10–11 rib cut, thorax, and shoulder of the left sides of the calves reared on whole milk. The weights of the dissectible muscular tissue of the loin and the rib cut were significantly heavier for the buttermilk-reared calves.

6. Cutting-out data on a limited number of sides showed no consistent differences between groups.

7. The meat trade did not differentiate against the buttermilk-fed calves despite their lower fat content. The high muscular tissue content at 65–68% makes veal a very desirable product.