Zinc deficiency is a common nutritional problem in calcareous agricultural soils, resulting in reduced crop yield and performance. The effects of zinc sulphate (0 and 40 kg/ha) on seed yield, its components and seed element contents of 21 wheat cultivars were investigated. Zinc sulphate application increased plant height, leaf area index (LAI), flag leaf area, biomass, spike length, number of seeds per spike, seed weight and harvest index (HI). The increase in HI indicates the greater effect of zinc on seed production compared to plant biomass. In most of the cultivars, zinc sulphate application decreased the content of phosphorus and nitrogen in seeds and increased the content of iron and potassium. The cultivars showed significant differences in all the traits measured, indicating the existence of genetic diversity in the cultivars studied. In the second year, which was hotter and drier than the first year, zinc sulphate application reduced the damage caused by drought and heat stress and improved seed yield and quality. The regression fit showed that newer cultivars had lower yields in unfertilized conditions compared to old cultivars and showed their superiority in zinc fertilized conditions. It seems that the newer varieties require more fertilizer because they have been bred on fertile soils.

The present investigation was intended to furnish information concerning:

(1) The movement of water-soluble and exchangeable potassium in the soil profile after successive fertilizer applications.

(2) The form of potassium—exchangeable, soluble, or non-exchangeable—into which added potassium fertilizer is converted in the soil.

(3) The effect of doubling the fertilizer ration on the absorption of potassium by the soil; and the effect of doubling the ration of irrigation water on the absorption and accumulation of potassium in the soil.

(4) The effect of frequent successive summer irrigation following fertilizer application on the distribution of the three forms of soil potassium.

(5) The effect of fertilization followed by irrigation on soil pH. value.

1. Fifty buffalo-cows were used for studying the pH of the vaginal secretion at different stages of the sex cycle.

2. Highly significant differences were found in the pH value of the vaginal secretions during the different stages of the sex cycle. The average was 7·3 during oestrus, 8·1 during dioestrus and 8·3 during pregnancy.

The effects of heat treatment, as measured by undenatured non-casein nitrogen (NCN gN/100 g total N), and of protein: energy ratio on the digestibility coefficients and utilization of milk substitutes by lambs were investigated.

Twenty-four Finnish Landrace × Dorset Horn lambs (12 males and 12 females) were given milk substitute diets in which approximately 20 or 30% of the gross energy was supplied by protein (PE20 and PE30). NCN levels were approximately 7, 12, 18 and 5, 11, 16 for diets PE20 and PE30 respectively.

All lambs were offered a daily allowance of milk substitutes containing 7·95 MJ of gross energy from 3 to 25 days of age, when they were slaughtered and the chemical composition of the empty body was measured. Gains in the chemical components were measured using the comparative slaughter technique.

For each unit increase in NCN value there was an increase in the apparent digestibility coefficients of dry matter (D.M.), crude protein (CP) and ash of 0·13, 0·13 and 0·93 percentage units, respectively. The apparent digestibility coefficients of all the dietary components, except lactose increased by 0·24 (d.m.), 0·24 (CP), 0·63 (fat), 0·75 (ash) and 0·32 (energy) percentage units and the metabolizability by 0·24 units for each 1% increase in PE.

Live-weight and empty body-weight gains increased with increasing PE and NCN. Lambs receiving diets PE20 had a daily live-weight gain 42 g less than those on diets PE30; increasing NCN from 5 to 18 gN/100 g total nitrogen, increased live-weight gain by 33 g/day.

Increasing PE and NCN increased water gain and nitrogen retention; increasing PE also increased ash retention and decreased fat gain.

Lambs on diets PE20 contained more fat and less protein, at the same empty body weight, than those receiving diets PE30.

Efficiencies of conversion of dry matter and energy to live-weight gain, and energy and N utilization all increased with increasing NCN, but increasing PE did not affect energy utilization and decreased N utilization.

Female lambs had lower growth rates than males (—14·5 g/day) and had a higher total fat gain (128 g).

Two breeds of zebu viz. Hariana and Sahiwal were examined for the possible existence of red cell K+ polymorphism. All the animals examined appeared to be LK type. However, red cell K+ concentration varied rather widely between 7 and 50 m-equiv/1. Within the major LK type three distinct subtypes, tentatively designated as low low (LLK), medium low (MLK) and high low (HLK) were observed. The mean red cell K+ concentration in the various subtypes in the same order were 12·5, 19·5 and 38·0 m-equiv/1 respectively. LLK animals were significantly more frequent in the Sahiwal than in the Hariana breed. The possible genetic basis of the occurrence of these subtypes within the major LK type is discussed.

LLK animals had significantly higher pcv, Hb and RBC, than MLK animals. The WBC and plasma protein values were also higher, though not significantly, in the former group. In addition, animals of the LLK subtype showed consistently lower rectal temperature at comparable levels of respiratory effort under conditions of thermal stress than MLK animals.

1. Of various objective measurements carried out on six carcasses from each of the three Australian grades 1, 2 and Canner, the minimum depth of fat above the eye muscle at the quartering point distinguished the grades to the most significant extent, as would have been anticipated from the importance of finish in visual grading.

2. The iodine numbers of fat from the tissues of the steers examined were lower than those which would have been expected in English steers at a similar level of fatness.

A total of 25 steer carcasses from a wide range of breeds and carcass weight and fatness were used to examine the relationship between a range of fat thickness measurements and the dissected fat content of beef carcasses. Fat thickness measurements included those on the hot carcass suitable for ‘commercial’ use and others on the cold carcass commonly used in research.

The mean of the measurements of fat thickness from the two sides of the hot carcass between the 12th and 13th ribs (12H) gave the most accurate prediction of carcass fat content (FPCT). The relationship was described by the equation FPCT = 14·61 + 1·85 (12H) (R2 = 0·92; S.E. of prediction of individual FPCT at the mean= ±2·17%).

The mean of four fat thickness measurements made on the quartered surface between the 10th and 11th ribs of the cold carcass was the next most accurate predictor (S.E. = 2·28%) of fat content. Fat thickness measurements made on the hot carcass between the 10th and 11th ribs were the least satisfactory.

Although the hot carcass measurements between the 12th and 13th ribs were made under commercial conditions and included a wide range of types of cattle the prediction of fat content from these measurements had a marginally lower standard error than the prediction based on measurements made under experimental conditions.

(1) The results of experiments on the rate of horizontal flow, and on the rate of gain in mass, or kerosene and of water in fine and crumb fractions of certain West Indian colloidal soils, comprising three siliceous soils containing different amounts of calcium carbonate, and two lateritic soils, are described and tabulated.

(2) The methods of experimentation employed were those elaborated by Green and Ampt, whose equations were found, however, not to fit the values obtained, as is to be expected.

(3) The siliceous soils examined possess relatively high swelling coefficients, and their component particles, when wetted, cohere to a greater or lesser extent, depending on lime content. These properties appear to account for the relatively low rates of permeability to water in these soils. Lateritic soils, on the other hand, possess low swelling coefficients, and low cohesiveness; water percolates through them relatively very rapidly.

Evidence is presented, based on feeding tests, that at Hanns Hall Farm it has been impossible to control bacillary white diarrhoea of chicks (pullorum disease) by blood testing when foods of c. 20% protein content have been fed as the sole diet of chicks.

Evidence is presented, based on feeding tests, that at Hanns Hall Farm epidemic bacillary white diarrhoea (pullorum disease) has occurred in brother chicks when fed foods of c. 20% protein content and that epidemic bacillary white, diarrhoea has not occurred in sister chicks which have been fed crushed oats for the first 72 hr. and thereafter have been fed a diet of c. 14% protein intake.

Evidence is presented, based on feeding tests, that at Hanns Hall Farm epidemic bacillary white diarrhoea (pullorum disease) not only did not occur in sister chicks in which B. pullorum had been demonstrated to be present in one of their number, but also epidemic bacillary white diarrhoea failed to develop despite the lack of hygienic precautions when these chicks had been placed in an uncleansed brooder from which the survivors of a severe epidemic of this disease had just been removed, and when they were brooded adjacent to chicks which suffered severe mortality from the disease, thereby undergoing all the chances of infection by wide dissemination of B. pullorum within a small area.

Theory for the non-steady-state diffusion flow of a spheroidal body is discussed and solutions are presented for estimating the time-dependent diffusivities at small and largo times following sowing in soil of germinating soya-bean, cow-pea and blackgram seeds. The validity and also the limitations of the equation for large times to estimate time-dependent diffusivities are discussed. Assuming that the time of germination was at infinity it was possible to reduce the equation for small times to a simple form. Thus, with the help of these two equations it was possible to study changes in the diffusivity of seeds at different soil matric potentials throughout the period, immediately after sowing until germination. The diffusivities showed gradual decrease at 0 bar potential for soya-bean and cow-pea, and increase at – 2 and – 10 bar potentials for soya-bean, cow-pea and blackgram seeds with time. The decrease in diffusivity with time under non-stress soil water condition is explained as predominantly a physiological phenomenon of the seed due to the increase in seed water content with time, while its increase with time under water stress conditions is probably because of the decrease with time of the initially large seed-coat resistance and tortuosity showing small values of diffusivity. The discussion suggests that the role of area of contact on the water uptake of the buried seeds as reported so far is contradictory and, therefore, not convincing.

Pastures of Digitaria decumbens (pangola grass) previously oversown with Lotononis bainesii at Mount Cotton, south-east Queensland, Australia, were grazed by sheep for 3 years (1985–87), using a factorial combination of seasonal variations in stocking rate.

Lotononis behaved as a short-lived plant with a mean half-life of 4·2 months (range 1·6–10·3); rate of mortality was positively related to initial seedling density. The proportion of lotononis remained very low for the first 2 years of the experiment, when conditions were unsuitable for large-scale seedling regeneration, which was also limited by the hardness of the seed reserves. Subsequently, lotononis regenerated well in treatments which combined the following features: (i) light grazing (5 sheep/ha) during the main flowering period of spring-early summer, (ii) heavy short-duration grazing in mid-summer to create a ‘gap’ and (iii) medium or heavy (18 or 27 sheep/ha) grazing during late summer-autumn to reduce competition from pangola grass.

The ecological niche of lotononis and the possible use of complementary pastures are discussed.

The management of non-leguminous annual forage crops can affect dry matter (D.M.) yields, chemical composition, and nutritive (feeding) values largely because of the stage of maturity at which the crop is harvested. After studies for selecting high-yield forage oat varieties for a highaltitude tropical climate (Haile, 1976), it was considered necessary to look into the management of forage oats so that the time of harvesting for maximum forage and crude protein yield could be established.

1. Biological trials have been carried out to determine the efficacy of petroleum ether as solvent for the extraction of pyrethrum flowers for analysis. 95% of the toxic material was extracted from flowers one year old after only 3 hr. percolation. An extraction period of 8 hr. with petroleum ether is suggested.

2. A method of preparing colourless extracts of pyrethrum and analytical data for such extracts are given. They are shown to be of value for the preparation of concentrates of the pyrethrins. The preparation of a colourless concentrate containing 93% of total pyrethrins, as determined by a modified Seil method, is described.

In the preparation of lime-sulphur solutions used for spraying purposes by boiling together lime, sulphur and water, the following equations represent reactions which might occur primarily:

(1) 3CaH2O2 + S4 = 2CaS + CaS2O3 + 3H2O,

(2) 3CaH2O2 + S12 = 2CaS5 + CaS2O3 + 3H3O.

According to the above equations 3 molecules slaked lime CaH2O2 or 3 molecules of quick lime CaO may combine with 4 to 12 atoms sulphur; or 1 part of quick lime (by weight) should combine with ·7619 to 2·2857 parts of sulphur.

Hanley & Ridgman (1979) reported the results from three cycles of six-course rotations on light land. The report was based on a rotation of sugar beet, barley, barley, potatoes, barley, barley, with treatments involving replacement of one, two or three of the first three crops by 1-, 2- or 3-year leys, the last three crops acting as test crops. One of the problems of drawing general conclusions from rotation experiments is that the test crops are really part of the experimental treatments and may not be the most suitable crops for determining either the direct effects of the ‘treatment’ crops or the longer-term effects of the rotations themselves.

The present work was carried out on 24 coarse-wool Barki and ⅝ Merino–⅜ Barki ram lambs to study the effect of vitamin A supplementation on some skin and wool characteristics. Lambs, at the age of 6 months, were allotted to three groups receiving no vitamin A supplement, 50000 i.u. and 100000 i.u. of vitamin A/head monthly. Blood samples were taken monthly for the assessment of vitamin A in the plasma. It was found that vitamin A in the plasma ranged from 42·4 to 17·50 and from 41·67 to 50·03/ μg/100 ml in the control and treated groups respectively, from the start of the experiment till the end at the age of 17 months.

Vitamin A supplementation caused increments in external diameters, of primary and secondary follicles in Barki and primaries in ⅝ Merino, higher than those encountered in internal diameters. An increase in staple length and clean fleece weight of ⅝ Merino and a slight increase in Barki fibre diameter was observed in vitamin-A-supplemented animals.