1. Four in vitro fermentation experiments, in duplicate, were carried out over 24 hr. periods, to estimate the production of v.f.a. and o.a from forages.

2. A new technique for determining the total organic acids produced in the rumen is described.

3. The o.a. produced in the earlier part of the fermentation are considerably higher than the v.f.a. but the difference then diminishes. There is practically no difference in the amounts produced after 24 hr.

4. Highly significant correlations were found between the in vitro production of v.f.a. or o.a. and d.e./kg. d.m., for all the roughages tested. Nonlegumes gave a more highly significant correlation than legumes.

5. Regression equations show that o.a. or v.f.a. were more accurate than in vitro cellulose digestion for predicting the d.e./kg. d.m. of non-legume forages. It is concluded that V.F.A. production in vitro is the best criterion in this respect.

1. Muriate of potash applied at rates of 0, 1 and 2 cwt./acre to herbage which had also received similar treatments in the previous year did not influence plasma magnesium or calcium values in lactating ewes.

2. 24 Cheviot ewes had slightly lower plasma calcium and magnesium levels than 24 Half-bred ewes of the same age both before and after lambing.

3. 6·6 g. of magnesium oxide given as a daily drench did not increase plasma magnesium values as measured by blood samples taken 24 hr. after drenching. Values were however increased by 0·5 mg. Mg/100 ml. four hours after drenching.

4. No clinical cases of hypomagnesaemic tetany occurred, even although the mean plasma magnesium level of all the ewes in the experiment was only about 1·0 mg./lOO ml.

5. Plasma magnesium values of ewes before lambing were significantly (P < 0·001) correlated with post-lambing levels. Values for the ewes during 1962 were equally significantly correlated with levels for the same sheep at comparable dates in 1961.

1. A preliminary study of the protein requirements of young steers of two breeds of African cattle has been described. These requirements were assessed by studying body weight changes of groups of animals fed for 140 days on rations varying in protein content.

2. There were only small differences between the breeds in their voluntary food intake while appetite seemed to be linearly related to protein content.

3. The two breeds were equally efficient in food and protein utilization.

4. Live-weight gain improved significantly as the protein content of the ration increased from 6 to 10%, but a further increase to 14% produced only a small subsequent improvement in growth.

5. Maintenance of weight was estimated to occur at a digestible protein intake of only 48% of that recommended by Brody (1945), while the required digestible protein for one pound daily gain was in agreement with the National Research Council (1950) standard.

1. Continuous waterlogging and 4 weeks' waterlogging immediately after transplanting produced plants with higher leaf and shoot numbers.

2. There was no difference in the final shoot number between plants continuously waterlogged and those waterlogged for 4 weeks, immediately and 4 weeks after transplanting. The shoot mortality was higher in the continuously waterlogged plants and those waterlogged for 4 weeks immediately, 8 weeks and 12 weeks after transplanting than in those waterlogged for 4 weeks, 4 weeks after transplanting.

3. Continuously waterlogged plants and those waterlogged for 4 weeks, 4 weeks after transplanting, were taller than those waterlogged for 4 weeks, immediately, 8 weeks and 12 weeks after transplanting.

4. Leaf area per bucket, leaf area per shoot and per leaf lamina were higher in continuously waterlogged plants and those waterlogged for 4 weeks, 4 weeks after transplanting, than in those waterlogged for 4 weeks immediately, 8 weeks, and 12 weeks after transplanting.

5. Continuous waterlogging and waterlogging for 4 weeks, 4 weeks after transplanting, increased the physiological age of the plants as evidenced by earlier ear emergence and grain ripeness.

6. Fresh-weight yield, yield of grain and panicle were greater in continuously waterlogged plants and those waterlogged for 4 weeks, 4 weeks after transplanting, than in those waterlogged for 4 weeks immediately, 8 weeks and 12 weeks after transplanting.

7. The critical period for waterlogging in the cultivation of the rice variety studied is 4 weeks after transplanting and waterlogging applied during this critical period for 4 weeks favours higher yield of grain than when applied for the same period earlier or later than this period. Where water supply is limited the plants should only be waterlogged at this period and the soil kept moist throughout the remaining growing period. However, where there is enough water to waterlog the plants for 8 weeks this should be started immediately after transplanting.

The problems involved in estimating the food intake of the grazing animal are considered and an account is given of studies made on eighteen Clun ewes and six Hampshire × Clun wethers. Results are given from sixty-eight observations on the relationship between food intake and a fraction dissolved in the faeces when a milled sample is left to stand in 0·2N-HCl for 18 hr. Using, in addition, data from grazing ewes subjected to total faeces collection during winter and spring 1959–60 it is concluded that 4 consecutive days of collection give a reasonable estimate of faecal output, and that where similar groups of sheep are grazing on the same pasture at the same time it is unnecessary to convert faeces output data to intake figures in order to compare intake-production relationships between individuals within a group. Where, however, comparisons are to be made between individuals or groups of sheep grazing different pastures at different times then it becomes necessary to allow for differences in food-faeces ratios; for this purpose the dissolved fraction discussed here is likely to prove a useful faecal indicator eliminating many disadvantages of earlier methods and some of the seasonal bias inherent in other indicators at present in use.

1. An experiment has been carried out using 64 pigs individually fed. They received a common ‘grower’ ration to 120 lb. live weight and were then divided into four groups. The ‘finisher’ rations contained 0, 2·5, 5 or 10% fat.

2. The rations containing more fat also had a higher protein content and the scales of feeding were so arranged that the pigs received the same daily intake of protein and ‘energy’.

3. The growth rate was slightly more rapid with the fat-supplemented diets and the carcass characteristics were not in any way impaired.

4. The efficiency of feed utilization (f.c.r.) improved considerably when fat was included in the ration: the f.c.r. was 3·93 in the absence of fat and 3·30 when the ration contained 10% added fat.

1. A range of soils were cropped exhaustively by perennial rye-grass for up to eleven months in the glasshouse; some were also cropped with Dutch white clover.

2. At least 100 lb./acre of magnesium was taken up from most soils, and some soils supplied more than 200 lb./acre. The amounts of magnesium taken up decreased with successive harvests, suggesting that the available magnesium was progressively depleted. Although the ‘exhaustion’ magnesium (Mg taken up by crops+residual exchangeable magnesium) was greater than the initial exchangeable magnesium, these two measurements were closely correlated (r = 0·99). If non-exchangeable magnesium was released during cropping, the releases were proportional to the initial exchangeable magnesium contents. However, the exchangeable magnesium measurements may have extracted only a proportion of the magnesium available naturally.

3. Any releases of magnesium were small compared with the amounts available from the outset, and the crops obtained magnesium mainly from the exchangeable form. Rye-grass and white clover gave similar results.

4. The exchangeable magnesium in some exhausted soils was increased by wetting and drying. This effect may occur in the field, where the magnesium lost in cropping could be replenished by only small releases of non-exchangeable magnesium.

1. Nine Ayrshire calves were subjected in a climatic room to temperatures in the range 15–41° C., and moisture vaporization rates were measured, by means of ventilated capsules, from various skin regions.

2. The rise in moisture vaporization rate, during the early part of exposures to high temperatures, occurred in a series of steps. This was attributed to bursts in sweat gland activity.

3. At low environmental temperatures the moisture vaporization rate was small and similar in all regions. At high temperatures evaporation differed widely between regions. The regional distribution was similar for all animals and agreed broadly with results that have been reported for other breeds.

4. The regional distribution of moisture vaporization was not appreciably altered as animals aged from 10 to 34 weeks, but the evaporation from all regions increased during this period.

1. Methods of fitting certain yield-density relations are given which are appropriate when the proportional rather than the absolute standard error of the yields is constant.

2. These methods are applied to relations discussed by Jarvis in connexion with his data on lucerne, and it is shown that no clear advantage can be claimed for any of the relations.

3. The role of significance tests in the interpretation of the data is briefly discussed.

The carcass-weight increase of beef steers of various ages receiving fattening rations of different roughage: concentrate ratios was calculated by making use of the average dressing percentage of a control group slaughtered at the beginning of the experiment.

It is shown that, in terms of t.d.n./100 lb. carcass-weight increase, which is probably the more accurate measure of efficiency, the 2-year-olds were better feed converters than the calves. When the criterion was t.d.n./100 lb. live-weight increase the calves were superior. Ration B (1 concentrates: 1 roughage) was utilized most efficiently in terms of calculated carcass-weight increase, followed in a descending order by the high-concentrate ration C and the high-roughage ration (ration A).

The relationship of live-weight increase to carcass- weight increase as calculated is discussed. The proportion of live-weight gain laid down as carcass varied with age, growth rate and type of ration. This percentage variation ranged from 57% in slow-growing calves to 81% in fast-growing 3-year-olds. On the average, calves converted 61% of their live-weight gain into saleable carcass, the 2-year-olds 70·8% and the 3-year-olds 75·9%. The steers on the A (high roughage) ration converted 65·7% of live-weight gain into carcass, those on the C (high concentrate) ration 71·5% and those on the B (1 concentrate: 1 roughage) 69·2%. Reasons for these differences are discussed in terms of so-called differential growth.

The live weights and carcass weights of steers were plotted and the regression equation

where Yis carcass weight and X is live weight, was derived. The correlation coefficient r = 0·98 and the slope of the curve indicated that for an increase of 1% in the live weight of the steers, the carcass weight increased by 1·13%.

Several methods of expressing ‘efficiency of the fattening’ were applied to the data and the results are discussed. The methods were unanimous in selecting the steers on the B ration as the most efficient followed by those on ration C and the poorest were those on the A ration. Methods based on live-weight increase showed the calves, but those based on carcass-weight increase the 2-yearolds, as the most efficient. Results obtained by applying the Efficiency Quotient and Efficiency Index suggested that the older animals wero the more efficient. They differed from all other methods since these indicated that efficiency declined with age.

Efficiency values calculated by different formulae vary and no efficiency index has yet been evolved that will embrace all the variable factors which may have an influence on the efficiency of growth and fattening.

Three sowings of marrowfat peas were made at about 20-day intervals at forty-seven centres in eastern England over 4 years. The sowing period ranged from late February to late April, varying with seasonal conditions. Bird damage caused considerable loss of sowings but satisfactory yield data were obtained from forty-one of the trials.

Highest yields were obtained from drillings made in the last 10 days of February. After mid-March each week's delay in sowing resulted in a yield loss of about 3/4 cwt. per acre. Quality fell off slightly from February onwards.

Early sowings suffered some loss of plant in tractor wheelings but were negligibly affected by cold weather.

Early sowings appear likely to encounter better harvest weather than late sowings and the chances of good harvest weather seem appreciably better in the centre and south of the pea-growing area than in the north. Early sowings mature before the cereal crop, enabling better attention to be given to the pea harvest.

It was concluded that the crop should be sown as soon after the middle of February as soil conditions allow.

1. The decline of a pea root eelworm (Heterodera göttingiana Liebscher) population, of which most eggs were formed in 1955, was measured annually from 1955 to 1958 in twenty-two microplots containing loamy sand, and measurements were continued in one of these microplots from 1960 to 1962.

2. Sampling errors increased when egg populations were more than 4 years old.

3. Two crop rotations (fallow, and maize, fallow, carrots) had no effect on decline rate from 1955 to 1958, nor did initial eelworm density.

4. After 3 years the egg population was still 48% of that in 1955. Subsequently the population declined on average by more than 50% per annum. It is suggested that host crops should not be grown more than once every five years.

5. Cysts declined more slowly, with a mean annual rate of 26%.

6. A sharp decline in eggs during the first year followed by at least one year's relative quiescence may be general in Heterodera species; with H. göttingiana unexpected crop failures may be associated in part with the prolongation of this relative quiescence for more than 1 year.

1. The growth of wheat plants at two depths of planting, from seed in which embryo size and endosperm size were varied independently was studied.

2. Embryo size was shown to have a negligible effect on growth, whilst endosperm size had a considerable effect; the influence of neither embryosize nor endosperm size appeared to be in any way modified by depth of planting. It is suggested that the relationship between seed size and plant size is governed by the amount of reserve material present in the seed.

3. During the first 6 days of growth small embryos had a higher relative growth rate than large ones, apparently regardless, within wide limits, of the amount of reserve material in the seed. Thereafter until the exhaustion of reserves growth appeared to be related to the amount of reserve material present.