1. Fifty buffalo-cows were used for studying the pH of the vaginal secretion at different stages of the sex cycle.

2. Highly significant differences were found in the pH value of the vaginal secretions during the different stages of the sex cycle. The average was 7·3 during oestrus, 8·1 during dioestrus and 8·3 during pregnancy.

1. In experiments on three calves it was shown that, under severe heat stress, the respiratory rate at first rapidly rose from 88 to a maximum of 218 respirations/min. and then fell to 167 respirations/min., while breathing at first became shallower and then deeper.

2. During the phase in which breathing became faster and shallower (panting), the heart rate rose at a mean rate of 13 beats/min. for each degree centigrade increase in rectal temperature. During the phase in which breathing became slower and deeper (‘second-phase breathing’) the mean rate of rise in heart rate was 50 beats/min. for each degree increase in rectal temperature.

3. The changes in respiratory rate and in heart rate occurred at mean rectal temperatures of 40·6 and 41·0° C., respectively, and, on average, the change in respiratory rate preceded that in heart rate by 8 min.

4. It is concluded that second-phase breathing was the cause of the steep increase in heart rate.

5. The steep increase in heart rate is discussed in relation to heat production of the respiratory muscles.

1. The results are reported of a series of 8-day magnesium metabolism trials carried out with milking cows fed a variety of typical winter stall rations.

2. Twelve cows fed a standard ration of 15 lb. hay plus 12 lb. of a concentrate mixture containing 3 parts dredge corn, 1 part bran, 1 part decorticated groundnut meal and 1 lb./cwt. Churn 105 minerals, showed variations in the proportion of the feed magnesium excreted in the faeces of from 66·53 to 76·98%, probably reflecting individual differences in the capacity of animals to absorb magnesium.

3. Wide differences in the utilization of the magnesium in typical winter rations were observed. Mean values, with a standard error, obtained for the proportion of the feed magnesium excreted in the faeces with various types of ration were as follows: hay plus concentrates, 71·48 ± 0·94; hay plus proprietary dairy cubes, 62·15 ± 2·73%; hay, proprietary dairy cubes plus decorticated groundnut meal, 91·98 ± 1·93%; hay, silage (1) plus concentrates, 79·53 ± 0·99%; hay, silage (2) plus concentrates, 74·07 ± 4·24%; hay, mangolds plus concentrates, 74·28 ± 5·91%.

1. Two groups of Rhode Island Red × Light Sussex pullets were housed respectively in batteries and in a fold unit.

2. Samples of the eggs produced were collected monthly and weights of egg fractions, quality tests on yolk and thick white, and porosity coefficients were determined.

3. The tests were continued for a 9-month period and no consistent differences were found in the quality of the eggs produced under the two systems of housing.

4. Colours of yolks produced by battery pullets were paler than those produced in the fold unit on grass. Yolk colour was improved by increasing the proportion of grass meal in the diet of battery birds.

1. Five out of six sheep ruminated more in terms of the total time spent ruminating when fed their food (dried grass) cut into approximately 2 in. lengths, than when fed the same quantity and quality of food in the long (uncut) state or when ground to a meal.

2. Grinding to a meal markedly reduced rumination times as compared with the same quantity and quality of diet fed long or chopped.

3. It is postulated that these effects may be related to the stimulation of rumination.

An investigation was carried out to determine the extent of the maternal influence on size of calves at birth and during subsequent stages of growth, by making reciprocal matings between large South Devon and small Dexter cattle. As a preliminary to the experimental results, data concerning the respective parent breeds were analysed. From the first part of the study the following information was obtained:

1. The mean weight at birth of purebred South Devon calves was 100·3 ± 1·47 lb. with a tendency, though not statistically significant, for male calves to be heavier. Calves born during the months April to July appeared to be heavier than those born at other times, but the age of the dam had no definite effect on the birth weight of offspring. It was found, however, that the sire may influence birth weight to a significant degree.

2. The mean period of pregnancy for South Devon females, carrying purebred foetuses, was 287·0 ± 0·42 days, the tendency being for males to be carried longer, but the difference of 0·97 days was not statistically significant. A statistically significant difference indicated that winter calvers carry their foetuses longer as a rule, but though heifers have shorter gestation periods than cows, the difference of 1·6 days was not significant.

1. Three experiments are reported in which magnesium metabolism trials were carried out with milking cows that had been changed abruptly from typical winter rations to herbage cut freshly from swards at an early or at a more mature stage of growth and fed in the stall.

2. The intake of herbage magnesium by individual animals varied from 9·5 to 15·2 g./day. Much of this variation was, however, associated more with differences in the palatability and dry-matter content of the herbage offered than with individual differences in appetite.

3. The mean proportion of the ingested herbage magnesium excreted in the faeces was similar in all three experiments, being 82·3, 83·0 and 82·4% respectively. With any given sward there were, however, wide variations between individual animals in their utilization of herbage magnesium.

4. The supply of ‘available’ magnesium to animals fed cut herbage in the stall varied from 0·5 to 4·2 g./day, as compared with values of from 2·6 to 10·5 g./day obtained previously (Rook et al. 1958) with cattle fed typical winter rations. In spite of this lower intake of ‘available’ magnesium, the animals maintained a positive magnesium balance.

1. Records of sheep with differing haemoglobin and potassium blood types were examined in a large flock of Scottish Blackface sheep.

2. Differences in reproductive performance, which would be subject to natural selection, and in growth rate, fleece characteristics, etc., which would be subject to artificial selection, were sought as an explanation for the gene frequencies observed in different breeds.

3. No significant differences were found in any weights or measurements.

4. The number of lambs produced by different types of ewe did not differ significantly, although there was some suggestion that haemoglobin heterozygotes produce a larger number of lambs at weaning.

5. Study of the equilibrium of the population, however, showed that any heterozygote advantage, if it exists at all, can only be small.

1. A co-ordinated trial has been carried out at twenty-six centres to study the effects of feeding different quantities of food to fattening pigs. The treatments studied were ad lib. feeding throughout, ad lib. feeding to 120 lb. live weight after which the amount of food given was restricted to 6·5 lb./pig/day and two scales of feeding according to live weight, one moderate and one severe (Table 1).

2. Food conversion was best for the pigs on the most restricted feeding scale, being 8% better than that for the pigs fed ad lib.

3. The slower growing pigs were less fat, slightly longer and their depths of eye muscle were greater.

4. The ad lib. fed pigs had higher killing-out percentages and higher weights into cure.

5. The bacon sides from pigs fed on restricted diets yielded a higher proportion of gammon and fore-end and had thicker streaks.

6. Restriction of feeds led to softer fats.

7. An economic appraisal has been made which shows that, on the basis of certain assumptions, the medium feeding scale would have led to a smaller profit per year than the ad lib. or the ad lib. restricted treatments under the price structure and system of grading prevailing during the period of the experiment.

1. Two adult sheep were housed and fed once a day. The time of feeding was advanced round the clock by 4 hr. periods, one advance was made each week. The jaw movements of both sheep were simultaneously recorded for 48 hr. after the sheep had become accustomed to each time of feeding.

2. The time when rumination occurred was found to be independent of any time-relationship with eating.

Field experiments were carried out in north-east Scotland on potatoes to measure the responses to, and the two-factor interactions between, nitrogen, phosphate, potash and dung, and have given the following results:

1. The responses to nitrogen, phosphate and potash are quite variable from centre to centre, but the mean results show moderately large increases to all three nutrients.

2. The mean responses to both nitrogen and phosphate are the same in the presence as in the absence of dung. The response to potash is reduced by two-thirds in the presence of dung.

3. There is a general trend for both nitrogen and potash to increase the linear component of the response to phosphate and vice versa. Nitrogen and potash show practically no interaction effects.

4. Dung produces a considerably larger increase in yield in the absence than in the presence of fertilizers.

5. The nitrogen and potassium contents of the tubers show appreciable effects of the nitrogen, potash and dung treatments.

6. Suitable fertilizer dressings are suggested for potatoes grown in the absence and presence of dung.

The course of pregnancy was followed in three groups of Peppin-strain Merino ewes. Group 1 of seven ewes, maintained on a high plane of nutrition, all lambed; the mean birth weight of lambs was 8 lb. 6 oz. The six ewes in group 2, kept on a low plane of nutrition, all lambed; the mean birth weight of their lambs was 1 lb. 9 oz. lower (P<0·01). The seven ewes in group 3 kept on a low plane of nutrition and subjected daily to temperatures of 112° F. dry bulb, 92° F. wet bulb, produced only four lambs; the mean birth weight was 4 lb. 6 oz. less than those from group 1, and 2 lb. 13 oz. less than those from group 2 (P < 0·001).

Scale photographs of the lambs, and X-rays and measurements of their long bones, after dissection, showed that the lambs of group 3 were miniatures: their skeletons were much reduced in size, whereas low nutrition alone (group 2), caused little skeletal reduction.

The mechanism of dwarfing is not clear. However, fore-cannon bone lengths and liver weights, considered in relation to lamb birth weights indicated that it was not a nutritional effect.

This study was undertaken at the Physiology Department, University of Queensland. It is a pleasure to thank Prof. W. V. Macfarlane for the valuable facilities, and for his help and encouragement.

1. Swards of S. 48 timothy and S. 215 meadow fescue growing alone or together were sampled at intervals of 3 weeks throughout the season. The number and weight of leaves, stems and ears were determined, and leaf area was estimated.

2. Despite high rainfall, the total number of tillers in both species declined from the beginning of the experiment until early July, but increased again from then onwards until the original complement had been approximately restored. The number of leaves failed to show a corresponding increase in the autumn because each tiller carried fewer leaves than earlier in the year.

3. In the spring total dry weight increased more rapidly in meadow fescue than in timothy which in turn out-yielded meadow fescue later in the season. Both species attained their greatest dry weight soon after ear emergence, a period which was marked by considerable crop growth and relative growth rates.

4. Leaf area index reached a maximum before total dry weight had increased to its highest level, but then declined in both species. Meadow fescue differed from timothy by producing a second crop of foliage after the summer with a leaf area index of about 7. This second rise appeared to be due mainly to increased leaf size in contrast to timothy whose leaves became progressively smaller towards the end of the season.

5. The differences in growth between the species discussed with reference to their dates of ear emergence which in this experiment differed by about 6 weeks.

1. Three experiments are described on the feeding of supplements of calcined magnesite, linseed cake and vitamin D to dairy cows for the control of hypomagnesaemia and the prevention of hypomagnesaemic tetany on spring pastures.

2. A daily supplement of 2 oz. calcined magnesite either contained in 2 lb. of dredge corn cubes or 4 lb. dredge corn mix, or as a drench, gave adequate protection against the development of hypomagnesaemia in the fifty-six cows to which it was given.

3. The supplements of 3½–4 lb. linseed cake and 12,500 i.u. vitamin D gave only partial protection.

4. The economics of providing dairy herds with magnesite during the early grazing period is discussed.

1. Of various objective measurements carried out on six carcasses from each of the three Australian grades 1, 2 and Canner, the minimum depth of fat above the eye muscle at the quartering point distinguished the grades to the most significant extent, as would have been anticipated from the importance of finish in visual grading.

2. The iodine numbers of fat from the tissues of the steers examined were lower than those which would have been expected in English steers at a similar level of fatness.

The literature specifically related to the effect of vitamin B12 on methyl group synthesis and its relationship to protein utilization in experimental animals is discussed.

The techniques and results of nitrogen balance experiments on control A.P.F.-deficient chicks and vitamin B12-treated chicks are presented.

Results show that vitamin B12 administration does not result in any direct effect on nitrogen retention or efficiency of utilization when control and B12-supplemented chicks are pair-fed. This finding is discussed in relation to the response of A.P.F.-deficient chicks to vitamin B12 and the significance of appetite as a factor in the response is suggested.

1. Data from a long-term experiment providing information on the effects on barley of undersowing the crop with various common species of grasses and legumes are discussed.

2. There is no evidence that the yield of grain, yield of straw, 1000 grain weight or the nitrogen content of the grain was affected in any way by undersowing with any of these species.

1. Carcasses of nineteen fat lambs (from six ewes and thirteen wethers weighing from 29 to 841b., aged from 78 to 365 days, all from the Suffolk breed and all fed in pens with no grazing) have been dissected into six joints, namely neck, thorax, loin, pelvis, shoulder (including shank), and leg (including shin). The subcutaneous and intermuscular fatty tissues and the muscular tissues have been dissected from each joint and analysed for fat. The iodine number of each sample of fat has been determined.

2. The average percentage of fat in the fatty tissues of the carcass ranged from 71·9 to 87·8 and the average iodine numbers from 43·6 to 56·1. With the muscular tissues these figures were from 4·8 to 11·1 and iodine numbers from 51·5 to 61·7.

3. The extreme ranges found in the subcutaneous fatty tissue of the joints were from 63·0 to 91·6 for percentage of fat and from 43·7 to 59·3 for iodine number. For the intermuscular fatty tissue these ranges were from 52·0 to 88·4 for fat and from 41·7 to 58·5 for iodine number. The kidney fat extended this range up to 95·7 for fat and down to 36·4 for iodine number. With the muscular tissue of the joints the ranges were from 2·7 to 17·3 for fat and from 48·3 to 65·0 for iodine number. The rectus femoris muscle extended this range down to 1·8 for fat and up to 66·2 for iodine number.

1. Dried molassed sugar-beet pulp was fed to dairy cows grazing abundant intensively managed pastures in two trials (spring and autumn), each of 8 weeks' duration. A change-over design (four 14-day periods) with twenty-four cows was employed in each trial. Apart from six changes for the autumn trial, the same cows were used throughout.

2. In the spring trial (May–July) 8 lb. beet pulp were fed daily. The herbage dry matter consumed contained, on average, 16·8% crude protein, and the general mean milk yield was 38 lb./cow/day. The milk yield of the supplemented cows was 1·3 lb. (3·7%) greater than that of the control animals (P < 0·05).

3. In the autumn trial (August–October) 10 lb. beet pulp were fed daily. The herbage dry matter consumed contained 23·8% crude protein and the general mean milk yield was 27 lb./cow/day. The milk yield of the supplemented cows was 2·9 lb. (11·3%) greater than that of the control animals (P < 0·001).

1. An experiment was carried out at ten farms in four winters to compare the value of three methods of pen warming.

2. Complete information on weightgain was available in seventeen replicates; the average increase in weaning weight from the use of heat was 2·41 lb.

3. Information on survival was available for thirteen replicates; the average benefit from the use of heat was 0·58 pigs weaned per litter.

4. The farmers' comments showed that they considered heating to be of value.