Crops of perennial ryegrass and lucerne were each ensiled without additives and after the addition of paraformaldehyde to provide about 0·1, 0·2 or 0·4% HCHO/t crop fresh weight. The ryegrass and lucerne silages were offered ad libitum to sheep in separate experiments of identical design.

All theryegrass silages were well preserved with low pH values, the level of butyric acid was very low and ammonia-N comprised less than 8% of total N. The lucerne silage made without additive had a pH of 5 and acetic acid comprised the major part of the total fermentation acids. Ammonia-N comprised over 12% of total N. All levels of paraformaldehyde addition restricted fermentation in both crops and led to an increase in the proportion of total N which was insoluble in hot water.

Voluntary intake of organic matter (OM) was higher for the lucerne than for the ryegrass silages but digestible organic matter (DOM) intake was higher for the ryegrass. Intakes of OM and DOM were not significantly affected by paraformaldehyde treatment. The addition of paraformaldehyde significantly depressed apparent digestibility of OM and cellulose with the ryegrass but had less effect with the lucerne. Nitrogen digestibility was significantly depressed in both crops at all paraformaldehyde levels. Paraformaldehyde addition resulted in increased faecal N output and decreased urinary N, but retention of N was not significantly affected.

The lack of response in feeding value to paraformaldehyde treatment may have been due to the relatively high intake and N retention of the untreated silages which were fairly well preserved.

The relationship between rate, spray interval and number of applications of Decis for pest control in cow pea was investigated. In 1978 and 1979, neither the rates nor the interaction effects were significant in grain yield when 12·5 and 25·0g a.i./ha of Decis were applied three times weekly or twice at intervals of 10 or 14 days.

Further trials in 1980 showed that for the contro l of thrips (M. sjostedti), rate, interval and number of applications were significant for samples at 49 days after planting and beyond, suggesting that the residual life of Decis is about 10 days. Three applications were significantly better than two for lowering the population of C. tomentosicollis and the number × interval interaction was also significant. The number, rate and interval were significant without interaction effects for shrivelled pods caused by all hemipteran pests. In all the trials in 1980 and 1981, damage by the pod borer M. testulalis was low. Rate and number × interval interaction were generally significant but no differences were observed in grain yield. However, in 1980 the higher rate and three applications gave better quality crop, resulting from less hemipteran damage.

An analysis of cost–benefit of the trial showed that 12·5 g a.i./ha gave higher returns than 25 g, as did two applications than three, but the trend in the spray interval was less consistent.

Sweating rates were analysed in relation to rectal temperatures of cattle to yield a measure of sweating response within and between animals. The measurements, performed over 36 days, were done in a natural radiant environment on six steers in each of three breeds, Brahman (B), Brahman × Hereford–Shorthorn cross-breds (BX), and Shorthorn (S). Each steer was recorded for 30 min on six occasions randomly distributed among 6 h between 08.00 and 13.00 h, and on six occasions between 11.00 and 16.00 h, all on different days. Sweating response, e.g. the linear slope of the relationship between sweat rate and rectal temperature, was greater for B (294 g/m2. h/°C) than for BX (146 g/m2.h/°C) or S (194 g/m2.h/°C) which did not differ; this helped to explain why the range and mean rectal temperature in B were lower and little affected by environmental heat. Curvilinear models of the sweating response indicated that in the environmental conditions of this study, the limit of sweating for B and BX was not reached, while for S, the sweating response approached a plateau. Between animals, the relationship of sweating response to mean rectal temperature was negative (P < 0·01) and its relationship to the time spent in the sun at pasture positive (P < 0·025). Thus this measure of sweating response was a good indicator of thermoregulatory ability of the cattle. However, the sweating response of the steers did not relate to their grazing time or growth. The reasons for this are discussed. Finally, the sweating response was found to be negatively correlated with metabolic rate between animals within breeds (P < 0·01) and this suggested that it may be difficult to combine the desirable traits of good heat adaptation and high metabolic potential in cattle.

Data from between 742 and 894 carcasses of hogs and of gilts of a British Landrace line of pigs selected for lean percentage were subjected to a heritability and genetic correlation analysis and to a multivariate regression analysis of phenotypic correlations.

Although overall fatness was the most important component of carcass profitability, other components relating to carcass conformation and muscle to bone ratio remained important, particularly in gilts.

Genetic correlation of backfat thickness with carcass value was low in hogs (–0·39) and exceedingly so in gilts (–0·13). Although genetic correlations of lean percentage with carcass value were high (0·80 in hogs, 0·77 in gilts) they were no larger than those relating yield of trimmed and boned joints to carcass value, which varied between 0·70 and 0·79.

It is concluded that, with skilled butchers, joint yields as a selection criterion for carcass value are preferable to backfat thickness and as efficient as, and cheaper than, dissection.

Pigs from different companies (source populations) in years 3–5 of the Meat and Livestock Commission's Commercial Pig Evaluation were characterized in terms of eight production characteristics and grading measurements using canonical variates analysis in a multivariate general linear model. For pigs fed to a restricted scale, the first canonical variate was strongly associated with fat thickness measurements and the efficiency with which feed was converted into live-weight gain (FCR); the second canonical variate was associated with killing-out percentage. For pigs fed ad libitum, a discriminant variate formed from the sum of the first two canonical variates was strongly associated with P2 and loin fat thickness measurements and FCR, and a discriminant variate formed from the difference of the first two canonical variates was strongly associated with killing out, length and shoulder fat thickness. The first three canonical variates accounted for 88 and 90% of the variation between source populations for restricted and ad-libitum fed pigs respectively. A graphical display of the source populations indicated that there were six to eight groupings depending on feeding regimen.

In principal component analyses of residual variation, the first principal component on both feeding regimens was strongly associated with fat thickness measurements. The first three principal components accounted for 91 and 90% respectively of the variation for restricted and ad-libitum fed pigs.

An analysis of pig carcass composition was carried out, using data for 11 genetic source populations in the Meat and Livestock Commission's Commercial Pig Evaluation (CPE). The data were from years 3–5 of CPE and a total of 720 carcasses were involved. Weights of dissected tissues and parts were considered simultaneously, and the effects of growth, source population, sex, feeding regimen and time period were incorporated into an integrated model, the multivariate allometric development model.

Canonical variates were constructed for each of the classifying factors except time period, and the residual variation in carcass composition was analysed by principal component analysis. The first canonical variate for source populations was interpreted as a tissue distribution characteristic associated with the distribution of lean between joints in the dorso-cranial and ventro-caudal regions of the carcass. It accounted for 39% of the variation between source populations. The second canonical variate was associated with the ratio of subcutaneous fat to lean in the carcass, and accounted for 20% of the variation between source populations. The results explain the bias found in predicting the proportion of lean tissue in a carcass from subcutaneous fat thickness (P2).

In a graphical display of differences between source populations, nine were shown to be distinct, with only two intermediate and not clearly differentiated from some others. The interpretation of canonical variates and the relative positions of the populations were closely related to those obtained from the analysis of production and grading characteristics in the first paper of the series.

Six varieties of winter barley were grown during the years 1979, 1980 and 1981 in Granada (southern Spain). Grain yield variation in the 3 years studied was a function of the pre-anthesis period (especially as a determinant of number of ears/m2). In comparison leaf area duration and grain: leaf ratio from anthesis to ripening had far less influence on grain yield variation. Though these findings contrast with the generally accepted view, they can be explained by environmental conditions prevailing in southern Spain during grain filling.

Relative adaptability of Chokla and Rambouillet × Chokla half-breds was compared by observing their responses on exposure to summer stress for 6 days and also under accentuated stress by deprivation of drinking water till the animals lost 30% of their body weight. Responses of both the breed groups were similar on 6 days exposure. Accentuated summer stress resulted in decreased feed intake followed by 15, 26 and 31% loss in body weight on 1st, 2nd and 3rd day of exposure, respectively. Progressive decline in faecal moisture, increase in rectal temperature and decrease in morning respiration rate were also noted in both the breeds while an increase in pulse rate was recorded only in the cross-breds. Increase in respiratory or pulse rate for unit rise in rectal temperature was found to be higher in the cross-breds. On accentuated thermal stress, haematocrit values were higher in the cross-breds and blood potassium concentration was higher in the Chokla while blood glucose decreased in both the groups. Under the conditions of short-term exposure to summer stress the cross-breds maintained homoeothermy as well as the Chokla.

Ultrasonically measured backfat depths and subjective fat and conformation scores taken on 123 Romney ewes were related to the chemical composition of the carcass in trial 1. Fat depths at one position over the eye muscle, determined using ultrasonic machines with a single probe, were similar to the best judge's fat scores at predicting carcass composition after adjustment for pre-slaughter live weight. Fat depths measured from a two-dimensional scan (Danscan) did not predict carcass composition as well as most of the judges' fat scores. Judges' conformation scores failed to improve the prediction of composition after adjustment for live weight and fat score.

In trial 2, two ultrasonic machines of the single probe type provided accurate measure of carcass fat depths on both full fleeced and shorn sheep. Ultrasonically measured fat depths would appear to be a useful method for selecting lean breeding stock and for training inexperienced stock judgesto assess fatness of sheep.

Cattle were fed four hays in mineral balance experiments. Two of the hays (Cenchrus ciliaris and Setaria sphacelala var. sericea) contained 1·8 and 1·3% total oxalates and provided above- and below-maintenance intakes of calcium respectively. These grasses contain calcium oxalate crystals. The other two hays (Aristida spp –Bothriochloa spp. mixture and Triticum aestivum) contained 0·1% oxalates, and also provided above- and below-maintenance intakes of calcium. The absorptions of calcium from the hays providing above-maintenance intakes were 51% for the high and 57% for the low oxalate hay. At below-maintenance intakes, the cattle were in negative calcium balance and calcium absorptions were 52% for the high and 64% for the low oxalate hay. While in negative calcium balance the cattle were given single doses of calcium oxalate, followed by single doses of either limestone or rock phosphate. The cattle fed S. sphacelata hay absorbed sufficient calcium from calcium oxalate to achieve positive calcium balance, although the amount absorbed was only 52% of that absorbed from limestone. The cattle fed T. aestivum hay also absorbed calcium from calcium oxalate, but in insufficient amount to result in a positive calcium balance. The amount absorbed was 47% of that absorbed from rock phosphate. The results demonstrate that in tropical grasses containing calcium oxalate crystals, the availability of calcium is about 20% lower than it is in grasses containing little oxalate. Adaptation to oxalate may improve the ability of the rumen to utilize calcium oxalate. It is suggested that the availability of calcium to cattle grazing tropical grasses should be considered to be a maximum of 50%. Neither magnesium nor phosphorus absorptions from tropical grasses were affected by oxalate.

Sixteen cultivars of beans (Vicia faba L.) were evaluated in a triple lattice experiment over 2 years. Differences among and within minor and equina groups were significant for most of the measured traits. In general, among equina and minor groups, the variability of means for yield components was higher than the variability for seed yield per plant. Most European cultivars were lower in yield potential and in number of branches per plant, taller and later in maturity than North African cultivars.

Significant positive correlations were found for seed yield per plant with weight of pods per plant and with number of pods per plant. These results indicate their value for improvement by indirect selection for seed yield. On the other hand, significant positive correlations were also obtained between number of seeds per pod and pod length and between number of seeds per pod and 100-seed weight. The correlation coefficients for height and number of days to maturity with seed yield per plant were negative but insignificant. Other correlation coefficients were also insignificant and low in magnitude.

The effect of drought on the growth and subsequent recovery growth of containergrown perennial ryegrass plants was assessed in a glasshouse. Dry-matter production and percentage of water-soluble carbohydrates were measured, and non-destructive measurements of growth components (leaf extension, leaf appearance and tillering) were made.

Drought had an effect upon all the variables recorded. Selecting for improved recovery growth was considered to be of more economic importance than selecting for improved growth during drought and the implications of defoliation are discussed in relation to drought recovery.

It was concluded that subjecting pot-grown plants to drought was a useful technique when screening selections for response to drought.

Halo blight resistance was transferred in a backcrossing programme from PI 150414 to a Michigan-type bean. The resistant selections obtained gave yields that were up to 10% higher than that of cv. Seafarer and had seed of good quality that was suitable for baking in tomato sauce. These selections were also resistant to the common strains of bean common mosaic virus (BCMV) and to the lambda race of anthracnose.

In addition, selections with white seed of similar size to Seafarer were obtained from crosses between Seafarer and cold-tolerant lines with large, coloured seeds. In trials over 4 years these selections gave 20% higher yields than Seafarer and were less sensitive to environmental changes. Like Seafarer, they were homozygous for the I gene for resistance to BCMV but were susceptible to halo blight and anthracnose. Although not as suitable for canning in tomato sauce as other material in the National Vegetable Research Station programme, they offer useful parental material for further cycles of breeding.

Two varieties of oil-seed rape were drilled in 1979–81 at a range of seed rates. Percentage establishment, plant weight, height, and the ratio of seed to total aboveground dry matter were lower in high-density plots. Seed yields were not increased when the seed rate was raised from 9·0 to 13·5 kg/ha (Expts 1 and 2) or from 4·5 to 18·0 kg/ha (Expt 3) owing to a compensating reduction in the number of pods per plant. Seed quality and 1000-seed weight were not influenced by the seed-rate treatments.

Experiments were conducted in association with farmers during 1977, 1978 and 1979 on a River Estate sandy loam at Valsayn and on a Cunupia clay loam at Piarco, Trinidad, to assess the relative importance of components in a set of practices for wetseason production of ‘yellow shell’ pods of ‘blackeye’ type of cow pea (Vigna unguiculata (L.) Walp.). Though the response of the cow pea growth, yield and seed quality characteristics were similar at both locations, crop performance was consistently better at Valsayn and was attributed to more favourable soil conditions and to a lower incidence of pests (mainly Ceratoma beetles), cow pea severe mosaic virus, and weeds. Overall, it was found that pest control was the most important management factor, accounting for a mean yield increase of 144%. The adoption of the improved cultivar, California Blackeye No. 5, increased yield by 77%. Other inputs resulting in significant yield increases were, in order of magnitude, weed control (40%), roguing of mosaic infected plants (37%) and high plant density of 110000 plants/ha (23%). A fertilizer treatment did not significantly increase yield. The results suggest that adoption of the insect control treatment by farmers in their cultivation of an improved cultivar sown at high plant density, the use of herbicide and roguing of mosaic infected plants have practical potential and would be economically justified for the production of high yields and good quality ‘yellow shell’ pods of vegetable cow pea for processing.

Herbage from a grass-white clover sward was dried in the field to the hay stage (< 0·3 g moisture/g dry matter) at four times of year in 2 years comparing, in each case, all combinations of three stages of maturity, three levels of applied nitrogen and three thicknesses of swath; 35, 55 and 75 days' regrowth, 0, 75 and 150 kg N/ha and, on average, 220, 474 and 728 g herbage dry matter/m2 were compared.

The least mature herbage had the highest moisture content at the time of cutting and dried most quickly at a given swath thickness, being slightly drier than the more mature herbage at the hay stage. At the cuts in late May-early June and late Juneearly July, when the crop was predominantly grass, the application of nitrogen increased both the moisture content at the time of cutting and the initial rate of drying at a given swatli thickness, so that in the middle and later stages of drying there was no effect of applied N on moisture content. At the cuts in early and late August, herbage from the plots that had received no applied N, which contained a substantial amount of white clover, had the highest moisture content at the time of cutting, dried fastest at a given swath thickness and had the lowest moisture content in the later stages of drying. In the very early stages of drying, herbage in a thin swath lost water much faster than herbage in a thick swath, but subsequently the rate of drying was consistently faster in a thick than in a thin swath so that, by the hay stage, herbage in a tick swath was at least as dry as herbage in a thin swath. There was almost no interaction between the different types, of treatment.

Rain during the drying period had little or no effect on the nitrogen content of the crop, but reduced digestibility by about 9 units. Stage of maturity and swath thickness did not affect the extent of this reduction in digestibility.

Trials were conducted during the summer seasons (1978 and 1979) at the Faculty of Agriculture, Elminia University, to evaluate the effect of some growth regulators on sex expression, sex ratio and yield production of snake cucumber. The results obtained showed that both sex expression and ratio could be modified with plant regulator sprays even under the long and high temperature conditions of Elminia governorate. All plant regulators induced the formation of the first female flower at lower nodes compared with the control. There was significant suppression of male flowers in plants sprayed with plant regulators. All the treatments gave an increase in total yield and improved fruit characters.

The benefits to establishment and growth of white clover cvs Aberystwyth S.184 and Grasslands Huia of inoculation with three strains of Rhizobium trifolii, using the peat or liquid inoculum techniques, were investigated during 1975–8 on improved hill soils ranging from brown earth through dry and wet peaty podzol to deep peat.

Inoculation induced positive response in either number of seedlings, plant cover or dry-matter production in 18 out of 139 comparisons, had no effect in 118 and produced a negative response in three. Most of the positive responses to inoculation were at sites with wet peaty podzol or deep peat soils but of the five sites where increase in clover D.M. production was found in the first harvest year one was a brown earth. The positive agronomic responses occurred only when the proportion of plants with nodules was high and where a substantial proportion ( > 50%) of the latter contained introduced Rhizobium strains at least in the year of sowing. The three negative responses were in numbers of seedlings on one brown earth and two dry peaty podzol soils and with the Huia cultivar only. Despite lack of statistical significance at individual sites the dominant overall trend was for inoculation to enhance seedling establishment and the early growtli of white clover in all soil types.

On one brown earth and one dry peaty podzol soil there was some evidence that spraying the Rhizobium on to emerging white clover seedlings was more beneficial, atleast in microbiological terms, than the customary peat inoculum procedure.

The incorporation of even a small amount of nitrogen (30 kg/ha) into the seed bed at the time of sowing adversely affected germination, establishment and growth of white clover in some soils. Sometimes the effects of this nitrogen persisted into the first harvest year.

A series of measurements of the heat production of 16 adult sheep made at intervals of not less than 4 weeks when they were given precise amounts of different diets at about the maintenance level of nutrition were analysed statistically. The total number of observations was 365. For some sheep the observations spanned periods of more than 3 years and none spanned less than 1½ years.

There were no time-related trends in the metabolizability of the gross energy of the diet. It was found that the measured heat productions, the heat productions corrected to zero energy retention and the heat productions corrected to zero feed intake (calculated fasting metabolism) were sinusoidal with time. The amplitude of the sine coefficient was about 14% of the mean value, and in some sheep there was in addition a linear secular trend. The phase of the sine function was such that minimal metabolism occurred in midwinter and maximal metabolism in midsummer.

The results suggest that the seasonal variation in voluntary feed intake is associated with a similar seasonal variation in basal metabolic rate. The fact that all animals were given maintenance rations throughout further suggests that the higher metabolism is not due to higher feed intake.

Field experiments on crop compatibility and spatial arrangements in sorghum were conducted at the Indian Agricultural Research Institute, New Delhi in irrigated conditions in 1976 and 1978. Grain yield of sorghum increased when grown in association with the legumes greengram, groundnut, grain and fodder cow peas and soya bean, compared with sole sorghum. Planting of sorghum in paired rows (30:90 cm) with two rows of intercrop in the 90 cm space produced maximum yields of sorghum and intercrops.