ALBERT

Description: SUMMARYEight Morino lambs equipped with simple cannulac in the duodenum and terminal ileum were divided into two equal groups and used to study the net absorption of calcium, phosphorus and magnesium from concentrate diets supplemented by soyabean meal or by ensiled poultry litter. Mean net absorption of Ca, P and Mg for the soya-bean meal and poultry-litter treatments, respectively, was 31·6, 10·1; 34·7, 35·4; and 51·5, 41·6.Irrespective of the diet, the small intestino was the major site for Ca and P absorption and the stomachs for the absorption of Mg. A large secretion of P in the stomachs was found with both diets; 8·50 and 9·32 g/day for the soya-bean meal and poultry-litter treatments, respectively.The results of the present study support the view that poultry litter is a good source of P and Mg for sheep and can be used with deficient diets. Owing to the low rate of Ca absorption from the poultry-litter diet, it appears that at limited levels of inclusion, the extra added Ca would not be a detrimental factor.

Description: SUMMARYThin-layer chromatography and infra-red spectrosoopy were used to identify the components of technical Thanite. A method is developed for qualitative and quantitative determination using a gas liquid chromatograph (GLC) equipped with a flame ionization detector. Two major peaks, having retention times 1 and 5 min, were obtained. This was achieved using a glass column (15 × 0·3 cm), packed with diethylene glycol (1·5%) on chromosorb W, 60–80 mesh, at temperature range 70–170 °C. The results obtained by GLC showed that 33·7–55·8%, and 36·6–68·3% of the initial deposit of Thanite on cotton leaves degraded within 12 h from exposure to sunlight and ultraviolet irradiation respectively. One fifth of the initial deposit of Thanite on cotton leaves was lost after 24 h from spraying, then 70 % of the compound was dissipated after 3 days. Incubation of Thanite with rumen liquor at 39 °C for 24 h under anaerobic conditions resulted in degradation of 45–74% of the initial concentration.

Description: SUMMARYA mass-selection scheme for outbreeding diploid potatoes of the Phureja-Stenotomum Group is described; the scheme includes both seedling and ongoing tuber populations. Provision is made for higher yielding clones to contribute more true seed to ensuing generations. A computer is used to document and randomize the plantings. Selection criteria and methods are described. Results are given from an experiment to monitor progress. The use of diploid potatoes in British breeding, and the historical development of breeding methods, are reviewed in relation to the present mass-selection scheme.

Description: SUMMARYThe growth and feed intakes of Corriedale wether sheep when grown from 30 to 50 kg body weight by five different growth paths are described.Group A (control) grew continuously (fed ad libitum). After reaching ca; 40 kg body weight, group B and C animals lost 21% of their initial body weight over 9 and 18 weeks and at 122 and 63 g/day, respectively, and began realimentation at 30 kg body weight. Group D and E animals were ca. 50 kg body weight when weight loss was imposed and they lost body weight at similar rates (125 and 157 g/day) respectively. Animals in group D lost 34% of their initial body weight over 18 weeks and began realimentation at 30 kg body weight (the same as groups B and C). Group E animals lost 23% of their initial body weight over 9 weeks to begin realimentation at 35 kg body weight. Except during periods of weight loss, animals were fed ad libitum. Compensatory growth was observed in all groups which had lost weight, with early recovery growth rates 1·6–1·8 times higher than control sheep of the same weight.Rate of body-weight loss did not induce any significant differences in response to realimentation but results (groups B and C) suggest that the more rapid the loss, the more rapid will recovery be during realimentation. When sheep at different body weights lost the same proportion of their initial body weights, the heavier sheep (group E) attained final slaughter weight quicker than the lighter sheep (group B). When the proportion of body weight lost to reach a particular lower body weight was varied (groups B and D), the greater weight loss was associated with higher and more persistent growth rates during realimentation.After weight loss, ad libitum dry-matter intake was significantly lower during the first 10 kg of gain during realimentation in all treatment groups (B, C, D, E) than in control group A. There were no differences between treatment groups in recovery of dry-matter intake.Gross efficiency in all treatment groups was higher than in the control group A during the first 10 kg of recovery of body weight, but it then declined rapidly. This increase in gross efficiency was considered to be due to a combination of increased growth rates, reduced feed intakes and lower maintenance requirements. When the complete growth paths from 30 to 50 kg were considered, there were no significant differences in total feed consumed by the sheep following the five different growth paths.

Description: SUMMARYPigs 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.

Description: SUMMARYA 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.

Description: SUMMARYHalo 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.

Description: SUMMARYThe 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.

Description: SUMMARYAn 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.

Description: SUMMARYThe 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.

Description: SUMMARYThe effect of treating soya-bean meal with formaldehyde was studied in cattle by supplementing a hay–barley diet with two levels of either untreated or formaldehydetreated soya-bean meal. The formaldehyde treatment had no significant effect upon apparent N digestibility in the whole tract; it increased the amounts of non-ammonia N and amino acid N entering the small intestine but this increase was not statistically significant. However, increasing the proportion of either soya-bean meal in the diet increased the flow of non-ammonia N to the small intestine and apparent N digestibility in the whole tract. The formaldehyde treatment reduced the apparent degradability of the soya-bean meal N, determined in vivo from 0·74 for the untreated meal to 0·38 for the formaldehyde-treated meal. The in sacco technique produced values for the apparent degradability of the two soya-bean meals which ranked them in a similar manner as did the in vivo technique but gave lower values for degradability than the in vivo technique.

Description: SUMMARYForty-five normal lactating buffaloes from Punjab Agricultural University, Dairy Farm herd, were used for this study and were divided into three groups as group I (control), group II (showers) and group III (wallowing). The study was conducted from May to September in two periods, May–June as period I (hot and dry) and July–September as period II (hot and humid). Potassium concentration was estimated on a flame photometer. The overall average values (m-equiv/l) were found to be lowest in the control group (21·5 ± 1·27) and highest in wallowing (24·3 ± 1·20). Lower values were obtained in period I than in period II. Different correlations of potassium concentration in red blood corpuscles with climatic variables are discussed. Erythrocyte potassium concentration may act as an index of heat tolerance in buffaloes.

Description: SUMMARYTwo experiments investigated the effects of raising crisp lettuce seedlings under different environmental conditions prior to transplanting, on transplant size and weight and head weight at maturity.The use of tungsten lighting for 4 h after the end of a 12 h period of fluorescent and tungsten lighting increased transplant size and weight and the weight of heads at maturity compared with fluorescent and tungsten lighting only. Glasshouse-raised transplants were larger than those raised under artificial lighting but gave heads of similar weight to transplants which had supplementary tungsten lighting for 2 weeks. Both these treatments gave significantly heavier heads than a drilled crop or plants raised without supplementary tungsten lighting. Increasing the number of weeks of the supplementary lighting treatment tended to increase the coefficient of variation (c.v.) of head weight. Nevertheless the drilled crop had a higher c.v. of head weight than any transplanted treatment.The variety Pennlake produced pointed (‘coned’) heads when grown in the open and its leaves were shorter and broader than those of plants grown in polyethylene tunnels, which did not show ‘coning’. It is suggested that ‘coning’ occurs primarily as a result of either lower mean temperatures or a lower amplitude of temperature when grown in the open. It occurred most frequently with glasshouse-raised plants indicating that a higher raising temperature may also contribute to the problem.

Description: SUMMARYMainstem leaf appearance and leaf extension were monitored at 7-day intervals throughout the vegetative development of field-grown winter wheat plants, during two growing seasons 1977–9. Using hourly air and soil temperature records, it was found that the rate of leaf appearance was controlled by soil temperature, with the best linear relationships being obtained using accumulated soil temperature above a base temperature of 0 °C at 1 and 5 cm depth. Leaf appearance could be predicted equally well using 09.00 G.M.T. screen air temperatures although deviations from each linear relationship were found during very cold periods when slow leaf extension rates delayed leaf appearance.Leaf extension was also found to be linearly related to temperature, with the best fit being obtained using accumulated soil temperature above 2·5 °C at 5 cm depth, suggesting a threshold of 2·5 °C for leaf extension. The response to temperature (extension per unit of accumulated temperature) was the same for all the leaves of a given plant, or sowing date; however, the fact that the rate of leaf extension increased progressively with sowing date suggests that plant response to temperature may be determined at crop emergence (possibly mediated by rate of change of day length). Leaf extension rates could be predicted satisfactorily using 09.00 G.M.T. soil temperatures (5 or 10 cm) but less so using screen air temperatures.The prediction of plant leaf areas or crop leaf area indices using such relationships between temperature and leaf growth was found to be hampered by rapid and irregular rates of leaf senescence.

Description: SUMMARYData collected from 1968 to 1981 were used to study the effects of annual precipitation and its distribution on grain yield of three barley and six wheat varieties from 19–47 environments.The percentage of the variation in grain yield explained by annual precipitation varied with variety and species (5–31% in barley and 31–79% in wheat). The distribution of precipitation was the major factor affecting grain yield, although it varied with variety, and explained 72–92% of the variation in barley and from 75 to 98% in wheat.Only 33 of the 144 simple correlation coefficients between grain yield and precipitation during each of the 16 fortnightly periods were significant. The expected average effect on yield due to additional precipitation above the mean showed positive effects in barley during the presowing and heading to flowering periods; no consistent trend was found in the wheat.Improved agronomic practices could alleviate the adverse effects of the low and unevenly distributed precipitation by reducing losses and increasing storage of water in the soil. Breeding could contribute greatly towards high and stable yields in drylands.

Description: SUMMARYTwo experiments at Wellesbourne studied the effects of cold treatments on the leaf and curd production characteristics of a range of annual and biennial varieties of cauliflowers.Cold treatments delayed curd initiation and had a variable effect on the final number of leaves, but reduced the spread of curd initiation of plants which were 5 weeks old when cold-treated. The overall rate of leaf production and the final number of leaves generally increased with later-maturing varieties while initial rates of curd expansion generally declined.The annual varieties produced a small number of leaves and fairly synchronously formed a curd which developed rapidly; the biennial varieties had a higher rate of leaf production after transplanting and then changed to the generative state over a more prolonged period, following which the curd developed slowly.

Description: SUMMARYThe 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.

Description: SUMMARYProtein synthesis was measured in non-breeding sheep and in sheep at two stages of lactation by constant intravenous infusion of [3H] tyrosine. In early lactation plasma tyrosine flux was 50% higher than in non-breeding ewes and it remained somewhat higher in late lactation. Estimates of protein synthesis per day in the whole body showed similar changes.In early lactation the weights of the longissimus dorsi and semitendinosus muscles were respectively 37 and 28% lower than those for non-breeding ewes, but both muscles regained weight in late lactation. There were corresponding changes in the total protein, total RNA and total lipid contents of both muscles.The fractional rates of protein synthesis in the longissimus dorsi and the semitendinosus were between 2 and 3% per day, but it was higher in heart muscle. At both stages of lactation the synthesis rate in the longissimus dorsi was similar to that in nonbreeding ewes, but in the semitendinosus and in the heart synthesis rates were lower in lactating animals. In both skeletal muscles the total protein synthesized per day was lower in early lactation because their total protein contents were lower at this time. It is concluded that the maternal skeletal muscles may undergo a controlled depletion during lactation.

Description: The area of groundnuts in the Sudan has greatly increased in the last few years, as a result of introducing the crop in the Kenana Scheme (15000 ha) and the Rahad Scheme (50000 ha), as well as the intensification of the Sudan Gezira Rotation (225000 ha).

Description: The response of three spring cultivars of oilseed rape to five levels of nitrogen fertilizer (0 to 200 kg/ha) was studied during 1978–9 (Scarisbrick, Daniels & Alcock, 1981). Sampling problems, practical difficulties of measuring yield components, and the high co-efficients of variation for these data were discussed. During the course of further investigations on the winter cultivar Jet Neuf (established on approximately 75000 ha in the U. K. during 1980–1) within-plot variability for plant weight was assessed in order to indicate the size of sample necessary to compare treatment means.

Description: SUMMARYGrowing beef cattle grazed six pasture types (all-grass or grass-legume mixtures) for 4 months on each. Live weight (mean of ten animals) and dietary energy concentration were measured at 2- or 3-weekly intervals. Values for feed intake estimated by back-calculating from feeding standards were on average 2·5% higher (range, 10% less to 12 % higher) than intake values estimated directly from dietary energy concentration and live weight. In contrast to this level of agreement of means, differences between methods within pastures were so large as to suggest the presence of overriding effects on predictors of voluntary intake. It was concluded that until these overriding effects are explained, there are no means of validating measured intakes in grazing cattle, or of accurately predicting the amount of beef produced from pasture.

Description: SUMMARYIn two grasses of low net energy value for growth and fattening of cattle, digestible cell-wall values were close to 40% of forage organic matter (OM), similar to the expected value for grass. A value of 14% of forage OM for apparently undigested cellular contents in both grasses was just outside the range of values for grass. The data supported previous evidence that total cell wall is the only value that can be used at present to define grass in terms of its digestible dry matter.

Description: SUMMARYForty pregnant sheep were allocated to four groups and maintained indoors in individual pens on a pelleted diet. During the last 6 weeks of pregnancy and the first 6 weeks of lactation groups were infected daily with 4000 larvae of Ostertagia circumcincta or remained as controls in a cross-over design. Thus groups were either not infected (CC), infected only during pregnancy (IC), during lactation (CI) or during both pregnancy and lactation (II). Food was offered on the basis of body weight at the beginning of pregnancy and lactation. Food intake, body-weight change, faecal egg counts, plasma pepsinogen and milk production were measured weekly, wool growth and fibre diameter during 21-day periods and tensile strength of wool over the whole experimental period.Eggs were seen in faeces of only three sheep infected during pregnancy, but in all sheep infected during lactation; maximum mean values were 467 ± 144 and 222 ± 58 eggs/g fresh faeces in CI and II sheep, respectively. Pepsinogen concentrations rose after 1 week of infection during pregnancy and lactation; peak values were 868 + 57 and 1104 ± 146 m-u/l, respectively.Infection reduced food intake by 16% during lactation but had no effect during pregnancy. There were significant interactions between pregnancy and lactational treatments on intake during lactation. Infection during lactation increased bodyweight loss; mean values were 57, 40, 114 and 78 g/day for groups CC, IC, CI and II respectively. Milk production was decreased during weeks 4–6 of lactation, mean values being 1·59 and 1·32 kg/day in control and infected groups, respectively.Infection reduced wool growth and wool fibre diameter by 20 and 7%, respectively, during the final 3 weeks of infection during lactation. The staple strength of wool grown during the experiment was reduced by 14, 45 and 23% in IC, CI and II groups, respectively. Infection moved the point of greatest wool tenderness from parturition in control sheep to a time during the period of infection, particularly when infection occurred during lactation.

Description: SUMMARYTwo sets of experiments were carried out to compare methods of selecting Festuca arundinacea (tall fescue) for improved seedling vigour.In the first, germination and seedling growth of four varieties (Goar, Lironde, S. 170, and ZW 42–6) were compared in hydroponic growth tanks. From each variety, groups of seedlings were selected for each of four vigour characters (speed of germination, leaf length, root length and speed of production of the second leaf) and a fifth group was selected at random as a control. Plants of each group were intercrossed in isolation and their progeny compared.In the second, S. 170 was studied through two cycles of selection in a soil-based compost. In the first cycle, groups of seedlings were selected for each of five characters (speed of emergence, leaf length, and speed of production of the second leaf, first axillary tiller and coleoptile tiller). Two further groups were selected randomly. In the second cycle, the progeny of each group were reselected for the same character as their parents. Both first- and second-cycle progeny were compared among themselves.Significant direct responses to selection were obtained in all characters except speed of germination in hydroponics. Indirect responses also occurred but were mostly smaller and in response to selection for a related character, e.g. selection for early tillering resulted in early second leaves and vice versa. Two cycles of selection raised the frequency of coleoptile tillers from about 5 to 55 %, but the concomitant advances in vigour characters were smaller than those achieved by direct selection. It is argued that for practical purposes the basic criterion in selecting for improved seedling vigour should be rapid attainment of a particular growth stage such as appearance of the first tiller. Since speed of emergence itself responded to selection, the attainment of such a stage should be related to date of sowing rather than of emergence or germination.In the progeny of the hydroponic selections, all characters showed significant varietal differences, some of them the reverse of differences between the parent populations of the varieties. These results illustrated the importance of seed provenance as a determinant of seedling vigour, and suggest that choice of parent material is important in breeding for improved vigour.

Description: SUMMARYA pot culture experiment was conducted on 11 soils differing in their physicochemical characteristics to study the occurrence of Zn-Cu interaction in relation to plant growth and Zn and Cu concentrations of wheat. The nature of the interaction was found to vary with the soils and the amounts of applied nutrients. The plant growth showed antagonistic interaction between Zn and Cu when one of the two elements was added in low amounts. However, when the two elements were applied in large amounts, their concentrations in the plants increased but the plant growth was adversely affected. The applied Zn generally failed to affect the uptake of native or low amounts of applied Cu whereas the applied Cu decreased the uptake of native zinc in five out of 11 soils.The DTPA extractable amounts of Zn in experimental soils were not affected signicantly by Cu application and vice versa. The fact that the application of Zn or Cu may not affect or increase the uptake of each other may depend upon the soil characteristics and the rates of their application.

Description: SUMMARYSix field experiments on the effects of rate and time of application of nitrogen, three variety trials and one trial combining varieties with rates of application of nitrogen, all on winter wheat grown continuously and direct-drilled on a single farm, are described and the results discussed.The experiments showed that worthwhile yield responses could be obtained to very high rates of N application and that percentage protein in the grain increased linearly with amount of N supplied even to the highest rate (350 kg N/ha) applied. The effects of time of application were variable but there was a suggestion that applying the nitrogen in two doses in the spring gave more yield than a single dose, in one experiment. Applying some N in the autumn gave no more yield than applying it all in the spring.The variety trials gave results reasonably consistent with those of the National Institute of Agricultural Botany but the variety x nitrogen trial showed clear differences between varieties in response to nitrogen; the oldest variety, Maris Huntsman, showed a maximum at about 240 kg N/ha whereas none of the new varieties had reached their maximum by 270 kg N/ha.It is argued that field trials devoted to improving crop yields for a particular farm are worthwhile if site x treatment interaction is large and season x treatment interaction is small.

Description: SUMMARYThe development of the maxillary teeth in cattle was studied by recording eruption into the oral cavity and by radiographic examination following bisection of the skull. Observations of second molar intra-oral eruption showed that varying stages were seen at different ages. Radiography of the teeth allowed determination of the degree of crown and tooth development in the permanent premolar and molar teeth as well as stages of temporary premolar tooth resorption. Radiographic inspection showed that in the same animal all the permanent maxillary cheek teeth except the first premolar were less well developed than their mandibular counterparts. It was suggested that the intra-oral eruption of the second maxillary molar and radiography of the maxillary teeth provided a better method of age estimation in cattle than the traditional one of examining the intra-oral eruption of the incisor and canine teeth.

Description: SUMMARYA bulk seedling test is described which can be applied shortly after completion of a crossing programme. The test assesses resistance to G. pallida in progeny derived from crossing programmes involving S. luberosum, S. vernei and S. tuberosum spp. andigena. It provides good estimates of both the mean level of resistance within progenies and the breeding value of the parents. The test was applied to a crossing schedule involving a half-diallel and a North Carolina 2 design utilizing a range of material. The results and their implications are discussed.

Description: SUMMARYIn a breeding programme to combine quantitative resistance to two important potato pathogens, Phytophthora infestans causing late blight in foliage and Qlobodera pallida (the cream potato cyst-nematode), tetraploid (4 ×) off spring were obtained by crossing dihaploids, mainly as females, with tetraploids. Glasshouse and field tests in the first and second tuber-years showed that most of the off spring of highly blight-resistant dihaploids had high resistance to P. infestans. Two such dihaploids, PDH 182 and PDH 247, crossed with a tetraploid selected for high general combining ability for potato cyst-nematode (PCN) resistance, gave off spring all of which were highly blight resistant. About one third also had high PCN resistance.Detached leaflet tests were used for rapid blight resistance screening of other progenies from dihaploid × 4 × crosses in their seedling year. Differences were found in the effects of 4 × parents on the mean resistances of progenies from blight-resistant dihaploids.The results also showed differences between dihaploids in their effectiveness in transmitting blight resistance to 4 × offspring. This could be due to differences in the mode of unreduced female gamete formation, i.e. first division restitution or second division restitution (SDR). If all the unreduced gametes were produced by SDR, the differences could be due to differences in homozygosity between dihaploids with respect to blight resistance genes.The dihaploid × 4 × crosses gave few offspring per pollination. The few seedlings obtained may be offset by a higher frequency with the required characters. Since fewer seedlings would have to be grown in order to find the required combination of characters, savings could be made in planting and resistance-testing facilities over those required in conventional breeding.The tetraploid hybrids obtained can be used in a second cycle of breeding in three ways simultaneously: by crossing with other tetraploids, by crossing with dihaploids selected for complementary characters and to produce dihaploids with combined resistances.

Description: SUMMARYS1 maize varieties and varietal hybrids were tested in six locations ranging in altitude from 236 to 1600 m in Cameroon. The grain yields of highland varieties were observed to increase with each increase in altitude while the yields of the lowland varieties decreased with increasing altitude.The highland × lowland S1 varietal crosses yielded the same as the lowland parental varieties in highland areas and better than highland parental varieties in lowland areas.Average yields of all varieties per location increased by about 1·1 t/km increase in altitude. Eberhart & Russell's (1966) stability method found no stable variety while Francis & Kannenberg's (1978) genotype-grouping technique found five highland × lowland crosses to be relatively stable.Number of days from planting to tasselling increased with increasing altitude by about 20 days/km increase in altitude. Highland and lowland varieties performed poorly outside their zones of adaptation because of high incidence of foliar diseases like leaf blights and rusts.

Description: SUMMARYForty-eight 4-month-old lambs, reared worm-free from birth, were allocated to six groups and offered ad libitum a complete diet containing 139 g crude protein/kg D.M. One group was killed at the outset as initial control (CI). Further groups, ALC, 1, 2, 3 and 4 were dosed daily for 84 days with zero, 1000, 3000, 5000 and 5000 larvae of Ostertagia circumcincta, respectively. Lambs in group 4 also received anthelmintic (fenbendazole, 5 mg/kg) on days 21, 42, 63 and 84. Lambs were killed after 98 days and their carcasses and those of the initial controls analysed for fat, protein and mineral contents.

Description: SUMMARYIn field trials made for two years in the dry period of a semi-arid tract under natural precipitation at the Indian Agricultural Research Institute, New Delhi, overnight seed-soaking of wheat in 0·5% solution of 2-chloro-ethyl-trimethyl ammonium chloride (CCC) prior to sowing increased the grain yield. When treated with foliar application of the chemical in concentrations ranging between 40 and 1000 mg/1, wheat plots yielded better than did the untreated control, but no consistency was noted between the concentrations or stages of their application. The benefit from CCC was due to more root growth, increased stomatal resistance and higher leaf water potential. Treated plants extracted more water from deeper soil layers, increasing their water-use efficiency.

Description: SUMMARYLiterature dealing with disposal of farm wastes is mainly concerned with smell, heavy metal toxicity, nutrient accumulation and soil physical conditions. Soil is required to filter and absorb the solid material and release a filtrate free from pollutants while remaining relatively unaltered. The importance of soil type in reducing pollution potential is recognized but little study has been made of the effect of pollutants on soil morphology. This paper reports changes observed in a fine silty and fine loamy typical brown earth of the Rheidol series on terrace gravels after treatment with pig slurry. It is concluded that pig slurry spread at the rate of 50 m3/ha per week will cause this permeable soil to deteriorate under an average rainfall of 1117 mm/year unless rest periods are given.

Description: SUMMARYThree experiments were carried out to investigate factors which might affect the voluntary intake of effluents.Effluent was introduced into the diet of pigs at rates of 25, 50 and 100 g D.M./day, replacing dry meal to maintain a constant amount of dry matter offered. The mean maximum daily intakes of effluent on the three treatments were similar indicating that, within this range, the rate of introduction of effluent had no effect on its potential maximum intake.When solutions with differing concentrations of effluent dry matter were offered it was found that the intakes at the 20 and 10 g/kg concentrations were progressively lower than when tho concentration was 30 g/kg or higher. This suggested a physical limitation to the intake of effluent at low concentrations. A physiological limit may operate at concentrations of 30 g D.M./kg or higher.In the third experiment daily air-dry meal allowances of 80, 90, 100 and 110 g/kg W0.75 were offered in addition to an ad libitum supply of effluent. The voluntary intake of effluent dry matter was not significantly affected by tho amount of meal offered and the total amount of dry matter consumed remained virtually constant.

Description: SUMMARYA mathematical plant competition model developed by Currah (1975), and subsequently modified by the author, is briefly described. The model has two useful properties: (a) it can cope with complex irregular row spacing systems such as occur in commercial practice and (b) it can be ‘calibrated’ to the yield values at any site by using data from previous crops.Parameter values of the modified model are calculated for both carrot and red beet crops. At least 70% of the variation in these data could be accounted for by fitting the model, a performance which was similar to, but never as good as, fitting analysis of ariance models. There were no systematic deviations between the fitted and observed values.Previously estimated parameter values were used to predict mean root weights of carrot and red beet storage roots. Overall agreement between predicted and observed data was good, although some systematic deviations occurred.The practical value of the modified version of the model and its strengths and weaknesses are discussed.

Description: SUMMARYThe digestible energy (DE) and metabolizable energy (ME) content of eight samples of barley, eight of wheat, four of maize and two each of oats and rye were determined using growing gilts. The DE content of barley ranged from 15·35 to 15·89 MJ/kg D.M., from 15·15 to 16·42 MJ/kg D.M. for wheat and from 16·05 to 16·47 MJ/kg D.M. for maize. DE values for the two oat samples were 12·48 and 12·74 MJ/kg D.M. and 15–04 and 15–47 MJ/kg D.M. for the two rye samples. There was a significant correlation between DE and ME:ME (MJ/kg D.M.) = 0·050 + 0·965 DE: r = 0·99; P 〈 0·001.The ratio ME/DE was significantly influenced by crude-protein content:ME/DE = 100–0·254 CP%: r = –0·77; P 〈 0·001.ME values were also corrected to zero nitrogen retention (MEno) and to 30% nitrogen retention (MEN30). The effect of such corrections was expressed as MEN0/ME and MEN30/ME. Values thus obtained were 0·98 and 1·00 respectively for the pooled values for all cereals.The data indicated that there was unlikely to be significant variation in the DE content of samples of the same cereal species, selected from commercial sources within the U.K. when evaluated under standardized experimental conditions.

Description: SUMMARYResults of visual and radiographic development of the mandibular caudal teeth were obtained from 135 cattle between 1 and 2 years old. Age ranges for each stage of tooth development were obtained. Using visual assessment of second molar intra-oral eruption the maximum age range before animals could be differentiated was 8 months (1 year 3 months from 1 year 11 months). Animals showed different stages of development in all six teeth using criteria based on resorption of the temporary premolar teeth and crown and root formation in the permanent premolar and molar teeth. The maximum age range before animals could be distinguished was 5 months (1 year 6 months from 1 year 11 months) and at all other ages the age difference before differentiation was less.

Description: SUMMARYCell walls of three bloat-causing legumes, lucerne, red clover and white clover tended to be thinner and disintegrated significantly (P 〈 0·05) faster during cellulase digestion than those of two non-bloat-causing legumes, sainfoin (reported to contain tannins) and cicer milkvetch (reported not to contain tannins). Response to one generation of selection for speed of mesophyll cell-wall disintegration was marked in a diploid red clover (h2 = 0·66, 1·13) but slight in a tetraploid (h2 = 0·10, 0·13).

Description: SUMMARYMature Merino ewes (n = 320) were fed either maintenance (100% M) or 25% maintenance (25% M) rations from the day after mating until embryos were collected at either day 11 or 21 after mating. On the 4th day after mating 223 ewes were ovariectomized and given 5, 10, 15, 20 or 25 mg progesterone/day (intramuscular) until embryo collection. A further group of sham operated ewes (n = 54) acted as controls. Despite live-weight losses of 10·7 and 15·8% from mating to days 11 and 21 after mating respectively, ewes on 25% M rations showed no evidence that embryonic survival was influenced by undernutrition. The embryos from ewes fed 25 % M rations were significantly (P 〈 0·05) smaller than those fed 100% M (crown-rump measurements were 5·93 ± 0·139 mm and 6·39 ± 0·116 mm at day 21 after mating in the 25 % M and 100% M groups respectively). Development, assessed by formation of the first pharangeal lobe and the fore- and hind-limb buds, was significantly retarded (P

Description: SUMMARYMaize was grown for grain or forage on the same site at Woburn for 7 consecutive years. Yields were satisfactory and there were no serious pest or disease problems, provided the small plots were netted until young plants were established. Different rates of nitrogen fertilizer were tested with and without annual applications of a soil sterilant, dazomet. Average yields of grain (85% dry matter) and forage (dry matter) were respectively 4·5 and 8·8 t/ha with 50 kg N/ha and 5·0 and 9·5 t/ha with 100 kg N/ha. Without dazomet there was a further increase with 150 kg N/ha. Weather influenced the response to nitrogen, and the response to a split dressing of the highest rate was variable. Except for plots receiving the split dressing of N in 1973 and 1974 dazomet always increased yields: grain yields were increased on average by 1 t/ha and forage by 1·6 t/ha. Dazomet-treated plots had taller and heavier plants with more stems, leaves and nodal roots, but fewer seminal roots than untreated plots. Dazomet-treated plots also had fewer migratory nematodes and smaller and less varied root myoofloras. Most of these differences were greatest in the young crop and possible reasons for this ‘early boost’ are discussed.

Description: SUMMARYThe carcass composition of phosphorus-deficient heifers of lower body weight was similar to ad libitumand restricted-fed controls supplemented daily with an extra 12 g phosphorus. The skeleton of heifers fed a phosphorus deficient diet for 63 weeks contained 18·8% less ash than restricted-fed controls given an extra 12 g phosphorus daily, but not less than ad libitum fed controls. Supplements of phosphorus and energy had different effects on the weights and concentration of bone minerals in skeletal components. A phosphorus supplement increased deposition of phosphorus in head, feet and tail, limbs and vertebrae and increased phosphorus concentration in head, feet and tail, vertebrae, ribs 1–5 and ribs 10–13. Extra energy intake slightly increased phosphorus accretion only in ribs 6–9 but had no effect on its concentration in this and other skeletal components. Only one (40 weeks) of the six biopsy samples taken from the cortex of the 11th and 12th ribs during the course of the experiment reflected the effect of uncomplicated phosphorus deficiency. No treatment differences were found in biopsy samples taken at slaughter in spite of differences in rib 10–13 analyses. The implications of this are discussed as they relate to the use of this method to monitor the phosphorus status of cattle.

Description: It has been reported that water deprivation reduces feed intake in Chokla sheep (Singh, More & Sahni, 1976; More & Sahni, 1978). Consequently, sheep production in terms of body weight, milk and lambs is also adversely affected (More & Sahni, 1980). However, no information is available on the metabolic aspects, particularly on urinary nitrogen and creatinine changes due to long-term intermittent watering. Creatinine is also used as a reference substance for evaluating urinary excretion rates of minerals (Field, 1964) and nitrogen (Powell, Plough & Baker, 1961) to avoid more laborious and time-consuming procedures, which also disturb animal behaviour and production (Langlands, 1966). The present paper attempts to examine the urinary concentration of total nitrogen, creatinine and their ratios; the ratios of potassium to creatinine and nitrogen are also considered.

Description: SUMMARYCrops 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.

Description: SUMMARYSixteen 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.

Description: SUMMARYUltrasonically 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.

Description: Hanley & Ridgman (1979) reported the results from three cycles of six-course rotations on light land. The report was based on a rotation of sugar beet, barley, barley, potatoes, barley, barley, with treatments involving replacement of one, two or three of the first three crops by 1-, 2- or 3-year leys, the last three crops acting as test crops. One of the problems of drawing general conclusions from rotation experiments is that the test crops are really part of the experimental treatments and may not be the most suitable crops for determining either the direct effects of the ‘treatment’ crops or the longer-term effects of the rotations themselves.

Description: Infiltration is the most important aspect in the hydraulics of surface irrigation, since the design of irrigation systems depends to a large extent upon the infiltration characteristics of the soil. Many workers have contributed to the theoretical understanding of the infiltration phenomenon (Kirkham & Powers, 1972). However, very little work is available on the evaluation of infiltration into cracked soils. Measurement of infiltration into these soils poses a special problem. Depending on the degree of cracking, a fraction of the water added on the soil surface flows down through cracks and goes to waste. The water flowing through the cracks does not contribute to the moisture storage of the soil profile which may subsequently be used by the crops. Also, infiltration rates measured using ring infiltrometers are erroneous. In order to have an efficient design for an irrigation system, realistic estimates of infiltration characteristics for this type of soil are essential. In the present paper an attempt has been made to estimate the effective infiltration rate into such cracked soils. The procedvire suggested has been tested under limited conditions and found useful under field conditions. However, extensive field testing under various soil conditions is necessary before it can be recommended for general use.

Description: Fungicide applications to wheat have been reported to maintain the green area of the leaves (Dickinson & Walpole, 1975; Stevens & Palmer, 1980). It is not known, however, whether the photosynthetic rate of the leaves is also maintained. It was therefore decided to investigate disease development, green leaf area and photosynthesis of the flag leaf of winter wheat in response to the fungicide propiconazole, which has not previously been reported to influence senescence in the field.

Description: SUMMARYForty-eight Friesian cows in weeks 4–20 of lactation at the start of the trial were used in a comparative evaluation of Desmodium–grass silage, Rhodes grass silage, maize silage and lupin green forage. The forages were group-fed ad libitum and a concentrate was offered according to a standard lactation of 4200 kg milk in a 12-week test period. A digestibility trial with five wethers was used to evaluate the nutritive value of the forages.Cows offered the Rhodes grass silage had the highest forage dry-matter intake and those on maize silage had the lowest intake. There was no significant difference between the intake of Desmodium–grass silage and lupin green forage. Milk and FCM production were not significantly different on the four treatments although lupin green forage gave appreciably less than the silages. The expected milk production from the energy and protein consumed suggested that the milk produced was mainly from the concentrate. It is concluded that low energy concentration in all the forages, and low crude protein content in the silages, were the main limiting factors for high milk production.

Description: SUMMARYField 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.

Description: SUMMARYHerbage 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.

Description: SUMMARYA study using 1150 lambs to estimate genetic and phenotypic parameters of some weight and fleece traits was carried out on coarse-wool Barki sheep. The weight traits were birth, weaning, yearling weights and daily gains whereas fleece traits included kemp score, staple length and greasy-fleece weight.Heritability estimates of weight traits were within the range 0·25–0·30. Those of fleece traits were 0·16, 0·21 and 0·43. The repeatability estimates of fleece traits were 0·18, 0·38 and 0·53 for staple length, greasy-fleece weight and kemp score respectively.Phenotypic correlations between body weight and fleece traits were mostly positive. Genetic correlations between greasy-fleece weight and body weights were mostly positive and of medium values. Those between kemp score and body weights were mostly negative, ranging from medium-high to high.

Description: SUMMARYObservations were made in three successive years on the dentition of Scottish Blackface ewes of 1½–4½ years old in a large hill flock in southern Scotland.The number of permanent incisor teeth was not a reliable guide to age, since at each age there was variation about the modal number. The length of the central permanent incisors increased slightly with age, and associated with this there was a slight forward movement in the position at which these teeth occluded with the dental pad. The modal position was 1 mm behind the anterior point of the dental pad of gum. About 1·5 % of the observations had bite positions deviating by 5 mm or more from the mode.Keeping the females during their first winter on low-ground pasture instead of the hill led to earlier eruption and slightly longer central incisors, but had little effect on bite position.The heritability of the number of incisors present at any one age was estimated to be 0·39 ± 0·11 by paternal half-sib correlation and 0·80 ± 0·27 by daughter-dam regression. Estimates of h2 for incisor length were less than half these values and those for the measure of bite position were very small and not significantly different from zero.For the ages up to 3½ years old, there were low but statistically significant correlations of number of incisors with ewe live weight (0·1–0·2) and fleece weight (around 0·1), incisor length with fleece weight (around 0·1) and at 1½ years old only between the bite measure and both weights (0·1). Weight of lamb weaned by the ewe was uncorrelated with these dental traits.It is concluded that in this flock, culling on the dental characters studied would not have improved performance, and selection would not change the position of the bite.

Description: SUMMARYTwo potential new kale cultivars were compared with five control cultivars in 12 trials involving five sites in the north of England and the south of Scotland, 2 years, and a range of sowing and harvest dates.The differences between cultivars were small for dry-matter and digestible organic-matter yield. Genotype-environment interactions were relatively large by comparison and hence only tentative estimates could be made of relative yield performance in a wider range of environments. However, the set of trials was satisfactory for determining the heights, dry-matter contents and digestible organic-matter contents of the cultivars despite the presence of statistically significant genotype-environment interactions.Joint regression analyses revealed that the two cultivars with the lowest mean freshweight yields were also the least responsive to environmental change and that environments resulting in low digestible organic-matter contents were best for discriminating between cultivars.

Description: SUMMARYA re-examination of the results from 374 sheep used in previovis studies of calcium metabolism show there is a highly significant linear relationship between endogenous faecal loss of Oa and food intake, endogenous loss increasing by about 0·64 mg/day/kg body weight for each 1 g/day/kg body weight increase in food intake. This loss was unaltered by Ca intake or by pregnancy and lactation but was slightly higher in young animals than in adult animals given the same Ca intake on a body-weight basis. It is suggested that a variable factor for endogenous Ca loss, based upon some measure of level of feeding, should be introduced into rationing schemes.

Description: SUMMARYPhosphates and nitrate were added to the gel used for fluid drilling without affecting its properties as a seed carrier. The addition of monosodium phosphate promoted early seedling growth but at concentrations higher than 30 g/1 it became phytotoxic. Nitrate added to the gel reduced plant growth and decreased the number of seedlings emerging. Ammonium phosphate was found to be an effective addition to the gel and could be used in the form of a proprietary liquid ammonium polyphosphate fertilizer. The earlier emergence of fluid-drilled germinating seeds and the enhanced growth brought about by phosphate addition to the gel increased plant size compared with that of the dryseeded controls. The results are discussed in relation to the early production of marketable-size carrots.

Description: Harvest index has become a character used in plant breeding programmes and in evaluation of responses to agronomic treatments (Donald & Hamblin, 1976). Donald (1962) defined harvest index as the ratio between weight of grains and the weight of total dry matter, and later described it as a measure of partitioning of photo - synthates (Donald, 1968)

Description: The apparent digestibility of a diet can be calculated from the amounts of food eaten and excreta voided. This ‘total collection’ method is laborious because it requires a period lasting several days. It can be circumvented by the inclusion in the diet of a suitable reference substance (Kotb & Luckey, 1972). From the concentration of the reference substance (marker) in the diet and in the droppings, apparent dry-matter digestibility can be calculated.

Description: SUMMARYA study was carried out for 2 years in the arid zone of the northern region of the Sudan to investigate the effects of watering intervals on flowering, growth, yield and yield components of three groundnut cultivars. The variation in air temperature prevailing above the canopy through frequent and extended watering intervals affected the periodicity of flowering. MH 383 gave the highest pod yield and it was drought tolerant compared with Ashford and Turkish cultivars. Pod losses were smaller with longer watering intervals. Number of pods per plant was the yield component most affected by watering. Leaf area index increased with frequent watering and reached a value of 5·8. Net assimilation rate decreased at first, but later increased with the pegging of gynophores.

Description: SUMMARYPhosphorus requirements for maintenance and growth were assessed by giving to growing lambs and non-pregnant ewes diets low in P and to growing lambs a diet containing the quantity of P recommended by the Agricultural Research Council (1980).Seven 14-week-old lambs were given ad libitum a pelleted diet containing 1·88 (LP) or 2·75 (NP) g P/kg D. M. for 13 weeks. There was no effect of P intake on feed intake or growth during the first 8 weeks when the P intake of the LP groups was 1·07 of Agricultural Research Council (1980) requirements. During the last 5 weeks the P intake of the LP group was only 0·87 of Agricultural Research Council (1980) requirements and growth and feed intake were higher in the male but not female lambs in the NP group. From the 3rd week the plasma concentration of P was significantly lower (P

Description: SUMMARYThe effects of virea and urea plus sodium sulphate on the production of microbial protein were studied in sheep fitted with rumen fistulae and re-entrant cannulae in the proximal duodenum and terminal ileum. Diets containing a high proportion (0·68–0·72) of sodium hydroxide-treated barley straw supplemented with starch, glucose and solka floe were fed at hourly intervals to the sheep at 830–870 g dry matter/24 h.The addition of the urea and urea plus sulphate supplements, although inducing a stepwise reduction in overall digestibility of OM, resulted in increased microbial protein synthesis in the rumen, which was reflected in increased quantities of amino acid nitrogen entering the small intestine (8–38, 12–03 and 17–84 g of total amino acid nitrogen (TAA-N)/24h respectively). The efficiency of microbial protein production (g bacterial TAA-N/kg OM actually digested in the rumen) was significantly increased by the addition of urea and still further by additions of urea plus SO4-S (11·1, 20·2 and 29·6 grespectively).Digestibilities of the individual amino acids in the small intestine were very similar on each dietary treatment. Apparent digestibilities of total amino acid-N within the small intestine (based on amounts entering the small intestine) were 0·623, 0·672 and 0·688 on the basal diet, basal diet plus urea and basal diet plus urea and S respectively.The proportions of cyst(e)ine-S in rumen bacteria synthesized from the rumen sulphide pool were 0088, 0·075 and 0·669 on the basal diet, basal diet plus urea and basal diet plus urea and S respectively. The data confirm appreciable recycling of S into the rumen.

Description: SUMMARYMean progesterone concentrations were measured in the peripheral plasmas of Merino and Border Leicester × Merino ewes which were fed from day 2 to day 16 after mating on rations designed to provide twice maintenance (2 M), maintenance (M) and one quarter maintenance (¼ M) of food requirements. Mean plasma progesterone concentrations were consistently higher in the ¼ ewes than in the M or 2 M ewes whether they had two corpora lutea (CL) and two embryos surviving or one CL with either one embryo surviving or no embryo surviving, and tended to be lower in the 2 M than M ewes. It is concluded that there is an inverse relationship between levels of nutrition and progesterone within an oestrous cycle in ewes.

Description: SUMMARYAlthough salt injury in plants is due to both osmotic and specific ion effects, little is known about the reaction of rice plants to salinity under increasing sodium adsorption ratios (SAR) in the growth medium. Therefore, a glasshouse experiment was conducted to study the effect of four levels of salt concentration (20, 40, 60 and 80 m-equiv/1 with respect to the sum of Na+, Ca2+ and Mg2+) and four levels of SAR (2, 25, 50 and 75) on growth and mineral composition of rice cvs IR 2153-26-3 and IR 26. The results show that as salt concentration increased, dry-matter yield and percentage water content of shoots decreased regardless of the variety. The rate of decline with salinity was most pronounced under low SAR and in the salt-sensitive variety IR 26. With increase in SAR, the yield, percentage water content and concentrations of Ca, Mg, and K in shoots and roots decreased, but the effects were more marked at the lowest salt concentration and in IR 26. Variety IR 2153-26-3 showed greater tolerance, maintaining a higher concentration of Ca and higher Ca/Na and K/Na ratios and a lower concentration of Na and Cl in the tops compared with IR 26.The degree of salt injury in rice seems to depend not only on salt concentration but also on SAR in the growth medium whilst salt tolerance is associated with tolerance for both high salt concentration and high SAR. Therefore, in studies on screening rice varieties for salt and sodium tolerance, the interactive effects of SAR and salinity must be considered so as to ensure greater adaptability by the varieties recommended for salt-affected soils.

Description: SUMMARYThe effects of plant population density, defoliation and removal of pods and apical buds on dry matter, nodulation and nitrogen accumulation in field bean (Viciafaba L.) were investigated in the field in 1973 and 1974.In 1973 seed yield, dry matter and nitrogen accumulation were similar at 50 and 150 plants/m2 while in 1974 40 plants/m2 was significantly different from 80, 120 and 160 plants/m2 which were similar in these attributes. At similar densities, these crops generally had similar leaf areas and nodule weights/m2 during the early pod-filling period while at earlier growth stages leaf area and nodule development were greater at the higher plant population densities. Leaf area and nodule weight per plant were positively correlated as were absolute growth rate per plant and nitrogen assimilation rate per unit weight of nodule.Substantial leaf removal reduced weight but not the nitrogen assimilation rate of nodules determined from plant nitrogen content. Leaf removal did not significantly reduce dry matter but reduced nitrogen yield by reducing seed yield provided that the removed leaves were accounted for.Pod removal reduced dry-matter and nitrogen yield as well as nitrogen assimilation rate of nodules. Pod removal, however, substantially increased number and weight of nodules. Most of these late-formed nodules were located on the older parts of the lateral roots. Removal of the shoot apex had minor effects on nitrogen yield but reduced nodulation towards the completion of pod-filling.

Description: SUMMARYWheat (Triticum aestivum L.) cv. Gamenya was grown in a Mediterranean type environment in two separate field experiments, to determine the effects of nitrogen application and date of seeding on floret survival. One treatment, intermediate in nitrogen level and sowing date, was common in both experiments. Rates and durations of spikelet initiation and durations of the floret initiation period were estimated. At maturity, yield and yield components were measured and occurrence of individual grains at each floret position on odd-numbered spikelets were recorded. The time of floret initiation relative to terminal spikelet formation and the subsequent occurrence of grain were examined.Florets developed first in spikelets 5-13 and last in spikelet 1. Added nitrogen hastened the initiation of florets but did not affect the number initiated; it also increased the numbers of grains per spikelet. In the last sowing date treatment, time to floret initiation decreased, but the sequence of floret initiation was unaffected.Numbers of florets and grains on tillers were less than on main shoots. Only about 28% of all florets initiated developed into grain.The main conclusion was that the florets which initiated before the terminal spikelet formed grain and those that initiated afterwards did not; we accordingly postulate that the vascular system between the rachis and the floret develops as the floret is initiated, but that after terminal spikelet formation, this is inhibited and further grains then fail to develop.

Description: SUMMARYCorriedale and Dorset Horn castrate male (wether) lambs reared at pasture were weaned at 19 kg live weight (LW), brought indoors and fed a high protein diet such that half of each group grew at ca. 200 g/day and the other half at ca. 100 g/day. Animals were slaughtered at 25 and 30 kg LW and chemical composition (protein, fat, energy, water and ash) of the body determined. The relationship between each body component and shorn empty-body weight was examined by regression analysis.Within levels of feeding the results were similar in the two breeds. When comparisons were made between feeding levels, the slower-growing animals contained more fat, energy and ash than the faster-growing group, less water, but similar amounts of protein at any given empty-body weight.

Description: SUMMARYExperiments were made on a sandy clay loam soil with five crops to determine the effects of thorough loosening of the subsoil and deep incorporation of nutrients on yields during the subsequent 4 years.Loosening to 0·9 m increased fresh-weight yields by between nil and 95% depending on the crop and season. Responses were still considerable 4 years after the initial loosening and there was no evidence of any decline with time. Deep incorporation of nutrients did not improve yields.Loosening gave a durable increase in the volume of coarse pores and decreases in bulk density and penetrometer resistance. It also nearly doubled the rate of root extension when estimates were made for one crop, consistently increased water extraction from below 30 cm and, on occasion, reduced plant water stress.It is concluded that most of the benefits from deep loosening resulted from improvements i the rate at which plants could extract water rather than nutrients from the subsoil.

Description: SUMMARYThe net energy values for growth and fattening of two artificially dried tropical grasses-, pangola (Digitaria decumbens) and setaria (S. sphacelata var. sericea cv. Nandi), of similar estimated metabolizable energy content (8·07 and 7·96 MJ/kg D.M.) were determined with cattle using a slaughter technique. Growing cattle with a mean initial weight of 175 kg were given equal quantities of dry matter of the two grasses at each of three planes of nutrition above maintenance for a period of 152 days.The initial energy, fat and protein content of the total body of the 24 test animals was estimated from regressions relating fasted live weight to theśe components, derived from 12 similar cattle slaughtered at the beginning of the feeding period. The final energy, fat and protein content of the test animals was determined directly by chemical analysis. The metabolizable energy (ME) content of the grasses was estimated from the level of digestible energy (DE) determined with eight cattle, assuming that ME = 0·815 DE.The cattle fed pangola gained more live weight, empty-body weight, fat, protein and energy than animals fed similar quantities of setaria. The net energy value for growth and fattening (NEf) was determined using regressions relating energy retention to the quantity of dry matter eaten. NEf in MJ/kg dry matter was 2·27 for pangola and 1·31 for setaria.Efficiency of utilization of ME for growth and fattening (kf) was.27·7% for pangola and 16·9% for setaria. These values for tropical grasses are lower than any values reported for temperate pasture species. Thus the lower efficiency of utilization of ME may cause the lower production of cattle which graze tropical grasses.It was concluded that as the kf values of different tropical grasses are not constant, kf values should be measured on a wider range of tropical grasses so that this factor can be taken into account when evaluating grasses in animal production systems.

Description: SUMMARYIn the first of two experiments 45 ewes were treated on day 141 of gestation with either prostaglandin F2a or saline. Doses of 10, 15, 20 or 25 mg PGF2a failed to induce lambing earlier than in control animals. A further 50 ewes were similarly treated on day 144; neither dose level of PGF2a nor day of administration had any effect on the interval from injection to lambing compared with controls. In a second experiment 159 ewes were randomly assigned to one of four treatment groups as follows: (1) 20 mg oestradiol benzoate (ODB); (2) 16 mg dexamethasone; (3) 15 mg PGF2a; (4) 2 ml saline. Ewes were injected on either day 143 or 144 of gestation and on each of those days animals were injected either in the morning or evening. The mean times to induction of lambing were 38·6 ± 20·8; 44·2 ± 18·1; 83·5 ± 39·8 and 82·9 ± 43·1 h for the four treatments respectively. Neither day nor time of treatment had any significant effect on the interval to lambing. Both ODB and dexamethasone induced parturition earlier than PGF2a or saline (P 〈 005).

Description: SUMMARYSoya-bean plants were grown for 40 days in a range of root temperatures from 10 to 25°C either in a root medium containing N but uninoculated or in a N-free medium but inoculated with Rhizobium japonicum. Low root temperature restricted growth in both cases but the plants depending solely on symbiotic N-fixation were much more affected. At 10 CC root temperature plants failed to nodulate but both nodulation and nitrogen fixation increased greatly in the range 15–25°C. It is concluded that soya beans sown in cool soils would benefit from applied nitrogen at sowing time.

Description: SUMMARYThe nature of the ectosymbiotic association between Rhizobium and such legume leaves as Bengal gram and mung bean was investigated using radioactively labelled compounds. About 8% of the 14CO2 fixed photosynthetically in the 70% ethanol soluble fraction was leached out within 1 h of contact with water. The 14C-compounds leached out include sucrose, serine glycine, glutamic acid, malate, alanine and succinate. A part of the 14C-activity was incorporated by Rhizobium cells sprayed on leaves. Association with rhizobia increased the rate of photosynthesis and leaching by 129–240% and 134–281%, respectively. Bacterial metabolites are translocated along the midribs and veins to different plant parts. The beneficial effects are not restricted to members of the same cross-inoculation group.

Description: SUMMARYIn an experiment on permanent grass at Rothamsted during 1975–9 fertilizer-N was applied each year either by injecting an aqueous solution of urea (supplying 250, 375 or 500 kg N/ha) in spring, or by broadcasting ‘Nitro-Chalk’ granules (supplying 100, 200, 300, 400 or 500 kg N/ha) in six equal dressings for each of six cuts.Dry-matter production was largest on plots injected with urea through knives 30 cm apart, and more N was recovered from the injected than from the broadcast applications. Aqueous urea injected at the 60 cm knife spacing nitrified more slowly and persisted in the soil longer than urea injected at 30 cm spacing; this persistence caused grass to grow more uniformly throughout the season, but yields were less. Injecting the nitrification inhibitor sodium trithiocarbonate (STC) with the aqueous urea postponed N uptake much less than doubling knife spacing, but the inhibitor substantially diminished percentage N03-N in harvested grass.In spring 1977 individual plots were split to measure N residues. Half-plots thus received N at the specified rates, either in 4 successive years (1975–8) or in two pairs of successive years (1975 and 1976; 1978 and 1979). In 1977 urea injected in the 2 previous years gave large residual effects, which were increased by STC and also by injecting in bands 60 instead of 30 cm apart. Broadcast ‘Nitro-Chalk’ had much smaller residual effects. In 1979 residual effects of N applied in the 4 previous years were apparently small, regardless of the method of application, because clover became abundant on plots not given N.In 1978 dry-matter production was smaller where N had been given each year during 1975–8 than where N was withheld in 1977. Analysis showed this was caused by a shortage of potassium. This effect was most pronounced where 375 or 500 kg N/ha had been injected in bands 60 cm apart.The results showed that a single, injected application of aqueous urea increased yields of dry grass as effectively as equivalent repeated dressings of ‘Nitro-Chalk’.

Description: SUMMARYHereford heifers were fed a diet (7·0 MJ ME/kg D.M.) containing 0·09 % phosphorus but complete with regard to other nutrient constituents. Only after 19 weeks wore the effects of subclinical aphosphorosis evident in the form of reduction in feed intake, cessation of weight gain, increased feed conversion and decreases in tho concentration of inorganic phosphorus in blood and saliva. Heifers supplemented daily with 12 g phosphorus sustained a weight gain of about 0–2 kg/day over 62 weeks as did other supplemented heifers whose feed intake was restricted to that of tho low phosphorus treatment. The effects of phosphorus supplementation were thus demonstrated without being confounded by concomitant increases in feed intake.Phosphorus supplementation resulted in significantly lowered apparent crude protein digestibility and a slight increaso in cell wall digestibility.

Description: SUMMARYField experiments consisting of three mulch treatments (no mulch, straw mulch and dust mulch) and six transpiration suppressants (no suppressant, kaolin, phenyl mercuric acetate, atrazine, mobileaf or alachlor and 2-chloro ethyl trimethyl ammonium chloride) were conducted under dryland conditions during the summer rainy seasons (July–November) of 1976, 1977 and 1978. Compared with no mulch, straw mulch increased yield in all 3 years, water use efficiency in 1977 and 1978, and uptake of N and of P in 1977 and 1978. Dust mulch had only a marginal advantage. Amongst transpiration suppressants, only kaolin and atrazine had a marked effect. Both these chemicals increased grain yield, water use efficiency and uptake of N and P, compared with no suppressant.

Description: SUMMARYCattle 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.

Description: SUMMARYRelative 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.

Description: SUMMARYTwo 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.

Description: SUMMARYExperiments 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.

Description: SUMMARYSix 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.

Description: SUMMARYSweating 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.

Description: SUMMARYA dynamic model of rumen processes is constructed. The nine state variables considered are: rumen metabolic volume, non-rumen-degradable β-hexose, rumen-degradable β-hexose, α-hexose, water-soluble carbohydrates, non-protein nitrogen, rumendegradable protein and non-rumen-degradable protein. The dietary and salivary inputs to the rumen may be continuous, or pulsed. Rumen outflow given by the model is compared with data on sheep fed with different diets. Reasonable agreement is obtained when the model is run in the continuous mode, but there are considerable discrepancies between the experimental data and the pulsed model.

Description: SUMMARYData 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.

Description: SUMMARYThe 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.

Description: SUMMARYVery experienced livestock judges and three ultrasonic machines were compared for accuracy in predicting carcass composition.Sixty-four steers of mixed breed were visually scored for fatness and meat yield by seven judges. Subcutaneous fat depths over the eye muscle at the 13th rib were measured with three different ultrasonic devices prior to slaughter. There was little difference between the ultrasonic machines and the best visual estimates of fatness for predicting weight of commercial trimmed or total dissected fat. Visual estimates of meat yield were not as accurate as the judges' fat scores for predicting carcass composition.Subcutaneous fat depths measured by ultrasonics were shown to be as well related to carcass composition as the best judge's fat scores.

Description: SUMMARYThiaminases from different sources exhibit varied responses to change in pH and to differing activators, cosubstrates and inhibitors. These properties are used in an attempt to characterize the extracellular thiaminases of 17 strains of Bacillus spp. isolated from the rumen contents of animals affected with cerebrocortical necrosis and to compare these with the endogenous thiaminase present in the rumen content of such animals and with other known thiaminase-producing bacteria. Statistical analysis of the results obtained using different activators classified the isolates into two main groups corresponding to the presence of thiaminase I or thiaminase II. The pH characteristics of the rumen content enzyme differed significantly from any of the bacterial isolates examined.

Description: SUMMARYTrials 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.

Description: SUMMARYExperiments with spring barley at Saxmundham, in each year from 1975 to 1978, compared two varieties (Julia v Wing), two amounts of granular N-fertilizer (50 v 100kg N/ha) and two times of applying it (seed bed v top-dressing), a liquid N-fertilizer spray (0 v 50 kg N/ha), mildew fungicides (with and without) and a rust fungicide (with and without), in factorial combination (26).Leaf diseases were assessed and grain weighed and analysed for % N each year. Thousand-grain weights were measured in 1977 and 1978.Yields were small in 1975 and 1976 because little rain fell in summer, but larger in 1977 and 1978, years with average rainfall.Mildew was most severe in 1975 and least in 1978, brown rust most severe in 1975 and 1978 and practically absent in 1976. Granular N-fertilizer was best applied to the seed bed in all years, whether or not leaf diseases were controlled. Late sprays of liquid N-fertilizer increased yield less than equivalent amounts of seed-bed N, but increased % N in grain more. However, because they also decreased grain size, less of the N applied as a liquid was recovered by grain than was recovered from granules given earlier. The mildew fungicides increased yields by ca. 0·25 t/ha in 1975 and 1977, but decreased them in 1976. They had little or no effect on % N in grain, but increased grain size in 1977. The rust fungicide, benodanil, increased grain yields each year and especially in 1978 (0·37 t/ha). It had no effect on grain % N, but consistently increased grain size and so enhanced grain yield and N uptake.

Description: It has long been known that the size and shape of sampling units used to assess crop yield may have significant effects upon the precision of the estimates (Smith, 1938; Hudson, 1939) but little is known about the effects when estimating incidence of disease. Gilligan (1980) showed that estimates of the incidence (i.e. presence or absence of disease) of stem canker (Phomx, lingam, perfect state Lepto sphaeria maculans)of oil-seed rape were more precise when large square sampling units rather than long rectangular units of similar area or small square sampling units were used. Moreover, estimates derived from the frequently used method of sampling by removal of 25 stems, supposedly at random from each plot, were shown to be biased.

Description: SUMMARYA field experiment was conducted on a saline sodic soil at Kanpur to study the effects of sedimentary pyrites and Zn on the yield, Zn and Ca utilization by rice and wheat crops and on the amelioration of saline sodic soil. The grain yield of the first crop of rice increased from 1·55 t/ha for the ‘control’ to 3·44 and 4·01 t/ha with the 40 and 80% gypsum requirement pyrites treatments. The grain yield of succeeding wheat and rice crops also increased significantly owing to pyrites residues. The favourable effect of pyrites on crop yield was associated with an appreciable decrease in the pH, electrical conductivity and exchangeable and soluble sodium content of the soil resulting in greater utilization of Zn and Ca by the crops. Zinc applications also greatly increased grain yield and Zn uptake by the crops. The higher levels of pyrites with adequate N, P and K fertilizers but without Zn did not give yields that were obtained by adding 11 kg Zn/ha.Significant yield responses were observed in the succeeding wheat and rice crops to Zn residues from the higher Zn treatments. The ‘pyrites+Zn’ treatment was most effective in decreasing the Na content and enhancing Ca uptake which increased the Ca/Na ratio in plants. The Zn treatment alone also decreased soil pH, electrical conductivity and exchangeable Na.

Description: SUMMARYThree successive generations (parents, F1, F2) and backcrosses of the common bean (Phaseolus vulgaris L.) hybrid between the cultivars Swedish Brown and Seafarer were used in this study.The investigation has concentrated on assessing the relationship between the seed weight per plant and the protein percentage of the seed. Protein percentage showed a higher estimated heritability and a greater stability over environments than seed weight.Partial dominance for low percentage protein and low seed weight was noted. Negative and low regression coefficients between these two characters was also observed.SDS-gel electrophoresis was used to examine the variation in banding patterns of total seed polypeptides and their stability over environments.

Description: SUMMARYFree amino·N estimations were used to monitor the movement of free amino acids in blood passing through the hindquarters of sheep and growing pigs. The net uptakeor release of free amino·N was calculated from arterio-venous differences in the concentration of free amino·N measured in whole blood and plasma at short intervals of time.In both species the net change was an apparent release of free amino·N into venous blood. The release increased on fasting. Net uptake of free amino·N from blood was occasionally found at single sampling times due to loss from the cell compartment in sheep and from the plasma compartment in pigs. The uptake measured in whole blood was always less than in a single compartment of blood. The greatest fluctuation in free amino·N concentration occurred in the cells of aorta blood.It is concluded that both blood cells and plasma have independent roles in the net flux of free amino·N requiring determinations of amino acids in both whole blood and plasma to describe the exchange of blood free amino acids with tissue. A negative arteriovenous difference of free amino·N in blood across skeletal muscle is normal for healthy well-fed animals. Fasting increases the negativity.

Description: SUMMARYThe Sudan Desert sheep are well adapted to the hot tropical climate, are thirst tolerant and can travel for long distances under nomadic conditions in search of water and pasturage. The ejaculate volume, sperm cell concentration, total number of sperms per ejaculate, motility, percentage live and percentage abnormal spermatozoa and the fructolytic index of semen were estimated throughout the hot dry summer (March-June), hot rainy season (July-October) and the winter (November-February). The semen characteristics were normal for about 7 months (May-November) covering the last 2 months in summer, the whole rainy season and the 1st month in winter and deteriorated slightly during the rest of the winter and early summer. Thus the Sudan Desert rams appear to be able to breed throughout the year and their spermatogenesis is not seriously affected by high environmental temperatures.

Description: SUMMARYTwo-year-old Romney wethers were fed diets with (a) varying proportions of N (0·5, 1·1, 1·4 and 3·4%) while on similar digestible organic matter (DOM) intake, and (b) the same proportions of N with different DOM intake.The composition of rumen volatile and unesterified fatty acids, as well as of lipids and fatty acids of plasma, liver, muscle and perirenal fat, was determined.When the proportions of dietary N were varied the findings were as follows: in the rumenahigh level of propionate (37%) was found on the 1·4% N diet, unsaturated fatty acids constituted between 20 and 30% of rumen unesterified fatty acids with diets containing 0·5 and 3·4% N, while sheep on 1·1 and 1·4% N diets had 70·80% unsaturated fatty acids. In plasma and tissues other than the liver there was a greater proportion of unsaturated fatty acids in sheep fed the 1·4% N diet. Total liver lipids were highest on the 0·5 and 3·4% N diets. Perirenal fat was highest on the 0·5% N diet.With the exception of unesterified cholesterol, tissue and plasma cholesterol concentrations decreased with increasing dietary N content.Increased DOM intake while the proportion of dietary N was kept constant caused few changes in lipid and fatty acid composition of rumen, plasma and tissues.

Description: SUMMARYTwo experiments were carried out with adult sheep to investigate the effects of chloral hydrate (CH) on rumen metabolism and on the sites and extent of digestion.Experiment 1 confirmed that CH is a very potent methane inhibitor; doses of 1 or 4 g/day reduced methane production to 4% of that observed in the absence of the drug. In both experiments, CH administration altered the proportions of volatile fatty acids in rumen fluid. The main changes were an increase in propionic acid and a decrease in acetic acid with smaller increases in the proportion of isovaleric, valeric and caproic acids. Stoichiometric calculations indicated that only 21% of the hydrogen saved by prevention of methanogenesis was diverted to the synthesis of additional propionic and butyric acids and the fate of the remaining hydrogen was not determined unequivocally.CH had little effect on the extent of biohydrogenation in the rumen of the long-chain fatty acids in dried grass.The apparent digestibility of ether extract was reduced (P 〈 0·05) by CH but those of other proximate constituents and energy were little affected. There were no s gnificant effects of CH on the extent of digestion of dry matter, organic matter, non-ammonia nitrogen or ash between the mouth and abomasum, abomasum and terminal ileum or ileum and anus.

Description: SUMMARYNineteen ecotypes from northern Britain and selected genotypes of a cultivar of L. perenne were assessed in controlled environments for shoot growth at low temperature and irradiance and also short daylengths. The ecotypes were collected from a range of altitudes at sites experiencing estimated mean monthly temperatures in the coldest month between -0·1 and + 4·2 °C.A clinal relationship between low temperature growth and the winter temperature at the place of origin of the ecotypes could not be found in these experiments. Low temperature growth was not generally associated with altitude of origin of the plants, but in this study some of the plants collected from mid-altitude were exceptional in leaf growth produced at 5 °C. Types of L. perenne which extended leaves quickly also produced heavier shoot weights than other types less able to show rapid leaf extension at low temperature. The exceptional ecotypes may provide useful basic plant material for breeding cultivars of L. perenne to grow at low temperatures, and irradiances and short daylengths. Several possible explanations are discussed for the differences in shoot growth found between L. perenne ecotypes at low temperature.

Description: SUMMARYHerbage characteristics of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.) and timothy (Phleum pratense L.) pastures were obtained whilst rotationally grazed by ewes and their single lambs at a fixed stocking rate of 25/ha on an upland site (305 m O.D.) in mid-Wales. Drymatter production of cocksfoot averaged 32·1 kg/ha/day over the 3-year duration of the trial (1975·7) and was 13·3 kg/ha/day lower than that of the other three grass species. This resulted in a 8 kg/ha/day reduction in dry-matter intake on cocksfoot; this was significantly lower (P 〈 0·05) than that achieved on the other grasses, which were similar to one another around 36 kg/ha/day.In vitro digestibility of the herbage ranked in the order perennial ryegrass 〉 timothy = cocksfoot 〉 tall fescue. Intake of digestible organic matter (DOMI) was lower on cocksfoot than on perennial ryegrass and timothy. Differences were also detected in crude protein, water-soluble carbohydrates and sodium composition between species.Dry-matter intake was positively correlated with herbage growth rates (r = 0·95, P 〈 0·001) but not to digestibility of herbage on offer (r = 0·18). Both ewe and lamb live-weight gains were positively related to intake of dry matter and DOMI.Reference is made to comparative yield data between the grasses obtained under cutting trials. In the 2nd and 3rd harvest years (1967–1967) growth rates in the grazing experiment were 76, 61, 81 and 80% of the 66·2, 66·7, 67·8 and 65·0 kg D.M./ha/day obtained under a cutting regime on perennial ryegrass, cocksfoot, tall fescue and timothy swards respectively. This illustrates the danger involved in assessing the potential of grasses based on such information.The results are discussed in relation to the value of the species for use under grazing in the uplands.