ALBERT

Description: SUMMARYSoluble ammonium nitrate (AN) and urea were compared with slow-release oxamide and sulphur-coated urea (SCU) as N sources for clipped annual ryegrass (Lolium multiflorum) or common bermuda grass (Cynodon dactylon) in four greenhouse experiments. Mixed and surface applications of a wide range of N rates were evaluated for 9 to 14 cuttings of grass forage. Both granular oxamide and SCU exhibited slow-release N properties, especially when surface-applied. Uptake distribution of N with high application rates of AN and urea tended to resemble that with the slow-release sources. Slow-release properties of oxamide and SCU were accentuated at high application rates. Lower N recovery from surface-applied urea than from AN indicated volatilization loss of urea N. Volatilization loss also occurred with oxamide, but low N recovery from oxamide and SCU resulted largely from incomplete dissolution of the granules during the 18- to 34-week experimental periods. Very low N recovery was obtained from urea formaldehyde having an activity index of 42.

Description: SUMMARY1. The Awassi ewes reached an average live weight of 45 kg at two years of age and a mature weight of 57 kg at four years of age.2. The average yearly production of grease wool has been 2·2 kg.3. When rams were kept with the flock throughout the year approximately 60% of the lambings occurred during January–February. It declined rapidly during the following months and no lambs were born in July–August.4. Single lambs had an average birth weight of 4·6 kg for males and 4·3 for females. Twin lambs were about 20% lighter than singles. The corresponding weaning weight at two months of age was 17·9 and 16·8 for singles and 13·4 and 12·4 for twins.5. The twinning rate increased from 5% at first lambing to 30–35% at 6th lambing, when the ewes were about seven years old.

Description: SUMMARYMerino lambs had higher serum protein concentrations at birth than Blackface lambs. In both breeds single lambs had higher concentrations than twins. The maximum mean immunoglobulin concentrations in Merino singles, Blackface singles and Blackface twins were 2·50±0·12, 2·50±0·19 and l·96±0·15 g/100 ml serum respectively, and were recorded 18 or 21 h after birth.

Description: SummaryThe carcass characteristics of a total of 43 infertile bulls were oompared with those of 42 steers from five independent trials. In most cases there was no significant difference between the bulls and the steers for dressing percentage, or fleshing index. Bulls were generally found to have greater hide percentages than steers, the difference being very highly significant (P 〈 0·001) in one of the trials and significant (P 〈 0·05) in another. Eye musole area expressed relative to caroass weight was greater in the bulls, the difference being significant (P 〈 0·05) in three of the trials. The depth of fat over the eye musole and the hind to fore-quarter weight ratio were greater in the steer carcasses. Head weights were found to be significantly greater (P 〈 0·05) and caul and kidney fat weights less (P 〈 0·05) in bulls than in steers in the one trial where these parameters could be measured.Carcass composition was estimated by the three-rib sample joint teohnique in four of the trials, and in these the bulls had a greater percentage of bone and muscle, but a lower peroentage of fat than the steers, the differences being significant in most oases. In the fifth trial composition was estimated by half carcass dissection. This, too, showed bulls to have a greater percentage of bone and muscle and a lower percentage of fat, the differences being highly significant (P 〈 0·01) and very highly significant (P 〈 0·001) respectively. On a fat-corrected basis the estimated retail value of the carcasses favoured the bulls by about $20.00 each.The studies, conducted over a range of nutritional conditions, showed that non-castration favoured muscle growth while suppressing fat deposition, and that this advantage was more pronounced when growth rates were high.

Description: SummarySymptoms of magnesium deficiency and take-all disease occurred during 1967 in wheat grown for the second year in succession on the ‘Classical’ cereal site at Woburn. Magnesium fertilizers, which cured the deficiency symptoms and increased wheat yields in 1968 and 1969, had no effect on take-all. Leaves from crops severely attacked by take-all contained less nitrogen and potassium than leaves from unattacked plants but not less magnesium. In 1969 magnesium fertilizer did not increase yields or affect takeall of spring barley on the site but, in contrast to 1968, increased potato yields. Magnesium fertilizer improved the establishment of clover, especially on soil containing least magnesium.Soil analyses show a tenfold decline in exchangeable Mg since 1888. Losses were most from soil given ammonium sulphate and more from the site where wheat was long grown than where barley was. Differences in soil magnesium did not explain large differences in yields of potatoes or leys between blocks of the experiments.

Description: SummaryMeat quality comparisons were made between a total of 43 infertile bulls and 42 steers in five separate trials. Tenderness, juiciness and flavour were tested by taste panel for each of the five trials, making 15 subjective tests, while objective tests were made of tenderness (Warner-Bratzler shear) and juiciness (industrial press) in the five trials, making a further ten tests.From this total of 25 different groups of assessments no significant difference between bull and steer meat was detected in 21; of the four groups of assessments where significant differences were detected, two favoured the bulls and two favoured the steers; the quality of all the samples was acceptable.It is concluded from the overall results that in terms of practical meat quality there was no difference between the bulls and steers used in these five trials.

Description: SummaryIn a series of field experiments from 1966 to 1969, on light sandy loam soils in the West Midlands, comparisons were made between two levels of application of herbicides based on urea, triazine and bipyridil compounds for weed control in early potatoes.Under conditions of adequate nutrient and water supply, the high application rate controlled about 94%, and the low application rate about 88% of the annual weeds. At equivalent application rates, urea compounds and herbicide mixtures containing ureas, gave superior weed control to triazine compounds and herbicide mixtures containing triazines, but the ureas were apparently more phytotoxic to the potatoes.In 1970, comparisons were made between three levels of application of ametryne and monolinuron, high, medium and low and an unsprayed control treatment.The highest yields of potatoes were associated with the low application rates of herbicides from 1966 to 1970.It was concluded that, on these light sandy loam soils, when irrigation is available, relatively low application rates of either monolinuron or ametryne, or mixtures of ureas or of triazines, or mixtures of bipyridils and ureas or triazines could give adequate control of annual weeds in early potatoes at low cost.

Description: SummaryAlthough it is not always valid to regard ‘within herd variation’ as a true measure of experimental error there are occasions when this may be the only feasible measurement. The effect is considered of regarding the animal as the experimental unit on the estimation of the ratio of production of two treatments and an approximate variance for the ratio is obtained. The conditions under which the approximation is valid are considered.

Description: SummaryPollination treatments were carried out on highly inbred lines of winter beans over a period of four years.Tripping produced an inferior seed-set compared with all treatments involving emasculation and hand pollination with either cross or self-pollen. It is suggested that with highly inbred lines the stigmatic surface requires some form of scarification to improve the seed-set. Most lines showed no preference for cross or self-pollen, and there was no evidence of self-incompatibility. Bud and mature flower pollination gave an improved seed-set over tripping in all lines.One inbred line gave a high seed-set in all pollination treatments. Results from another line were consistent with a short period of ovule receptiveness.Using data obtained from three experiments, two self-pollination treatments were used to screen breeding lines for their suitability as components of synthetic varieties. Significant differences in seed-set were found between the lines.

Description: SummaryBlood samples were obtained at monthly intervals for 12 months from 8 HK and 8 LK wethers of the Marwari breed maintained at Jodhpur (26° 05′ N, 73° 01′ E). The samples were analysed for packed cell volume (PCV), red blood cell count (RBC), haemoglobin concentration (Hb), mean cell volume (MCV), mean cell haemoglobin concentration (MCHC), plasma inorganic phosphorus and plasma specific conductance.The HK animals, on average, had significantly higher PCV, RBC, Hb, MCHC and plasma inorganic phosphorus values than the LK animals but the MCV was significantly higher in the LK group. There was no difference in the plasma specific conductance.PCV, RBC and Hb values differed considerably from animal to animal within each group. These individual variations could help the breed to survive in a desert environment.No particular tendency or pattern in the effect of season on the blood characters studied has been observed. This indicates that the animals of both groups responded in a similar way to the environmental changes.

Description: SUMMARYMeasurements made on soils from the Ley–Arable rotation experiments and some of the Classical experiments at Rothamsted and Woburn are described. Values of exchangeable K, equilibrium activity ratio, equilibrium K potential, and buffer capacity are given for each plot. Potassium quantity/intensity relationships measured for each plot showed that no differences in K exchange behaviour have arisen as a result of manuring or of ley or arable treatments. The only fundamental variation was in the quantity of K in the soils. Continuous ley plots, whether given N fertilizer or containing clover, contained much more K than plots carrying crop rotations. In the Classical experiment soils, quantity of K depended largely on manuring.Potassium uptakes by ryegrass grown on the soils from the various plots are discussed. Potassium uptake was well-related to quantity of K, better so than to the other K parameters. The release of non-exchangeable K to the crop was non-linearly related to the fall in exchangeable K in the soils from the Rothamsted Ley-Arable experiments.Drying and re-wetting the cropped soils released K in amounts inversely proportional to the amount of K in the moist cropped soil. This release of K was unrelated to the original exchangeable K contents of the soils.

Description: SUMMARYA trial to compare the reliability of yield of a quick maturing maize (Taboran) with the medium maturity local maize was carried out at two low rainfall sites in Southern Province, Kenya, from 1957 to 1961. Each variety was grown at two spacings, giving plant densities of 1·8 and 3·6 pl./m2. Results showed a consistent difference in ‘days to 50% silking’, Taboran being on average 17 days earlier than Local White. There was no overall difference between varieties or spacings in yield per ha. There were highly significant interactions of seasons with varieties and with spacings. These were interpreted in terms of different linear yield/rainfall relationships for each variety and each spacing. A variety/spacing interaction was also demonstrated.Analysis of components of yield showed that similar linear relations between rainfall and each yield component obtained. There were significant differences between varieties and between spacings in both mean number of cobs per plant and yield per cob. Taboran had a higher mean number of cobs per plant and Local White a higher mean yield per cob. Seasons x varieties interactions were again interpreted in linear regression terms. Earliness of the Taboran variety often enabled plants to produce silks before development was arrested by drought and so was responsible for its relatively high mean number of cobs per plant in low rainfall seasons, giving it an advantage over Local White in yield per unit area in such circumstances. Taboran was shown to have a potential value in local agriculture, because of its consistency of yield. The expected advantage or disadvantage of Taboran over Local White was calculated for an area of known rainfall from the respective yield/rainfall regressions and the seasonal rainfall probabilities.Selection for earliness was shown to be of basic importance in a breeding programme for the low rainfall areas. Within a specified early maturity range, selection for yield improvement through the yield per cob component could be practised. A maturity length similar to Taboran would ensure a high value of mean cobs per plant in low rainfall season, i.e. confer the necessary reliability of yield.

Description: SUMMARYSteers fed low nitrogen diets were infused intraruininally with water.Increasing the water load increased the urine volume and urinary urea excretion and depressed the plasma urea level.The effect of intraruminal water loading was studied in association with intravenous urea loading of 25 and 65 g N/day. When 25 g N/day as urea was infused intravenously, water loading did not significantly increase the urinary urea excretion but the plasma urea level was depressed. At 65 g N/day water loading increased the urinary urea excretion and decreased the plasma urea level.Significantly different relations between plasma urea and urea load existed for the ad lib. water and the water-loaded treatments but the relation between rumen ammonia level and plasma urea level was not affected by the water loading.The results are discussed with reference to the recycling of urea.

Description: SUMMARYThe growth patterns of impetus groups of muscles were mostly not significantly affected by rate of growth of the musculature. One small group – the low/average impetus muscles – had a significantly lower ‘b’ value in the calves fed at a high plane. It appears that under differences of feeding encountered commercially, no changes of practical importance in the relative growth of muscles are likely to be produced which are attributable to rate of growth of the musculature.

Description: SUMMARYCalves were slaughtered at predetermined weights after being fed individually on fresh and reconstituted whole milk at three levels. The highest level of feeding was ad libitum and the lowest was aimed at keeping the calves at their birth weight for 72 days before providing extra milk to allow growth to proceed.Dressing percentage did not decline with age as it did in a previous experiment using roughage in the diet. The faster-grown calves had a higher dressing percentage. It is concluded that both rate of growth and the physical nature of the diet influenced dressing percentage.Muscle: bone ratio and the amount of fat and bone in the carcass were not significantly affected by the rate of live-weight increase.

Description: SUMMARYAttempts were made to relate various parameters of growth in wheat substitution lines to final yield of grain and assess the extent to which such relationships could be useful as early predictors of yield. The associations were measured by calculating correlation coefficients, partial regression coefficients, standard partial regression coefficients and independent contribution to yield. Significant correlation coefficients were common but significant partial regression coefficients were rare. The remaining estimates provided a ranked order of characters associated with yield. Those parameters of vegetative growth showing most association with final yield were themselves related fairly directly to ear and grain size. It was concluded that direct estimates of yield must remain the most appropriate character on which to base selection in cereals.

Description: SUMMARYSeveral criteria which have been used hitherto in the hope of selecting large-yielding clones of tea have been examined. The heights, girths, root weights and branching a gles of young seedlings in the nursery are correlated with the sizes and yields of the same plants when mature, but not with the rates of growth in the nursery, or the yields at maturity, of the plants derived from these seedlings by vegetative propagation. The pruning weight, size and yield of a mature plant grown from seed are not related to the rate of growth in the nursery or the yield at maturity of the clone derived from that plant. The proportion of cuttings which form roots and the growth rate of the cuttings of a clone are not related to the yield of the clone. It is concluded that these criteria are, at best, of limited value in the selection of large-yielding clones.Phloem Index, which is the number of calcium oxalate crystals counted in the phloem parenchyma in a cross-section of the petiole, varies with the age and rate of development of the shoot from which the petiole is taken and with the concentration of nutrients in the soil. It is therefore not useful as an alternative selection criterion under normal field conditions.

Description: SUMMARYStocking rates of 3, 6 and 9 acres per 2- to 3-year old steer on Acacia-Cymbopogonj Themeda complex pasture in Ankole, Uganda, demonstrated that 3 acres per head gave significantly lower individual live-weight gains, but that there was little difference between 6 and 9 acres over a 6-year period. Although cattle grazed at 3 acres averaged only 175 lb per head per annum, compared with 207 lb at 6 acres per head, the income was Sh. 34 per acre compared to only Sh. 20–50 at 6 acres per head. At 9 acres/head the return was Sh. 13–50 an acre.A comparison of a 2 paddock/1 herd system with continuous grazing revealed no differences in production, despite the heavier capital investment involved in the former system. Growth rates at all three stocking rates were similar for most of the year, but in the dry season when all the cattle lost weight those stocked at 3 acres per head suffered the greatest losses (50–60 lb) and those at 9 acres per head the least (20–30 lb).

Description: SUMMARYThe metabolizable energy (ME) values and net absorption of tallows containing 20, 40, 60, 80 or 98% free fatty acids were determined using mature laying hens. By restricting food intake, the intake of the tallows was controlled to 3, 5, 10 or 20 g per bird d. The tallows were added to a diet of known ME content and the ME's of the tallows were calculated from the data collected from 6- or 7-day energy balances.ME and net absorption values of the tallows were significantly (P 〈 0·001) lowered when the level of intake was increased from 3 to 20 g/bird d. The values were also significantly (P 〈 0·001) lowered when the free fatty acid content was increased from 20 to 98%. The effects of free fatty acid level (F) and level of intake (L) on the ME and net absorption values were considered in terms of curved surfaces represented by equations embracing the factors and their product. The equations obtained were:ME(kcal/g) = 8·745 – 0·004F – 0–361 log10L–0·011 F log10L,Net absorption (%) = 95·82 + 0·02F – 4·65 log10L – 0.13F log10L.

Description: SUMMARYThe wool growth cycle in six rams and eight ewes was studied by taking monthly coat and skin samples for 3 years from each. Coat length was measured, and the percentage of inactive follicles was noted as well as the percentage of medullated fibres.In the spring moult ‘mainland’ sheep (stock removed from St Kilda 60 years ago) cast less completely than ‘St Kilda sheep’ (Soays removed more recently from St Kilda). Mainland rams cast less than the ewes, but St Kilda rams began casting earlier, and completed casting more quickly than the ewes. Despite differences between years in the rate of casting, similarities in the pattern of casting were observed between years in the same animal, and between parent and offspring.This apparent annual cycle was confirmed by graphs of follicle inactivity which showed that most inactivity occurred from September to March in the rams, and from October to April in the ewes. It was possible to fit sin and cos waves of 12-month duration to the graphs and further analysis revealed superimposed a 6-month cycle in one group, and a 4-month cycle in another group, which were associated with subsidiary peaks of inactivity in the summer. There were suggestions of a cycle about 2 months in length throughout the year, and sin waves of this duration could be fitted to the data from one of the groups of ewes. Possible control mechanisms for the annual and shorter cycles are discussed.Peaks of follicle inactivity were frequently followed by troughs in coat length which suggested actual loss of the longest fibres.Medullation was absent or minimal from December to March, and there were two peaks during the period of maximum medullation, that in the spring being greater than the one in the autumn.

Description: SUMMARYField experiments were carried out in central Scotland to assess the lime and fertilizer dressings required for the establishment and growth of grasses and clovers on deep acid peat. Without lime, the sown grasses and clovers failed when ammonium sulphate and mono-ammonium phosphate were used, but with Nitro-Chalk and single superphosphate a poor establishment was obtained. With adequate P, lime at rates as low as 0–25 metric ton Ca per ha produced a marked improvement. The yields obtained with 1, 2 or 4 metric tons Ca per ha were similar, but the herbage from the last treatment contained the highest Ca percentage.Even with adequate lime, the grasses and clovers failed in the absence of applied P. Superphosphate and basic slag gave similar establishments but the former produced higher yields. Ground mineral phosphate was inferior to basic slag in the first and second years but in the fourth, fifth and sixth seasons it was equal to superphosphate and superior to slag. After establishment the 98 kg P rates were always better than the 49 kg levels. The 490 kg P treatment of superphosphate did not produce a bigger yield than the 98 kg rate, but it did give a higher percentage of P in the herbage.Dressings of N and K had appreciable effects on establishment and growth, especially on the botanical composition of the sward and yield of herbage produced in the second year.The effects of treatment on the pH value of the peat and on the Ca, P and K extracted by 2·5 % acetic acid were measured. To get a satisfactory establishment of grasses and clovers on deep acid peat it is suggested that about 3 metric tons Ca, 35 kg N, 100 kg P and 140 kg K per ha should be applied.

Description: SUMMARYThe current status of herbage grass breeding is considered in relation to the utilization of first-generation hybrid vigour. A breeding scheme is outlined by which it is suggested that interpopulational F1 hybrid varieties could be developed to provide a simple and effective means of exploiting heterotic potential in herbage grass species. A survey of interpopulational F1 heterosis expressed, under two levels of fertility in non-competitive spaced-plants conditions, by the hybrids of a group of six adapted perennial ryegrass varieties, is reported here.Although the F1 hybrid populations studied were not on average superior to the parental varieties there were large variations between specific hybrids. Two hybrids were particularly promising, exhibiting 25% and 31% heterosis over the higheryielding of their parents for total green-matter yield over two harvest years and two fertility levels. The bulk of this heterosis arose under high-fertility conditions, when the mean yield response of the interpopulational F1 hybrid was twice that of the parental varieties.The effects of inherent relationships between the parental varieties on the observed levels of heterosis are considered, as are the possibilities for the practice of recurrent selection procedures for the enhancement of heterotic expression in some of these hybrids. It is concluded that there is sufficient evidence for the existence of interpopulational heterosis in this species to merit an extension and application of this approach to include a wider range of varieties and. populations, both adapted and introduced.

Description: SUMMARYThe two experiments described here were the 3rd and 4th in a series of experiments investigating the effect of time of application of nitrogen and potassium on the growth and yield of potatoes.The effect of applying all the fertilizer nitrogen in the seed bed was compared with applying all the nitrogen at the time of tuber initiation or dividing the dressing between these times. Similar times of application were tested for potassium. CCC was applied after a leaf area index of 3 had been reached (on all but the no N treatments) in order to offset the tendency for late nitrogen to increase stem growth, but to avoid any tendency for CCC to depress yield by reducing leaf area indices (L) below an assumed optimum value of 3. These treatments were applied in separate experiments to a second early variety (Craig's Royal) and a maincrop variety (Pentland Dell), planted a month later.In both crops the response to nitrogen was large and delaying or splitting the application of nitrogen increased tuber yield compared with nitrogen applied in the seed bed. Responses to potassium were small, but there was a tendency for split applications to be superior to late or early applications.The beneficial effect of delayed or split applications of nitrogen was associated with an improvement in the recovery of nitrogen in the crop which was largely ascribed to a reduction in loss due to leaching. Total and tuber dry-matter yields were linearly related to leaf area duration (D) in both crops, although the earlier variety was more efficient per unit of D. High values of L (6) were recorded for both crops, but there was no indication of an optimal value of L; consequently CCC which reduced L also reduced yield. D was closely related to the maximum quantity of nitrogen accumulated in the leaves per unit area of ground.

Description: SUMMARYThe mineral content of N, P and K in leaves, stems, roots and seed of field beans, subjected to four watering regimes were compared in 1976 and 1977, and of a foliar nutrient spray in the latter year.N, P and K content increased in all treatments with the increase in plant size and then declined at about the time of podding and death of the leaves.Water shortage reduced the amounts of N, P and K throughout the growth period and for the seed at final harvest; the decrease was more pronounced in 1976 than in 1977. The plants under stress conditions benefited from the foliar nutrient spray more than the unstressed plants.

Description: SUMMARYResults are reported from four separate trials carried out to determine the precision of the Sonatest (simple A-mode ultrasonic machine) and the Scanogram (modified linear scanner) for predicting the body composition of live cattle. Cattle in the four trials differed in breed, sex and origin, and the data provided an opportunity to determine the consistency of results in different circumstances. A total of 210 cattle were involved.Fat thickness measurements (Sonatest and Scanogram) and fat and M. longissimus areas (Scanogram only) were taken at the 10th and 13th ribs and at the position of the 3rd lumbar vertebra. Their precision as predictors of carcass tissues percentages was examined when they were used in addition to live weight at evaluation.There was little consistency between trials in the positions and measurements which gave the most precise prediction. The lowest within-breed residual standard deviations of carcass lean percentage obtained with fat thickness measurements taken by Sonatest were in the range 2·5–2·7 and there was little advantage in using additional measurements in multiple regression.Fat areas taken by Scanogram were more precise predictors (within-breed residual standard deviations were close to 2·0). Precision was improved marginally to about 1·8 by using combinations of fat areas but M. longissimus areas were of little additional value.

Description: Differences in the partitioning of fat in the carcass may affect ‘carcass quality’ and depending upon the particular market requirements the optimum partitioning of fat may vary. Differences in fat partitioning may also affect the accuracy with which total carcass fat can be predicted from an assessment of subcutaneous fat (Pomeroy & Williams, 1974).

Description: SUMMARYThe relationship between calcium and phosphorus metabolism in wether sheep given high or low Ca diets, with or without 1α-hydroxycholecalciferol (1α-0H-D3) has been studied by a mineral balance and radioactive technique.Ca absorption was not related to Ca intake but was stimulated by 1α-OH-D3. More Ca was absorbed by treated animals from the high Ca diet than from the low diet and all the extra Ca absorbed was retained, increased retention being brought about largely by an increase in the rate of bone accretion.P absorption was increased to approximately the same extent from both diets suggesting that stimulation was due to the 1 α-0H-D3 treatment rather than increased Ca absorption. Whereas the extra P absorbed from the high Ca diet was retained, together with Ca, in bone and soft tissues, that absorbed from the low Ca diet was largely excreted in the urine. It is suggested that this difference in P retention reflects a difference in availability of Ca for retention in bone and P retention was in fact found to be directly related to Ca retention.The roles of secretion of P into the gut, absorption of P from the gut and urinary excretion of P are discussed in relation to P homoeostasis.As absorption of P from the intestine and loss of P to bone, soft tissues and urine increased, so endogenous faecal loss decreased until it reached a value of approximately 35 mg/day per kg body weight when it remained constant. It is suggested that this value may represent the inevitable loss of endogenous P in the faeces from a hay and concentrates diet and that this minimum value may have a bearing on the calculation of P requirements.

Description: SUMMARYAnimals fed sole diets of kale (Brassica oleracea) were compared with animals fed ryegrass-clover pasture grown on the same soil type in two experiments. In Expt 1 young cattle grazed the two forages for 24 weeks, with supplementary copper and iodine being administered by injection. In Expt 2 young sheep were individually fed the two forages indoors at equal D.m. intake.Animals grazing kale in Expt 1 showed the characteristic symptoms of haemolytio anaemia from ruminal fermentation of S-methyl cysteine sulphoxide (SMCO) (Smith, 1974). This was most severe over the first 6 weeks, during which live-weight gains were very low (250 g/day). In the absence of copper supplementation animals grazing kale showed symptoms of copper deficiency. This was characterized by live-weight gain remaining low throughout the experiment (mean 280 g/day), rapid depletion of liver copper reserves, progressive reductions in serum copper concentration, reductions in erythrocyte copper and reduced glutathione (GSH) concentrations and a massive hepatic accumulation of iron. Copper deficiency only slightly lowered heart muscle copper concentration in kale-fed cattle, and this was counteracted byheart hypertrophy. The major effects of copper deficiency in kale-fed cattle were in erythrocytes, and a metabolic diagram is presented showing these effects to be biochemically similar to those produced by ruminal fermentation of SMCO.Copper supplementation of animals grazing kale increased live-weight gain (mean 425 g/day), reduced Heinz body formation, allowed the animals to recover gradually from the haemolytic anaemia and prevented other symptoms of copper deficiency. In contrast, animals grazing ryegrass-clover pasture showed only a very mild depletion of copper, there being no response in live-weight gain to copper supplementation.Activity of the enzyme glutathione peroxidase (GSH-Px) in whole blood was dependent upon blood selenium concentration in cattle fed both diets. In cattle fed on kale, bub not on pasture, reductions in erythrocyte GSH due to ruminal fermentation of SMCO and to copper deficiency were also associated with depressed blood selenium status.Glucosinolates were present in the kale (11μM/g D.M.) but absent from the pasture diet. Despite this, neither T4 production from the thyroid gland nor the conversion of T4 to T3 appeared to be impaired by kale feeding in either Expt 1 or Expt 2. In Expt 1 serum T3 concentration was better relatedto live-weight gain than was serum T4 concentration, in accord with T3 being the active form of the thyroid hormone.It is concluded that supplementation with copper but not iodine is essential where growing cattle are fed sole diets of kale for periods in excess of 12 weeks

Description: SUMMARYThe aim of the experiments reported here was to investigate the possibility of minimizing yield losses due to late sowing by increasing leaf area and radiation interception during the pre-flowering period. The use of large seed did increase leaf area, radiation interception and crop weight at flowering. Normally this would be expected to lead to increased yield of late sowings, but hot, dry conditions severely affected all crops during seed growth. Applying fertilizer nitrogen in the seed bed boosted pre-flowering growth of early but not late sowings, probably because low temperatures prevented a response in the latter. Increasing plant population density did improve leaf cover and radiation interception until just before flowering, but leaf canopies in late-sown, low density crops were then able to expand more and function for longer owing to less shading by flowers and pods. Seed retention was improved and, even with as few as 8 plants/m3 in 1973–4, a worthwhile yield was still obtained.

Description: Maize grain production in Nigeria is the collective effort of several growers individually cropping small areas. In these farms, maize stands are at suboptimal densities, soil fertility is low and crop loss from pests is high. Consequently, grain yields are characteristically low. By planting maize at closer spacing than the current standard, 90 x 25 cm, Fayemi (1963), Chinwuba (1967), and Okigbo (1972) were able to raise grain yield. However, the effect on pest population in Nigeria of increasing host plant density has received little research attention. Cromartie (1975) showed that host plant density and arrangement affect insect population dynamics. Other reports by Ficht (1932), Finch & Skinner (1976), Ralph (1977), Zepp & Keaster (1977), Adesiyun (1978) and Mayse (1978) indicate differential insect colonization, establishment and damage on host plants sown at different densities.

Description: SUMMARYIn a study of two breed groups, coarse wool Barki and ⅜ Merino ⅜ Barki, data were obtained on skin histology from birth to the age of 1 year, birthcoat fibre type arrays and fibre-follicle relationship.The ⅜ Merino exceeded Barki lambs in the maximum S/P ratio, values of which were 3·40 and 5·64 obtained at 6 and 8 months in Barki and ⅜ Merino respectively.Internal diameters of primary follicles ranged from 39·0 to 64·7 and from 41·0 to 56·8 μm; those of secondaries ranged from 19·8 to 34·9 and from 22·6 to 33·3 μm in Barki and ⅜ Merino respectively.The ratio of primary to secondary follicle diameters showed high values in both breed groups; averages were 1·89 and 1·71 for internal diameter and 1·86 and 1·71 for external diameter in Barki and ⅜ Merino respectively.Birthcoat fibre type arrays were mostly saddle, only 8·3% were plateau (P3) in both breed groups.In Barki primary centrals grew halo hairs, super sickle (A, A′, B), primary laterals produced super sickle (A, A′, B), sickles, coarse and medium curly tips, and secondaries mostly grew medium and fine curly tips and histerotrichs.In ⅜ Merino primary centrals produced halo hairs, super sickle (A, A′, B), primary laterals grew super sickle (A, A′, B), sickles, medium curly tips, and secondaries produced medium and fine curly tips and histerotrichs.

Description: SUMMARYAutomatic plot covers were used in a study of the effects of drought on the yield and water use of two spring wheat genotypes. The experiment tested the effects of drought at different stages of growth on yield and yield components. There was complete control over the water supplied to the plots, and a fully irrigated control treatment was included.The yields of the two genotypes were similar under fully irrigated conditions, but the yield components differed: Highbury had more grains per ear and TW 269/9/3/4 more ears per unit ground area and a higher mean grain mass. An early drought, which began 4 weeks before anthesis, caused a reduction in number of grains per ear in Highbury, which was outyielded by TW 269. Late drought also reduced yields differentially, reducing mean grain mass, and hence grain yield, more in TW 269 than in Highbury. Total shoot dry matter and grain yield were found generally to increase as water use increased. The average water use efficiency was found to depend upon the genotype and treatment.

Description: SUMMARYIn Expt 1 40 lactating British Friesians, 20 cows and 20 heifers, were used to study the effect of crude protein (CP) content of the whole ration on milk yield, milk composition and live-weight change when maize silage was fed as the basal ration. There were four treatments with five cows and five heifers on each. During lactation weeks 4–12 the cows on treatments 1, 2, 3 and 4 all received 7 kg maize silage dry matter (D.m.) plus 8 kg D.m./day of a concentrate containing either 14, 18, 22 or 24% CP, respectively; heifers received 1 kg/day less of both silage and concentrate. This produced whole-ration CP contents of 11·7, 13·9, 16.·0 and 17·1%. In the subsequent lactation weeks 13–20 silage feeding was increased to 9 kg D.m./cow/day and concentrate feeding decreased to 5 kg D.m./cow/day. Heifers again received 1 kg/day less of both silage and concentrate. This decreased whole-ration CP contents to 10·5, 11·7, 12·9 and 13·4%.During lactation weeks 4–12 and 13–20, with the exception of milk fat content in weeks 13–20, there were significant linear effects of whole-ration CP content on milk yield, milk fat, protein, lactose and total solids. There were no significant curvilinear relationships. Thus, despite the fact that the highest numerical values were generally recorded for the animals on treatment 3, the results indicate that a whole-ration CP content of at least 17·1 and 13·4% are required in early and mid-lactation respectively.In Expt 2 the loss of D.m., acid-detergent fibre and nitrogen from maize silage suspended in nylon bags in the rumen was measured. Compared with feeding either a low or high protein supplement, losses were greater for silage fed alone. If it is accepted that nitrogen loss can be approximated to protein degradability, then the value for maize silage was between 0·6 and 0·7. Using the same technique in Expt 3, comparable nitrogen losses for fish meal, decorticated groundnut meal and soya-bean meal were 0·3, 0·9 and 0·9, respectively, after 24 h incubation.

Description: Research has shown that it is now possible to control the oestrous cycle of ewes with a high degree of precision (Robinson et al. 1967; Gordon, 1975; Boland, Kelleher & Gordon, 1978). There is general agreement that a high concentration of progestagen, followed by rapid withdrawal and adequate ovarian stimulation is necessary for acceptable fertility (Robinson et al. 1967; Gordon, 1975; Colas, 1975). Application of artificial insemination in France has involved the use of a 40–45 mg Cronolone sponge (Cognie, Mariana & Thimonier, 1970; Colas et al. 1973) while controlled breeding in sheep in Ireland has been used in conjunction with a 30 mg Cronolone pessary (Gordon, 1975; Smith, Boland & Gordon, 1978, 1981). The present experiment was designed to compare the relative effectiveness of two doses of Cronolone (30 or 45 mg) when administered in conjunction with two quantities(375 or 750 i.u.) of pregnant mare serum gonadotrophin (PMSG), given by intramuscular injection.

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

Description: SUMMARYThe pH of soil cropped with ryegrass increased with calcium nitrate as a fertilizer and decreased with ammonium nitrate, especially in the mid-range of pH. Changes above pH 7·2 and below pH 4·5 were small.Yields of 4 cuts of grass given either N-fertilizer were similar over a pH range (in 0·01M-CaCl2) from 4·3 to 7·4. However, the composition of the grass and nutrient uptakes were affected by both soil pH and form of N-fertilizer.

Description: SUMMARYIsocaloric quantities of casein, and glucose were infused into the abomasum and duodenum of sheep given perennial ryegrass silage ad libitum. Casein infusion significantly increased nitrogen retention but failed to affect silage consumption, suggesting that the positive relationship found between silage intake and silage nitrogen content is unlikely to be due to a low nitrogen status in sheep fed all-silage rations.

Description: SUMMARYA perennial ryegrass silage was treated to give a range of acetic acid contents (2·0–8·8); pH and moistvire levels were held constant by adding solutions of the acid and of potassium hydroxide. When fed to sheep, ad libitum, the pattern of eating during the day was affected by acetate content in the silage but the intake over 24 h was unaffected. In a second experiment the infusion of acetic acid into the rumen depressed silage intake but this effect was not observed when part of the infusate was replaced by potassium acetate. It is considered unlikely that high acetate level per se will result in a low intake of silage.

Description: SUMMARYThe voluntary intake by sheep of seventy silages was measured in experiments in several years. Linear and multiple regression analyses were made between these voluntary intakes and the contents of dry matter, various acids and nitrogen and the digestibility value determined in vivo. There were some differences in these relationships for silages made from different groups of species, particularly those made from legumes. Voluntary intake was positively correlated with the contents of dry matter, nitrogen, lactic acid as a percentage of total acids and with the Flieg index. Voluntary intake was negatively correlated with the contents of acetic acid and ammonia as a percentage of total N. Although pH alone did not account for a significant part of the variation in intake, multiple regressions in which pH and one of the measurements of fermentation quality were included were significant, with pH positively related to intake. When all silages were considered, the correlation between voluntary intake and the apparent digestibility of dry matter was not significant. However, for legumes this correlation was significant and positive and for grasses other than ryegrass the correlation was significant and negative.

Description: SUMMARYThe systemic fungicide benomyl was used as a seed dressing and as a spray at two concentrations, 250 and 500 ppm, on the winter barley variety Pella. An additional treatment was a spray application of CCC at 500 ppm. All spray treatments were applied at growth stage 3–4. Without fungicide treatment, total yield in the inoculated plots was approximately 40% of that in the uninoculated plots. The 500 ppm fungicide-spray treatment significantly decreased incidence and severity scores of eyespot, the seed dressing being significant only for the latter. The seed dressing and 500 ppm spray treatments significantly increased mean yield/head, fertile tiller number and 1000 grain weight. All the fungicide treatments significantly increased total yield in the inoculated plots. There were no significant effects of CCC upon disease or upon yield, neither was there any interaction between benomyl and CCC.

Description: SUMMARYA model is derived that relates yield to levels of applied fertilizer in terms of parameters that have direct physical meaning. N8, P8, and K8 define the contribution of the soil to the supply of nitrogen, phosphorus and potassium for plant growth; BN, BP and BK define the responses to nitrogen, phosphorus and potassium fertilizer at low nutrient levels and aN is the level of nitrogen required to raise the osmotic pressure sufficiently to prevent growth.To test the model, field experiments were carried out on French beans and summer cabbage in which 125 different combinations of levels of nitrogen, phosphate and potassium fertilizers were applied. The yield data from each block of each experiment fitted the model very well. Fitted values differed from block to block but these differences could be attributed to the fact that for each block equally good fits were often obtained with widely differing parameter values. Estimates of N8 were made from chemical analysis of the (NH4 + NO3) — N of soil samples from the field plots, and P8, and K8 from chemical studies of the adsorption of phosphate and potassium on untreated soil. They were in substantial agreement with the average values obtained by the entirely different procedure of fitting the model to the yield data. Also estimated values for BN, BP and BK and aN from other chemical studies were consistent with those obtained by model fitting.It is concluded that although the theory has limitations it is broadly in accord with the results of the detailed field experiments.

Description: SUMMARYThe growth and development of the spring wheat varieties Kolibri, Sirius and TB 435 ranging in height from relatively tall to semi-dwarf were compared when sown at 50, 200 and 800 plants m−2, with and without a spray application of CCC at the six-leaf stage. Growth analysis measurements were made throughout the season. Yield and yield components were determined at final harvest.A number of varieties x density and variety x CCC interactions were found which support the hypothesis that genotypic variation and environmentally induced differences in GA metabolism affect the agronomic performance of the crop.

Description: SUMMARYThree wheat experiments are described in which a range of plant populations were shaded during different periods of development; in two of the experiments plant thinning was also carried out at a number of growth stages. Shading during the period of ear development caused an appreciable decrease in grain yield by decreasing the number of grains per ear. Shading during the grain filling period also reduced grain yield, this being brought about by decreased grain size. Thus in contrast to the barley experiments reported earlier (Willey & Holhday, 1971), these particular results gave no indication of a potential surplus of carbohydrate for grain filling and an associated limited ear capacity. However, when plant thinning was carried out at anthesis to make more carbohydrate available for grain filling in the remaining ears, grain yield per ear did not increase. It is argued, therefore, that grain yield probably was determined at least partly by a limited ear capacity. Plant thinning at earlier stages showed how the development of competition during the ear development period progressively reduced the potential capacity of the ear; the greater competition of higher plant populations accelerated this reduction in ear potential.From an examination of the effects of plant population, it is suggested that the number of grains per ear is the component having greatest influence on the decline in grain yield at above-optimum populations. The possible importance of the number of grains per unit area as an indicator of ear capacity on an area basis, and as a determinant of grain yield per unit area, is emphasized. A close relationship between grain yield per unit area and number of grains per unit area is illustrated for a number of plant-population response curves, and it is suggested that the decrease in grain yield at high populations is probably determined by a decrease in the number of grains per unit area. Evidence is presented to substantiate the idea put forward in the barley paper that this decrease in the number of grains per unit area may be attributable more to a lower production of total dry matter by the high populations during the later stages of ear development, than to an unfavourable partitioning of such dry matter between the ear and the rest of the plant.

Description: SUMMARYTwo barley experiments are described in which a range of plant populations were shaded during different periods of development. Shading during the ear development period caused considerable reductions in grain yield, largely by reducing the number of grains per ear. Shading during the grain-filling period caused no reduction in grain yield. It is suggested that under conditions of these experiments there was probably a potential surplus of carbohydrate available for grain filling and that grain yield was largely determined by the storage capacity of the ears. The importance of the number of grains per ear as an indicator of individual ear capacity is emphasized.The effects of plant population on grain yield and its components are also examined. It is concluded that the number of grains per ear is the component having greatest influence on the decrease in grain yield at above-optimum populations and attention is again drawn to the possible importance of ear capacity. It is argued that on an area basis the number of grains per unit area may give a good indication of ear capacity. Examination of this parameter shows a close relationship with grain yield per unit area for both the shading and population treatments. It is particularly evident that a decrease in grain yield at high populations was associated with a comparable decrease in the number of grains per unit area. It is suggested that this decrease in grain number may be due to a lower production of total dry matter during ear development rather than an unfavourable partitioning of this dry matter between the ear and the rest of the plant. This lower production of total dry matter is attributed to the crop growth rates of the higher populations having reached their peak and then having declined before the end of the ear development period. This crop growth rate pattern, through its effect on grain number per unit area, is put forward as the basic reason why, in the final crop, grain yield per unit area decreases at above-optimum populations.

Description: SUMMARYThe contribution of the legume Stylosanthes gracilis to the nitrogen economy of mixed swards was assessed under both cutting and grazing conditions. In a cutting experiment, carried out during two wet seasons, a S. gracilis/Chloris gayana sward gave the same yields of dry matter and crude protein as a C gayana sward receiving 75 lb N and 167 lb N/acre (84 kg, 187 kg/ha) respectively. Lower yields were obtained from mixed swards containing Centrosema pubescens and Desmodium scorpiurus.In a grazing experiment the mean live-weight production from a S. gracilis/Digitariasmutsii sward was equivalent to that produced from a pure grass sward receiving only 13 lb N per acre (5·9 kg/ha), although greater beneficial effects of the legume were apparent under high stocking conditions. In both experiments the legume tended to become dominant after 2 years.Herbage yields from a S. gracilis/C. gayana pasture were significantly increased by phosphorus and sulphur; S. gracilis was particularly responsive to these elements. Under lenient defoliation, nitrogen reduced the proportion of the legume in the mixed sward, although frequent defoliation reduced the harmful effect of the nitrogen.The results are compared with other published data and are discussed in terms of ways in which the grass/legume balance can be altered by different management practices.

Description: SUMMARYIn an 80 acres (32·4 ha) grazing trial carried out over a 2-year period significant increases in cattle live-weight gains were achieved following the oversowing of savanna grassland by 4 lb/acre (1·8 kg/ha) of Stylosanthes gracilis (stylo) seed. The beneficial effects of the stylo was particularly apparent during the early part of the dry season. The early growth and subsequent survival of the stylo was not outstanding.Better results were achieved in a second experiment where stylo was grown as a pure crop and ration-grazed in the dry season in association with unimproved savanna. The live-weight gain of cattle grazing the stylo only during the 12 h night period was the same as cattle receiving 1·8 lb (0·82 kg) whole cotton seed per day. In general, cattle live-weight gains were directly proportional to the time spent on the stylo.

Description: SUMMARYThe graphical and statistical analyses of competition diallels devised by Durrant were applied to an experiment investigating competition between four spring-wheat varieties. The results indicated that at low seed rates mixtures between varieties having a wide phenotypic difference between them in competitive characters, such as height and early maturity, could significantly outyield pure-stands of the component varieties. However, the results of a second experiment, in which these mixtures were grown at a range of seed rates, indicated that the yield advantage of mixtures over pure-stands was unlikely to occur at normal seed rates.It is suggested that, at the low seed rates likely to be used in growing F1 hybrid wheat crops, mixtures of F1 hybrids and male parental lines might achieve very nearly the same yield as the pure F1 hybrid variety with a seed bulk that was cheaper to produce.

Description: SUMMARYExperiments were carried out to assess the effect of the following diets: unwilted and wilted silage, barn-dried hay and wilted silage and ensiled mixtures of grass and barley on the ruminal VFA patterns in sheep.There was a tendency for the unwilted silage to result in a slightly higher level of rumen acetate and a lower level of propionate than grass, wilted silage or barn-dried hay. In two of the experiments (Exps. 2 and 4) significant direct relationships were found between rumen acetate and the crude-fibre content of the diets and significant inverse relationships were found between the rumen propionate and the crude-fibre content of the diets.Significant relationships were also found between the rumen acids and the metabolizable energy content of the diets and in Exp. 2 there was a significant relationship between the rumen acetate and the water-soluble carbohydrate content of the diet.The addition of barley meal to grass produced different ruminal VFA patterns in sheep fed the ensiled material and the resulting silage.

Description: SUMMARYA population of 12 ryegrass genotypes was grown at densities of 0·25, 16 and 8 ryegrass + 8 white clover plants per sq ft and was periodically cut to stubble heights of O5 in. or 3 in. For individual plants, yields, tiller numbers, tiller lengths and emerged inflorescence numbers were recorded. Density was the main determinant of plant size, but cutting-height effects were shown, most markedly for the number of inflorescences.Initially the frequency distribution of plant weight was positively skewed under all treatments, but became less skewed for the population at 0–25 plants per sq ft and more skewed for the population at higher densities. Development of the skew was delayed where white clover was grown. Generally, increasing skew was associated with increasing positive kurtosis.Frequency distributions of tiller numbers were less skewed than those of yields. Frequency distributions of tiller length were less skewed than the corresponding higher density distributions of yield and tiller number.Treatment effects on population means demonstrate the different responses which may be obtained with widely spaced plants or those grown in swards. Changes of the frequency distribution of the population are interpreted using the model of Koyama & Kira (1956) and are related to procedures assessing the performance of plants under selection for growth in swards.

Description: SummaryA partial castration technique is proposed for use in cattle husbandry where bulls are used for slaughter beef, whioh renders the animals sterile apparently without otherwise impairing the expression of their male characteristics.Fifty such infertile bulls were compared with an equal number of steers in six growth trials under a range of nutritional conditions. In all cases the bulls grew faster than the steers. The results showed that the higher the rate of gain achieved, the greater was the advantage in favour of the bulls from about 1% at under ½ kg/day to over 25% at 1 kg/day). Accordingly, it is suggested that under conditions of good growth rate (in excess of about ¾ kg/day) complete castration is contra-indicated for efficient beef production, and that partial castration might be adopted as a routine management procedure.

Description: SummaryThe feed conversion efficiency of four intensively fed, partially castrated male cattle, measured over an 11-week period from approximately 9-months of age, was found to be significantly higher (P

Description: SummaryA preliminary investigation on interplanting of maize with nine different tropical legumes in the rain-forest zone of the Western State of Nigeria at Ibadan indicated that Popondo (Phaseolus lunatus) and Mucuna (Mucuna utilis) lowered maize yield, while calopo (Calopogonium tnucunoides) Cowpea (Vigna sinensis) and greengram (Phaseolus aureus) had much less effect on maize and were themselves tolerant to maize shade. These three legumes were interplanted with maize continuously for four growing seasons, during which there was a significant response of maize to fertilizer treatment only in the control (no legume) treatment. Maize interplanted with the legumes gave no response to applications of 50 lb N per acre.High yields of maize were maintained during the four growing seasons in both the fertilized control plots and those interplanted with different legumes without fertilizer, whereas the yield of maize in plots with neither legume nor fertilizer was reduced to half of the yield of the first maize crop.Starting from the third cropping season, there was a significant interaction between the presence or absence of legume and fertilizer.The planting pattern of the maize and legumes (intercropping or growing maize after the legume harvest) did not affect the yield of maize.Legumes tended to compete with maize during the late cropping season. This did not affect the maize yield seriously during the investigation, but legume yield was significantly suppressed by maize shade.

Description: SummaryImmunoglobulin concentrations in 2-day-old Finnish Landrace × Dorset Horn lambs were remarkably high and uniform and were unrelated to litter size. The mean concentrations in singles, twins, triplets and quadruplets were 2.95 ± 0.215, 2.95 ± 0.099, 2.94 ± 0.105 and 3.03 ± 0.142 g/100 ml respectively.

Description: SummaryConsiderable information is available in the literature concerning the levels of organic and inorganic constituents of blood of normal animals. It is well established that levels of many of these constituents are affected by season, age, breed, growth and other factors (Greatorex, 1957; Bhannasiri, 1960; Luitingh, 1962; Wilson, 1965). It is surprising, however, that little attention has been given to the relationship between these constituents of blood. Occasional reports on the relationship of a few constituents are available, but these were mostly studied in connection with the response of animals to a specific ration or certain ailment.

Description: SummaryPreweaning litter traits of 289 Large White (LW) and of 167 Landrace (LR) litters born between 1 January, 1967 and 31 December, 1969 were analysed for seasonal effects. The month during which farrowing occurred exerted highly significant effects on the average piglet weight at birth and at weaning, as well as on the preweaning piglet weight gain (P

Description: SummaryForty cross-bred ewes were individually fed from the end of week 13 of pregnancy to parturition on two diets whioh were designed to provide intakes of metabolizable energy above (treatment El) and below (treatment E2) the maintenance requirement of the non-pregnant ewe.Energy intake had no significant influence on birth weight of single lambs but twin lambs from ewes on treatment E1 were 25% heavier than twins from ewes on treatment E2. A net loss of body weight occurred between week 13 of pregnancy and the day following parturition in all groups of ewes. These losses represented 5 and 10% of body weight in ewes carrying singles on treatments E1 and E2 respectively. In ewes carrying twin lambs losses represented 11 and 16% of body weight on treatments E1 and E2 respectively.Levels of plasma N.E.F.A. and acetone were used to characterize the state of nourishment of ewes at 16, 18 and 20 weeks pregnant. Values obtained indicated that ewes carrying one lamb on treatment El were ‘moderately’ undernourished. Ewes carrying one lamb on treatment E2 and those carrying twin lambs on treatment E1 were undernourished to a similar degree characterized as bordering between ‘moderate’ and ‘severe’. Ewes carrying twin lambs on treatment E2 and all those carrying triplets were ‘severely’ undernourished.

Description: SummaryPassive lability of body core temperature during brief exposures to thermal stress is an efficient means of thermoregulation which few species of domestic animals appear to utilize. The body temperature changes of 30 shorn sheep and 10 shorn goats have been measured during standard heat and cold exposures lasting 7 h. During exposures to heat, air temperature was increased from 20 °C to 45 °C then reduced again to 20 °C. Rectal temperatures of goats and Soay, Welsh Mountain, Merino and Clun Forest sheep rose by an average of 1·96 °C, 1·22 °C, 1·04 °C, 0·85 °C and 0·80 °C respectively. All animals had similar increases in respiratory rate. During exposures to cold, air temperature was reduced from 20 °C to about 6 °C then increased again to 20 °C. Rectal temperatures rose by 0·18–0·20 °C in goats and in all sheep except Soays in which they fell by 0·28 °C. All animals showed moderate to vigorous shivering. None of the animals exhibited passive body temperature lability as an adaptation to thermal stress.

Description: SummaryA number of species of desert-dwelling ungulates (e.g. Grant's gazelle and oryx) can apparently survive desert conditions without drinking. We were interested in finding out whether goats and sheep herded in the arid Northern Frontier Region of Kenya utilized the same physiological strategies for reducing water requirements as the wild ungulates.Using simulated desert conditions (12 h per day at22 °C alternating with 12 hper day at 40 °C) we found: (a) both goats and sheep used water amounting to about 8% of their body weight per day when water was available ad libitum; and (b) this was reduced to about half (or 4% body weight per day) when the water intake was restricted.Evaporation was the major avenue of water loss under all experimental conditions. It was reduced from over 6% of body weight per day to about 3% in the simulated desert by restricting water intake.Restricting water intake had no effect on the temperature regulation of goats and sheep as had been observed in the wild desert-dwelling ungulates.It would appear that African goats and haired-sheep lack the physiological mechanisms and are not free to utilize the behavioural mechanisms involved in freeing wild desert-dwelling ungulates from their dependence on drinking water.

Description: SummaryTwelve Friesian cows were given six complete diets ad libitum in an experiment designed as a double 6 × 6 Latin Square balanoed for residual effects. The main energy components of the diets were rolled barley and 20, 35 or 50% chopped barley straw. The diets were given either as a loose mix or extruded through a fin. die. Dry-matter intake, milk yield and solids not fat % declined while butter fat % increased progressively with increased levels of straw in the complete diets which were fed in the loose form. In comparison with the loose diet containing 20% straw, the corresponding cubed diet was associated with a depression in dry matter intake and a decreased butterfat %. In contrast, the oubed diets containing 35 and 50% straw supported higher dry-matter intakes, higher solids oorrected milk yield but lower butter fat % than the corresponding loose diets. The effect of cubing the 35 and 50% straw diets was to make the voluntary dry-matter intakes and lactational performances comparable to those obtained with the loose mixes containing 20 and 35% straw respectively. In general the voluntary intake data agrees with a previously proposed model. However, the depressed intake obtained with the 20% straw diet in the cubed form would not have been predicted by the model. It is suggested that complete diets could be used in large units to combine the low labour costs of self feeding of dry feed with a high degree of control over nutrient intake and laotational performance.

Description: SummaryExperiments were conducted at Gezira Research Station during the 1964 and 1965 seasons to determine the effect of time and number of weedings on pod yield of Ashford groundnuts.Natural stands of annual weeds, mainly Ipomoea cordofana and Rhynchosia memnonia, reduced the pod yield by an average of 80%. Results showed that groundnuts must be weeded at least once after the first 30 days from sowing. Groundnut pod yield was increased from 986 kg/ha in the unweeded plots to 4690 kg/ha in the plots weeded 30 and 60 days after sowing. Three weedings, i. e. 15, 30 and 45 days from sowing, yielded less than 30 and 60 days from sowing because weeding stopped too soon. For practical purposes weeding at 30 and 60 days only was adequate.Number of pods per plant was the most important factor determining yield. Maximum pod yield was obtained from 15–20 pods per plant, and the earlier the 20 flowers produced, the higher was the pod yield.Weeds decreased number of branches per plant and consequently number of pods per plant. Weight of 1000 seeds, shelling percentage and harvest index was also affected by weeds.Ipomoea cordofana was the most noxious weed because it emerged about the same time as the groundnut plants and also the seeds germinated throughout the growing season.

Description: SummaryExperiments were done on three sheep fed several diets to determine the usefulness of the marker 51Cr-EDTA in the caecum of the sheep to study changes in weight of digesta and its turnover time. The activity of the marker decreased exponentially with time, indicating that it had mixed with a pool of digesta. Variation in the results was attributed mainly to the slowness of mixing and to the periodic nature of filling with digesta from the ileum.Most estimates of weight of digesta were compatible with the digesta being contained in the caecum and the proximal colon but in one sheep some estimates obtained by one method of calculation were so large as to be unrealistic. Both the estimated weight and the rate of turnover of digesta varied with the weight of the sheep and the level of food intake.

Description: SummaryThe nitrogen requirements for maximum production of perennial ryegrass swards in August/September were shown to be of the order of 4 kg N/ha/day. Further increases above this level had no appreciable effect on dry-matter production, leaf area or light intercepted, but maximum tiller numbers were considerably enhanced. Shortage of nitrogenous fertilizer had comparatively little effect on crop growth rate in the early stages of regrowth, but thereafter caused the rate to fall increasingly short of potential. At high fertilizer levels crop growth rate based on total above-ground parts was linearly related to percentage light intercepted in the first month after defoliation, but values subsequently became erratic and at times negative. This change in crop growth rate and the resulting halt in effective net dry-matter production could be associated with the overall pattern of leaf and tiller formation and death, maximum net yield being achieved at the point in time when three new leaves had been produced on each tiller since cutting. It is concluded that in August and September worth-while increases in harvestable net dry matter are unlikely to occur after this stage has been reached, and that managements based on the maintenance of a complete crop cover are not likely to be successful at this time of year.

Description: SummaryBarley plants were grown at low, high, increasing and decreasing densities in an attempt to manipulate the environment. The effects on tiller production and development were measured.Increasing density with time had less effect than decreasing it. Tiller number was the most plastic character, tiller production being earlier in those plants which emerged into low density, being delayed or inhibited in other treatments. The number of spikelets/ear and the length of the inflorescence were found to be less stable characters than the stage of ear development. Percentage spikelet survival showed a downward trend, with increasing density stress.

Description: SummarySeven, groups of adult Merino wethers were fed for 16 weeks on a diet of pelleted oat straw and urea, either alone or supplemented with trace minerals and various combinations of the major minerals. In some treatments, the same diet was fed throughout; in others, diets were changed after 8 weeks.Sulphur (S) was by far the most important mineral supplement; sheep fed diets supplemented with all minerals except S performed as poorly as those on the basal diet. Of the other minerals, only calcium (Ca) and magnesium (Mg), which were fed in combination, had a small, additional beneficial effect. Supplementary phosphorus (P) had no effect whether or not S was included.Intakes of sheep on S-supplemented diets increased over the first 6 weeks to reach stable levels of 1200–1400 g D.M./day compared with approximately 800 g/day for controls, while O.M. digestibilities stabilized at about 40 and 33% for S-supplemented and unsupplemented diets respectively. Live-weight change and wool growth were closely related to intake. Mean live-weight losses during the first and second 8 weeks for sheep without supplementary S were 9·5 and 4·8 kg respectively, and were about 50% of this for supplemented sheep. Sheep which were changed from diets without supplementary S to S-supplemented diets after 8 weeks showed slight increases in live weight from then on. Wool growth was about 115 g clean wool/sheep on all treatments during the first month, after which it remained steady at about 105 g/month on S-supplemented diets and fell to 60 g/month on diets without supplementary S.Sheep without supplementary S were in negative nitrogen (N) and S balance throughout. With the S-supplemented diets, urinary excretion of N and S was high, and few positive balances were recorded until the final 4 weeks of the experiment. Serum urea levels were high (60–130 mg/100 ml) throughout, and showed no effect of diet or period. Phosphorus balances were uniformly negative in sheep without supplementary P, and generally positive in P-supplemented sheep. Serum inorganic P levels were apparently affected by P intake and by live-weight loss, but mean values never fell below 4·5 mg/100 ml.Sheep without supplementary Ca were in negative Ca balance throughout the experiment; however, Ca supplementation generally resulted in high faecal Ca losses and few positive balances were recorded. In some sheep, serum Ca fell to moderately low levels (7·5 mg/100 ml), but this appeared to be associated more with high serum inorganic P levels than low Ca intake or retention. All sheep were practically in Mg, Na and K balance throughout, and supplementation had little effect on the retention of these elements.All sheep were in very poor condition at the end of the experiment, even when their D.M. intakes had been high, and wool growth rates were mediocre throughout. It appears that urea was poorly utilized in this experiment, and that satisfactory sheep production on diets of ground straw supplemented only with urea and minerals is unlikely.

Description: SummaryThe effects of crop density and fertilizer application on three varieties of marrowstem kale were investigated. The yield of stem, yield of leaf, components of leaf yield and plant height were studied separately. Varietal differences and effects of density and fertilizer application were significant for all characters, except for the effect of crop density on leaf and stem yield per ha.Significant variety x treatment interactions occurred for a number of the characters measured. The possible importance of these is discussed.

Description: SummaryThe absorption and translocation of phosphate by roots of intact seedlings of rape, oats, flax and buckwheat were studied. Two hydroponic experiments were conducted in the greenhouse. A split-root technique was used in which a single root of the culture plants was grown in one solution and the rest of the roots in another solution in a twocompartmented glass jar.The presence of other nutrients had a favourable effect on root growth and was essential for efficient phosphate absorption. There was a positive relation between the extent of root growth and phosphorus uptake. On the basis of unit weights of a single root, rape was not any better than oats and buckwheat. A single root of rape, in the presence of other nutrients, absorbed two-thirds of the phosphorus absorbed by all the other roots, whereas single roots of buckwheat, oats, and flax were much less efficient than the rest of the roots. In the absence of other nutrients, single roots of buckwheat, rape and oats absorbed 4·61, 0·18 and 3·49%, respectively, of the phosphorus supplied. However, in the presence of other nutrients, the corresponding values were 21·68, 43·86, and 7·62%, respectively. Both in the presence and absence of other nutrients the single root of flax did not absorb phosphorus from solutions high in phosphate. The results indicate that the age of the plant has an important bearing on the uptake and translocation of phosphorus.

Description: SummaryWhen incoming radiation was reduced artificially to 50% daylight during the postflowering period in peas, the rate of abscission of flowers and pods increased in the same way as when the density of planting is raised. Shading from flowering onwards reduced yield almost to the level of peas that were shaded throughout the growing season, even though peas that received full daylight until flowering had many fertile tillers and a greater reproductive potential in terms of the total number of flowers produced. Conversely, when shades were removed at flowering time the crop was able to compensate and yields approached those of peas grown entirely in full daylight, this was mainly due to a reduction in absoission losses of flowers and pods so that the majority of pods formed on the main stem contributed to final yield.It is suggested from these results that the major source of dry matter for pea yield is the photosynthate produced during the post-flowering period rather than that translocated from roots or stems following storage during the vegetative period.

Description: SummaryTwo perennial ryegrass swards – one consisting of S. 24, a diploid variety, and the other of Reveille, a tetraploid variety – were compared in a 20-week grazing experiment with 16 Ayrshire cows in 1968 and again with 12 cows in 1969. Each grass sward was grazed at either a high or a low rate of stoeldng and no other feeds were offered to the cows. On average, the amount of herbage dry matter on offer to the cows was slightly greater on the S. 24 than on the Reveille sward but the contents of total soluble sugars and digestible organic matter were significantly higher in the dry matter of the Reveille than in that of the S. 24. The crude protein contents of the herbage dry matter were similar on the two swards. The mean daily milk yields from cows grazing at the high and the low rates of stocking in 1968 were 14·0 and 15·7 kg/cow respectively on the S. 24 sward and 14·7 and 16·1 kg on the Reveille sward. In 1969 the milk yields from these same treatments were 15·4 and 17·2 kg on the S. 24, and 16·5 and 17·7 kg on the Reveille. The fat content of the milk was not significantly affected by the treatments. In both years the solids-not-fat and the crude protein contents of the milk were higher on the Reveille than on the S. 24 sward, but these differences were significant at the low rate of stocking only. The live weight of the cows did not differ significantly between the two swards. The average output of milk per hectare was approximately 4% higher from the Reveille than from the S. 24 sward but the major factor influencing milk production per hectare was the stocking-rate. On average over the 2 years the output of milk per hectare was 36% higher on the high than on the low rate of stocking. It is suggested that in selecting herbage for milk-production purposes attention should be paid to material with a high digestible organic-matter content and a high content of soluble sugars.

Description: SummaryIn field experiments carried out over a period of three years studies were made of the effects on soil moisture characteristics and crop yields of incorporating pulverized fuel ash into the surface 30 cm of a sandy loam and a coarse sand. Ash from two different sources was used at rates equivalent to 0, 125, 251, 502 and 753 t/ha and crops of carrots, lettuce, radish and red beet were grown.On every occasion when determinations were made the available-water capacities of the soils treated with 251 t/ha or more of ash were greater than the untreated soils; the largest increase (93%) was obtained with the highest rate of ash. Moisture release characteristics indicated that the increased amount of available water was retained in the soils at matric suctions between 0·05 and 1·0 atmospheres.Despite the increased amount of available water retained in these soils there was generally no beneficial effect on crop growth and yields.

Description: Summary1. In a series of experiments with cannulated lambs the amounts of 2, 6-diaminopimelic acid (DAPA) and a-amino nitrogen passing daily through the abomasum, terminal ileum and rectum were measured. While there was a very significant net absorption of α-amino nitrogen between the abomasum and terminal ileum, there was no net absorption of DAPA between these points. Indeed, there was a tendency for more DAPA to leave the terminal ileum than entered the abomasum, though this was only significant at the 10% level. In all cases significantly less DAPA passed out of the rectum than passed through the terminal ileum, indicating extensive degradation of this amino acid in the hind-gut, probably as a result of microbial activity.2. In adult sheep given control rations no DAPA could be detected in the blood, even when 643 ml plasma were analysed. These sheep usually excreted less than 5 mg DAPA daily in the urine.3. When synthetic DAPA was introduced into the peritoneum, blood, abomasum, rumen or caecum of cannulated adult sheep in physiological amounts, approximately 80, 83, 53, 5 and 0 % of the administered dose was recovered in the urine. Furthermore, when introduced into the abomasum, DAPA could be measured in plasma from the anterior mesenteric and jugular veins.4. It was concluded that in the normal sheep the DAPA-containing fraction of the bacterial cell-wall material synthesized in the rumen is not digested in the small intestine. In the caecum and colon, however, this fraction is extensively degraded by hindgut bacteria.

Description: SummaryA protein index for animal feeds is suggested as a basis for the criteria relating nutritive value to chemical composition. The feeds were classified into four main groups: legumes, non-legumes, straws and concentrates. The regression equations for predicting the nutritive value gave a reasonable level of accuracy (0·18–14·74% error). Higher levels of accuracy were attained employing regression equations formulated for more homogenous feed subgroups classified according to their protein and fibre contents. The percentage error resulting from the use of the specific equations was found to range between zero and 9·88.

Description: SUMMARYConcentrations of Cu, Ca, P, Mg, K and Na were examined in the blood plasma (whole blood for P) of 149 adult ewes and their 244, 15-week-old lambs in a grassland flock of sheep. The ewes were 3 or 4 years old and of five crossbred types produced by mating Scottish Blackface females to Border Leicester, dun Forest, Dorset Horn, Finnish Landrace and Tasmanian Merino rams. The lambs in turn were the offspring of these crossbred ewes, and two rams of each of the Oxford Down, Southdown, Soay breeds and one Cheviot ram.Breed of sire (but not sire within breed) was a significant source of variation in the concentration of all the minerals, except Na, in the blood of both ewes and lambs. Other factors considered were age of ewe and sex, birth type, type of rearing, and date of birth of lamb. None of these appeared to be significant sources of variation except that twins and triplets, if reared as such, had higher concentrations of Ca in their blood than lambs born and reared as singles; however the ewes with singles were on different pasture from those rearing 2–3 lambs. For the mineral levels in the blood of the lambs there was no significant interaction of breed of ram with cross-breed of ewe. The lambs had substantially higher concentrations of Cu and P in their blood than their mothers and also significantly higher concentrations of Ca, Mg and possibly K. This may not be attributable to age alone because the lambs and their mothers also differed in genotype.Heritability estimates based on parent-offspring regression were 0·4 ±0·14 for Cu and less than 0·2 for the other minerals.

Description: SUMMARYThe gross energy and nitrogen contents of muscle, fat, and connective tissue of calves were determined, and from these data and feed analyses the gross energetic (GEE) and nitrogen efficiency (GNE) of growth, and the gross efficiencies of accretion since birth (GEA, GNA) were calculated.The percentage range of actual efficiency values for calves were GEE 55·3–7·7, GEA 18·1–1·4, GNE 58·1–22·8, and GNA 28·1–7·3. Within each treatment group these values were higher in the heavier calves. An hypothesis for the apparent temporary rise in these values in the heavier calves is that a compensatory mechanism acts in calves on low energy and possibly low N intake to enable them better to utilize their food. The results were obtained in calves whose diet was comprised of a reconstituted milk of low-solid content which led to low growth rates.

Description: SUMMARYOn the Abu-Ghraib Experiment Station, milk production was investigated in 31 Awassi ewes of different ages and 12 newly imported Hungarian Merino ewes, two years old, together with the effect of age, lactation period, number of lambs born and reared and stage of lactation on milk production in the Awassi ewes. The relationships between milk production, birth weight and weaning weight of lambs were also investigated.First-lactation milk yield during the suckling period (90 days) based on 12 h milking interval was 114·58 kg in the Merino and 75·29 kg in the Awassi.Age had no significant effect on milk production in Awassi ewes although first-lactation yield was lower than that from subsequent lactations. Ewes that produced and nursed twins gave significantly more milk than ewes that produced and nursed single lambs.Milk yield in Merino and Awassi ewes increased with the decrease of milking interval from 12 to 4 h. The correlation coefficients between milk yield during 12 and 4 h were positive and significant.Correlation coefficients between birth and weaning weights and milk production were positive in both breeds. The correlation coefficient between weaning weight and milk production was 0·78 in the Awassi (P

Description: SUMMARYMicro-organisms from the rumen of a hay-fed sheep rapidly synthesized an intracellular polysaccharide (starch) when growing or resting suspensions of cells were incubated in vitro with easily metabolized sugars.In 30 min incubation periods the optimum pH for the synthesis of starch by resting cultures was about 6·0 when glucose or fructose were substrates. Relative to glucose (as 100%) in ability to form the polysaccharide were, fructose, 75%; sucrose, 80%; soluble starch, 18·6%; maltose, 6·9%; cellobiose, 4%; and xylose, 2·1%. No starch was formed from galacturonic, acetic, propionic, butyric, lactic or succinic acids. A bacterial fraction of the microbes was reponsible for about 80% of the starch formed from glucose, fructose or sucrose.In incubations of 24 h, resting cultures formed more starch per unit of microbial protein than growing cultures. The utilization of microbial starch and lactic acid, formation of which often accompanied starch synthesis, gave rise to volatile fatty acids. Acid production was maintained from these substrates at rates similar to those obtained from the fermentation of glucose. The acids were in molar proportions of 65–70% acetic, 20–27% propionic and 8–15% butyric. The maximum starch calculated to be synthesized by the microbes from 100 ml of rumen liquor, in media containing excess sugar, amounted to over 250 mg from glucose, 200 mg from fructose, 200 mg from cellobiose and 50 mg from xylose. It is calculated that under optimum conditions for synthesis about 25 g of starch would pass daily from the rumen of a sheep.

Description: SUMMARYIn an incomplete block 2x2x2 factorial experiment seventy-two Large White type pigs, after having been fed individually and identically up to 120 lb (54·5 kg) live weight, were fed from that weight up to 200 lb (90·9 kg) live weight maize or barley based diets (factor 1), with each diet having either a wide or a narrow calorie/protein/lysine (CPL) ratio (factor 2). The feeding was effected in individual feeders in a Danish type piggery (with six pigs per pen) with all diets offered as wet mashes and according to scales which gave two different calorie intakes (factor 3). There were, therefore, four different diets and eight different feeding treatments.

Description: SUMMARYThe mechanisms responsible for moving K from soil to root were studied by growing perennial ryegrass in pots containing a flinty silt loam from Rothamsted and a sandy Woburn soil, with and without added K, at 0.75 water-holding capacity. More water was taken up from the Rothamsted soil than from the Woburn soil, and less was taken up when K was added without affecting dry-matter production. After 25, 52, 83, 122, 194 and 276 days, K uptake, water uptake and the K concentration in the soil solution were measured and the mass-flow contributionto K uptake calculated.Without added K, mass-flow accounted for only about one-sixth of the K taken up from the Rothamsted soil and about one-third from the Woburn soil. Except at first, diffusion probably accounted for the remainder of uptake but was the rate-controlling step for uptake from the Woburn soil only. With added K, mass-flow became much more important relative to diffusion in both soils, and transported more than enough K to account for the measured K uptake. Root interception probably did not contribute to K uptake after the early part of the experiment, because the pots used were small.

Description: SUMMARYThe performance of a series of intervarietal F1 hybrid populations was determined in simulated swards in a range of environmental conditions. On average the hybrids were more stable in performance than their parental varieties, but they showed no general yield advantage. Several hybrids were markedly heterotic at the higher-parental level, however. More heterosis was exhibited in high productivity conditions than in less favourable environments. A generally poor correlation between parental and F1 hybrid performance under competitive simulated-sward conditions and performance in noncompetitive spaced-plant conditions was found.

Description: SUMMARYP and K fertilizers were applied over a 5-year period to plots that were either cut, individually grazed or communally grazed. Residual effects were assessed in the sixth year when the sward was ploughed and sown with Italian ryegrass. The residual study supported the earlier published inference that (a) P returned to the sward in sheep dung is not an effective P source under field conditions, (b) communal grazing can lead to appreciable transfer of K from one plot to another.

Description: SUMMARYObservations were made on the development of the testes and epididymides of thirty-two Clun Forest ram lambs. There were no significant differences between the weights and volumes of the left and right testes and epididymides.The rate of increase in testicular and epididymal weights was linear up to a body weight of 46 lb (20·9 kg) followed subsequently by a significantly greater rate of increase at higher body weights. Similar patterns of growth occurred in relation to age, although at a given age there was a wide range of testicular and epididymal weights. There was a close relationship between the development of the testis and the epididymis at body weights greater than 46 lb (20·9 kg).There were two distinct phases in the dimensional growth of the testis. Increases in testicular length and breadth proceeded at much the same rate at testis weights of below 20 g. During the subsequent phase testicular length increased at a significantly greater rate than testis breadth.

Description: SUMMARYThe growth of ewe lambs of the Shropshire breed declined and in some cases ceased at the end of July, when they grazed permanent pastures at the Experimental Farm, Nappan, Nova Scotia. This decline in growth coincided with a decrease of about three orders of magnitude in the numbers of viable rumen bacteria. At the end of July an increase of one to two orders of magnitude was observed in the numbers of viable fungi collected from the pastures. Lambs grazing pastures developed from tidal marsh of the Bay of Fundy had a better growth performance than lambs grazing adjacent pastures developed from mixed conifer-deciduous forest. The forest soils supported a greater fungal population than the marshland soil, and several species were found predominantly on the forest soil.

Description: SUMMARYExperiments were devised to establish suitable techniques of screening seedling material of Lolium perenne for cold tolerance under controlled conditions: these techniques were then used to distinguish between varieties and ecotypes from contrasting climatic regions. For the wide range of material used, greatest discrimination was achieved by 14 days hardening at 2 °C and 8 h photoperiod, followed by 2–4 days freezing at -8 °C in the dark. There were indications that the light intensity and/or temperature before and during hardening could considerably modify the cold tolerance.The most useful criterion of cold tolerance was the percentage of tillers surviving 14 days after thawing. In some instances, death of tillers and whole plants continued after this time, and this tendency appeared to be related to growth habit; southern ecotypes were particularly susceptible.Varieties from north Europe were generally more cold tolerant than ecotypes from the Mediterranean region, but tolerance depended also on the altitude of the original habitat. The cold tolerance of a population could, in part, be related to the average lowest temperature in the coldest month and in part to environmental conditions of solar radiation and/or temperature during the autumn in its place of origin.Along with the experiments under controlled conditions, spaced plants of the same populations were grown in the field in order to evaluate winter hardiness under local conditions. The overall correlation between winter hardiness in the field and cold tolerance as assessed in the growth rooms was not high. Results from one year's field testing showed that indigenous varieties such as S. 23 and S. 24 were more winter hardy than foreign ecotypes and varieties, even if these came from colder climates and showed greater cold tolerance in the growth room.

Description: SUMMARYAn analysis of germination characteristics of progeny from a diallel cross between five sugar-beet plants showed that the genotype of the maternal parent controlled to a marked extent the behaviour of the progeny. This may be related to the presence in the fruits of inhibitory substances.Some evidence was found for genie and maternal interactions but these were always of less importance than the maternal effects. Heritability estimates from parent, off spring regression and analysis of half-sib family variances demonstrated that genetic variation for germination characteristics had not been eliminated during the improvement of sugar beet from the wild form.

Description: SUMMARYThe environment, design and methods of this 2-year Kedong grazing trial in the Rift Valley of Kenya were described in Part I.Crude protein of grasses varied seasonally, usually between 3 and 6 %, while most shrubs and herbs, leguminous and non-leguminous, were in the 10–20 % range, although contributing only about 3 % by weight of the total sward, excluding large bushes and trees. Steers selected herbage of 2–3 % units higher C. P., more Themeda leaf and more herbs than the sward average. Treatment effects on sward and diet C. P., and their relationships, were generally small and inconsistent. Higher C. P. in post-burning ro-growth declined to average levels after 2–3 months, except when grazed at one steer to 4–4 acres, rotational (i.e. 1–5 acres available). At this pressure available herbage fell below 1000 lb D.M./acre (1120 kg/ha). In all other treatments 2500–4500 lb D.M./acre wore available at all times. Estimated herbage production varied from almost nil to 320 lb D. M./acre/month. Burning removed 3000 lb D.M./acre. Relationships between herbage C. P., diet c. p. (oesophageal fistula samples) and faeces N were determined.

Description: SUMMARYTriple superphosphate (21.6% P), potassium metaphosphate (25.0% P) and magnesium ammonium phosphate (19.0% P) were compared as phosphate fertilizers alone and in combination, and as powders and granules, in two experiments on acid soils. Basal nutrients were adjusted to allow for the amounts of N, K, and Mg in the test fertilizers. Immediate effects of the fertilizers were measured by early potatoes and barley, and residual effects by radishes and ryegrass.All powdered fertilizers, alone or in combination, were equivalent to powdered superphosphate for early potatoes. The value of granular fertilizers for potatoes increased with the proportion of superphosphate in the mixtures. Superphosphate equivalents of the granular fertilizers were: magnesium ammonium phosphate, 14%; potassium metaphosphate + magnesium ammonium phosphate, 36%; potassium metaphosphate, 53%; superphosphate + potassium metaphosphate + magnesium ammonium phosphate, 54%; superphosphate + magnesium ammonium phosphate, 60%; superphosphate + potassium metaphosphate, 81%.Residues from powdered fertilizers, applied to potatoes, were equivalent, for radishes, to residues from powdered superphosphate. Residues from granular fertilizers were more effective for radishes than residues from powders.All powdered fertilizers were equivalent to powdered superphosphate for barley cut green. Granular magnesium ammonium phosphate, either alone or mixed with potassium metaphosphate, was slightly less effective than powder.Residues from all powdered fertilizers applied to barley were equivalent for ryegrass. Residues from granular fertilizers, especially potassium metaphosphate and magnesium ammonium phosphate, produced more grass than residues from powders.Apparent recoveries of P by the four crops ranged from 24% to 32% and were more from granules than from powders. Residues from all fertilizers increased 0.5M-NaHCO3-soluble P in soils, and mean yields of ryegrass, the final test crop, increased by 3.2 to 5.1 cwt dry matter/acre/ppm NaHCO3-soluble P in the soils.

Description: SUMMARYThe phosphorus requirement of the buffalo (Bos bubalis) for maintenance has been determined from the data of two feeding and balance experiments each with twelve animals in randomized block designs and one with six animals using 3x3 latin square designs in duplicate. The level of phosphorus intake was varied by adding appropriate quantities of sodium dihydrogen phosphate in Exp. 1, by adding wheat bran in Exp. 2 and by adding dicalcium phosphate in Exp. 3.Regressions of phosphorus outgo (7) on P intake (X) gave values of 14–7 g/day in Exps. 1 and 2 and 17–2 g/day in Exp. 3. These values can be taken to be estimates of the P requirement of the adult buffalo for maintenance.The initial and final serum inorganic phosphorus in Exp. 1 also indicated that the phosphorus requirement was between 12 and 17 g/day.

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

Description: SUMMARYField experiments were conducted for 2 years (1977–8 and 1978–9) at the Indian Agricultural Research Institute, New Delhi under semi-arid seasonally dry tropical conditions to evaluate the possibility of growing two crops under natural precipitation, where traditionally one crop is grown. Short-season fodder crops of cow pea (Vigna unguiculata), guar bean (Cyamopsis tetragonoloba), moth bean (V. aconilifolia), soya bean (Glycine max.) or pearl millet (Pennisetum typhoides) harvested before the end of monsoon rains enabled sufficient recharge of the profile from the precipitation received subsequently to enable barley to be sown in the winter season. Although the pearl millet yielded more biomass, the soil fertility enrichment was greater from the legume fodders. The grain yield and total nitrogen removal by barley was higher after the legume fodders than after the non-legume fodder pearl millet. Benefits from the previous fodder legumes were equivalent to or more than 40 kg N/ha applied to barley crop following a previous crop of pearl millet.

Description: SUMMARYFive rumen-cannulated Cheviot lambs were used in two successive experiments to differentiate the effect of osmolality from the specific effects of the soluble compounds in maize silage on voluntary intake and ruminal motility. In Expt 1, extracts from fresh (FCE) and ensiled (CSE) maize were adjusted to pH 6·5 andtonicities of 200, 400, 800, and 1600 m-osmol/kg with NaCl, then infused into the rumen according to a 5×5 repeated latin-square design. Water was infused as the control. In Expt 2 solutions of NaCl, with tonicities similar to those in Expt 1, were also infused into the rumen. The lambs were fed ad libitum a diet of pelleted lucerne, but on the morning of infusion they were deprived of food for 4 h and infused continuously for 4 h commencing after 1 h of food deprivation. The infusion of FCE and CSE resulted in no significant difference in cumulative dry matter (D.M.) intake. However, increasing the tonicities of the infusates caused a linear increase (P 〈 0·05) in ruminal osmolality and a corresponding linear reduction in food intake during the first 30 min of feeding. Infusion of NaCl alone produced a similar effect on intake. The linear regression coefficients of food intake (Y) (g D.M./kg W0·75) against rumen osmolality (X) (m-osmol/kg) were –0·077±0·0085 (r2 = 0·78), –0·082±0·0095 (r2 = 0·76) and –0·073±0·0065 (r2 = 0·84) for FCE, CSE and NaCl, respectively, with no significant differences among the infusates. The frequencies of ruminal contractions during the infusion of FCE and CSE were similar (P 〉 0·05) and were unaffected (P 〉 0·05) by ruminal osmolality up to 550 m-osmol.

Description: SUMMARYOver three grazing seasons a sward of perennial ryegrass, cv. Gremie, was grazed on a rotational paddock system by growing beef cattle weighing on average 185·5 kg when turned out to grass in April. Six grazing treatments were compared: grazing at 20- or 35-day intervals at each of three herbage allowances of 5·3, 4·3 and 3·3 kg grass D.M./100 kg live weight (4·0, 3·2 and 2·4 kg D.M./IOO kg live weight in the 1st year).Measurements of net herbage accumulation and herbage consumption throughout each grazing season were made by taking grass sampling clips to ground level before and after grazing. Animal live-weight gain was assessed by regression on weighings of stock taken either every 7 or every 4 days depending on regrowth interval treatment. Adjustment of allocation treatment was made by varying the weight of stock grazing on a fixed paddock area.In no year did annual net herbage organic-matter accumulation (NHA) differ significantly according to length of grazing interval. NHA showed a 4·7 % advantage for the longer interval in the first 2 years which changed to a deficit of 4·1 % in the final year of the experiment. Herbage allowance treatment produced no significant effect on NHA in any year. The interaction effect of herbage allowance and grazing interval was not significant.Herbage consumption was greater in 2 years out of three under the 20-day regrowth period than with the 35-day treatment, although average degree of defoliation was slightly greater (44·0 v. 38·4%) with the longer interval.Animal live-weight gain was significantly (P 〈 0·05) affected by herbage allowance in all 3 years; decreasing herbage allowance generally resulted in reduced live-weight gain. Only in 1 year was there a significant difference (P 〈 0·001) in live-weight gain with the different rotation length treatments.

Description: SUMMARYA study was made to determine the effects of feeding, arginine injection (0·5 g/kg live weight) and insulin injection (0·5 i.u./kg live weight) on plasma insulin, prolactin and glucose concentrations in ten growing castrated male lambs. The effect of feeding on thyroxine concentrations was also determined. Each test was performed once in each of four periods which commenced at 84, 98, 113 and 127 days of age respectively.Feeding stimulated the release of insulin and this response was larger during period 4 than period 1. The release of prolactin following feeding did not change with age. Thyroxine concentrations, which were generally higher in periods 1 and 2 than 3 or 4, decreased from 1 to 12 h after feeding.Arginine injection stimulated a similar insulin response in lambs of all ages but the prolactin release following arginine injection diminished with age.Insulin injection caused marked hypoglycaemia in all periods, followed by dramatic increase in prolactin concentrations which increased with age.

Description: SUMMARYFour mature castrate Malawi goats, mean live weight 29·66 kg, were offered diets of poor quality Rhodes grass hay, or hay plus a concentrate comprising either maize bran or maize bran-cotton seed cake mixed in varying proportions, so that N intake varied from 4·76 to 20·81 g/day in a series of four metabolism trials.By extrapolation metabolic faecal N loss was estimated to be 9·94 g/kg faecal D.M. and that of endogenous urinary N to be 0·121 g/kg W0·75. The daily maintenance requirement for nitrogen was shown by a factorial method to be 0·682 gN/kg W0·75, and by use of regression equations to be 0·688 g N/kg W0·75 or 0·314 g apparent digestible N/kg W0·75. The mean daily requirement was 8·8 g N, with a mean apparent digestibility of N of 43·4%, and a true digestibility of 80·0%.

Description: Milk production of cows grazing Rhodes grass without the addition of grain supplements can be increased by feeding casein protected from deamination in the rumen with formaldehyde (Stobbs, Minson & McLeod 1977; Flores, Stobbs & Minson, 1979). No increase in milk production was achieved when unprotected casein was fed, indicating that production on a tropical grass was limited by the quantity of amino acids absorbed from the small intestines (Stobbs et al. 1977). Formaldehydetreated casein (formal-casein) increased by 5% the milk production of cows grazing ryegrass in New Zealand when an energy supplement was also fed but had no effect oh milk yield when only ryegrass was fed (Wilson, 1970). In a review of this subject Clark (1975) reported that pen studies showed post-ruminal supplementation with casein increased milk production from 1 to 4 kg/day. The result with ryegrass in the absence of an energy supplement is therefore unexpected and warrants further study.

Description: SUMMARYThe forage potential of Andropogon gayanus (gamba grass) was assessed in cutting experiments on a low fertility, acid Ultisol in Colombia. This grass recently introduced from Africa outyielded Hyparrhenia rufa, Panicum maximum, Brachiaria decumbens and Digitaria decumbena in various mixtures made up of a single grass and a single legume. A. gayanua performed well as a companion grass with the legumes Styloaanthes guianensis, Stylosanthes capitata and Centroaema sp., while B. decumbena suppressed the legumes planted in these trials during the 2nd year following establishment.

Description: SUMMARYThree successive sowings of marrow-stemmed kale (cv. Maris Kestrel) were grazed with lambs (initial weight 22·5 kg) for two consecutive 6-week periods, so that crop yield at the time of grazing was kept relatively constant at 6·5 t D.M./ha. Three crop allowances, 3·9 (H), 2·6 (M) and 1·3 (L) kg D.M./animal/day were imposed in a replicated design. Halfof the 32 lambs grazing each allowance received intraperitoneal injections of L-methionine + L-threonine three times per week. Twelve lambs were slaughtered at the start of the experiment and 48 at the end of each period.Leaf tissue, the diet of the H groups, contained 0·5% D.M. as S-methylcysteine sulphoxide (SMCO) and 0·7–1·5% total N as nitrate. Whole plants, the diet of the L groups, contained 0·75% D.M. as SMCO and 4·0–7·5% total N asnitrate. The diet of the M groups was intermediate.Rates of live-weight gain (LWG), empty-body weight gain (EBWG) and carcassweight gain (CWG) were lower in period 1 than in period 2 for animals grazing at all three allowances. A Heinz-Ehrlich body anaemia developed that was more severe in the first period, but did not differ between groups receiving the different allowances. Methaemoglobin was only detected in significant quantities at the time of peak Heinz body formation in period 1. CWG/EBWG was increased by the amino acid supplementation during period 1 but not period 2, showing that there was a temporary amino acid deficiency corresponding to the time when tho anaemia was most severe and body growth most depressed.In both periods animals grazing at L allowance had lower rates of LWG, EBWG and CWG than M and H animals, who performed similarly. Most of the differences in EBWG between feed allowance treatments and between periods could be explained by changes in estimated intake. Wool growth rates increased with increasing feed allowance and were slightly stimulated by amino acid supplementation.Copper true availability was calculated to be 1·6–2·7% with the lowest values for leaf tissue due to its high sulphur content. Truly available Cu/kg plant D.M. was below the minimum requirement for lamb growth, thus leading to a reduction in total liver Cu as the experiment progressed. Some indication was obtained that this could have been depressing LWG in the second period, especially in H lambs. Slight increases in thyroid gland weight were observed as the experiment progressed, but these were considered unlikely to have depressed body growth. It was concluded that the major factor limiting the feeding value of B. oleracea was its high content of nonprotein sulphur compounds, especially SMCO.