In two earlier papers (Henderson, Edwards & Hammerton, 1962a, b) data on the yields of dry matter and crude protein obtained in an experiment carried out at Aberystwyth over the period 1954–56 were presented. The experiment compared the productivity of five leys, each based on a single grass species with white clover, at six levels of compound fertilizer, under a management regime of three cuts per annum. Subsequent to 1956 the fertilizer application and cutting regime were continued, but no yield data were collected. Early in 1960, the experimental area was ploughed up and sown to barley, in order to study the effects of the previous experimental treatments on arable productivity. Barley was also sown in 1961 and 1962, and the present paper is concerned with the yields of the three successive crops of barley.

Pregnancy toxaemia in ewes is a metabolic disorder which may occur during the last month of pregnancy. Typical symptoms are anorexia, hypoglycaemia, hyperketonaemia, blindness, ataxia and recumbency. The condition usually proves fatal. Reid & Hogan (1959) have put forward the suggestion that pregnancy toxaemia is an adrenal steroid diabetes. However, pregnancy toxaemia in ewes is generally associated with starvation or severe undernutrition, and McClymont & Setchell (1955) have suggested that under these conditions the symptoms of pregnancy toxaemia are due to cerebral depression caused by hypoglycaemia. As part of investigations on pregnancy toxaemia, adrenal steroid metabolism in ewes was studied. This paper presents data on plasma cortisol levels during the last month of pregnancy in ewes, and the possible effects of undernutrition and cold on these levels.

The soil used in this experiment was a sandy clay low in phosphorus and in nitrogen from the College Farm. A (3 x 3 x 2) factorial experiment with three replications using an upland rice variety, Agbede, was carried out in the open on the College Farm between January and May 1963. Ten-litre plastic buckets 25 cm. deep and holding 11 kg. of soil, which was thoroughly mixed and the pH brought to 6.0 by liming, were used in growing the plants. These buckets were left standing on the ground, and there was no rain during the experimental period.

Many trials have been carried out in Australia to assess comparative values of breeds of rams and owes for fat lamb production in various environments and for different markets. Although general trends have appeared, there is much conflicting evidence in the reports of these trials as to the order of superiority of breed for a particular environmentmarket situation, especially for that of the rams. Much of this conflicting evidence arises because no completely satisfactory method of assessment of superiority has been used. Many of the studies undertaken to compare different breeds of ram have used as their basic criterion the returns per ewe (for example, McConnell, 1910; Elliot, 1926; Colebatch & Scott, 1927; Coleman, 1927; Cook, 1934; Thompson, 1951; Coleman & McDonald, 1952). In this situation random fluctuations in lambing percentages and in percentages of lambs surviving to slaughter can affect the order of superiority of the breeds. In view of the comparatively small numbers of sheep often used in the breed comparison groups (and this is, of course, particularly true in the case of rams), these deviations can bo sorious. For example, McConnell (1910) found that Border Leicester x lambs had a higher return per ewe than Southdown x lambs, but in 1911, the same author found the reverse situation which appears to have been due to a reversal in order of lambing percentages.

The importance of water for the function of the reticulo-rumen has been stressed by the classic work of Schalk & Amadon (1928). The aspiration theories of regurgitation of Chauveau & Toussaint (Toussaint, 1875) and of Wester (1926) differ, but both imply that before rumination can proceed normally there must be a sufficiency of fluid in the reticulo-rumen. However, Kick, Gerlaugh & Schalk (1937) noted that, with cattle, rumen contents which were so firm as to be almost impossible to break up by hand did not prevent rumination. The writer has noticed a similar phenomenon in sheep. In both cases the animals were given a high level of roughage and a low level of concentrates in their diet. But, even if apparently firm ingesta can be regurgitated, it is still likely that the regurgitate is in fact of a fluid consistency and therefore water intake will be a limiting factor. Transport of ingesta in suspension from the reticulo-rumen through the omasum likewise requires an adequate supply of water.

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.

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.

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.

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.

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.

To obtain large yields of grass much N fertilizer is usually needed, and when such grass is cut and conserved large amounts of K soon are removed from the soil. Some soils contain so little ‘available’ K that yields are soon limited unless grass is given enough K fertilizer, but other soils supply more K and so need less K fertilizer. Soils differ so greatly in their ability to supply crops with K that it is difficult to generalize about the fertilizer K requirements of grass, especially as the use to which the grass is put greatly affects the soil K ‘balance sheet’. On average, grass in England grows well for not much more than 6 months each year. This implies that, when cattle are maintained on hay or silage for much of the remainder of the year, on average one-third of the grass product each year may have to be cut, removed from the field, and conserved. Much of the N, P and K contained in this grass is not returned to the soil.

Fourteen experiments were carried out in various parts of England to compare ammoniumsulphate, ammonium nitrate, calcium nitrate andurea applied to grassland in early winter, latewinter and spring at rates supplying 40 and 80lb./acre of nitrogen. Yield of herbage and of nitrogen were recorded at one cut in spring..

The effects of rotational grazing (twice weekly pasture change) and two systems of set-stocking on plasma calcium and magnesium levels of lactating ewes have been studied.

The authors of most of the papers dealing with the seasonal breeding of sheep agree that the summer months are the less favourable season for sexual desire of the rams (Moule, 1960), their semen quality (McKenzie & Berliner, 1937; Gunn, Sanders & Granger, 1942; Comstock, Green, Winters & Nordskog, 1943; Phillips, Sohott, Eaton & Simmons, 1943; Sapsford, 1951; Hafez, Badreldin & Darwish, 1955; Cupps et al. 1960; and many others), and for spermatogenesis (Maqsood, 1951; Ortavant & Thibault, 1956).

Semen characteristics of local and imported rams were studied over a period of 2 years.

Awassi and Border-Leicester rams with regular Awassi and Border-Leicester rams with regular semen collections throughout the year showed definite seasonal variations in the volume and number of sperms in their ejaculates: maximum levels during the autumn and minimum during the spring months. The sperm density reached its maximum during the spring and its minimum during the autumn as a result of the opposite changes of the semen volume. In the rams without regular semen collections, as those kept in the flock, these seasonal changes were not distinct. In the imported rams from breeds without a

The metabolic activity of spermatozoa, obtained from Awassi, German Mutton Merino, Corriedale and Dorset Horn rams, waa measured every 2–4 weeks over a 2-year period.

Exhaustion tests were carried out with two Awassi rams 4 times a year for 2 years. The maximum sperm number was obtained in October and the minimum in January. If we consider that the time needed for one spermatogenic cycle and for the migration of the sperm cells through the epid i dymal canal is over 2 months, we may assume that the spermatogenic activity changes with the length of day and reaches its maximum and minimum values during the longest and shortest days, respectively, whereas its androgenic activity is delayed by 3–4 months after the length of daylight changes.