The growth, development, chemical composition and nutritive value of sunflower (cv. Fransol), was examined from the flower-bud (12 July) to milky-ripe seed (late September) stages. Dry-matter yield increased from 2·1 to 14·1 t/ha over the period. Drymatter content was low (100–110 g/kg) up to flowering, early in August, and then increased to 193 g/kg. Crude protein content declined after flowering and ether extract values were low throughout the period. Organic-matter digestibility in vitro and derived metabolizable energy values declined rapidly with the onset of flowering. Gross energy values, calculated from the proximate constituents, increased to 17·6 MJ/kg D.M. at the end of the period. Calcium to phosphorus ratios varied from 5·6 to 7·4:1.

Sunflower was cut and fed to eight Friesian heifers over 3 weeks from the onset of flowering. Average daily D.M. intake was 63·5 g/kg W0·76 and the organic-matter digestibility was 0·684. Average live-weight gain was 0·79 kg/day.

Fresh sunflower was successfully ensiled without an additive 2 weeks after flowering and the silage (pH 4·0) was fed to three cross-bred wethers in a feeding trial. The organic-matter digestibility was 0·649, the metabolizable energy 8·0 MJ/kg D.M. and the average D.M. intake 6·73 g/kg W0·75. In a metabolism trial, with four fistulated sheep, the organic-matter digestibility was 0·718, the metabolizable energy 9·4 MJ/kg D.M. and the D.M. intake 43·1 g/kg W0·75. Rumen pH decreased and total volatile fatty acid concentration increased markedly within 2 h of feeding the silage. Molar proportions of acetic and propionic acid (0·539 and 0·381), 1 h after feeding, were typical of cereal-based diets. Ammonia-nitrogen concentration increased to a maximum of 216 mg/1 within 2 h of feeding.

The good yield and animal performance from fresh sunflower make it a possible annual crop for zero-grazing in late summer in northern Britain. Satisfactory results from feeding sunflower silage suggest that the crop has potential for ensilage if the problem of effluent can be overcome.

The self-fertile cultivar of swede rape (Brassica napus) Maris Haplona does not usually autopollinate. The entomophilie pollen grains cannot be transferred by wind alone; anthers when flicked by insects or artificially under dry conditions behave like catapults raising a cloud of pollen grains.

Variability in the concentration of sugar in its two types of nectaries (within a single flower) may increase the range of visiting insects. All visiting insects, including honey bees, carried out pollination; it is suggested that beehives should be placed in fields of oil-seed rape in order to increase pollination.

Cold dehardening responses of seedlings of three cultivars of Lolium perenne L. (Premo, S.23 and Grasslands Ruanui) were studied in different temperature regimes following hardening at 2 °C. Seedlings of the three cultivars dehardened rapidly at 15 °C after partial hardening for 4 days, whereas there was a lag before dehardening occurred in seedlings of Premo and S.23 which were hardened for 28 days. At 10 °C dehardening did not occur in Premo and S.23 and occurred only slowly in Grasslands Ruanui. Alternating temperature regimes of 15 °C(day): 2 °C (night) gave increased levels of hardiness when the daily period of exposure to 15 °C was 8 h but only maintained the level of hardiness when it was extended to 16 h.

A tentative scheme of threshold temperatures for hardening and dehardening is proposed.

Mineral analyses for calcium and phosphorus were carried out on lambs which had been fed diets contrasting in protein or energy or calcium concentration and had been slaughtered at defined live weights. Despite considerable variation in rates of growth arising from the widely different nutritional programmes, the mineral content of these lambs at a given weight remained remarkably stable on practical diets.

In a field experiment on the effects of drought on spring barley, the crop was protected from rainfall by automatic rain shelters; a range of drought treatments was achieved by irrigating various plots according to a predetermined schedule. There were 12 treatments which ranged from no irrigation to full irrigation from emergence to harvest; results from seven treatments are discussed in this paper.

The rate of water uptake was determined for four soil horizons centred at 0·15, 0·50, 0·80 and 1·10 m. For all treatments, the rate of uptake in each horizon decreased as the soil dried, and although there were large differences in root density between horizons, maximum rates of uptake were similar in all horizons down to 0·80 m. Treatment effects showed that prolonged drought decreased the rate of uptake from the 0·80 and 1·10 m horizons: root density at and below 1·0 m probably differed between treatments.

Differences between treatments in leaf water potential (ψL) and osmotic potential (πL) were small, and there was no evidence that osmotic adjustment contributed to the drought response of this crop. Near anthesis, pre-dawn ψL was near zero for irrigated treatments and between – 3 and – 5 bar for unirrigated. During the day, ψL decreased to a minimum of – 15 to – 18 bar for irrigated plants, and was generally 3 bar lower for unirrigated. For all treatments, ψL was greater than π for the major part of the day, i.e. positive turgor was maintained; however, turgor was usually greater for irrigated than for unirrigated plants. The relationship, for leaf 8, between ψL and transpiration flux density was markedly non-linear, and was of a similar form for irrigated and vinirrigated plants. As the form of this relationship was independent of treatment, the non-linearity could not have been caused by variations in soil water potential through the profile.

Stomatal resistance differed markedly between treatments. A detailed analysis is presented, relating measured resistance for leaf 8 to ψL and to environmental variables: irradiance (I), water vapour pressure deficit (vpd), and temperature (T). The analysis showed no significant dependence of resistance on ψL or T, but marked dependence on I and vpd; a mathematical model combining a hyperbolic response function for I and an exponential function for vpd fitted the data well. The responses of abaxial and adaxial surface resistances to vpd were similar, but their light responses differed because of their different exposures to incident irradiance.

Field beans (Vicia faba L.) were given three irrigation treatments in the field during two seasons to examine reduction in leaf area by water shortage, through effects on number of cells, cell volume and cell arrangement.

The two crops behaved differently in the two seasons, presumably because of differences in environmental conditions. Season 1976 was brighter, warmer and drier than 1977. Water shortage reduced leaf area, dry matter and economic yield. The rate of leaf appearance and leaf longevity were also decreased by water shortage. The greatest biological and economic yields were produced by the wet treatment, followed by the medium and dry treatments. The treatment open to natural rainfall yielded least in 1976, but the second most in 1977. The yields of 1976 were considerably less than those of 1977.

The reciprocal relationship commonly used in the analysis of plant yield-density relationships in monoculture is extended to allow a similar treatment of binary mixtures, using the model:

w–1a = Aa × Baapa × Babpb

where wa is the plant weight of component a in mixture with component b, and pa and pb are the plant densities of a and b respectively. The model gives a good fit to fresh weights taken from a glasshouse experiment involving monocultures and mixtures of red clover (T. pratense L.) and Italian ryegrass (L. multiflorum L.) in different proportions, all grown at a range of plant densities. The interpretive and predictive uses of the model are discussed.

In one experiment during 1972 and 1973 five irrigation regimes of every 4, 6, 8 and 10 days and according to stomatal opening, as estimated by the infiltration method, were compared, using an early-maturing variety Zankawa and a late-maturing variety G51. In both experiments early crop growth was checked by the shortest and the longest irrigation intervals.

Late growth, on the other hand, was promoted by the shortest intervals in both seasons. Thus the highest yield in 1972 was obtained from the 4–day regime, followed by the infiltration method, then progressively greater yields with shorter intervals. In 1973, however, the shortest interval resulted in the lowest yield, which was significantly less than the other treatments, which showed a similar trend to those of 1972.

In a second experiment during 1974 and 1975 a medium-maturing variety 22/9/1 and a late–maturing variety 44/E were added to those of the previous experiment. Watering every 4 and 6 days were eliminated and watering every 12 days added, during the early growth period. Each of these regimes was given irrigation every 6, 8, 10 and 12 days during the late growth period. The early-maturing varieties yielded best when irrigated every 12 days in the early stages, and every 10 days in the late stages, whereas the late-maturing varieties yielded best when irrigated every 10–2 and 8 days in the early and late stages of growth, respectively.

The mineral content of N, P and K in leaves, stems, roots and seed of field beans, subjected to four watering regimes were compared in 1976 and 1977, and of a foliar nutrient spray in the latter year.

N, P and K content increased in all treatments with the increase in plant size and then declined at about the time of podding and death of the leaves.

Water shortage reduced the amounts of N, P and K throughout the growth period and for the seed at final harvest; the decrease was more pronounced in 1976 than in 1977. The plants under stress conditions benefited from the foliar nutrient spray more than the unstressed plants.

Carcass characteristics were studied in young red deer raised on a Scottish hill farm with heather·dominant pasture. Stags slaughtered in September when 15 or 27 months old were very lean, and entire and castrate animals were similar in weight. At 15 months they were barely a half of their expected mature weight. With no pre-slaughter fasting, dressed carcass weight was 49–51% of live weight. A more detailed analysis of carcass conformation was made in a study of entire stags, castrate stags and hinds slaughtered when 15 months old after being held overnight without food or water. The three groups were similar in that their dressed carcasses weighed about 52% of live weight and the content of first class lean meat amounted to 32% of live weight. There was only 4·5% of chemical fat in the empty carcass.

The pH of the meat 36 h post mortem often remained high in the stag groups, relative to a mean value of pH 5·7 found in shot wild stags. This high-pH character was little affected by the severity of stress immediately before slaughter, nor by the availability of food. It seemed to be caused by holding the animals in unfamiliar surroundings for some 16 h before slaughter.

Nuclear staining with acridine orange was used to study death of the root cortex of winter wheat grown after grass and non-graminaceous break crops in a field trial site in 1978. The top 5·4 cm of first seminal root axes had several anucleate cortical cell layers by late-February, and nearly five dead cell layers (of a maximum six) by mid-April. One of the next pair of roots to emerge (designated ‘2’) showed similar cortical death, but one of the subsequent pair (designated ‘4“)showed substantially less death at these times.

Significantly more root cortex death was seen in first to third wheat crops after 1 or 2 years of grass than after swedes-potatoes, and in one replicate block compared with the other in the trial. But there was no significant difference in cortical death between first, second, third and 16th successive wheat crops.

Root cortex death could not be attributed to infection by Gaeumannomyces graminis, Phialophora radicicola var. graminicola or the nematode Rotylenchus robustus. But its implications for root–infecting parasites are considered and, in particular, the enhanced cortical death in some crops compared with others may help to explain the reported differences in infection of wheat by P. radicicola var. graminicola, a biological control agent of take-all.

Experiments to determine the effects of a range of applied lime and phosphate treatments on the establishment of species and the subsequent herbage production in the first and second seasons following sowing on four sites in the Falkland Islands are described and the results discussed.

Festuca rubra, Dactylis glomerata, Phleum pratense and Poa pratensis established, successfully yielding up to 4·5 t D.M./ha per year with inputs of 55 kg N, 50 kg P and 20 kg K/ha. Applied P increased the yield of herbage and produced a small, though significant, increase in P status of the soil.

The lowest level of applied lime (0·63 t/ha) increased the soil pH to 5·0 and although this did not affect the yield or botanical composition of the grass component of the sward it did affect the presence and nodulation of white clover.

The problems of establishing white clover are presented in view of the severe limitations on the use of lime and fertilizer in the Islands. The implications of grazing this improved pasture are discussed in relation to increased pasture production and improved soil fertility.

Four mature castrate Malawi goats, mean live weight 29·66 kg, were offered diets of poor quality Rhodes grass hay, or hay plus a concentrate comprising either maize bran or maize bran-cotton seed cake mixed in varying proportions, so that N intake varied from 4·76 to 20·81 g/day in a series of four metabolism trials.

By extrapolation metabolic faecal N loss was estimated to be 9·94 g/kg faecal D.M. and that of endogenous urinary N to be 0·121 g/kg W0·75. The daily maintenance requirement for nitrogen was shown by a factorial method to be 0·682 gN/kg W0·75, and by use of regression equations to be 0·688 g N/kg W0·75 or 0·314 g apparent digestible N/kg W0·75. The mean daily requirement was 8·8 g N, with a mean apparent digestibility of N of 43·4%, and a true digestibility of 80·0%.

Four lactating Friesian cows with cannulae in the rumen and in the proximal duodenum were subjected to each of four different dietary treatments. Treatments differed with respect to concentration of crude protein, supply of urea nitrogen and frequency of feeding. The rations used consisted of hay, maize silage and concentrates and were offered to the animals according to milk yield.

During the last 5 days of each experimental period (5 weeks), ingesta flow at the proximal duodenum was estimated by Cr-EDTA. Samples were taken from the duodenum at 2 h intervals and were analysed for thiamin, total nitrogen and microbial nitrogen. Labelling of microbial N was achieved by continuous infusion of 16N-urea into the rumen.

With treatment 2 (26% less N than with treatment 1) thiamin net synthesis in the forestomachs and total thiamin entering the duodenum were significantly reduced whereas treatment 3 (substitution of 26% plant N by urea-N) and treatment 4 (six times instead of twice feeding daily) had no effect on synthesis and flow of thiamin to the small intestines. There were significant linear regressions between flow of microbial N and flow of thiamin to the duodenum and between organic matter digested and flow of thiamin.

Soil fauna of irrigated olive and vine farms and a rain-fed farm at the Egyptian western desert were surveyed and analysed between September 1977 and August 1978. In samples from these farms, Collembola and Acari constituted the highest fraction of total arthropod fauna while Aranea, Myriapoda, Crustacea, and Pseudoscorpionida comprised the lowest fractions. Populations of annelids and nematodes differed from one farm to another. The study revealed that plant cover, irrigation system, human interference and the physical and chemical properties exerted a considerable effect on the number and type of soil fauna components at each farm.

A study was made to determine the effects of feeding, arginine injection (0·5 g/kg live weight) and insulin injection (0·5 i.u./kg live weight) on plasma insulin, prolactin and glucose concentrations in ten growing castrated male lambs. The effect of feeding on thyroxine concentrations was also determined. Each test was performed once in each of four periods which commenced at 84, 98, 113 and 127 days of age respectively.

Feeding stimulated the release of insulin and this response was larger during period 4 than period 1. The release of prolactin following feeding did not change with age. Thyroxine concentrations, which were generally higher in periods 1 and 2 than 3 or 4, decreased from 1 to 12 h after feeding.

Arginine injection stimulated a similar insulin response in lambs of all ages but the prolactin release following arginine injection diminished with age.

Insulin injection caused marked hypoglycaemia in all periods, followed by dramatic increase in prolactin concentrations which increased with age.

Data on 902 ewes (1755 records) bom over 7 years in the synthetic ABRO Dam Line were analysed by least squares. Reproductive traits of the ewe were not affected by whether she was a single or a twin or by the age of her dam. Ewe age had major effects on all reproductive traits. Litter weight traits were affected by the sex distribution and the age of the litter when weighed.

Heritability estimates, both by half sib and regression methods, were low for litter size, low to moderate for litter weights, and higher for ewe and fleece weights. Genetic correlations among the litter-weight traits were high. Together with the heritability estimates, they indicated that selection on litter weight at birth (and perhaps other traits) might give a greater change in total litter weight at weaning, the main measure of ewe productivity and the objective in improvement, than would direct selection.

Over three grazing seasons a sward of perennial ryegrass, cv. Gremie, was grazed on a rotational paddock system by growing beef cattle weighing on average 185·5 kg when turned out to grass in April. Six grazing treatments were compared: grazing at 20- or 35-day intervals at each of three herbage allowances of 5·3, 4·3 and 3·3 kg grass D.M./100 kg live weight (4·0, 3·2 and 2·4 kg D.M./IOO kg live weight in the 1st year).

Measurements of net herbage accumulation and herbage consumption throughout each grazing season were made by taking grass sampling clips to ground level before and after grazing. Animal live-weight gain was assessed by regression on weighings of stock taken either every 7 or every 4 days depending on regrowth interval treatment. Adjustment of allocation treatment was made by varying the weight of stock grazing on a fixed paddock area.

In no year did annual net herbage organic-matter accumulation (NHA) differ significantly according to length of grazing interval. NHA showed a 4·7 % advantage for the longer interval in the first 2 years which changed to a deficit of 4·1 % in the final year of the experiment. Herbage allowance treatment produced no significant effect on NHA in any year. The interaction effect of herbage allowance and grazing interval was not significant.

Herbage consumption was greater in 2 years out of three under the 20-day regrowth period than with the 35-day treatment, although average degree of defoliation was slightly greater (44·0 v. 38·4%) with the longer interval.

Animal live-weight gain was significantly (P < 0·05) affected by herbage allowance in all 3 years; decreasing herbage allowance generally resulted in reduced live-weight gain. Only in 1 year was there a significant difference (P < 0·001) in live-weight gain with the different rotation length treatments.

A blood sample was taken at each hourly interval between 07.00 and 16.00 h on five consecutive days from each of two groups of five lactating and two groups of five nonlactating cows. The sampling was organized so that each cow was sampled twice daily and once at each time of day. Samples were analysed for blood glucose and haemoglobin, serum urea, inorganic phosphate, Ca, Mg, Na, K, total protein, albumin, Fe and Cu and plasma β-hydroxybutyrate. The sources of variation in the concentration of each constituent were determined.

Definite patterns of changes in concentrations with time of day were observed for β-hydroxybutyrate, urea, Ca, Na, Mg and Cu. In lactating cows there was a 2½-fold increase in the concentration of β-hydroxybutyrate from the lowest at 07.00 to the highest at 11.00 h. Variation in the concentrations of the other constituents with time of day was a relatively small proportion of the total variance.

It was concluded that diurnal variation in blood composition was unlikely to be a major source of error in interpretation for the usual constituents of a metabolic profile test. However, if β-hydroxybutyrate were to be included great care would be required in selecting a time for sampling.

In an initial experiment four mature sheep were injected with saline or 25, 75 or 150 m units bovine thyroid stimulating hormone (TSH)/kg live weight. All doses of TSH stimulated a similar release of thyroxine.

In a second experiment ten lambs were fed chopped dried grass from weaning until 108 days old (period 1). Five of the lambs (group 1) were then fed 30% barley: 70% grass until 178 days of age; the remaining lambs (group 2) continued to receive grass (period 2). After 178 days group 1 was fed 70% barley: 30% grass and group 2 30% barley: 70% grass (period 3). All lambs were injected with 25 m units TSH/kg live weight at 105–108 days of age, 174–178 days and 220–227 days. The thyroxine response to TSH was greatest in lambs fed 30% barley: 70% grass in periods 2 and 3. Plasma insulin and glucose concentrations tended to decrease after TSH.