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. In the summer of 1958, 15 mg. of hexoestrol was administered to Blackface wether lambs in one of the following ways; 5 mg. before weaning followed by two 5 mg. tablets at weaning, three 5 mg. tablets at weaning, and thirdly a single 15 mg. tablet at weaning. In a further series of experiments in 1959 the effect of both raising the pre-weaning implantation to 10 mg., and the total hexoestrol dosage to 20 mg. was studied.

2. Suckled lambs implanted with 5 mg. of hexoestrol at the milk clip gained significantly more in live-weight (18%) up to weaning in 1958 than did untreated lambs; in 1959 the difference was only 11%.

3. Between weaning and the end of the trial all treatments with the exception of that in which hexoestrol dosage was raised to 20 mg. showed a very highly significant increase in live-weight gain over untreated lambs, the increases ranging from 26 % to 54%.

4. In neither year was the overall gain in live-weight from pre-weaning to the end of the trial significantly increased by implanting part of the hexoestrol dose prior to weaning.

5. Live-weight gain of the lambs was not significantly increased when three 5 mg. tablets of hexoestrol replaced a single 15 mg. tablet.

6. The implanting of lambs with 20 mg. hexoestrol failed to give a response superior to that obtained with 15 mg. hexoestrol.

7. Each group of lambs receiving hexoestrol treatment showed an increased average carcass weight.

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.

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.

The gestation lengths of cattle are considered in terms of variation due to the month in which calving occurs. The well-known summer decrease in gestation length is re-established but in addition there is a short-term decrease in April which appears to be related to the cattle being put out to grass at a late stage of pregnancy after they have been housed for the winter.

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.

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.

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.

Blood grouping was used to investigate 1000 parentage cases in Swedish cattle. The blood samples were tested for 39 antigenic factors belonging to 9 different systems. One of the two possible bulls could be excluded as the sire in about 80% of the complete parentage cases in the Swedish Friesians (SLB) as well as the Swedish Red and White breed (SRB). The additional use of the transferrin systems in 79 of these cases resulted in a considerably increased efficiency. The probability of making exclusions with the aid of the various blood grouping systems was estimated from gene frequency data and showed good agreement with the results actually obtained. In the SRB the combined use of tests for cellular antigens and transferrins is expected to give solutions in about 84% of the complete paternity cases with two possible sires.

The value of using genotypic classifications in the complex blood group systems in parentage tests is discussed. Finally, attention is given to the difficulty encountered in parentage cases involving twin-born animals with erythrocyte admixture.

The results are given from trials which were designed to demonstrate the effects of feeding antibiotics and a tranquiliser to beef cattle. In Trial 1 the feeding of 80 mg. aureomycin daily produced no significant effect. In Trial 2 the feeding of neither 2·5 mg. hydroxyzine nor 80 mg. terramycin nor the two combined produced any significant effect except to depress the level of intake of dry-matter over the whole trial period. This reduction in drymatter intake did not lead to an increase in efficiency of conversion (lb. dry-matter intake per lb. live-weight gain). In trial 2 the tranquiliser tetrahydrozoline was unsuccessfully used at the beginning of the trial in an attempt to reduce the loss in live-weight suffered when the animals were tied up.

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.

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.

1. High and low dry-matter silages were fed to fattening bullocks on the self-feed system giving daily live-weight increases per head per day of 2·6 lb. and 1·7lb. respectively, over a feeding period of 10 weeks.

2. Chemical data on the composition of a low dry-matter silage and high dry-matter silage are presented.

3. Digestibility studies using sheep were carried out to obtain the starch equivalent values of the two types of silage. The starch equivalent of the high dry-matter silage was 12·4 while that of the low dry-matter silage was 9·9. This difference in starch equivalent explains the extra 0·9 lb. per head per day live-weight increase made by the bullocks on the high dry-matter silage.

4. Mineral balances were carried out. The results show that the low dry-matter silage would supply an inadequate amount of calcium for satisfactory production.

Observations on duration of the period of receptivity in two groups of Milking Criollo, one of Jersey and one of Brahman cows are presented. After one or two oestrus periods measured without service the cows were bred naturally in the case of Jerseys, Brahmans and one group of Milking Criollos. In the other group of Milking Criollos, artificial insemination was used. The period of receptivity was shortened after natural service by 8·7 hours in Milking Criollo and by 4·1 hours in Brahman cows. No shortening of oestrus occurred in the Jerseys and no significant shortening in artificially inseminated Milking Criollos.

Nine of the cows under observation (and seven other cows with some Zebu blood) allowed only one service by the bull.

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.