1. The visual judgement of bacon quality called the ‘proportion of lean to fat’ has been simplified by breaking down the overall assessment of the surface seen on the cut bacon side at the last rib into four simpler scores—of the ‘eye’-muscle size and shape, the amount and distribution of fat on the back rasher, the streak thickness and the proportion of lean to fat in the streak, each judged on a 10-point scale. An experiment is described in which eight experienced judges attempted to score these new characteristics in conjunction with the overall assessment.

2. The judging standard adopted in the overall assessment of the proportion of lean to fat varied less from batch to batch in this experiment (in which the seven batches were arrayed in fixed positions and assessed in one day) than in an earlier experiment (when the examples seen in each batch could be shuffled and the eleven batches were seen several days apart). The ranking of judges according to their discrimination and repeatability for the overall assessment was also changed in the second experiment.

1. A survey of the reasons for disposal of 1000 sows from farms in a selected area of East Anglia showed that the most important causes of sow wastage were ‘failure to breed’, ‘piglet mortality’, ‘old age’ and ‘low fertility’ which together accounted for 64·3% of the sows.

2. The average length of breeding life was 3·75 litters per sow and the modal number of litters was only two. This expectation of life is very short but is in agreement with an earlier estimate based on Breed Society records.

3. Failure to breed was the most important cause of sow wastage and accounted for 21·4% of the sows. The incidence of reproductive failure was greatest in young sows and of all the sows discarded as sterile 30·3% were discarded after having had only one litter. Cases of failure to breed were divisible into two broad groups.

1. Two series of simple nitrogen manuring trials, one on level of sulphate of ammonia applied to the seedbed at twenty-two centres and the other on the time of top dressing with ‘Nitro-Chalk’ at nineteen centres, were conducted on commercial farms in south-east Scotland during 1954 to 1957.

2. The optimum level of sulphate of ammonia varied with season and farm type. The optimum dressing was at least 0·9 cwt. N/acre in the dry season of 1955, and in the other years was estimated to be 0·9 cwt. N/acre on arable farms and about 0·-25–0·4 cwt. on ley rotation farms when the barley did not follow sheeped turnips. In the latter event no fertilizer was best.

3. The nitrogen content of the grain increased little until after the 1 cwt. sulphate of ammonia level, although the optimum yield was not obtained in many experiments without some rise in the grain nitrogen content.

1. The mean velocity ῡ and the velocity frequency distribution f(υ) of bull spermatozoa with normal motility have been determined in standardized eggyolk—citrate buffers at different pH values, ranging frompH 5·70 to 8·35.

Under assumed approximately anaerobic conditions at37·0 ± 0·1° C. the mean velocity was found to show a straight-line relationship -with pH in the physiological region pH 5·70–7·50, according to the general equation

Statistically, k was shown to be a linear function of a, namely,

Consequently, the dependence of the mean velocity of the spermatozoa from any ejaculate can be characterized by the one parameter a = dῡ/dpH. (dimension μ/sec./pH), determining the slope of the ῡ υs. pH curve.

The mean velocity of all individual spermatozoa (measurements of all ejaculates at the same pH value pooled together) could be described accurately by the equation:

For some ejaculates the linear relationship was found to hold up to pH 8·00.

2. The velocity frequency distribution curves were found to change with pH. At pH 5·70 the curves are skew with a relatively high top value. At increasing pH values both the top value and skewness decrease. The mean standard deviation of the velocity distribution f(υ) was found to be proportional to pH and could be described by the equation

This means that the variability in swimming speeds of the individual spermatozoa of any ejaculate increases proportionally with pH, indicating a strain effect of increasing alkalinity on the population, irrespective of the general stimulation of motility in the region up to pH 7·50.

3. At each pH value the mean velocity decreases with time. Under assumed approximately anaerobic conditions at 37° C. the speed of velocity decrease as a function of pH was found to differ so much between different ejaculates that no generalization could be derived from the available material. The same holds for the effect of pH on the number of normally moving spermatozoa in the diluted ejaculate.

4. The total number of spermatozoa moving normally depends on pH, but the optimum varies with the individual ejaculates.

1. In an experiment conducted on an established perennial rye-grass/white clover sward close cutting was carried out over a 3-year period (1956–58), either with a lawn mower to simulate gang mowing or with a reciprocating-knife mower. The sward was cut either six or eight times in each season, and received 0 or 2 cwt. ‘Nitro-Chalk’/acre for each cut.

2. Swards cut with the gang mower yielded from 3·5 to 12·5% more herbage dry matter than swards cut with the reciprocating-knife mower and also gave a greater mean yield of crude protein.

3. The difference in dry-matter yield between swards cut with each of the mowers is attributed to the slightly closer cutting level of the gang mower having a greater inhibiting effect on flower development in the grasses and hence stimulating leaf production and increasing total yields.

4. In the second and third years of the experiment swards cut with the gang mower outyielded those cut with the reciprocating-knife mower by a proportionately greater amount when eight cuts rather than six cuts were taken in the season.

5. When no nitrogenous fertilizer was applied the proportion of broad-leaved weeds in the sward increased more rapidly over the 3-year period where the herbage was cut with the gang mower rather than the reciprocating-knife mower. This disadvantage of gang mowing did not apply where the fertility was maintained at a high level by applications of nitrogenous fertilizer.

6. It is concluded that the gang mower is a more suitable machine than the reciprocating-knife mower for close cutting on a field scale.

1. Sixty-two commercial sows with a history of sterility were served either less than 7 days or between 12 and 21 days before slaughter and the ovaries examined at autopsy. Thirty-eight sows had apparently normal ovaries and twenty-four abnormal ovaries. Of the sows with normal ovaries, seven out of ten served within 7 days of slaughter were pregnant, but only four out of twenty-two served between 12 and 21 days were pregnant. Two sows were not served because they did not come into oestrus. Of the sows with abnormal ovaries only one out of nineteen which had been served was pregnant. Thus in sows with apparently normal ovaries it is suggested that the main cause of sterility is embryonic mortality, whereas in sows with abnormal ovaries the main cause is lack of fertilization.

2. Sterility associated with cystic ovaries was studied in inbred sows and the oestrous cycle in such sows was found to be irregular, usually with an abnormally long dioestrous interval. There were no cases of nymphomania associated with cystic ovaries.

3. The ovaries of ten sterile sows were examined by successive observational laparotomies. In some cases cysts were present together with apparently normal ovulations and it is suggested that the cysts developed from follicles which failed to rupture. In other cases cyclical growth and regression of cysts occurs without ovulations, whereas in others where the cysts are very large (30-50 cm. in diameter) the cysts may be permanent structures. Sows with large multiple cysts frequently show no signs of oestrus and it seems likely that the breakdown in the ovulation process starts with irregular ovulations and tends to proceed towards the development of these large multiple cysts.

4. Intravenous injections of Prolan (l.h.) had no effect on the ovarian cysts. Implantation of stilboestrol tablets reduced the cystic condition but the treated sows did not come into oestrus although corpora lutea were found in the ovaries at autopsy. Intramuscular injections of stilboestrol also reduced the cystic condition and in one case a sow actually became pregnant.

5. No response was obtained to p.m.s. injections in sows in which the ovaries had reverted to an infantile condition.

6. Cystic ovaries were produced by subcutaneous injections of progesterone and these closely resembled those found in sterile sows. The ovaries of gilts with progesterone-induced cysts tended to revert to normal after the cessation of the injections but the fertility of the gilts was low due to failure of fertilization.

7. Preliminary attempts to graft ovaries met with little success probably due to immunological reaction against and imperfect vascularization of the grafts. Further attempts were postponed pending the results of trials with sheep using a different grafting technique.

8. Evidence as to the effect of fatness in causing sterility in gilts was obtained from the records of the National Pig Breeders' Association. Two overfat experimental gilts which did not come into oestrus were found to have apparently normal ovaries at autopsy and a third came into oestrus and was mated after a period on a submaintenancediet, but though it ovulated normally the ova were unfertilized.

1. An analysis of pre-weaning mortality in inbred Large White pigs showed that the over-all mortality in ten generations of sows was 47·3%. During the first four generations mortality fluctuated between 30 and 45%; from the 5th to the 9th it fluctuated between 50 and 68% and in the 10th rose to 88%.

2. 70·2% of all deaths occurred in the first 3 days post-parturition and the average birth weight of pigs which died within 3 days was only 1003·5 g. compared with 1258·5 g. for those which survived. 83·0% of pigs weighing less than 900 g. at birth died within 3 days, whereas only 18·5% of pigs weighing more than 1400 g. died within the same period.

3. There were marked seasonal variations in mortality, this being highest during the winter months. Mortality was highest in litters of under 5 and over 15, but between 5 and 15 there was no increase in mortality with litter size. There was no difference in mortality between males and females.

4. Foetal growth was studied in 80 outbred sows of various breeds. Foetal weight was affected not only by age but also by litter size. The withinlitter variation in foetal weight increased with litter size but no increase in between-litter variation with litter size could be demonstrated statistically. Male foetuses were slightly heavier than females at all stages of pregnancy investigated.

5. The growth of the inbred Large White foetus was also studied at an early and late stage of inbreeding, and the reduced birth weight in the latter was shown to be reflected in slower growth of the foetus from mid-pregnancy onwards.

6. The anatomical composition of inbred Large White foetuses at a late stage of inbreeding has been compared with that of similar foetuses at an earlier stage and also with normal outbred Essex foetuses, at 51, 74, 97 and 108 days of pregnancy. The chemical composition of inbred Large White foetuses of a later stage of inbreeding was compared with that of outbred Essex foetuses at 51, 74, 97 and 108 days. The differences in anatomical composition between the smallest and largest foetuses within litters are comparable with those found postnatally in pigs fed on a high or low plane of nutrition, but this was not reflected in a very definite way in the chemical composition. X-ray photographs showed that ossification was more advanced in the largest foetus within a litter than in the smallest but the appearance of the ossification centres was not delayed in the latter.

7. Attempts to make reciprocal ovum transfers between inbred Large White and outbred Essex sows met with little success, probably due to the low fertility of the Large Whites, the prolonged exposure of the ovum during transference and the necessity of effecting the transfer of the ova at the 2-cell stage. The latter was conditioned by the rate of passage of the ova through the tube and the fact that they enter the uterus in the 4-cell stage.

1. Alternate husbandry systems containing 1-, 2- and 3-year grazed leys were compared with continuous arable cropping at Jealott's Hill during the period 1945–56. Kale and wheat were used as successive test crops to measure the fertility accruing from the following crop sequences: (a) 3-year ley; (b) wheat, 2-year ley; (c) wheat, barley, 1-year ley; (d) wheat, barley, barley. A study was also made of the effect on crop yields of compost, dung and N fertilizer dressings applied to kale.

2. The yields of kale and wheat were improved considerably by 1-, 2- and 3-year leys. Increments were: 5·2 tons fresh kale per acre and 8·7 cwt. wheat grain per acre from 1-year ley, 9·0 tons kale and 13·5 cwt. wheat per acre from 2-year ley and 9·2 tons kale and 15·0 cwt. wheat per acre from 3-year ley. Two- and 3-year leys were markedly superior to 1-year ley in their effects on kale and wheat. The slight benefit apparent in wheat yields from 3-year ley compared with 2-year ley was not significant and so the 2- and 3-year leys may be considered equal in their effect on the succeeding arable crops. In the third arable crop, wheat, the 2-year ley was still effective to the extent of 3·9 cwt. grain per acre but the residual effect of the 1-year ley had largely disappeared. Yields under the all-arable system were considered to have been reduced by the poor physical and nutrient status of the soil, by increased incidence of ‘take-all’ in wheat and by more weed growth.

3. The response of kale to dung averaged only 1·1 tons per acre over all four rotations but this was largely obtained in the ley systems and little after all-arable cropping. Compost was generally ineffective on kale with some signs of detrimental effect, especially in the arable system. Wheat following kale benefited equally from dung and compost applied in the previous year; the average response to organics was 1·6 cwt. grain per acre and this was unaffected by rotation. The residual value of dung on subsequent crops amounted to an average of 2·0 cwt. grain per acre per annum but compost had no significant effect.

4. The response to an additional 0·4 cwt. fertilizer N per acre to kale was greatest after continuous arable cropping and virtually nil after 3-year ley. Wheat grain yields were improved by 1·0 cwt. per acre on average by the addition of the extra 0·4 cwt. fertilizer N per acre to kale in the previous year.

5. It was concluded that when mixed farming is practised the aim should be to have the land under grass for at least as long as it is under arable, e.g. 3 years of ley with 3 years of arable.

1. A study was made of the effects of a milk diluent on bull, ram and boar spermatozoa. Respiration and fructolysis of spermatozoa were used as the two main criteria of sperm activity. The milk diluent was a standardized and commercially available milk product, consisting of sterilized and homogenized milk, supplemented with milk fat.

2. The rate of oxygen uptake measured manometrically in the presence of air was increased by the addition of the milk diluent throughout the entire incubation period. Fructose utilization was assessed by the rate of lactic-acid production. The rate of the anaerobic lactic-acid formation was higher in the presence of the milk diluent during the later stages of incubation.

3. The effect of the milk diluent on sperm respiration was most striking in experiments with the sperm-rich portion of boar ejaculate obtained by fractionated collection. A somewhat less marked effect was observed with bull semen, and in ram semen the effect was comparatively weak.

Soils collected from paddy fields were kept in a waterlogged condition in glass cylinders with and without drainage. After about 2 months of waterlogging soil samples were collected from each cm. depths of the cylinders, both from the bright and dark sides of the cylinders. The soil samples were analysed for iron, manganese and phosphorus. At the beginning these elements were uniformly distributed throughout the entire soil depth, but as a result of waterlogging a distribution pattern developed. More of these elements concentrated on the surface and illuminated sides of the cylinders. It is assumed that such a phenomenon also occurs in the paddy field. These elements by concentrating on the soil surface limit the feeding zones to the top 3–5 cm. of the soil.

During the course of the main investigation the following observations were made on some other aspects of reproduction in the sow.

An examination of the reproductive tract of sows killed at slaughterhouses in East Anglia showed a high percentage of cystic abnormalities in the ovaries (Perry & Pomeroy, 1956). However, the sample of sows necessarily excluded any gilts, so an examination has been made of the incidence of ovarian abnormalities in post-pubertal gilts at two bacon factories. The ovaries of 273 gilts were examined and divided into (a) ovaries containing corpora lutea, (b) ovaries not containing corpora lutea. These were then further classified as normal or abnormal. The chief criteria of abnormality were the presence of cystic follicles, i.e. of greater than ovulatory size (10 mm. in diameter) or cystic corpora lutea, i.e. large flabby corpora lutea with hollow centres. Gilts with numerous haemorrhagic follicles in the ovaries were also classified as abnormal, but it is quite possible that this condition is a common occurrence in gilts just before puberty. However, rather than underestimate the incidence of abnormalities these ovaries were classified as abnormal.

Gilts of the ‘Palouse’ breed were divided into two groups; one group was full fed from weaning to 1501b. and the other group was fed 70% of full feeding. After six generations, one-half of the pigs in each group were shifted to the other plane of nutrition, thus forming four groups: high-high (HH), low-high (LH), low-low (LL) and high-low (HL). F10 gilts were slaughtered 38 or 100 days post-coitum to study reproductive and prenatal phenomena.

1. Ten successive generations of controlled feeding had no significant effect on: length of Fallopian tubes, weight of corpus luteum, percentage of implantation, number of viable foetuses, foetus weight, weight of placental membranes, volume of placental fluids or embryonic mortality.

2. There were significant differences between the high and low planes of nutrition in: weight of pituitary, thyroid and adrenals, weaning weight, puberty weight, puberty weight to birth weight, puberty weight to weaning weight and puberty age. The effect of six generations of controlled feeding was not maintained when the plane of nutrition was changed from high to low or low to high.

3. The frequency of silent heat and the number of services per conception was lower in the low planes than in the high planes.

4. Ova migration occurred in both directions in 41% of the gilts; one to four ova migrated. The foetal sex ratio ranged from 4:0 to 1:7 with an average of 1:1. The sexes were unevenly distributed in the horns.

5. Foetus weight at 38 or 100 days post-coitum was not affected by plane of nutrition or sequence in the uterine horn.

6. Within-litter variations were highest in the volume of allantoic fluid followed in order by variations in weight of placental membranes and then the amniotic fluid and foetus.

7. Foetal mortality was not related to sequence in the uterine horn or the number of implantations.

8. There seemed to be two peaks of early prenatal mortality, one at implantation and another at the onset of organo-genesis.

1. The serum β-globulin phenotype of 141 bulls located at Cattle Breeding Centres in England and Wales was determined by starch-gel electrophoresis.

2. The distribution of the contemporary comparison values of these bulls with respect to β-globulin type was investigated. The great majority of the bulls were βAA, βAD, or βDD with very few βAE and βDE and no βEE types.

3. The contemporary comparison values for 130 bulls of the three types βAA, βAD and βDD each fell into a normal distribution. The mean and its standard error and the standard deviation of the mean and its standard error were calculated for each of the three curves. The mean contemporary comparison value for the βAA bulls was + 12·2 ± 5·4 gal., for the βAD bulls + 26·8 ± 5·4 gal., and for the βDD bulls + 38·2 ± 5·5 gal. The βAA and βDD means were significantly different (P < 0·01).

4. The pooled contemporary comparison values of the βAA, βAD and βDD bulls did not give a normal distribution curve, neither did the contemporary comparison values for a sample of 1028 bulls quoted by the Milk Marketing Board. However, when the contemporary comparison values of the βAA, βAD and βDD groups were superimposed around the same mean, the ensuing distribution was normal.

5. It is concluded that the β-globulin locus is concerned in the genetic control of milk yield. The estimated mean genetic value of βD over βA is approximately + 50 gal. This is about one-sixth of the total genetic variation in milk yield in the major milk breeds.

6. The distribution of butterfat percentages with respect to β-globulin phenotype in four Ayrshire and one Friesian herds was investigated. No difference between the mean first lactation butterfat percentage of the βAA, βAD, and βDD cows in each herd was found. There was an indication (not significant) that the mean butterfat percentage of the βAE and βDE cows in three of the four Ayrshire herds studied was higher than the mean of the other groups.

Dilution of fowl semen with phosphate or saline diluents depressed respiration, while dilution with seminal plasma did not affect respiration. Dilution with Tyrode solution resembled dilution with seminal plasma with respect to respiration. The effect of Tyrode solution seemed to be mainly due to its NaHCO3 content.

The effect of Ca, Mg and K ions depended on the anions in the diluents. Phosphate depressed respiration and glycolysis when it replaced saline in the Tyrode diluent.

Dilution did not consistently increase respiration and in most cases depressed respiration.

Fowl sperm preferentially utilized glucose when glucose and fructose were initially present in equal concentration in the diluent. The sperm metabolize glucose at a faster rate than fructose. No evidence was found for the formation of glucose from fructose under our experimental conditions.

Initial respiration and glycolysis of fowl semen was depressed by the addition of glycine to the Tyrode diluent. However, the glycine addition resulted in a less sharp decrease in the hourly respiration rate.

A field experiment was carried out to study the effect on spring oats of undersowing with broad red clover, Italian rye-grass and a mixture of both. Two levels of nitrogen were used, namely, no nitrogen and 3 cwt. per acre of ‘Nitro-Chalk’.

1. Oat shoot weight was reduced by undersowing, Italian rye-grass having a greater effect than red clover, particularly where nitrogen was applied.

2. In the absence of nitrogenous fertilizer undersowing did not reduce oat plant height, but where nitrogen had been given, Italian rye-grass either alone or in a mixture with the clover, reduced the height; the legume alone had no effect.

3. Undersowing generally reduced the number of oat panicles. Italian rye-grass had no effect when nitrogen was not applied, but a marked reduction was observed when nitrogen was applied. The legume had the greater influence where nitrogen was not applied.

4. Red clover increased the number of whorls, and the number of single-grained spikelets per panicle. Grass sown alone or with clover reduced the number of single-grained spikelets per head.

5. The total number of grains per panicle, 1000 grain weight, percentage husk and the percentage of saleable grain were not influenced by undersowing.

6. No lodging occurred but there was an indication that resistance to bending of the straw was affected by undersowing with Italian rye-grass.

7. Seeding herbage under the oats had a bigger influence on the yield of straw than grain. Italian rye-grass sown alone or with clover reduced the yield of straw where nitrogen had been applied. The legume alone had no effect. Grain yields showed a similar trend.

8. Yield and percentage crude protein in the straw were reduced by Italian rye-grass alone or in a mixture with clover when nitrogen was applied, but there was no effect where nitrogen was withheld. The grass had a greater effect than red clover while a mixture of both was intermediate to the legume and grass sown separately. Italian rye-grass greatly reduced the recovery of applied nitrogen by the cereal.

9. The percentage moisture in the oat sheaves was increased by undersown herbage and red clover had a bigger influence than the grass. The application of nitrogen reduced the bulk of clover under the cereal and its adverse influence on the harvesting of the oats. In the absence of undersowing, nitrogen had no effect on the percentage moisture in the sheaves.

1. The effects of annual applications of 0–12 cwt. per acre of sulphate of ammonia on the herbage levels and yields of sulphate sulphur and total sulphur were investigated in four seeds mixtures 1 year and 4 years after seeding down.

2. There were significant increases in the levels and yields of both forms of sulphur up to the 2 or 4 cwt. per acre level of application in both years. The maximum values occurred at the 6 or 8 cwt. level and the corresponding values at the 12 cwt. per acre rate of application declined in many cases.

3. The cumulative effects of the annual dressings of sulphate of ammonia resulted in substantial increases of approximately 50% in the levels of sulphate sulphur and total sulphur with much smaller increases in the levels of non-sulphate sulphur.

4. Duplicate plots which received 2, 4 and 6 cwt. per acre of sulphate of ammonia also received an additional 2 cwt. per acre immediately after the first cut each year. This splitting of the dressings had no significant effect on the accumulation of sulphur by any seeds mixture. A second cut from the cocksfoot plots in the first year showed the sulphur levels in the plots which received the additional sulphate of ammonia to have increased less than the levels in those which received only the initial dressing. This was explained in terms of the yields of the components.

5. There was a tendency for the rye-grass mixture to contain more sulphate than the other mixtures particularly in the fourth year.

6. The possible significance of the increases found in sulphate levels in the copper-molybdenum metabolism of grazing animals is discussed.

1. EUN and MFN excretions have been determined in goats on a N-low ration and also on a N-free ration. The values obtained were,

EUN = 0·052 g./kg. live weight and

MFN = 0·41 g./100 g. dry-matter feed intake.

2. The values so determined with the two feeding regimens, for both the EUN and MFN agreed very closely.

3. The minimum protein requirement of goats for maintenance, as calculated from the EUN value, is 0·65 lb./1000 lb. live weight.

4. The formula for calculating the utilizable protein requirement for this species is found to be P = 0·89. W0.734, and is almost identical with the one given by Mitchell.

5. The usefulness of the above formula in predicting the EUN of immature goats is discussed.

Three experiments were carried out to obtain more information upon the effects of varying the plane of feeding for bacon pigs.

Exps. 1 and 2 followed the same 3 × 2 factorial design in which (a) diets were fed with or without procaine penicillin and (b) a comparison was made between very high (VH-VH), high (H-H) and low (L-L) planes of feeding for pigs from about 8 weeks old to slaughter at about 200 lb. live weight. The planes of feeding were defined according to the amount of t.d.n. offered to each pig daily.

For each of these two experiments eight lots of six litter mates were used. One pig from each litter was allocated to each of the six treatments, and although litter mates were housed as a group, all pigs were fed individually in separate compartments.

Exp. 3 was a 2 × 3 × 2 factorial to compare two breeds and three planes of feeding during 2 years. During each year three lots of pure-bred Landrace and three lots of Wessex Saddleback × Large White litter mates were used. Each lot consisted of three gilts and three barrows and one pig of each sex was allocated to each of the three feeding treatments. From the start of the experiment, when the pigs were about 8 weeks old, to about 100 lb. weight, all animals were kept to a very high (VH) plane of feeding. From then to slaughter at about 200 lb. live weight the following planes of feeding were compared: (1) very high plane (VH), (2) increasingly restricted plane (R) and (3) low plane (L). As in Exps. 1 and 2 these planes were denned in terms of t.d.n., and litter mates were housed together but fed individually in separate compartments.

In both Exps. 1 and 2 pigs with procaine penicillin in their feed grew very slightly faster and more efficiently than those not fed antibiotic, but the differences did not reach the 5% level of statistical significance. The feeding of antibiotio did not affect the response of the pigs to variations in the plane of feeding.

In comparison with pigs kept to the VH-VH plane of feeding, pigs kept to the H-H and L-L planes grew 13 and 22% more slowly in Exp. 1, and 11 and 26% more slowly in Exp. 2, but plane of feeding had no effect upon food conversion efficiency in either experiment. These results are for the total experimental period.

In both Exps. 1 and 2 reductions in plane of feeding had no significant effect upon length of carcass or thickness of streak, but they caused increases in killing-out percentage and decreases in all measurements of fat thickness. They also caused increases in the area of ‘eye’ muscle (statistically significant in Exp. 2, but not in Exp. 1) and a lengthening in the shape of the ‘eye’ muscle in the bacon rasher (statistically significant in Exp. 1, but not in Exp. 2).

In Exp. 3 the Wessex crosses grew faster and more efficiently than the Landrace, but these differences were considerably larger during one year than during the other. In comparison to the Landrace, the Wessex-cross carcasses had a tendency to be shorter (P < 0·10) and to have thicker shoulder fats. They also had 1% more ‘fore’ and 1% less ‘ham’.

Compared with pigs kept to the VH-VH plane of feeding, those kept to the VH-R and VH-L planes grew 18 and 36% more slowly, respectively, during the finishing period. Over the total experimental period there was no difference in food conversion efficiency between pigs kept to the VH-VH and VH-R planes, but efficiency was poorer by 4–5% with the VH-L plane. There was no breed × feeding interaction in the data for growth rates or food conversion efficiencies.

In Exp. 3 plane of feeding had no significant effect upon killing-out percentage, shape index of ‘eye’ muscle or thickness of streak. The two lower planes of feeding caused reductions in the average rump fat, fat (1) over the ‘eye’ muscle and in the proportion of ‘middle’ in the carcasses; they also caused increases in the proportion of ‘ham’ in the carcasses.

Other carcass quality data contained significant interactions which complicated their interpretation. The effects of plane of feeding were inconsistent between:

(A) years, for length of carcass, maximum shoulder fat, area of eye muscle and iodine values of the back fat;

(B) breeds, for minimum back fat and percentage ‘fore’;

(C) sexes, for dressing percentage and fat (2) over ‘eye’ muscle;

(D) breeds and years, for dressing percentage;

(E) breeds and sexes, for maximum shoulder fat.

The results of the three experiments have been compared with other data on planes of feeding from Rowett Research Institute. A table has been given showing the probable average effects of using different planes of feeding in preference to a VH-VH plane for pigs to be slaughtered at about 200 lb. live weight. The variability in these effects under different circumstances has been discussed and a note has been made of the relative improvements in carcass quality which can be affected through feeding and through breeding.

1. The crude protein requirement of goats for maintenance has been determined from balance studies. The requirement per kg., as found by three different methods of treatments of the balance data, is practically the same, viz. 2·63 g. crude protein.

2. The digestible crude protein requirement also has been calculated, again by two different methods, and is estimated at 1·12 lb./1000 lb. body weight. This value is undoubtedly very much higher than the value (0·65 lb./1000 lb.) obtained previously from the endogenous urinary nitrogen determinations alone.

3. The dry-matter requirement of goat per 100 lb. live weight has been determined. Calculated on the basis of live weight raised to the power 0·734, the requirement was found to be 2·6 lb./100 lb.

1. A comparison has been made of the progenytest figures for father and son in the Friesian breed.

2. There was a significant regression of contemporary comparison of son on contemporary comparison of father (0·22) and on r.b.v. of father (16·4 lb. per unit of r.b.v.), though both figures were about one-quarter lower than expected. The observed figures were consistent with a heritability of heifer yield of 0·19. The regression of contemporary comparison of son on the average production of the herds in which his half-sibs were milked was small and not significantly different from zero.

3. For fat content, the regression of son's daughter average on father's daughter average was 0·32, in agreement with expectation.

4. A less-detailed analysis for the Ayrshire breed on the above points gave essentially similar results.

5. The possible extent of selection on the basis of progeny-test results was looked into. For yield, the selection was small, leading to a probable improvement of 1–2 gal. a year. For fat content, the probable increase was 0·01% a year.

6. A method is described for evaluating the progeny test of a son in relation to his father's own progeny-test results, which can serve as a method of combining the progeny-test figures from different bulls.