Interest in the gain of heat by farm animals exposed to sunshine has largely been confined to countries in which air temperatures are high and in which exposure of stock to sunshine leads to their distress. Riemerschmidt's (1943) studies indicated the considerable magnitude of the heat gained by oxen standing in the sun in South Africa, and studies by MacFarlane, Morris & Howard (1956) in Australia showed that with sheep standing in the sun the wool surface temperature could rise to 85° C. These studies of MacFarlane have been confirmed in Egypt by Eyal (1963), and were subject to a theoretical analysis by Priestley (1957). Such observations, together with earlier ones reviewed by Findlay (1958), show that in many equatorial regions solar radiation is a major factor accounting for heat stress in farm ruminants.

It has been repeatedly shown that bacterial populations of different composition become established in the rumen of animals conditioned to different diets (Bryant & Burkey, 1953; Maki & Foster, 1957; Hungate, 1957; Warner, 1962). On changing ruminants from one diet to another, a reproducible physiological response of the animal to the new diet is often obtained only after a lapse of some weeks. This has been attributed to fluctuations in the levels of different groups of bacteria participating in the digestion of the ration before a new equilibrium between the species is attained. However, little is known about the rate at which these changes occur, mainly because the counting methods for specific bacteria which depend upon the isolation and cultural identification of the organisms are too laborious and time-consuming for examining samples of rumen contents at short intervals after a change of diet.

1. The effect of rest during the autumn and winter on the dry-matter production and botanical composition of a cattle-grazed pasture was studied for four consecutive seasons.

1. Agricultural crops can be grown to maturity with their root systems and associated soil sealed into 1680 1. respirometers. The crops appeared to grow normally and produced the expected agricultural yields.

2. The mean daily oxygen consumption at maturity of the roots of the following crops grown at normal agricultural spacings were: potatoes 2·8 l./m2, marrowstem kale 5·6 l./m2 and tobacco 3·0 l./m2.

1. The suitability of three ratios of sorghum grain to sorghum silage (40:60, 60:40, and 80:20) with and without a supplement of 60 g. urea per head per day for the finishing of cattle in yards was examined.

The extent of mineralization of organic carbon (carbon dioxide production) during incubation at 28° C. of a sandy loam was determined (a) over 6–12 weeks at varying static moisture levels over the range from air-dried to waterlogged, (b) over a second 6-week period after changing soil moisture level, maintained at various moisture levels during the first 6-week period, to 50% saturation or to waterlogging.

For optimal growth and production animals require an adequate supply of each nutrient in the diet. This means that within the total of the ration every constituent is allocated its own appropriate proportion and that all the components fit into an ideal balance one with the other. It is reasonably straightforward to define the principles of allocation for vitamins and minerals where a particular chemical entity serves a reasonably well-defined specific function. The definition of the protein component reflects a requirement for certain essential amino acids and for the materials necessary to synthesize the non-essential ones. There remains, however, a major portion of the diet that is not amenable to such specific definition. This fraction includes various chemical entities—fats, carbohydrates and fibrous materials—which are not in themselves indispensable nutrients. It is now accepted, however, that the nutritive value of these components can for convenience be expressed as a whole in terms of their capacity to release energy upon oxidation.

Information on the effect of the inclusion of typical farm foods in the diets of cattle on the ruminal concentrations of the individual volatile fatty acids (V.F.A.'s) is limited. The most extensive investigations are those of Balch & Rowland (1957) and Shaw and his co-workers (see Shaw, 1961), which have given values for a variety of hay and concentrate diets. Few figures are available for other types of cattle foods. The present paper describes a study of the V.F.A.'s in the rumen of dairy cows given various roughages or succulent foods, including a range of herbages of different species and at different stages of growth.

1. Two perennial grasses, rye-grass S24 and cocksfoot S37 have been sampled at 7 to 10-day intervals from the stage of growth just prior to flower emergence to seed shedding. Each sample was separated into leaf, leaf sheath, stem and head (where present) and the fractions examined histologically for lignin formation and chemically for lignin and nitrogen percentages. The in vitro digestibility of most of these fractions was also determined.

1. In a 3 x 3 x 3 factorial experiment of two replications, with three-factor interactions partly confounded with block effects, the effects of lucerne variety (du Puits or one of two Institute synthetics), tall fescue variety (S.170 or one of two Institute bulks) and spacing (mixed drills 6 in. apart, alternate grass and lucerne drills 6 in. or 12 in. apart) and their two-factor interactions were studied on yield of dry matter and proportion of lucerne. Data are reported for the total of fourteen cuts, for the annual total for three harvest years and for spring, summer and autumn cuts.

1. Data are presented indicating that both the total yield of potatoes and the proportions of the yield in size grades were a function (independent of set size) of the number of main stems per unit area for the maincrop varieties Majestic and King Edward.

The traditional method of producing white clover seed is to grow it in a mixed sward with grass, usually ryegrass. Wild white clover was originally harvested from old permanent pastures, which were heavily grazed, especially in the spring. This system has been perpetuated in the production of white clover seed from leys, and in many areas where sheep and cattle are a major item in the farming enterprise, grazing is an integral part of the system and contributes to the cash return of the ley: seed is not the sole objective. However, the general belief in the advantage of grass companion appears to be so strong that many arable farmers with no livestock produce clover seed from grass/clover swards. No doubt the seed ley on such farms is not only a valuable cash crop but it raises soil fertility and provides an alternative crop in arable rotation. The presence of grass, however, makes the management of successful seed production extremely difficult. Excessive grass growth in spring may result in a serious depression of clover, because of the shading effect produced at certain critical growth stages in the life of the sward.

1. A radio-telemetric system linked to a thermistor- probe embedded in deep muscular tissue has been used to record continuously variations in deep-body temperature during 46–66 hr. in three Hereford (temperate) and three East African zebu (tropical) cows under similar temperate field conditions.

2. The limitations of the ‘probe’ technique for measuring deep-body temperature are discussed.

It is a general practice in Israel to breed the local fat-tailed Awassi ewe during the summer. However, data on its sexual season are not available. There are reports (Finci, 1957) of late lambings, until April in a small percentage of the mature ewes. In yearlings such lambings have been reported as a majority (Finci, 1957). It seems, therefore, that the breeding season extends under specific conditions from June to December, but it is not known if this prolongation is characteristic of a small portion of the population and special conditions, or if all the ewes can breed so late. Hafez, Badreldin & Darwish (1955) reported that in the region of Alexandria the local fat-tailed ewe can breed throughout the year.

1. A technique has been established for the determination of fat and fatty acid intake and excretion in weaned pigs.

Italian rye-grass was grown in the greenhouse in clay loam soil in winter 1962 with several rates of a nutrient solution containing NO3-N and P, K, Ca and Mg to see whether the grass had maximum values for sums of the cations and anions (σ cations, σ anions). Two other experiments were done in summer 1962 with a similar nutrient solution containing either NO3-N alone or NO3-N plus NH4-N.

At the same level of added nutrients summer yields of grass were about twice those in winter and there was little difference when nutrient mixtures with NO3-N+NH4-N or with NO3-N alone were used. The sum of the cations (m-equiv./lOO g. dry matter) in the grass was positively correlated

A co-ordinated trial has been carried out at twenty-six centres to compare the effects of three practical rations on performance and carcass quality of fattening pigs. The simplest of these was the ‘Shinfield ration’ (SR) and this was compared with the more elaborate National Pig Progeny Testing Station rations, the ‘old’ ration (OPT) as used until January 1963 and the ‘new’ ration (NPT) as used since January 1963.

The OPT ration was significantly worse than the SR and NPT rations in respect of growth rate and food conversion. The simpler and cheaper SR ration did not differ significantly from the NPT ration. Ration differences were not significant for any carcass measurements.

This study deals with the first 2 years of grazing trials on improved pastures of tropical grasses and legumes at Ibadan in Nigeria. The mixtures consisted of (i) Cynodon plectostachyus and Centrosema pubescens (legume), (ii) (i)+Chloris gayana and Digitaria decumbens, (iii) (ii) +Stylosanthes gracilis (legume). The mixtures were sown and planted in four blocks, the treatments being repeated four times, and were grazed rotationally by N'Dama cattle. During the first year's trial a uniform stocking rate of 1·7 steers/acre was adopted and a recovery period of 11 weeks was allowed. In the second year's trial the stocking rate was increased to 2·7 beasts/acre by the addition of nine yearling heifers and the recovery period was reduced to 5 weeks. Herbage yield and intake were measured by the clipping technique.

The apparent and corrected digestibilities of beef tallow, H.E.F. and soyabean oil have been determined in the newly weaned pig. Determinations of the individual fatty acids in the food and faecal lipids allowed the digestibility of each acid to be calculated separately. The purest available forms of oleic, stearic and palmitic acids and their corresponding triglycerides were also used in the determination of digestibility. Although the digestibility of each fatty acid is to some extent a characteristic of the acid, the extent of absorption can also be modified by the other acids in the diet. The results.of these experiments give no clear indication of a difference between feeding fatty acids in the free form or as the triglycerides. The digestible energy values of the fats have been calculated as the product of gross energy value and corrected digestibility.

The effects of soil temperature, light intensity, soil-water tension and amount and form of N, on cation-anion relationships in Italian rye-grass were tested by growing grass in a clay loam in three experiments under glass. The grass had six levels of NO3-N or NH4-N with a uniform dressing of P, S, K, Ca and Mg; NH4-N was treated with 'NServe' to prevent nitrification. In the first experiment the grass was grown at 11°, 19-5° and 28° C, in the second in 100, 68 and 44% glasshouse ' daylight', and in the third at three soil-water tensions. Yields were greatest at 19-5° C, 100% glasshouse