A comparison of leaf-area index (L) in the postflowering period was made between a single cross maize hybrid in Rhodesia and a winter and a spring wheat variety in England. At the beginning of the period L of the maize was lower than that of the wheat but it remained near its initial value for a relatively long time, whereas L of the wheat decreased rapidly. The proportion of L consisting of sheath was much lower in the maize than in wheat. Grain yield was higher in the maize largely because of its longer period of grain growth. In Rhodesia maize might benefit from a greater L than that recorded in this study. The high yields achieved by maize are partly due to the relatively long life of its leaves.

An experiment is described in which the growth rate and conformation changes of cattle subjected to different levels of nutrition during their yearling winter, and then re-alimentated on grass, were studied.

For this purpose thirty-six Sussex x Shorthorn steers between 38 and 52 weeks of age were randomly distributed on the basis of live weight into three groups, each of twelve animals.

The data on the conformation and age at slaughter, together with that on the slaughter and carcass work obtained from the thirty-six animals which had been subjected to differential winter feeding (see Part I), is presented and discussed.

Seed production stands of S 48 timothy and S 215 meadow fescue were obtained with varying plant densities by utilizing two driE widths, removing sections of drill, or oversowing drilled material.

Annual tiller counts were made in preselected quadrats, and performances of tiller populations were assessed from these quadrats.

1.Two experiments were carried out to investigate the possibility of sustaining good growth rates and high feed conversion efficiency on restricted levels of feed under conditions of high temperature and humidity.

2. Large White pigs were used over the weight ranges 50-90 lb. and 90-160 lb. live weight.

3. In Exp. 1, three groups each of eight pigs were fed on three planes, high, medium and low, the aim being to restrict energy intake while providing adequate protein intake for good growth. In Exp. 2, two groups each of eight pigs were fed on the medium plane from 50-90 lb. live weight and thereafter one group remained on the medium plane, while the other was fed a very low plane. The very low plane consisted of a daily feed allowance of 31b. 4oz. from 90 to 1601b. live weight. All the pigs were individually fed.

A randomized block experiment has been carried out with 42 Friesian heifers over a 2-year period to examine the protein and energy requirements in late pregnancy. Rations were based on good quality hay fed to appetite plus various quantities and combinations of oats and decorticated groundnut meal. Minerals were given daily.

1.Within a flock of 55 Welsh Mountain ewes maintained under lowland conditions the first ewecame into oestrus on the 14th October. The mean cycle length of 44 normal cycles was 16 days 3 hr.

2. The onset of oestrus as assessed by the time of mounting of the ram does not appear to beevenly distributed throughout the day (24 hr.).

The performance of four varieties of lucerne, du Puits, Provence, Grimm and S 205, as spaced plants, in broadcast plots and in drills, with and without a companion grass was compared by yield of dry matter, percentage and yield of crude protein, leanness, weediness and reaction to leaf spot (Pseudopeziza medicaginis).

1. Ten experiments were carried out on winter wheat in various parts of England in 1959-61, to compare 60 lb./acre of nitrogen broadcast as ammonium sulphate, ammonium nitrate and calcium nitrate (a) all in autumn, (6) one-third in autumn and two-thirds in spring, (c) all in spring. The winter rainfall was high in four experiments and moderate in six.

A plot trial compared the herbage yields of Hyparrhenia veld and giant Rhodes grass (Ghloris gayana cultivar) cut at grazing and hay stages of growth at four levels of N fertilizer. Veld outyielded Rhodes grass in all treatments.

The milk yields from Hyparrhenia veld and a giant Rhodes grass pasture were similar when grazed at low and high stocking rates with and without N fertilizer.

The distribution of whole blood potassium concentration in 1783 Welsh Mountain sheep showsmarked bimodality, varying about two modes, of 44 and 14 m-equiv./l.

The difference between high (HK) and low (LK) potassium types was not clear-cut. About 5 % of animals lay in the area where the tails of the two distributions merge.

Haematocrit values and plasma potassium concentrations were used to estimate erythrocyte potassium levels. They confirmed that the bimodality is due to variation within erythrocytes but did not offer a satisfactory method of allocating intermediate animals.

Little information is available on the composition of the milk of British breeds of sheep under conditions prevailing in this country.

1. This paper presents results of the analysis of milk from 46 Clun Forest ewes suckling lambs during 1961 and 1962. Three groups of ewes were used, two of which grazed while a third was fed indoors. Milk samples were obtained by handmilking one quarter while the lamb sucked theother, after a period of 5 hours during which suckling was prevented by means of udder covers.

The use of changeover designs and of covariance analysis in experiments on lactating cows is reviewed. Continuous treatment designs are criticized because of their large coefficients ofvariation, e.g. of the order of 20 % for milk yield. Although changeover designs have smaller errors they are criticized because the results have strictly limited practical application. Covariance analysis applied to the data from continuous treatment designs offers a means of increasing their precision. Measurements made in a preliminary period may be used to adjust experimental measurements made subsequently for animal to animal variation. The covariance method was tested on data from thirtytwo heifers in an experiment involving factorial sequences of treatments. Weeks 5-12 of lactation formed the control period and weeks 13-22 the experimental period.

The chemical composition of plants depends on many things, the species, the type of soil, the climate, the manuring, and it also changes during the growing season as different results can be obtained from samples of the same plant taken at different times. For plant analysis to be used in assessing the nutrient status and manurial requirements of crops there is need for knowledge not only about the above factors which can affect the chemical composition of crops but also about others that are less obvious, such as ion interactions. Ions can interact in two ways called antagonism and synergism; antagonism means that the uptake of one ion decreases the uptake of another ion and synergism that uptake of one increases the uptake of another.

The ratios of S cations (Na + K + Ca + Mg in m-equiv./100g.):2 anions (N + P + Cl + S in mequiv./ lOO g.), R values, in over 100 samples of Italian rye-grass grown in the field ranged from 0-33 to 0-92. Italian rye-grass, grown in the greenhouse at 11 levels of a nutrient mixture, had R values ranging from 0-58 to 1-36.

The ratios of sum of the cations: sum of the anions (R) of sixty-two agricultural and horticultural crops and pasture herbs were measured or calculated and found to be negatively correlated with % N in the plants. This suggests that the proposal that Italian rye-grass has a mechanism regulating the proportion of cations to anions taken up may also apply to other plant species. Dicotyledons had greater B values than monocotyledons at the same N level, but this is probably not because their roots have greater cation exchange capacity.

1. Six diets in which the percentage of hay varied from 0 to 100% and the percentage of flaked maize varied conversely from 100 to 0% were each given to three sheep and three steers in a series of 72 calorimetric experiments. In addition the fasting metabolism of each animal was determined on two occasions.

2. The loss of energy in the faeces increased linearly with the percentage of flaked maize in the diet, but the loss of N in the faeces did not, the loss being proportionately smaller for diets containing more than 60 % maize.

The nutritive value of a sample of artificially dried lucerne was determined calorimetrically in twelve experiments with three sheep.