Experiments made with winter fodder crops, lucerne (Medicago sativa), berseem (Trifolium alexandrinum) and oats (Avena sativa) and summer fodder crops, cow pea (Vigna unguiculata), guar (Cyamopsis tetragonoloba), sunhemp (Crotolaria juncea) and pearl millet (Pennisetum americanum) showed that a sequential crop of Sudan grass yielded more after the legumes than after the cereal fodders, oats or pearl millet. The legume advantage was noted in the crop not given fertilizers but also when Sudan grass was given N fertilizer. The yield increase in Sudan grass grown after legumes was equivalent to 32–60 kg fertilizer N/ha applied to Sudan grass following pearl millet.

After harvesting the legumes more available N and NO3-N was present in the soil and the apparent recovery of fertilizer N by a subsequent crop was increased by the legume.

Six experiments which compared a range of contrasting varieties are reported. Two experiments were at a very early, coastal site in N. Pembrokeshire (Trefin), two at a site in South Pembrokeshire (Trefloyne) and two at a coastal site in N. Norfolk (Brancaster). No variety was in every experiment but several were in the majority of experiments. In some experiments sprout growth was manipulated by control of storage temperatures. A variety classified as early or second early produced the highest yields in all experiments but the yields of the best maincrop varieties were high and substantially better than many early varieties. The highest-yielding variety at the first harvest maintained this advantage throughout June and July. At two sites (Trefin and Brancaster) the highest-yielding variety was consistent from year to year but overall the ranking order of varieties for yields was inconsistent, e.g. Arran Comet was the highest-yielding variety at Trefin in both years and one of the lowest yielding at Brancaster.

The results suggest that it is unwise to attempt to rank varieties for early yields by an overall score. The maturity classification of varieties is not necessarily an accurate guide to the utility of a variety. A consideration of the physiological age of the seed and growing conditions provided some explanation of these effects and their implication for breeding are discussed.

Measurements of foetal head diameter (HD) and trunk diameter (TD) were made using ultrasonic scanning of 11 pregnant llamas (Lama glama). Each llama was scanned fortnightly to obtain measurements of HD and TD from c. 84–271 and 65–168 days since mating respectively. There were approximate linear relationships between TD and days after mating and between HD and the logarithm of days after mating.

Calibration equations for predicting the number of days after mating (d) from foetal measurements constructed using (i) the inverse method in which d is regressed on HD or TD and (ii) the classical method in which HD or TD are regressed on d. These calibration methods were assessed by crossvalidation, treating each animal in turn as the individual for which predictions were required. Analysis of the prediction errors showed bias in the classical method, which consistently underestimated d at low values. A components of variance analysis indicated substantial variation between individuals which must be taken into account in calculating standard errors of prediction (S.E.P.) and confidence intervals. S.E.P. of d from TD can be reduced from 12·5 to 10·4 days by increasing the number of observations on an individual from one to four at fortnightly intervals. For prediction from HD, the equivalent figures are size dependent: examples are from 8·3 to 5·6 days, and from 26 to 18 days, for HDs of 2 and 6 cm respectively. The effect of small positive correlations between residuals of successive fortnightly measurements on the same llamas had a negligible effect on S.E.P.S, increasing them by c. 0·2 days. Ultrasonic scanning is suitable for determination of stage of pregnancy of llamas providing S.E.P.S which are small in relation to their long gestation period (335–360 days).

Acquisition of high-yielding stable cultivars, a major target for breeding, is achievable by repeated trials across different locations and seasons. The hypothesis is whether evaluation of sowing date and season could be used to assess yield stability for tropical soybean, a photoperiod-sensitive plant. Determinate growth cultivars BRSOY-1, BRSOY-2, BRSOY-3, BRSOY-4, BRSOY-5, BRSOY-6, BRSOY-7, BRSOY-8 and BRSOY-9, of early, mid-cycle and late maturity, were tested at six sowing dates in three growing seasons (2005–2008), in Planaltina, DF Brazil. Data on degree days to first flower and physiological maturity, plant and first pod height, and grain yield were analysed. BRSOY-3, BRSOY-5 and BRSOY-7 were the most stable, measured across 18 environments (year×sowing date), demonstrating selection effectiveness. Determinate growth explained low yields in late-sown treatments, as the photoperiod response reduced the reproductive phase. Late cultivars had photoperiod effect confounded with dry spells at the end of the rainy season. Genotypic stability for high yield in soybean is envisaged as a function of maturity group and long reproductive period. Manipulating the response to maturity and introduction of indeterminate growth habit is expected to increase yields across the sowing period, consolidating tropical soybean production. The method could be used for cultivar release and to define selection schemes aiming at recombinants for delayed maturity.

Experiments were carried out to assess the effect of the following diets: unwilted and wilted silage, barn-dried hay and wilted silage and ensiled mixtures of grass and barley on the ruminal VFA patterns in sheep.

There was a tendency for the unwilted silage to result in a slightly higher level of rumen acetate and a lower level of propionate than grass, wilted silage or barn-dried hay. In two of the experiments (Exps. 2 and 4) significant direct relationships were found between rumen acetate and the crude-fibre content of the diets and significant inverse relationships were found between the rumen propionate and the crude-fibre content of the diets.

Significant relationships were also found between the rumen acids and the metabolizable energy content of the diets and in Exp. 2 there was a significant relationship between the rumen acetate and the water-soluble carbohydrate content of the diet.

The addition of barley meal to grass produced different ruminal VFA patterns in sheep fed the ensiled material and the resulting silage.

The effect of implantation of trenbolone acetate and oestradiol into lambs soon after birth on the metabolism of alanine in the presence and absence of propionate has been studied in isolated perfused livers obtained from suckling and from ruminating lambs. The effect of butyrate on the metabolism of alanine in the presence and absence of propionate has been studied in livers obtained from the steroid implanted lambs.

Glucose production in the presence of alanine by livers from non-implanted suckling lambs was more than 3 times greater than that by livers from non-implanted ruminating lambs. Steroid implantation did not affect alanine uptake by the livers but metabolism within the livers was altered. Significant interactions were observed between the age of the lambs and whether or not they had been implanted with steroids for the rates of net glucose production in the absence of propionate (P < 0·01) and for the rates of release of urea by the livers in the presence of (P < 0·05) and absence of propionate (P < 0–01).

Propionate did not affect alanine uptake by livers obtained from either suckling or ruminating lambs, but there was a significant interaction (P < 0·05) between the age of the lambs and whether or not butyrate was infused, indicating that butyrate depressed alanine uptake by livers obtained from implanted ruminating lambs perfused in the absence of propionate. Despite this depression of alanine uptake the rates of net glucose production and urea production were unchanged, indicating that butyrate modified the metabolism of alanine in the livers of implanted ruminating lambs in that a greater proportion of the alanine carbon taken up must have been converted to glucose. Butyrate stimulated net glucose production in the presence of propionate and alanine in livers from suckling (P < 0·05) but not ruminating lambs. Butyrate was ketogenic and the release of 3-hydroxybutyrate accounted for 45 and 30% of the carbon taken up as butyrate by livers from suckling and ruminating lambs respectively perfused in the absence of propionate. Propionate was antiketogenic. Propionate inhibited urea formation from alanine by livers from implanted suckling (P < 0·05) and implanted ruminating (P < 0·001) lambs. This effect was diminished by the presence of butyrate. Lactate was released in the presence of propionate and accounted for approximately 12–5% of the carbon taken up as propionate.

It may be concluded that implantation of lambs with anabolic steroids maintains hepatic gluconeogenesis from alanine at rates more closely resembling those found in younger suckling lambs. The effects of the volatile fatty acids on alanine metabolism are likely to be of physiological significance when sheep are fed diets which result in a markedly altered pattern of rumen fermentation.

The effect of phosphorus fertilizer on the performance of an improved semi-dwarf (100 cm), long duration (170 days), photosensitive rice variety CR 1016, grown under conditions of intermediate deepwater (15–50 cm) and simulated flash flooding (80 cm), was investigated at Cuttack, India in 1985, 1987 and 1988. Growth and yield of rice subjected to overhead flash flooding (complete submergence) at the vegetative stage for 10 days was decreased significantly compared with partial submergence in water of intermediate depth. The adverse effect of complete submergence was due to greater tiller mortality and lower number and/or weight of panicles at maturity. Rice plants fertilized with P tolerated flooding better and produced significantly higher grain yields than when no P was applied. There was no significant effect of P application on the crop grown under natural unsubmerged conditions, except when it was raised in the same plots as the previous year and may therefore have benefited from residual effects. Therefore, application of 8.7–17.5 kg P/ha along with 60 kg N and 16.7 kg K/ha at sowing was essential to overcome the deleterious effects of submergence on rice grown under waterlogged conditions.

1. Field experiments on the use of cut ware setts with the potato varieties Arran Banner, King Edward and Majestic have shown that with proper handling no loss in plant establishment need result. When the cut setts are planted at the same distances as whole setts, there is liable to be a reduction in the yield per acre because of the lower yield per plant, but the actual rate of increase may be increased considerably by cutting because of the larger number of plants obtainable.

2. No benefit has been found from the practice of dusting the cut surfaces of tubers of Majestic with slag, lime or ashes, while adverse effects resulted from the use of a fungicide and alum.

3. The exposure of cut setts to drying conditions lowers their resistance to attacks by micro-organisms, and encourages the breakdown of the tuber flesh by bacteria of the carotovorum group.

4. In general, the use of certain fungicides, either directly on the cut surface, or as a means of moistening sack coverings, is not to be recommended because of the adverse effects of the fungicide on the natural resistance of the live tissue of the tuber flesh.

The results of three cotton irrigation experiments in the western Negev region indicate that by increasing the intervals between irrigations and by applying the first irrigation at the beginning of flowering, maximum yields of 1700–2100 kg/ha can be obtained with three irrigations. In all treatments except the one with four irrigations, about 0·31 kg of lint was produced for each 1 m3 of irrigation water. In the three driest treatments, where cotton suffered from moisture stress during various periods of growth, no differences in lint quality could be detected in comparison with wetter treatments. As long as there were clear drought symptoms, such as in the three driest treatments, additional irrigation increased the number of bolls/plant, while the average boll weight remained unaffected. Additional irrigation in treatments where there were no clear water stress symptoms did not increase the number of bolls/plant, but increased the average boll weight.

Herbage from a grass-white clover sward was dried in the field to the hay stage (≤ 0·33 g moisture/g dry matter) at three times of year in 2 years comparing, in each case, all combinations of two stages of maturity, two levels of applied nitrogen and two thicknesses of swath. Samples taken at intervals during drying were analysed for nitrogen, phosphorus, potassium, calcium, magnesium and sodium.

When there was little or no rain during drying, there was no change in the concentration of any of the six elements in the herbage dry matter between cutting and the hay stage, whatever the stage of maturity, level of N applied or swath thickness.

The concentrations of potassium and sodium in the crop were greatly reduced by rain in the later stages of drying, but were less affected by rain in the early and middle stages; the concentrations of calcium and magnesium appeared to be reduced by rain as readily in the middle as in the later stages; the concentrations of nitrogen and phosphorus were relatively little affected by rain, but seemed likely to be more at risk in the later stages. The extent of the reductions in the concentration of elements was not markedly affected by the stage of maturity or level of N applied. There were reductions in the thin but not in the thick swaths when rain fell during the early and middle stages of drying, probably partly or wholly because the herbage in the thin swaths was drier, with a higher proportion of dead cells, at that time than the herbage in the thick swaths. At least 70 kg K/ha was leached out of the crop in the thick swaths by rain in the late stages of drying.

A suitable method of fluorimetric determination of riboflavin was developed, and riboflavin in various poultry feeding stuffs was determined by its use.

Riboflavin was determined in fodder plants, vegetable refuse and wild plants. The influence of seasonal changes and of different stages of growth on the riboflavin content in fodder plants was investigated. Summer-grown plants contain more riboflavin than those grown in the rainy winter season. The riboflavin content of the plants declines in the course of their growth.

Forty-four turkeys including both sexes of two genetic strains were drawn at mean weight-for-age at 2 week intervals from a flock of 380 birds from hatching to 20 weeks post-hatching. Birds were dissected and linear measurements of skeletal units and breast dimensions were compared with keel length using the logarithmic form of Huxley's allometric growth equation. Live weights and weights of selected muscles were similarly compared with breast muscle weight. Wing bones and the biceps brachii muscle grew at approximately the same rate as keel length and breast muscle, respectively. However, leg bones and semitendinosus and gastrocnemius muscles exhibited slower growth than the breast region. Growth of maximum breast length and width was closely matched to keel length but growth in keel depth was much slower. The desirable convexity in breast shape lateral to the keel was considered to be directly proportional to maximum meat depth over the sternum and inversely proportional to keel depth. Maximum meat depth increased at a faster rate than either keel length or depth.

A study was made of the relationship between yields in particular size grades of carrots and onions and the number of plants per unit area with a view to providing adjustments to yields for differences in plant densities. It is concluded that the relationship for individual small grades cannot be fitted consistently by a single mathematical equation but that estimates of yields in small grades are best obtained by fitting a common equation to the accumulated yield at the limits of the grade and obtaining the yield by difference. Eleven previously published equations which have been shown to fit the relationship between total yield and plant density for a number of crops are compared with one newly developed for graded produce. It was found that the latter,

where y = yield/ha, ρ = number of plants/m2 and A, B and C are constants, generally leads to the best fits when a large range of densities is present, but it is argued that, for adjustment of yields for small differences in densities such as are obtained in variety trials, a simpler equation such as a second degree polynomial is equally effective.

The effects of two, symmetrically opposing, light treatments on the semen of Suffolk rams were investigated over two years. The light rhythm had an amplitude of 12 h and a cycle of 24 weeks. Data on semen volume, spermatozoa concentration, total spermatozoa per ejaculate, fructose concentration, seminal fluid fructose concentration and total fructose were collected during 38 semen collection periods. During the last 20 periods libido was assessed on the interval to mounting.

The effects of treatments were assessed by fitting Fourier curves with 24-week cycles to the observed fluctuation of the differences between treatments and with 52-week cycles to the means of treatments. From periodic regression analysis of the treatment differences it is concluded that the Suffolk rams were susceptible to the artificial light rhythms and that both groups adapted to the imposed rhythms. Some effects of the pretreatment photic environment appeared to persist during the first year of the treatment period. There appeared to be a lag between the fluctuations of the semen attributes resulting in a series of sequential changes.

Herbage yield obtained from grass swards is influenced by the presence of grazing animals (Brockman, Rope & Stevens, 1971a, b; Holmes, 1968; Shaw, Brockman & Wolton, 1966). The net effect of grazing in a particular situation depends on the balance between the effects of excretal-N return, which tends to increase yields (Brockman & Wolton, 1963) and those of treading and other sward damage, which tend to reduce yields (Edmond, 1970). This net grazing effect on yield can be measured by comparing yields of cut and grazed swards under management that is in all other respects identical (Shaw et al. 1966). Available data have been examined to obtain quantitative estimates of the net effect of grazing and of the changes in these effects that occur with changes in sward N supply.

Seeds of cowpea, melon, and tomato were planted in moist soil and subjected to a heat stress of 45 °C for 10 h on the day of sowing (day 0), 1 day after sowing or 2 days after sowing. The heat stress subsequently resulted in retarded hypocotyl elongation for all the crops, but the greatest retardation was due to heat stress applied on day 1 for cowpea, day 2 for melon, and day 0 for tomato. The growth-retarding effect of heat stress was associated with a delay, by 1 day, of the maximum rate of elongation of the seedlings.

Geranium (Geraniaceae) is an important aromatic plant grown for its light yellow to light brown or green coloured volatile essential oil obtained bysteam distillation of the green overground biomass. Geranium oil is extensively used in many perfumery formulations. The crop is generally raised from rooted cuttings whose initial slow growth leaves a large portion of land uncovered. Under identical situations in many other crops, it has been observed that growing grain or fodder legumes as intercrops resulted in monetary or yield advantages (Willey, 1979a,b; Mead & Willey, 1980; Rajeswara Rao & Singh, 1982, 1983; Rajeswara Rao & Sadaphal, 1983). The objective of the present investigation was to study the feasibility of growing a short-duration leguminous intercrop during the initial lag phase of geranium in such a way as not to affect the yield of geranium.

Two experiments done at the University of Ilorin, Nigeria, in 1992/93 investigated the effects of dietary levels of thevetia cake on the performance and nutrient retention of broilers. In Expt 1, dayold broiler chicks were fed either a control diet or diets containing 5, 10 or 15% thevetia cake during a 4-week period. In Expt 2, day-old broiler chicks were fed a standard diet until 4 weeks of age and were then switched to diets containing 0, 5, 10 or 15% thevetia cake. Inclusion of thevetia cake in broiler diets, irrespective of level of inclusion, drastically reduced feed intake and weight gain (p < 0·01) at both the starter and finisher stages. Dietary thevetia cake also caused a significant increase in mortality rate (P < 0·01). There was a reduction in protein and fibre retention and dietary ME with increases in the dietary level of thevetia cake at both the starter and finisher stages (P < 0·05). It is concluded that thevetia cake is toxic to broilers and needs further processing before it can effectively be used as an ingredient in broiler feed.

The rate of production of bacteria in the rumen of buffalo calves kept on two rations was measured using 14C labelled Streptococcus bovis and 35S whole ruminal bacterial cells. The animals received daily either 15–20 kg green maize or 25–30 kg green cow pea in 12 equal amounts at 2-h intervals. The bacterial cells from the rumen of animals maintained on the same diet were tagged with 35S by in vitro incubation in the presence of 35S-sodium sulphate. Similarly Streptococcus bovis of rumen origin was grown in the presence of U-14C dl-leucine. The cells were injected into the rumen in a single dose. The dilution of the specific radioactivity of bacterial cells in the rumen with time was taken for calculation of the turnover time and rate of production of bacteria.

The average production rates of bacteria were 88·3 ± 3·88 and 92·3 ± 1·82 g/kg digestible organic matter and 101·8 ± 1·55 and 103·3 ± 1·49 g/kg digestible organic matter in animals fed green maize and cow pea, when estimated by using mixed rumen whole bacterial cells and Streptococcus bovis respectively. There was no significant difference in the rate of bacteria production when estimated by either method.