1. Twenty-eight experiments on sugar beet in 1956–8 compared ammonium sulphate, calcium nitrate and urea applied to the seedbed before sowing. The three fertilizers were compared at rates which supplied nil, 0·6 and 1·2 cwt. N/acre. Treatments in which 0·6 cwt. N/acre was held back until the end of June were also included.

2. Average responses in sugar yield were low, 0·6 cwt. N/acre provided virtually all the nitrogen required for maximum sugar production. The heavier nitrogen dressing, on the other hand, substantially increased the yield of tops.

3. Calcium nitrate and urea were as effective as ammonium sulphate at raising sugar yield. There was no damage to germination with any fertilizer, and when urea containing 4·5% biuret was used for topdressing in 1956, no damage was seen. Calcium nitrate and, to a lesser extent, urea produced more tops than ammonium sulphate.

4. Putting all the nitrogen into the seedbed was as effective as a split dressing in raising sugar yield. Leaching of nitrogen in a wet summer is therefore not important to sugar beet. Late nitrogen, on the other hand, never harmed sugar production if some had been given to the seedbed.

The beneficial effect on the nutritive value of bread and similar cereals of adding small amounts of lysine and other essential amino acids has recently aroused considerable interest both in Great Britain and in America. Tests carried out with rats have shown considerably improved growth rates accompanied by increased efficiency of food conversion.

Three creep rations were fed in the form of meal, pellets and ground pellets. The compositions of the first two rations were similar to those of the rations used in general farming practice; the compositions of the pellets and ground pellets were identical. The experiment was carried out for 8 weeks from birth at thirteen centres and involved a total of 152 litters. No difference between meal and ground pellets was found in either food consumption or weight gain. Pigs on pellets consumed 18% more than pigs on meal, but this did not result in a significant improvement in weight gain. Treatment × centre interactions were not significant.

In this paper the results are described of experiments on bull sperm cells with the photo-electric device for measuring the ‘motility’, as developed by Rikmenspoel, van Herpen & van Dam (1956).

It was found that the velocity distribution of sperm samples differs only slightly from a Gaussian one. The form of the distribution curve, which is a bit skew, is rather constant between ejaculates. This means that generally the ‘motility’ of a sperm sample can be characterized by the mean velocity of the sperms, the standard deviation of the velocity distribution and the number of cells moving normally. The mean ratio of velocity and frequency of rotation (the ‘speed’ of the screwing movement of the head of the sperm cell) was found to be a less important motility characteristic for most experiments.

The scattering of the above-mentioned properties in various ejaculates were measured, while the sperm samples were all kept in the same conditions. It was found that the mean velocity has a rather constant value.

A linear relationship between the mean velocity of the sperms of a sample and the viscosity of the diluent is found. This holds also for the dependence of the ‘speed’ of the head movement and the viscosity.

The mean velocity of sperm cells was found to increase approximately in a straight-line relationship with the temperature in the range 33–41° C. There were indications that the mean velocity may reach a maximum in the region of 42–45° C.

If sperm samples are stored at 4° C, the mean velocity and the number of cells moving normally is found to decrease exponentially. The decrease of the number of cells moving normally is three to four times faster than that of the mean velocity. Some evidence was obtained that the characteristic time for the decrease of the number of cells moving normally is bull-specific.

The influence of various night- and day-temperature regimes on inflorescence initiation and earing in vernalized and unvernalized Lolium temulentum, L. multiflorum, short-rotation ryegrass, and two varieties of L. perenne, and also in the Athabasca strain of Poa pratensis, is described.

Vernalization response curves for the ryegrasses, when grown under controlled conditions, are presented, and are consonant with the operation of a first-order reaction as the rate-limiting step in the vernalization ofLolium perenne. Velocity coefficients for the rate of vernalization in various conditions are deduced, and are shown to be higher in seedlings than in seeds, and higher in short days at 10° C. than at 4° C. The Q 10 for the velocity of vernalization over this range is about 2·7.

Low-temperature vernalization in L. perenne can occur when low night temperatures are combined with moderately high day temperatures, and it can take place during abundant vegetative growth. In short days and in continuous light mean temperatures up to 10° C, at least, are fully effective, but in 16 hr. photoperiods even 7° C. was not a fully effective vernalizing temperature. The requirement of perennial ryegrass plants for cold treatment may be replaced by short-day induction if light intensities are low and if the plants are continually divided.

1. The live-weight gains and food consumption of groups of chickens subjected to two different patterns, (A) and (B), of allocation of a restricted quantity of food, were compared with the live-weight gains and food consumption of a control group (C), fed ad lib. throughout the experiment.

2. Group B (compensatory growth regime), showed a greater relative growth rate after re-alimentation than group A (mild restriction followed by ad lib. feeding). The growth rate of group B was shown to be significantly greater than that of the control group at equivalent live weights. In addition, it was shown that the increased growth rate, induced by periods of restriction of similar severity and duration, was very similar for birds within the ranges of 200–300 g. live weight and 750–1100 g. live weight.

3. The differences, due to treatment, in the growth rate after re-alimentation were in part caused by a concurrent increase in appetite. The severity and duration of the undernutrition immediately prior to re-alimentation would appear to affect appetite during re-alimentation more than the total restriction imposed. Measured in terms of food consumed, the restriction imposed upon groups A and B was the same, but in terms of live weight gain group B was very slightly more retarded than group A.

1. Experiments are described in which retention time of digesta in the reticulo-rumen, fermentation rates of rumen contents, and dry-matter digestibilities were studied simultaneously in four grade European and three zebu steers.

2. Fermentation rates and rumen retentions were significantly negatively correlated.

3. Correlations between digestibility and the other two factors were not significant at a high level.

4. The multiple regressions calculated for retention time and fermentation rate were significant at the 5% level and that for digestibility approached this level.

5. While only fermentation rates show significant differences for the two types of cattle, the results suggest that grades and zebus differ also in the rate of passage of digesta through the rumen.

6. The loss in weight of substrate per unit of fermentation products was measured in in vitro experiments.

7. Using certain assumptions, estimates are made of the extent to which the measured fermentation rates could account for the loss in weight of dry matter during digestion, and are compared with the loss actually found.

1. There were many distinct, consistent, individual differences in the thyroid activity of several of the animals used in this study. Graphic indications of breed differences were present at several high temperatures, and statistical analyses supported differences between the Jerseys raised at each temperature and the other two corresponding breeds. The Jerseys displayed higher rates. In no instances were there thyroid 131I release rate differences between Holsteins and Brown Swiss.

2. There was a negative correlation between thyroid 131I release rate and temperature for each breed raised at each temperature. Correlations for the 50° F. animals were statistically significant below the 0·05 level of probability and for the 80° F. animals they were significant below the 0·01 level. As the environmental temperature increased from 35° to 80° F. there was a gradual decrease in thyroid 131I release rate. Above 80° F. there was a sharp decline in thyroid 131I activity.

3. Within the range of environmental temperatures from 35° to 70° F. the animals raised at 80° F. displayed thyroid release rates higher than those of the animals raised at 50° F. At 80° and 90° F. the 50° F. Jerseys exhibited higher activity. The Jersey differences approached statistical significance. At the lower temperatures graphic differences between the Brown Swiss and the Holsteins raised at the two temperatures appeared to be present, but they were not generally supported by statistical analysis.

4. At temperatures of 80° F. and above, when regulatory mechanisms could not control body temperature, both groups showed considerable rises in body temperature concomitant with decreases in thyroid 131I activity and TDN consumption. The 80° F. group showed a rise less sharp than that of the 50° F. group.