1. Comparisons are made of the results obtained in the analysis of clays, especially of clay fractions separated from soils, by the standard sodium carbonate fusion method and by attack by means of mixed acids. Provided certain precautions are taken, in the latter case, the percentages of silica obtained are shown to be comparable with those given by the fusion method.

2. A possible disadvantage of the acid method is that the attack of the clay is not invariably successful, but treatment of the silica with hydrofluoric acid provides a convenient and reliable means of detecting those cases in which failure occurs. Such clays must be decomposed by fusion with sodium carbonate.

In a comparative study of some factors that influence the body weights of 36 Friesian, 54 Holstein, 22 Holstein-Friesian, 24 Jersey and 17 Brown Swiss calves born during 1964–9 at the Moor Plantation dairy herd, Ibadan, breeds differed significantly (P <0·01) at all ages. Highly significant sex differences (P <0·01) existed at 4 and 8 weeks of age. The season of birth significantly influenced the weight at 4 and 8 (P < 0·05) and at 12 weeks (P < 0·01). The season × sex and season × breed interactions significantly affected the weights at virtually all ages but the sex × breed interaction did not. The birth weight exerted a highly significant influence (P < 0·01) on all other body weights. It reduced the residual variation as well as the differences and interactions between the main effects. After adjusting for birth-weight differences, body weight was significantly (P < 0·05) influenced at various ages by breed of calf, season of birth, sex × breed and season × breed interactions. The sex and season × sex interaction effects on adjusted body weights at all ages were negligible (P > 0·05).

The growth and yield of maize grown on an unploughed newly opened secondary forest in Nigeria in 1985–87 was studied. In each year, trash was either removed or burnt in situ and each of these treatments was given N fertilizer or none. In the first year, only N fertilizer increased yields. In the second and third years, yields were increased by N fertilizer and by trash burning. Trash burning consistently increased the amount of P in the soil.

The writers do not mean to infer that the maintenance requirement of the adult sheep, as calculated by Wood and Capstick, is incorrect. The value obtained by these investigators is probably as reliable as any other which could be calculated from their data. The writers fully agree that Wood and Capstick's value is probably more accurate than previously estimated values of the maintenance requirement of the adult sheep.

Steers fed low nitrogen diets were infused intraruininally with water.

Increasing the water load increased the urine volume and urinary urea excretion and depressed the plasma urea level.

The effect of intraruminal water loading was studied in association with intravenous urea loading of 25 and 65 g N/day. When 25 g N/day as urea was infused intravenously, water loading did not significantly increase the urinary urea excretion but the plasma urea level was depressed. At 65 g N/day water loading increased the urinary urea excretion and decreased the plasma urea level.

Significantly different relations between plasma urea and urea load existed for the ad lib. water and the water-loaded treatments but the relation between rumen ammonia level and plasma urea level was not affected by the water loading.

The results are discussed with reference to the recycling of urea.

The amount of oil in the diet and its degree of unsaturation are known to exert an important effect on the nature of the fat deposited in the body of the growing pig, foods of high oil content tending to give rise to bacon carcasses containing fat of an undesirably soft and unsaturated character. For this reason, authorities on pig nutrition are agreed on the desirability of excluding from the dietary of the bacon pig all foods containing more than a small percentage of oil. It has been stated that, in order to avoid the danger of producing carcasses with soft fat, the meal ration of the fattening pig should be made up so as to contain no more than about 3% of oil.

This prejudice against the use of feeding stuffs rich in oil has been transferred, somewhat unquestioningly perhaps, to feeding stuffs rich in fat. Feeding meat meal, for example, contains normally from 8 to 10 % of fat, and manufacturers complain of the difficulty of securing sales of this product for pig-feeding on account of the view generally held that its high fat content would occasion the production of soft fat in the resultant bacon or a carcass with an excessive amount of fat. To meet this prejudice, therefore, the meat meal as ordinarily produced is frequently submitted to a process of de-greasing with petroleum benzine at about 200° F. so as to give a meat meal containing about 3% of fat. This procedure, however, not only adds to the cost of the manufacture of meat meal, but may actually lead to a distinct lowering of the digestibility of the product (Woodman & Evans, 1937).

An account is given of artificial insemination of 733 grade cows in Kenya from January 1936 to August 1939. 76·8% of the cows inseminated calved, with an average of 1·88 inseminations per conception. The different doses and dilution of sperm used gave very similar results, as did two inseminations, compared with one insemination, in a single heat period.

The pigeon pea (Cajanus indicus or C. cajan) grown extensively in India, Africa, and other tropical and semitropical countries has attained considerable prominence as a stock food in Hawaii, where it is being grown as an important field and pasture crop in some sections. Its culture and utilisation in Hawaii have been exhaustively treated in a bulletin of the Hawaii Agricultural Experiment Station written by F. G. Krauss(1).

Much work has been done in America, on the Continent and in this country, to determine the effect of different finely-ground naturally-occurring phosphatic substances on plants of various natural orders, grown under differing conditions as to the character of the soil and the use of other nutrient substances. In a few cases results or conclusions appear to conflict. Not nearly so much attention has been devoted to the effect of artificially prepared insoluble salts of phosphoric acid on the growth of plants. When these are employed in the absence of ammonium salts, and acid soil substances, definite information should be obtained as to the powers possessed by plants themselves of utilizing insoluble phosphates. With the object of making a contribution to such knowledge, oats, peas and swede turnips were grown in artificial soils made up of white sand and pure chalk, and the particular salt of phosphoric acid under investigation. The other essential nutrient substances were supplied in a dilute solution of salts.

As part of their normal behaviour, buffaloes need to wallow in water or mud for a period of the day and, in general, show a greater affinity for water than other domestic ruminants. It has been reported (McFarlane, 1971) that buffaloes turn over more water than other domestic ruminants. This, in turn, should make them more susceptible to deprivation of water, even for short periods. Requirements for water are also known to change with the physiological state of animals. The experiment described in this paper was carried out to compare the effects on the daily turnover of body water in growing, pregnant and lactating buffaloes, under normal management, when denied wallowing and when drinking water was restricted.

There have been considerable changes during the last ten years in the ways in which agricultural research is organized in many countries. These changes are of interest to our readers and for this reason the Editors have invited the Agricultural and Food Research Council of the United Kingdom to explain present structures within that organization. The Agricultural and Food Research Council receives funds for research directly from the Department of Education and Science (c. £54 million per year) and through commissions from the Ministry of Agriculture, Fisheries and Food (c. £44 million) as well as from commercial and other organizations (c. £13 million). It advises the Department of Agriculture and Fisheries for Scotland, which is the body responsible for the Scottish agricultural research institutes (spending c. £22 million per year), on scientific aspects of the research they finance and also provides support to universities and other educational establishments for the support of scientific studies relevant to agriculture and food.

1. Selections from a cross of varieties of Triticum vulgare and T. Turgidum have been backcrossed repeatedly to the turgidum and vulgare parents and selections of turgidum and vulgare type respectively made within each series.

2. The yield and morphological stability of turgidum- and vulgare-type selections from the straight cross have been compared with those of selections backcrossed up to four times to T. turgidum and T. vulgare respectively.

3. In the case of backcrosses to T. Turgidum the highest yielding selections have been derived from the most frequently backcrossed material, but the vulgare-type selections from the straight cross have outyielded those from the material backcrossed to T. vulgare.

4. An analysis of the yield components of the parents and of the most promising selections, in terms of ears per plant, spikelets per ear, grains per spikelet and 1000-grain weight, has shown no evidence of a combination of the characters determining the high yield of the parents in these high yielding selections.

The C3 and C4 plant components in extrusa samples from oesophageally fistulated cattle can be estimated by δ13Canalysis. However, contamination with saliva containing bicarbonates could cause bias in the estimation of the C3 or C4 components. Saliva from animals fed C4 and C3 diets had δ13C values of – 4.37/103 and –15.97/103, respectively. Both values showed a large positive shift of c. 10 units relative to the diets, but the difference between feeds was maintained in the saliva. On theoretical grounds, contamination of the ingested feed with saliva should have caused a small (1·3–3·4% legume) negative bias when estimating legume percentage in the diet. This did not occur when saliva of known (PC was added to mixtures of C3 and C4 forages which were dried, ground and analysed for δ13C. It is postulated that CO2 was lost from bicarbonate when saliva was dried in contact with fresh plant material, and so no significant bias was detected. It would appear that the δ13C technique can be used to estimate the proportion of C3 and C4 components in oesophageal extrusa samples without significant bias from salivary contamination.

Leucaena leucocephala (Lam.) de Wit, a leguminous shrub, has come into use as a fodder plant for animals in the Ryukyu Islands as it provides highly palatable, high quality feed (Kitamura, 1985). It is superior to other feeds available in this regard (Higashiohmine, Aramoto & Yamashiro, 1971; Isa et al. 1982).

Periwinkle (Catharanthus roseus (L.) G. Don) is an important medicinal plant grown in different parts of India. Its leaves contain vincristine and vinblastin, alkaloids which are used in the treatment of various leukaemias and limphomas, and its roots contain ajmalcine, another alkaloid, used in the manufacture of antihypertensive drugs. Cultivation of periwinkle has recently gained importance in India. The yield of periwinkle can be increased with the use of mineral fertilizers (Pareek et al. 1981, 1982; Rajasekharan et al. 1982; Reghunath & Sethumadhavan, 1982a, b; Hegde, 1986). The effect of fertilizer application on the alkaloid concentration is not clearly established though there are a few reports which suggest that application of N increases alkaloid concentration in roots (Rajasekharan et al. 1982; Reghunath & Sethumadhavan, 1982a) and leaves (Pareek et al. 1982). Therefore, the present experiment was designed to study the effect of application of nitrogen and phosphatic fertilizers and farmyard manure on the root and leaf yields, and total alkaloid concentrations in roots and leaves in Catharanthus roseus (L.) G. Don.

Relations were developed between the carrying capacity or production of fat-corrected milk (FCM)/ha and various measures of pasture growth for six pasture treatments grown in a subtropical environment. The pasture and animal production variables were obtained from pastures grazed on a weekly rotation using stocking densities which were varied so that a target weight of leaf material remained on the pasture at the conclusion of each grazing.

Within a treatment, there was a curvilinear relation between the rate of leaf growth and carrying capacity, with the greatest efficiency of conversion at the lowest leaf growth rates. This relation generally varied between pasture treatments because of differences in grazing intensity. There was little variation in the production of FCM per cow between grazing periods within a treatment, reflecting the experimental technique of matching the stocking density to the amount of forage. Consequently FCM/ha largely mirrored the stocking density with some adjustment for differences in production per cow caused by differences in grazing intensity between treatments. Production of FCM/ha was affected more by a unit change in residue leaf yield than by a unit change in leaf yield before grazing.

Using the rate of leaf removal (intake plus grazing losses) per cow as an inverse index of grazing intensity, it was apparent that the use of variable stocking densities to obtain specified residue yields after grazing did not necessarily equalize the grazing intensity because the rate of leaf removal per cow varied according to the before-grazing leaf yield. Also soiling by dung caused differences in the acceptability of forage for grazing, resulting in differences in grazing intensity between pastures with the same yield and stocking density.

Sampling methods for the estimation of annual production and mean egg weight have been examined, and an attempt made, by a combination of theoretical considerations and practical observations, to derive general expressions for the standard error of such estimates. Numerical values of these errors have been tabulated in a form suitable for direct application by the practical poultry worker.

The author wishes gratefully to acknowledge the assistance and criticism given him by Dr F. Yates, and by Mr F. J. Dudley of the National Institute of Poultry Husbandry.

Three pot experiments were performed in unheated glasshouses at the University College of North Wales College Farm, Aber, Gwynedd in 1980–1983. Two experiments tested the effects of sowing date and N supply, the third sowing density and nitrogen supply. Extension growth of main-stem leaves was measured by ruler and expressed in thermal time units to allow comparisons between sowing dates. Rate and duration of leaf extension were determined from linear regressions of leaf length against thermal time.

Increasing N supply increased leaf extension rate but had no significant effects on leaf extension duration. Leaf extension rate increased with leaf position on the main shoot, but decreased slightly in leaves extending at the time of stem elongation. Leaf extension duration also increased with leaf position on the main shoot and was related to mean temperature during the leaf extension phase. Plants sown in September were able to compensate for lower radiation receipts by having a faster rate and longer duration of leaf extension, by producing larger leaves with a greater specific lamina area and by partitioning a greater proportion of extension growth into lamina and less into sheaths. In plants sown in June, the largest leaf occurred at a lower stem node and leaves emerging later showed a strong response to N. It is suggested that this is attributable to earlier onset of internal competition for assimilates. Variation in leaf extension rate was the main factor influencing variation in final leaf area. There was a strong positive relationship between leaf extension rate and leaf N content.

Increasing sowing density increased the area of the first four leaves on the main shoot and decreased that of later leaves, changes mainly associated with changes in leaf extension duration. It is concluded that progress in the modelling of leaf area expansion, light interception and dry matter production requires more information about how sowing date, sowing density and N supply interact to influence crop development and leaf growth.

1. Loss of ignition at 450°C. and the organic carbon content of some shale soils are positively correlated (r = +0·99).

2. Base exchange capacities and exchangeable cations were determined on soils, treated and untreated with hydrogen peroxide solution.

3. Oxidizing the organic matter lessened the exchange capacities of all samples; the exchange capacity of the organic matter varied from 67·5 to 97·0 m-equiv./1OO g. dry material.