Data representing 1928 lambing records were analysed to study the effects of inbreeding and cross-breeding on lamb survival to the ages of 7, 30, 120 and 180 days. The sheep flock consisted of two native breeds, Barki (B) and Rahmani (R); and the imported Fleisch Merino (M) as well as the crosses M × B and M × MB. Analysis was made by fitting a least-squares linear model that included the main effects of year and season of birth, sex, age of dam, type of birth, inbreeding of the lamb (Fd) and the dam (Fd) and breed group and the interactions season × type of birth, season × Fo and season × breed group. Lambs were classified into six groups according to the magnitude of the inbreeding coefficient: F ≤ 0·05, 0·05 < F ≤S 0·10, 0·10 < F ≤ 0·15, 0·15 < F ≤ 0·20, 0·20 < F ≤ 0·25 and F > 0·25. The average inbreeding coefficient in the flock was 0·12 and 0·08 For the lambs and their dams, respectively.

Sex of lamb and age of dam had no significant effect on lamb survival at any age while single-born lambs had a higher (P < 0·01 or P < 0·05) survival than twins at all ages except 7 days. Inbreeding of the lambs showed significant effect at 7 and 120 days. Increase in inbreeding of the dams was associated with higher mortality at all ages but the trend was not significant.

Differences among breed groups were not significant at 7 and 30 days, but were highly significant at later ages. The contribution of breed group to the total variance in survival increased with age. Hybrid vigour was highly significant in both crosses at 120 and 180 days.

The loss of potassium through the cutaneous route was measured in three Chokla rams by balance trial and by washing the animals (ambient temperature 28–33 °C, 28–30 mmHg vapour pressure). The excretion of potassium through urine and faeces was 46·7 and 19·4% of the intake, respectively. The excretion through skin recorded by washing the animals was 29·1% against 33·7% potassium available for excretion through the thermoregulatory route. About 2·56 g potassium was thus excreted through the cutaneous route per day. There was a net retention of 9·8 g sodium/ram/day.

Two indigenous breeds of sheep in Nigeria, the Yankasa and Uda and crosses of these with exotic breeds, were evaluated for lamb weights at birth, 3 months and 6 months of age and for adult ewe weight. The cross-bred lambs were significantly (P < 0·05) heavier than the indigenous breeds at all ages. Differences among the indigenous breeds were not significant. Mature ewe weight was 40·8 kg in the cross-bred and 36·0 and 31·1 kg in the Uda and Yankasa respectively, differences between all breeds being significant (P <0·05). Lamb productivity (lamb weight per kg of ewe metabolic body weight) estimates demonstrated that the differences between breeds were small.

Least-squares estimates of effects of environmental factors on lamb performance showed that type of birth and age of dam were important for lamb weights at the three ages. Season and sex also had significant effects on birth and 6-month weights respectively. Correction factors for lamb weights were derived from least-squares estimates.

The correlation coefficient between birth and 3-month weight was significant in all breeds and ranged from 0·39 to 0·55. Three-month and 6-month weights were highly correlated with estimates of correlation coefficients ranging from 0·71 to 0·74. Repeatability estimates of birth, 3·month, 6·month and ewe weights, all as traits of the ewe in the Yankasa, were 0·25, 0·21, 0·09 and 0·48, respectively.

Hofuf-Alhassa is one of the important agricultural areas of the Kingdom of Saudi Arabia. The water available for irrigation purposes is limited in quantity and saline in nature.

To maximize the use of available water sources, a technique is described to mix irrigation water with drainage water, taking into consideration the salt balance effect in the soil under the Alhassa conditions.

Since 1966 a closed line of Hereford × Shorthorn cattle (selected line) has been selected principally for growth rate under conditions of moderate to high environmental stress. Responses in growth rate were measured over the years 1970–5 as differences from an unselected control line. Birth weight declined but live weight at all other ages increased.

Groups of animals were taken from each line in 1976 and 1977 and used to determine the reasons for the differences in growth rate. Growth rate of the groups was measured when they were exposed to several different levels of stress, namely, the plane of nutrition, high ambient temperature, infection with bovine infectious keratoconjunctivitis(BIK) or gastro-intestinal helminths. The selected line was shown to be more heat tolerant, to have lower maintenance requirements and greater resistance to infection with BIK and helminths and, in consequence, always had higher growth rates in the presence of these stresses. However, they did not have superior growth rate at low levels of these stresses. Thus, selection had not increased the components associated with growth potential, and the improvement in growth rate was achieved entirely through increases in resistance to environmental stresses which affected growth rate.

The application of these findings to selection for growth rate, particularly in harsh environments, is discussed.

Observations were made on high resolution radiographs of foetal sheep, from ewes slaughtered at 7-day intervals from 34 to 55 days after mating, to examine the onset of ossification of some of the major components of the axial and appendicular skeleton. There were 83 foetuses measured, retrieved from 24 Finnish Landrace × Polled Dorset Horn ewes mated to Suffolk rams. The litters comprised five sets of twins, eight of triplets, seven of quadruplets, three of quintuplets and one set of sextuplets.

Half of the ewes were subjected to a 50% reduction in food on the 28th day of gestation, but this was considered not to have affected skeletal growth and development.

There were major changes in skeletal mineralization from one slaughter date to the next, particularly between 34 days, when no skeletal elements were detectable, and 41 days, when components of the skull, thorax, fore and hindlimbs were clearly seen. There were some differences in the number of primary centres present both within and between litters of the same gestational age. The mineralized shaft of the fibula was seen in 30/35 of the foetuses at 41 days, but only in 9/25 at 55 days; other transient centres were also observed.

Changes in the linear dimensions of six limb bones were measured and the mean values are presented in tabular form.

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.

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.

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.

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.

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.

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.

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.

The growth and mortality of red deer hinds from 3 months of age were analysed using data from a farmed stock. Calf mortality from 3 to 15 months of age was 11 % and was highest in the 2 months immediately after weaning. Mortality in the 8 years subsequent to the hinds reaching 15 months was low and based on 924 yearly records of survival was 1·8% per annum.

The rate of growth of the calves during their first winter was markedly affected by the amount of feed given and slightly (though highly significantly) greater for the larger calves. In the subsequent summer there was no effect of weaning weight on gain. This varied considerably from year to year.

The subsequent growth of the hinds showed that an equilibrium weight of about 82 kg was achieved, and that body weight at the beginning of the year, age, and whether or not the hind produced a calf, all affected the increase in body weight during a particular year.

The results are combined to estimate the effects of culling the hind stock at different ages on the number of surplus female calves and the effects on lifetime reproductive performance of the body weight of hinds when 15 months of age. The latter can be predicted from weaning weight and winter feed intake provided gain from 10 to 15 months at pasture can be estimated. The partial effects of giving additional concentrated feed in the first winter were estimated and found to be appreciable.

Comparisons of the results are made with mortality rates and body weights estimated by others for wild populations.

Experiments started in 1976, 1977 and 1978 on Clay-with-Flints soil at Rothamsted tested the effects of combinations of eight two-level factors on spring-sown field beans. Factors tested, presence v. absence, were irrigation, nitrogen fertilizer, aldicarb, fonofos (dieldrin in 1976), benomyl to the seed bed, permethrin (fenitrothion in 1976), pirimicarb, benomyl foliar spray (not tested in 1976).

The main pests and diseases present were nematodes of the genus Pratylenchus, the pea aphid Acyrthosiphon pisum, the pea and bean weevil Sitona lineatus, root blackening associated with the fungal genera Pythium and Fusarium, the foliar diseases chocolate spot, Botrytis spp., rust, Uromyces fabae and bean leaf roll virus.

Incidence of these pests and diseases varied between years. Controlling those present increased yield by about 0·7 t grain/ha each year. The difficulty of apportioning this increase to particular pests and diseases is discussed.

Irrigation increased total dry-matter production and grain yield in 1976 and 1978 but only total dry-matter production in 1977, when grain yield was lost because of lodging. Nitrogen fertilizer had little or no effect.

The most favourable combinations of treatments gave yields of 3·4, 5·0 and 6·4 t grain/ha in the 3 years respectively. Small yields in 1976, despite irrigation, were attributed to premature senescence caused by exceptionally high temperatures. It is suggested that with good control of pests and diseases yields of at least 5 t/ha should be attainable on Clay-with-Flints soil without irrigation in years of average temperature and rainfall and yields in excess of 6 t/ha when the soil-moisture deficit is lessened by either above-average rainfall or irrigation.

Treatments applied to the beans had little or no effect on two following crops of winter wheat.

Skin biopsy samples from imported Merino and ⅝ Merino/⅜ Barki were examined from birth to the age of 1 year. Birthcoat fibre type arrays and fibre-follicle relationships were also studied.

Merino lambs had a greater S/P ratio than ⅝ Merino at all ages; values at 1 year of age were 9·98 and 6·87 respectively.

The ⅝ Merino lambs showed a wider range of follicle diameters than Merinos from birth to 1 year of age.

The ratio of primary to secondary follicle diameters showed higher values in ⅝ Merino than in Merinos. Merino gave lower values of follicle wall thickness than ⅝ Merino.

In Merino birthcoat samples, only one array was plain, representing 4%, whereas the rest were saddle. In ⅝ Merino the majority of fibre type arrays were plain, representing 75 %, whereas the rest were saddle and plateau.

In Merino, because of the absence of halo hairs and super sickles, only two samples had few super sickle B; primary central follicles were occupied by sickle fibres, medium with large sickle ends as well as curly tips, and primary lateral follicles had mostly medium and fine curly tips, only four samples had sickle fibres, and secondary follicles produced medium and fine curly tips and histerotrichs.

In ⅝ Merino primary central follicles produced halo hairs, super sickle A, A', B and occasionally sickle fibres, primary lateral follicles grew super sickle A, A', B, sickle fibres and curly tip fibres, and secondary follicles had medium and fine curly tips and histerotrichs.

Processed straw, both ground and ground–NaOH treated, has been compared with long straw in diets of straw and concentrates fed to yearling dairy heifers. Protein allowances were varied by the addition of fishmeal.

Improved growth rate was consistently observed with those animals receiving fishmeal. When a fixed amount of barley straw was offered neither digestibility nor growth was affected by the form of the straw. With wheat straw grinding–NaOH treatment resulted in increased growth when fed in diets containing some long roughage. Voluntary intake of straw was additively increased by grinding and by treatment with 5% (w/w) NaOH. Ground-NaOH treatment of straw increased in vitro digestibility.

The effects of water deficit on growth of spring barley were analysed under five irrigation treatments. One crop was irrigated at weekly intervals from emergence throughout the growing season, and one was not irrigated at all after emergence. Soil water deficits in the other treatments were allowed to develop early, intermediate or late in the crop's development.

Weekly irrigation produced a crop with a large leaf area index (maximum value 4) and maintained green leaf and awns throughout the grain-filling period. Early drought decreased leaf area index (maximum value 2) by slowing expansion of main-stem leaves and decreasing the number and growth of tiller leaves. Leaf senescence was also increased with drought. Drought late in the development of ears and leaves and during the grain-filling period caused leaves and awns to senesce so that the total photosynthetic areas decreased faster than with irrigation. Photosynthetic rate per unit leaf area was little affected by drought so total dry-matter production was most affected by differences in leaf area.

Early drought gave fewer tillers (550/m2) and fewer grains per ear (18) than did irrigation (760 tillers/m2 and 21 grains per ear). Late irrigation after drought increased the number of grains per ear slightly but not the number of ears/m2. Thus at the start of the grain-filling period crops which had suffered drought early had fewer grains than irrigated (9·5 and 18·8 × 103/m2 respectively) or crops which suffered drought later in development (14 × 103/m2).

During the first 2 weeks of filling, grains grew at almost the same rate in all treatments. Current assimilate supply was probably insufficient to provide this growth in crops which had suffered drought, and stem reserves were mobilized, as shown by the decrease in stem mass during the period. Grains filled for 8 days longer with irrigation and were heavier (36–38 mg) than without irrigation (29–30 mg). Drought throughout the grainfilling period after irrigation earlier in the season resulted in the smallest grains (29 mg).

Grain yield depended on the number of ears, the number of grains per ear and mass per grain. Early drought decreased tillering and tiller ear production and the number of grains that filled in each ear. Late drought affected grain size via the effects on photosynthetic surface area.

Drought decreased the concentrations of phosphorus, potassium and magnesium in the dry matter of crops, and irrigation after drought increased them. Concentration of nitrogen was little affected by treatment. Possible mechanisms by which water deficits and nutrient supply affect crop growth and yield are discussed.

The weights of 44 twin foetuses, 99 triplets and 44 quadruplets, varying in gestational age from 55 to 145 days, were studied in relation to age, sex, litter size, uterine position, placental structure and weight, and ovulation rate. Triplet and quadruplet foetuses were more variable in weight, within litters, than were twins. The difference increased with foetal age and was attributed to increased competition between foetuses which were located within the same horn of the uterus. The effect was largely associated with differences in placental development, i.e. numbers of cotyledons and weight, but those differences did not entirely account for the reduction in foetal weight with increasing litter size. Differences in placental development, arising from embryo mortality, also accounted for the reduction in foetal weight when ovulation rate exceeded litter size. In contrast, differences in foetal weight associated with the sex of the foetuses were only partly mediated by differences in cotyledon weight. Foetuses in the larger litters are thus not only lighter in weight but are more variable in weight, the increased variability being controlled by events in early pregnancy.

Two strains of commercial layers, 42 weeks old, were fed ad libitum, 85 and 70% of ad libitum for five 28-day periods to study the effects of feed restriction on body weight, carcass characteristics, laying performance and mortality. There were highly significant strain effects on all traits (P < 0·01) except dressing percentage. Period differences were also observed for egg production, egg weight and feed efficiency. In addition, in all cases the relationship between period and these traits was non-linear and was affected by strain or treatment.

Feed restriction had significant effects (P < 0·01) on all traits except dressing percentage and mortality. Feed restriction to 70% of ad libitum reduced egg production, egg weight, body weight and feed consumption and improved feed efficiency. However, in most cases there was no difference between ad libitum feeding and 15% feed restriction.

Strain × treatment interaction had significant effects on egg production and feed efficiency.