Influence of season on the terpene composition of Pinus halepensis and Pinus sylvestris was investigated. The essential oil of twigs and needles from a preselected plot of pines was investigated from October to June. In P. halepensis, the average composition during this time was 27·2% α-pinene, 65·0% sabinene, 7·2% 3-carene and 0·5% β-pinene in the essential oil of twigs; 32·1% α-pinene, 35·9% sabinene, 18·5% terpinolene, 4·3% 3-carene, 3·1% β-pinene and 6·1% thujene, limonene, β;-phellandrene and γ-terpinene in the essential oil of needles. In P. sylvestris, the average composition was 49·2% α-pinene, 30·1% sabinene, 14·9% β-pinene and 7·9% limonene in the essential oil of twigs; 69·5% α-pinene, 14·9% camphene, 9·1% β-pinene, 3·6% sabinene and 2·8% limonene in the essential oil of needles. The maximum amount of sabinene coincides with the minimum of α-pinene, both in twigs and needles essential oil from P. halepensis and P. sylvestris. The month-to-month changes in the oil composition are statistically significant for the most part. It is of interest to point out the decrease of sabinene content of needles essential oil in comparison with the twigs essential oil, with the simultaneous increaseof terpinolene in P. halepensis and camphene in P. sylvestris.

Diets containing 10·5, 13, 15·5 or 18% protein were formulated by progressively replacing barley by a 2:1 mixture of soya-bean meal and fish meal. Each diet was given at three levels of intake proportional to (body weight) 0·73. A total of 144 pigs were used at two centres.

Growth rate increased with food intake at each protein level, but to the greatest extent with the 13% crude protein (CP) diet. Growth rate also increased with protein level; the results suggested that there would be no further improvement above 18% CP. The effects of protein concentrationon food conversion generally reflected those on daily gain.

Carcass fatness, estimated by both midline and introscope measurements of fat thickness and by specific gravity, increased significantly with the intake of all but the 18% protein diet. When theeffects of food intake were taken into account, carcass fatness increased steadily with reductions in protein level down to 13%; the reduction from 13 to 10·5% produced a much greaterincrease in fatness.

The reductions in daily food intake necessary to achieve equal carcass fatness as protein level wasreduced were of the order of 0·1 kg per 1% CP from 18% to 13% CP, but ofthe order of 0·3 kg per 1% CP below 13%.

Differences between the sexes were greatest at high protein concentration; significant differences between the centres were found only with the low protein diets.

Studies were conducted to determine possible leaching or fixation problems in growing sudangrass (Sorghum Sudanese Stapf.) when urea, ammonium sulphate plus triple superphosphate, and ammonium polyphosphate fertilizer were applied as a seed-bed application to the very sandy soils of the Libyan Sahara near the Kufra Oasis. The effectiveness of the nitrogen source was measured by plant colour, leaf analysis, and seedling height.

The urea nitrogen plus single superphosphate when applied and watered-in did not supply enough nitrogen to obtain a vigorous green seedling compared with ammonium polyphosphate (21% N, 53% P 2O6), which produced excellent vigorous green seedlings. The ammonia source supplied more nitrogen than the urea imder the conditions of these trials.

The application of urea 1, 2, 4, and 8 days before sowing was inadequate in supplying nitrogen to meet the early demand of the sudangrass seedlings. Sudangrass seedlings after 26 days were only 5–6·3 cm tall. With a seed-bed application of 36–72 kg N/ha as ammonium sulphate under comparable circumstances, sudangrass seedling height was 21·7 cm. The plants receiving no nitrogen applied before sowing were 6·7 cm high, similar to those which received urea.

Under these virgin sandy soil conditions, the ammonium sulphate and ammonium polyphosphate (21% N, 53% P2O5) fertilizers applied to the seed bed were retained within the root zone in sufficient amounts to give a vigorous, non-deficient sudangrass seedling. Nitrogen from urea was deficientand presumed leached beyond reach of the seedling root when applied to the seed bed. Applied post-emergence, however, urea was a very satisfactory source of nitrogen.

Carcass data for 424 castrated male lambs, comprising seven breed-type groups, were used toevaluate a series of linear measurements, subjective scores and the lean content of sample joints as predictors of percentage lean in carcass. The groups represented the main types of British lamb and mean carcass weights ranged from 12·8 kg (Welsh Mountain) to 20·8 kg (Lowland Longwool). Lambswere selected from commercial abattoirs to cover the ranges of fatness and conformation normally found in practice within each group. The pooled within-group S.D. for percentage lean was 3·70 and theoverall S.D. (ignoring groups) was 3·96.

Predictors were compared in terms of precision and the stability of their prediction equations. Of the characteristics measured on the intact carcass, subjective scoring of external fatness gave the most precise prediction both within groups and overall (R.S.D.within = 2·82, B.S.D.overall = 3·17). Fat thickness over the eye muscle (0) was the best predictor among those taken on the quartered carcass (R.S.D.within = 2·76, R.S.D.overall =3·00). The most precise individual predictors were percentage lean in the best end neck and shoulder joints (R.S.D.within = 1·51 and 1·59 respectively). Among pairs of predictors not involving dissection, the combination of C and percentage kidney knob and channel fat in the side gave the most precise prediction (R.S.D.within = 2.51, R.S.D.overall = 2·68). The stability of the prediction equations between groups tended to increase with the precision of the predictors. Among the more precise predictors, the equation for percentage lean in the leg was a notable exception, being particularly variable from one group to another.

Measurements of O2 consumption (Vo2), CO2 production (VCO2) evaporative water loss and rectal temperature (Tr) have been made and metabolic heat production (H), evaporative heat loss (—E) and respiratory quotient (RQ) calculated with individual and groups of 1-day-old chicks at constant ambient temperatures (To) in the range 20—43 °C and 80 or 20% relative humidity (R.H.).

Minimal metabolism (10·7 kJ/kgJ/h) occurred at 35 °C.

One-day-old chicks act as heterotherms outside the zone of minimal metabolism since neither H nor —E are sufficiently developed mechanisms to maintain homeothermy.

Huddling allows chicks to maintain a higher TT at a lower H per unit metabolic body size.

Reducing E.H. from 80 to 20% raised the upper temperature survival limit (UTSL) from 41·5 to 43 °C.

Panting was initiated when Ta = 38 °C and Tr was between 39·5 and 39·9 °C.

Three buffalo calves and four Holstein x Hariana cross-bred calves of 4–6 months of age were fed for 21 weeks either on a normal protein ration according to National Research Council (1966) standard or 25% below or above it. The scheme of feeding was as follows:

Blood urea was determined every week from 6th to 21st week except in 10th, 14th and 15th week. When the animals attained the age of 15–17 months, their blood urea was again determined.

Blood urea of buffalo calves was found to be significantly higher than that of cow calves under similar conditions of feeding from 4 to 11 months of age. This difference disappeared at 15–17 months of age. Probable causes for this difference between species are discussed. Blood urea in both species tended to increase on high protein and decrease on low protein rations.

The effect of soil salinity (ECe range 2–9 mmhos/cm) on the growth of and ion uptake by barley, sugar beet and broad beans (crops increasingly sensitive to salinity) was investigated in a glasshouse experiment.

Barley and sugar-beet yields benefited from the added Na in the soil but broad beans were always adversely affected. Changes in growth and ion uptake are discussed in terms of Na:K synergism and antagonism.

Sodium:potassium antagonism was observed in barley just after germination, and in sugar beet throughout growth, but not in barley at other growth stages nor in broad beans. Greater Na uptake promoted increases in dry-matter yields of all plant parts with barley and sugar beet, indicating that Na played a specific role in their metabolism. In sugar-beet roots, sugar concentrations and dry-matter yields increased with added Na by half as much more than without added Na, suggesting that Na is an essential nutrient.

We conclude from our experiments that the effects of salinity caused by Na salts when water is not limiting, is related not only to plant species but also to their stages of growth.

Dry matter and Kjeldahl nitrogen estimations were made on the roots and shoots of the barley varieties Riso 1508, Hiproly and Maris Mink from the seedling stage to maturity under three nitrogen treatments. After heading, the shoots were further separated into ears and stems plus leaves. Total plant nitrogen uptake was greatest in the high lysine variety Riso 1508 and was associated with a greater production of dry matter. However, the proportion of total plant nitrogen and dry matter in the grain was highest in the variety Maris Mink and this effect increased with increasing nitrogen supply. The comparative efficiency of dry-matter production and nitrogen translocation of these varieties is discussed in relation to breeding barley of improved protein yield and quality.

The results of experiments in which Navy beans (cv. Purley King) were precision drilled at the beginning, middle and end of May in 1972, 1973 and 1974 suggest that the optimum time to sow is mid-May when soil temperatures at 10 cm depth have reached 12–13 °C. Earlier sowing usually led to a reduced plant stand and low yields whilst in 1972 and 1974, two exceptionally cool years, later sowing resulted in lower yields following a reduction in 1000-seed weight.

Despite contrasting weather conditions acceptable yields of seed were obtained in all 3 years from mid-May sowings although cool wet conditions in the autumn of 1974 curtailed drying of the seeds below 30% moisture content. Accumulated temperatures (Ontario units) were successfully used to predict stages in crop development and the data used to demarcate the areas in England most suitable for Navy-bean production.

The experiment described was carried out to compare the effects of some combinations of dietary ingredients which were within the bounds of current commercial use but which differed in their lipid characteristics.

The four dietary treatments used were either low or high in lipid content with a high or low proportion of unsaturated fatty acids in that lipid. Fourteen pigs (seven gilts and seven barrows) were assigned at random to each dietary treatment. The major dietary constituents were barley × wheat × dried skim milk (treatment 1), barley × wheat × soyabean meal (treatment 2), barley + wheat + dried skim milk × tallow (treatment 3) and barley × wheat × maize × fish meal (treatment 4).

Production performances were satisfactory on treatments 1, 3 and 4. The pigs on treatment 2 ate less food, grew more slowly, had poorer feed conversion ratios and fatter carcasses than the animals on the other treatments; the reason for the poor performance on this diet is not clear.

Comparison of the fatty acid compositions of the backfat triglycerides and the dietary lipid shows that the dietary lipid had little effect on the backfat lipid characteristics; only in the case of linoleic acid was there a dietary-induced effect on the amount of this fatty acid in the backfat triglycerides of pigs on treatment 4.

Treatment 4 which produced the backfat with the greatest linoleic acid content also produced the softest backfat. The subjective fat scores of the carcasses of pigs fed the other diets were not related to the fatty acid compositions of the backfat triglycerides or the monoene/saturated fatty acid ratio.

These results are discussed in relation to the effects of diet and triglyceride structure on pig backfat lipid characteristics.

Lettuce obeys the Shinozaki–Kira relationship in which the reciprocal of plant weight is linearly related to plant density. The intercept (a) represents the reciprocal of the weight of an isolated plant and the slope (b) represents the reciprocal of yield/unit area at high densities (the ‘ceiling yield’). This work examines the time course of (a) and (b) in an ‘ideal environment’ in which water and nutrients are non-limiting, and the light/temperature regime is constant.

Two pot experiments are described: the first showed that the growth of isolated lettuces follows a logistic expression, which can therefore be substituted for a–1 in the Shinozaki-Kira equation. It was then hypothesized that b–1, the ‘ceiling yield’ would be constant over time. This was confirmed by the second experiment, giving the equation

w–1t = w–10 e1–kt × w–1max × bd,

in which wt is mean plant weight at time t, w0 and wmax are the initial and final weights of isolated plants, k is the early relative growth rate of such plants, b–1 is the constant ceiling yield, and d is the plant density.

Two examples of the use of the equation are given: one shows how it predicts the interaction between seed size and plant density within a species (subterranean clover): the other illustrates how it can be used to explain why lettuce growth appears to be log-linear against time whereas cereal growth is more nearly just linear.

Soils from 55 maize fields in southern and eastern England were tested for available zinc, copper, magnesium and potassium by routine extraction procedures. A high proportion (64%) of the samples contained less than the recommended 50 mg/kg available magnesium, and 24% were within the deficiency range (< 25 mg/kg) for this element. Fewer sites were deficient in copper (7%) and zinc (5%) and these were mainly sandy soils or loams developed on Clay-with-Flints over Chalk. Zinc deficiency in maize does not appear to be a serious potential problem in Britain even though it occurs frequently in other countries, including parts of France.

A field of maize with growth problems of varying severity was studied in detail and the available magnesium concentrations found to correlate most closely with the degree of stunting. Soils with healthy plants differed from those in stunted patches of the crop by having higher extractable magnesium, copper and potassium contents. In general the composition of the maize leaves tended to reflect the supply status of the soil, except in the case of chlorotic plants.

The influence of factors affecting the availability of the elements investigated and the significance of marginal deficiencies of magnesium and micronutrients in maize are discussed.

In this paper the method proposed by Jones & Sandland (1974) for testing the linearity of the animal gain–stocking rate relationship is examined. It is shown that the method cannot be used to establish such linearity. An examination of the biases in estimation of optimum stocking rate and gain per animal and per unit area at the optimum stocking rate arising out of assuming linearity where the true relationship was quadratic led to the following conclusions. Quite large biases can arise. Selection of stocking rates straddling the true optimum reduces these biases. If experimental stocking rates are lower than the true optimum stocking rate the optimum stocking rate is overestimated and the animal gain at optimum is underestimated and vice versa if the experimental stocking rates exceed the true optimum rate.

Twelve Finnish Landrace × Dorset Horn ewes with a mean litter size of 1·92 and a mean body weight of 75±3 kg were individually penned from 80 days of gestation to parturition and offered a diet with a metabolizable energy (ME) and crude protein content in the dry matter of 9·7 MJ/kg and 11·4% respectively. At 120 days of gestation daily ME intake was abruptly reduced from a mean of 0·48 to 0·25 MJ/kg W0·75 for a period of 10 days.

The observed increase in the plasma concentration of urea due to the reduction in food intake was better correlated with lamb birth weight (r = 0·87) than was the increase in plasma free fatty acid concentration (r = 0·53) or the decrease in plasma glucose concentration (r = 0·76). Mean daily nitrogen balance decreased from a mean of 5·6 g before food restriction to – 1·8 g after food restriction. Although the effect was not significant, single bearing ewes excreted more total and urea nitrogen in the urine than multiple bearing ewes before food restriction. During food restriction the trend was reversed. The change in urea nitrogen excretion (Y, g/day) that resulted from the reduction in food intake was correlated (r = 0·73, P < 0·01) with lamb birth weight (X, kg); the relationship was Y = 0·54(±0·16)X – 3·48. It was estimated that the daily loss of nitrogen from the maternal body during the period of food restriction was approximately 80% of published values for the urinary nitrogen excretion of fasting non-pregnant sheep.

The residues from a continuous millet–maize rotation, grown at two levels of phosphate and two levels of nitrogen fertilization, were either burned and the ash incorporated; chopped and incorporated unburned; or completely removed. After 3 years, differences in soil organic matter were small and largely non-significant, but the ash treatment had minimized the general fall in soil pH, and the ash and the unburned residue treatments had both conserved topsoil exchangeable K and Mg, which, where the residues had been removed, had declined by 44 and 12%, respectively. Fertilizer effects were also significant; single superphosphate had increased exchangeable Ca and lessened the fall in soil pH; calcium ammonium nitrate had depleted exchangeable Mg generally and had lowered pH and exchangeable Ca particularly where unburned residues had been returned.

A balance sheet of soil cations (0–30 cm), drawn up from soil and crop analyses and known fertilizer inputs shows, first, that whereas the calcium added in single superphosphate increased the exchangeable reserves of this nutrient, that added as calcium ammonium nitrate did not and must be presumed lost by leaching; secondly, the decline in exchangeable K where residues were removed was much less than the total crop removal, indicating a probable substantial release from non-exchangeable form.

In the fourth season, treatment-induced soil differences, in particular the ratios between exchangeable cations, significantly affected the chemical composition of the maize test crop but not its final yield.

Although the administration of pregnant mares' serum gonadotrophin (PMSG) to induce superovulation is a well established procedure (see Anderson, Schultz & Melampny, 1963), the unpredictability of the response to this treatment continues to impose a constraint on the commercial application of egg transfer techniques in the large domestic animals. In sheep, the additional use of human chorionic gonadotrophin (HCG) has been mainly centred on attempts to control the time of ovulation (Ortavant, Thibault & Wintenberger, 1949; Braden, Lamond & Radford, 1960; Dziuk et al. 1964; McGovern, Williams & Hancock, 1969). However, Killeen & Moore (1970) found that the proportion of follicles which rupture was increased in PMSG-treated ewes which had been given HCG at the beginning of oestrus. The purpose of the observations recorded here was to examine the possibility that a further gain in ovulation rate in PMSG-treated sheep might be obtained with the use of luteinizing hormone releasing factor (LHRF). No attempt was made to reproduce physiological levels of the releasing factor and dosage was aimed at achieving a superovulatory effect.

The grazing feed intake of four ¾ Brahman and four purebred Hereford steers was measured on four occasions during 12 months while they grazed improved pastures in a cool temperate environment. When pen fed roughage diets, the excretion pattern of chromic oxide and faecal nitrogen–digestibility relationships were also investigated in these animals.

There were no breed differences in the relative recovery of Cr2O3 in the faeces when bulking 10.00 and 17.00 h samples nor were there breed differences in the faecal nitrogen–digestibility regression obtained. However, although there were large discrepancies between feed intake and live-weight change when measured in different seasons, the Herefords had the higher feed intake on each occasion while breed differences in live-weight change were non-significant.

MCPA and 2,4-D sprays at up to 1/20 the dosage normally vised for weed control in cereals severely distorted sugar beet, which subsequently grew at near normal rate but remained distorted. The severity of symptoms and yield depression depended on the stage of growth of the beet when sprayed. Sugar-yield loss was greatest when plants were sprayed at the 6–8 leaf stage.

Penned Romney wether sheep were fed ad libitum diets of untreated silage and hay made from the same pasture (Expt 1), untreated silage (Expt 2), and high quality fresh pasture (Expt 3). Voluntary intake and wool growth were measured. In each experiment half of the sheep were given intraperitoneal injections three times per week which supplied the equivalent of 1·03 g DL-methionine/day.

Relative to silage in Expt 1, hay increased voluntary dry matter intake, depressed apparent nitrogen digestibility and increased wool growth. Methionine supplementation increased voluntary intake and wool growth with animals fed on hay or silage in Expt 1 and with those fed on silage in Expt 2, but had no effect on either variate with the diet of fresh pasture.

Wool sulphur content, measured in Expts 2 and 3, was increased by methionine supplementation, and it was calculated that 34 and 15% respectively of the sulphur administered as methionine was recovered in the wool.

The effects produced by methionine supplementation in this work are compared with those produced from different forms of post-ruminal amino acid supplementation in sheep fed a variety of diets. Factorial estimates of the requirements for sulphur of sheep and cattle in different physiological states have been calculated, and are discussed in relation to results of trials involving supplementation with sulphur-containing amino acids.

Gas liquid chromatography was used to investigate the influence of several T, S and unclassified cytoplasms on the fatty acid composition of oil from A632 and CrS4HLA maize seeds. The fatty acid compositions of the A632 and CrS4HLA seeds differed markedly from each other with respect to oleic and linoleic acids but were stable within each seed line with respect to all sixteen of the cytoplasms tested.