ALBERT

Description: SummaryA radiography unit was developed with which two technicians and two assistants were able to diagnose number of foetuses in 400–600 ewes per day on farms. Diagnoses made between 100 and 120 days of gestation in flocks where weekly mating records were made were 95–98% accurate as judged by lambing records. In most flocks more than 90% of twin pregnancies were correctly diagnosed. Agreement between diagnoses and lambing records was reduced when weekly mating records were not available. The radiographic examination had no detrimental effects on ewes or lambs.

Description: SummaryA winter barley variety, from the USSR, 13031, lacking vernalization requirement but sensitive to short days and more frost resistant than varieties now commercially grown in Britain, was hybridized with Shimabara, a Japanese variety which requires vernalization but is less sensitive to short days and more susceptible to frost than 13031. The resulting segregating population was then selected under short days and non-vernalizing conditions and in artificial freezing tests, in order to isolate recombinant lines.Five lines derived in this way, together with the parents and the standard winter barley variety, Maris Otter, were included in a detailed developmental study made in a glasshouse under cool, short days.Four of the lines had very similar developmental characters, namely few leaves and a high rate but short duration of spikelet initiation. Developmentally these selections resembled the parent Shimabara more closely than 13031 but the rate of spikelet initiation was faster than that of either parent and the duration of spikelet initiation was shorter. The fifth selection also resembled Shimabara more closely than 13031 but had more leaves and a lower rate and longer duration of spikelet initiation than the other selections. This selection was found to have a strong vernalization requirement.One selection closely resembled 13031 in its frost resistance but had low short-day sensitivity and no detectable vernalization requirement. The complementary characters of the two parents were therefore recombined in this line.Vernalization had little effect on the development of any of the genotypes under cool, short days in a glasshouse.

Description: SummaryAn experiment was designed to investigate the effect of a sustained lactation pattern on the intake of milk or solid food by lambs and on their consequent growth rate. Normal lactation pattern was compared with sustained lactation, achieved by fostering lambs at 24 days of age on to newly-lambed nurse ewes. Two genotypes of lamb were used; these were pure-bred Scottish Blackface and Textel × Blackface. Lambs were offered one of two qualities of pelleted concentrate food from 4 weeks of age.Maximum daily intakes of milk were 2·16 and 1·87 kg/day, respectively, for fostered and non-fostered lambs. This differential was maintained until the 10th week. Pattern of lactation had no significant effect on total energy intake from milk and solid food combined or on live-weight gain up to 10 weeks of age. Texel cross lambs consumed more food than did pure Blackface lambs and showed correspondingly higher rates of live-weight gain. Lambs ate slightly more of the higher quality pellets than the lower but there was no effect of solid food quality on milk intake. Within breed of lamb there was a negative relationship between intake of milk and of solid food.

Description: SummaryThe rate of production of bacteria in the rumen of buffalo calves kept on two rations was measured using 14C labelled Streptococcus bovis and 35S whole ruminal bacterial cells. The animals received daily either 15–20 kg green maize or 25–30 kg green cow pea in 12 equal amounts at 2-h intervals. The bacterial cells from the rumen of animals maintained on the same diet were tagged with 35S by in vitro incubation in the presence of 35S-sodium sulphate. Similarly Streptococcus bovis of rumen origin was grown in the presence of U-14C dl-leucine. The cells were injected into the rumen in a single dose. The dilution of the specific radioactivity of bacterial cells in the rumen with time was taken for calculation of the turnover time and rate of production of bacteria.The average production rates of bacteria were 88·3 ± 3·88 and 92·3 ± 1·82 g/kg digestible organic matter and 101·8 ± 1·55 and 103·3 ± 1·49 g/kg digestible organic matter in animals fed green maize and cow pea, when estimated by using mixed rumen whole bacterial cells and Streptococcus bovis respectively. There was no significant difference in the rate of bacteria production when estimated by either method.

Description: SummaryA technique is described which uses the ratio of the natural 12C and 13C isotopes of carbon to calculate the proportions of Calvin pathway (or C3) species and C4 dicarboxylic acid pathway (or C4) species in mixed samples of shoots, roots or seeds. Mean percentage of a particular component can be predicted to within ± 2% of actual values with average standard errors of less than 1% with two component mixtures under good conditions using threefold replication. The technique is particularly useful for estimating the proportion of C3 and C4 species in samples of visually indistinguishable, intermingled root systems from mixed field communities or from competition experiments. The proportion of C3 and C4 species in both oesophageal fistula and feed samples can be obtained using this technique, and it is proposed that data from fistula and pasture samples could be used to determine the extent to which animals selectively eat C3 or C4 species. The advantages and disadvantages of the technique are discussed.

Description: SummaryA comparison was made between an intensive system of lamb production based on Italian ryegrass RvP and one based on perennial ryegrass S. 24, over 2 years, each at three stocking rates (14, 17, 20 ewes/ha). More grass was grown in the first year than in the second when the yield of RvP was particularly reduced. The ewes and lambs ate more RvP than S. 24 but there was no difference in lamb growth rate. The lambs grew faster at the low stocking rate from 0 to 18 weeks and from 0 to slaughter than at the medium and high stocking rates, in both years. Ewe intake and lamb growth rate were higher in the second year than the first. The Masham ewes with two lambs ate significantly more grass per unit of body weight than the Finnish Landrace × Scottish Halfbred and Finnish Landrace × Scottish Blackface ewes, and their lambs grew significantly faster. It was concluded that for an intensive system of lamb production from grass, S. 24 was more suitable than RvP.

Description: SummaryDespite much experimental evidence showing that sodium fertilizer increases sugar–beet yield and decreases need for potassium, there is resistance to its use on some soil types through fears of deterioration in soil structure. Twelve field experiments with sugar beet were made in Eastern England, testing all combinations of autumn and spring applications of 0, 150 and 300 kg Na/ha and 0, 83 and 333 kg K/ha. Fields were chosen with soils of loamy very fine sand, very fine sandy loam, sandy clay loam and clay loam textures. Micro–plot and controlled environment studies were also made with the same soils to examine effects of sodium on seedling emergence and growth.Visual assessments of soil physical state following sodium application revealed no effect in the year sugar beet was grown nor in the following spring when cereals were grown. Measurements of physical properties of soils treated with sodium suggested that applications of several times the recommended amounts of sodium fertilizer would not damage soil structure. However, sodium fertilizer increased the osmotic suction of soil solution which, under some circumstances, e.g. dry springs or giving the fertilizer close to the time of sowing, decreased germination and seedling growth. For this reason and not because it has a detrimental effect on soil physical condition, sodium fertilizer best given in the autumn or some weeks before sowing.

Description: SummaryThe possibility of a sub-clinical state of thiamine deficiency in young cattle and sheep is discussed. A trial was carried out on six MAFF experimental husbandry farms in which groups of animals were given 100 mg of thiamine per day orally throughout the rearing period. Measurement of erythrocyte transketolase showed that the dosed group gave a significantly lower percentage thiamine pyrophosphate effect than the control group. There was no difference in weight gain of the two groups during the limited period of the trial.

Description: SummaryThree spring barley varieties, Proctor, Vada and Mosanne, were inoculated with Rhynchosporium secalis(Oudem.) J. J. Davies at Growth Stages 3, 7, 10·1 and 10·5 (Large, 1954). The treatments included single inoculation at each growth stage and multiple inoculations at two, three and four of the above growth stages. There was no effect of inoculation oil the number of fertile tillers. Thousand-grain weight was reduced in all seven inoculation treatments in Mosanne but only the quadruple inoculation adversely affected the other two varieties. Numbers of grains of both Mosanne and Vada were reduced by treatments which included an inoculation at ear emergence but Proctor was affected only by the quadruple inoculation. In terms of disease assessment Mosanne was very susceptible and Proctor moderately resistant but Vada, with symptom scores only slightly better than Mosanne, exhibited a degree of tolerance which was reflected by the grain weight results in which small increases were recorded. This tolerance mechanism, possibly acting through compensation in this variety, is compared with compensation reported in wheat.

Description: SummarySeventy-four field experiments on the nitrogen requirement of sugar beet were made in eastern England in. 1966 to 1974. Considerable differences in sugar yield response to nitrogen were found between the six soil types used, and these differences were found (on five of the six soils) to be related to sugar yield. Nitrogen response was large on chalk and limestone soils in Lincolnshire, intermediate on East Anglian boulder clays and least on East Anglian chalk and light drift soils. On the lighter soils (limestones, East Anglian chalks and light drifts) nitrogen response was greater with high summer rainfall than with low. Fenland silt soils were very high yielding, but nitrogen response was moderate.Optimum nitrogen rates differed between soils, in the range 100 kg/ha on East Anglian chalks and light drifts to 180–200 kg/ha on Lincolnshire chalks and limestones.

Description: SummaryThe oestrogenic isoflavones genistein, biochanin-A and formononetin, as well as the coumestan derivative coumestrol, were identified by thin-layer, paper and gas chromatography in berseem clover (Trifolium alexandrinum) grown in Israel. Under the conditions studied, the concentration of these oestrogens in the berseem clover (total 〈 0·01% in the dry matter) was considerably lower than those found in clover species known to be associated with infertility in ruminants.

Description: SUMMARYThe effects of six amounts (0, 17, 34, 51, 68 and 85 kg N/ha) of fertilizer N, applied at sowing time as calcium ammonium nitrate, on the crude protein (N × 6·25) content of barley straw sown as the first, second and fourth or later tillage crop after grazed pasture were studied over three seasons at a total of 126 sites. In addition total N uptake and apparent recovery of fertilizer N were calculated for each cropping sequence.The mean crude protein content of the 126 sites was 4·1% without N, increasing to 4·8% with 85 kg N/ha. Maximum protein content with 85 kg N/ha ranged from 4·4% in 1971 to 5·4% in 1973. It was highest in the year which gave the lowest straw yields. Protein content was higher when the barley was sown as the first or second crop after pasture than when it was sown as the fourth or later crop. Incremental of fertilizer N gave only small increases or decreases in straw protein contents. Over all sites straw protein content amounted to about 36% of grain protein contents. There was a significant positive relationship between grain and straw protein contents.Nitrogen uptake in the straw without fertilizer N was 19, 18 and 12 kg/ha in barley sown as the first, second and fourth or later tillage crop after grass. The total uptake of N in the grain and straw combined was 93, 102, 107, 109, 111 and 116 kg N from applications of 0, 17, 34, 51, 68 and 85 kg/ha of fertilizer N. The mean apparent recovery of fertilizer N in the straw varied from 12% with 17 kgN/ha to 8% with 85 kg N/ha.

Description: SummarySix late pregnant and six non-pregnant Finnish Landrace × Dorset Horn ewes were fed a standard diet. Blood and liver samples were taken and the concentrations of the following metabolites measured: adenine monophosphate (AMP), adenine diphosphate (ADP), adenine triphosphate (ATP), citrate, 2-oxoglutarate, phosphoenol-pyruvate, pyruvate, lactate, 2·phosphoglycerate, 3·phosphoglycerate, malate, β·hydroxybutyrate, acetoacetate, glutamate, alanine, NAD+ and NADH. Comparing non-pregnant with pregnant ewes the liver of the pregnant animals had reduced concentrations of lactate, ADP, NAD+ and NADH, and in the blood there were reductions in lactate, pyruvate, lactate/pyruvate ratio and urea. The concentrations of the other metabolites of the pregnant ewes receiving adequate nutrition were little changed from those of the non-pregnant ewes. The significance of these findings is discussed.

Description: SummaryThe effects of paraquat (l, 1'-dimethyl-4, 4'-dipyridylium dichloride or Gramoxone) and diquat (l,1'-ethylene-2, 2'-dipyridylium dichloride or Reglone) on inhibition of flowering and the effect of such an inhibition on improvement of cane yield and juice quality in late maturing sugarcane varieties Co. 853 (early-season flowering) and Co. 419 (mid-late season flowering) planted in February were studied under field conditions at Coimbatore (latitude 11° N). In Co. 419, the spray of paraquat @ 0·35 kg a.i./ha and diquat @ 0·45 kg a.i./ha (diluted in 3000 1 of water) in two equal doses at 3–4 day intervals during the 1st and 2nd week of August suppressed the flowering almost completely, while in Co. 853 flowering could not be checked successfully by chemical spray. Flowering in Co. 853 could be checked only when the spindle leaves were cut continuously from 15 July to 12 August at 4–5 day intervals. In Co. 419, cutting leaf spindles at any day between 1 August and 12 August prevented flowering totally.The sprayed non-flowered crop of Co. 419 gave 13·84–15·69 t/ha more cane yield in February and 16·14–18·07 t/ha in April, whereas sugar yield increased by 1·16 t/ha in February and 3·56 t/ha in April compared with the control flowered crop. There was practically no difference in paraquat and diquat sprays. Suppression of flowering by defoliation in Co. 853 also increased the cane and sugar yield in and after February.

Description: SUMMARYField experiments were conducted at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, for four seasons to evaluate the effect of harvest interval on yield, quality and viability of indeterminate cowpea (Vigna unguiculata (L.) Walp.) seeds. Decreasing harvest frequency from every week to every 4 weeks reduced seed yield, quality and viability. Rate of yield losses was highest at close spacing and intermediate at wide spacing during the first rainy season, and lowest at wide spacing with supplementary irrigation during second rainy season. Time of harvest study conducted with six cultivars indicated that these yield losses were attributable to reduced seed weight and increased pod losses after mature pods were exposed to weathering for more than 1 week. The reduction in seed quality and viability was associated with a high degree of fungal and bacterial infection in the seed. Varietal differences in resistance to weathering were noted among the cultivars tested. TVu 2616 P-O1D, that has thick, leathery pods and smooth, tan seed coat was the most resistant to weathering.

Description: SummaryDuring four winter seasons eight spacing and density experiments were made under irrigated high fertility conditions in north-west Mexico (latitude 27° N). Experiments included various Triticum aestivum and T. durum genotypes of spring habit, short stature derived from Norin 10 genes, and contrasting plant type. Measurements included dry-matter production, photosynthetic area index, and light interception during one experiment, total dry matter at maturity in most others and grain yield and its numerical components in all experiments.Grain yield and most other crop characters were unaffected by row spacings within the range 10–45 cm interrow width. The optimal seeding density for maximum grain yield was 40–100 kg/ha (80–200 plants/m2). Yield reductions at lower densities (20, 25 kg/ha) were slight and accompanied by reduced total dry-matter production. Yield reductions at higher densities (160–300 kg/ha) were also slight and were associated with more spikes/m2 but fewer grains/m2 and reduced harvest index. It is suggested that lower than normal preanthesis solar radiation or weather conditions leading to lodging can magnify these yield depressions at higher densities.Measurements showed rapid approach of crops to 95% light interception, reached even at a density of 50 kg/ha within 50 days of seeding. It is suggested that provided this occurs before the beginning of substantial dry-matter accumulation in the growing spikes (60 days after seeding) there will be no loss of grain yield with reduced seeding density. Results point to a ceiling photosynthetic area index for maximum crop growth rate although there was a tendency for rates to fall at very high indices (〉 9). This tendency was associated with very high density, high maximum numbers of shoots, poor survival of shoots to give spikes (〈 30%) and reduced number of grains/m3;. The relatively low optimal densities seen here may be characteristic of genotypes derived from Norin 10.Genotype × spacing, genotype × density and spacing × density interactions were generally non-significant and always small. There was a tendency for the presence of non-erect leaves or branched spikes to reduce the optimal density, but large differences in tillering capacity had no influence. Differences in lodging susceptibility can however lead to substantial genotype x density interactions.

Description: Output from grazing animals in Britain could be increased by extending the growing season of grasslands. In particular the growth of hill pasture species is highly seasonal with 75% of annual production occurring in three summer months (Newbould, 1974). Stocking rates, limited by winter carrying capacity, are therefore low and summer leaf production is undergrazed. The consequent accumulation of mature senescing herbage seriously reduces pasture quality (Eadie, 1968). As a result of this and lack of grass growth, ewes are often poorly nourished prior to mating (November) and throughout pregnancy and early lactation. Hence fertility levels and lamb birth weights and growth rates are low, and mortality rates high (Gunn, 1967).

Description: SummaryA mathematical model of whole plant growth in soil is presented. Particular emphasis is given to those factors which relate to the absorption of nutrients and water by the root system. There are two basic premises; that a plant is made up of two pools, structural material and precursors to structural material, and that structural material is produced by a reaction between a given ratio of precursors. The precursors are soluble carbohydrate and unbound nitrogen, probably nitrate. Increase in leaf area and root length is a consequence of absorbed nitrogen combining with photosynthate.The absorbing power and the distribution throughout the soil of the roots is controlled, through feedback mechanisms, by the ratio of the precursors, within the plant. The description of plant growth is interfaced with a model of one-dimensional flow of water and solutes in soil, and gives a model for investigating plant growth, or competition between root systems of more than one plant. The results of a number of simulations are presented. A sensitivity coefficient is defined to compare the effect of various properties on overall growth. Its value is calculated for 11 plant properties. It is some measure of the competitive advantage conferred on the plant by a change in the value of each property. The results of the competition experiments are given as replacement diagrams.The model has weaknesses. Because it is explicit, it defines in precise detail the experiments which would support the hypotheses, or suggest modifications to them. As a holistic analysis, it brings together ideas from different disciplines into one comprehensible framework.

Description: SummaryFinnish Landrace sheep with low red cell GSH concentrations resulting from a defective transport system for certain arnino acids were crossed with Tasmanian Merino sheep with a red cell GSH deficiency due to impaired activity of the enzyme γ-glutamyl cysteine synthetase. Inheritance data showed that the two types of GSH deficiency were under independent genetic control. In the Finnish Landrace breed, the gene coding for the transport defect (Trn) was inherited as an autosomal recessive and sheep homozygous for this gene had high red cell concentrations of lysine and ornithine (Ly ×) as well as low levels of GSH. In the Tasmanian Merino breed the GSH deficiency behaved as if controlled by an autosomal dominant gene (GSHL). Backcross breeding experiments resulted in lambs which had inherited both types of GSH deficiency. Evidence suggested that such ‘double low’ GSH lambs had an impaired viability. In Tasmanian Merinos the GSH deficiency was established prior to birth. Newborn Finnish Landrace lambs were clearly separable into two types on the basis of their red cell lysine and ornithine content but not on their GSH concentrations.

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

Description: SummarySplit-plot (or split-block) analyses are commonly applied to experimental results where several successive observations of the same variable have been recorded on each experimental unit. The assumptions required for such analyses receive scant attention and it often seems unlikely that these assumptions would be satisfied in experimental situations. Five sets of results are presented to support this proposition. An alternative analytical approach is suggested in which contrasts over time are analysed; such a method is always valid, computationally simple, and readily interpretable, and may also be used to gauge the validity of the split-plot analysis.

Description: SummaryPrimed continuous intravenous infusions of tracer amounts of [2·3H]gluscose were used to measure glucose entry rates before and after the administration of triamcinolone acetonide or trienbolone acetate to sheep eating 1200 g/day of chopped hay.The intramuscular injection of triamcinolone acetonide caused hyperglycaemia with a maximum plasma glucose concentration 24 h after the injection. Twenty-four hours after the injection of 0·5 mg/kg of steroid the mean glucose entry rate rose from 1·44 to 2·14 mg/min/kg. The difference between these means is significant (P 〈 0·02). Twenty-four hours after injecting 0·05 mg/kg of steroid the mean glucose entry rate had risen from 1·34 to 1·86 mg/min/kg. The difference between these means is significant (P 〈 0·05). The intramuscular injection of trienbolone acetate (0·5 mg/kg) had no effect on plasma glucose concentration or on glucose entry rate.These results are compared with the effect of betamethasone and are discussed in relation to the treatment of ketosis in cattle and sheep.

Description: SummaryLeaf samples were collected, at weekly intervals, throughout the growing season, from potato (Solanum tuberosum L.) plants supplied with varying amounts of nitrogen (0, 60, 120, 180 and 240 kg N/ha) and analysed for total N. Application of nitrogen increased the N concentration in the green leaves at all stages of growth. There was a significant curvilinear relationship between the final tuber yield and the total N concentration in the leaves at 48–90 days after planting in 1968–9 and at 79–107 days after planting in 1969–70. The N concentration at 70–90 days after planting was consistently related to the final tuber yield in both years. Thus this period was ideal for assessing the nitrogen status of potato plants. The critical concentration of total nitrogen generally decreased with advance in age. It ranged from 4·65% at 76 days to 3·30% at 90 days during 1968–9, whereas in 1969–70 it ranged from 4·20% at 79 days to 3·80% at 93 days. During the period from 83 to 86 days the critical percentage was around 3·6% in both the years.

Description: SummaryExamples of response surfaces for pairs of nutrients and results of 41 multi-level experiments with N only were used to compare the goodness-of-fit of polynomial, inverse polynomial, exponential and intersecting-straight-lines models.Whereas no one model fitted best at every site, many results were well represented by two intersecting straight lines and on average, this model had the least residual mean square. Of 17 experiments with spring barley in south western England the few results best represented by smooth curves were from crops much affected by leaf diseases.Fertilizer response was poorly represented by models without a falling asymptote, like the simple exponential and inverse linear. Study of residuals after fitting the quadratic showed that this widely used model consistently over-estimated both the amount of fertilizer needed for maximum yield and the yield loss when too much fertilizer was given.When fitted to the mean yields of each nitrogen treatment, most models had residual mean squares equal to or less than the error mean square, repeating a result obtained at Rothamsted as early as 1927. We question the validity of some well-known evidence for block and treatment additivity.For 12 experiments in 1970, between-site differences in the parameter values of the two straight lines representing grain yield were related to leaf area at ear emergence.

Description: SummaryTwo experiments designed to compare lambs born to Merino ewes subjected to either nutritional deprivation or high ambient temperatures (diurnal: 8 h at 42·2 °C, 16 h at 32·2 °C) during the last two thirds of gestation are described.In Expt 1, lambs from ewes group-fed to maintain maternal body weight at high ambient temperature were lighter (P 〈 0·01) and had shorter metacarpal bones (P 〈 0·01) than those from ewes fed to either lose, maintain or gain weight at prevailing temperatures (– 2·0 °C to + 16·4 °C). The regression of metacarpal length on the cube-root of birth weight (‘linear equivalence’) was linear. Simple maternal under-nutrition was thus not indicated as a cause of foetal stunting in heat-stressed ewes, though the proportions of affected lambs closely resembled those of the nutritional dwarfs.In Expt 2, in which all ewes were individually fed, heat-stressed ewes fed ad libitum consumed 40% less feed and produced lambs which were markedly lighter than those from controls at prevailing temperatures. Other control ewes pair-fed at the level of intake of heat-stressed ewes gave birth to lambs of similar weight to those fed ad libitum. Thus, although feed intake was substantially reduced at high temperatures, the amounts actually eaten by heat-stressed ewes were sufficient to enable control ewes to produce lambs of normal weight. The relationships between birth weight and the weight of the adrenals, cerebellum, cerebrum, heart, kidneys, liver, spleen and thyroid were linear, irrespective of treatment, and as in Expt 1 metacarpal length was linearly related to the linear equivalence of birth weight. However, not all changes in body components were directly proportional to changes in the body as a whole, and heat-affected lambs were thus neither true miniatures nor achondroplastic dwarfs. Until these relationships are clarified it is suggested that ‘stunting’ is the most appropriate description of the influence of high ambient temperature on the sheep foetus.The findings are consistent with the suggestion that the adverse effects of high temperature arise from an extreme form of foetal undernutrition.

Description: SummaryWeed control in irrigated peanuts was evaluated under arid conditions over an 8-year period. Weed competition during the first 8 weeks of the growing season, affected the yield in three out of eight experiments. Mechanical cultivation and herbicides alone or in combination did not control the weed population completely. The best weed control was accomplished by the combination of two herbicides, a system which allowed a complementary effect and long-term control of annual weeds.

Description: SummaryA linear relationship between the amount of allantoin excreted in the urine of cattle and the digestible dry-matter intake, has been found for cattle fed different roughage diets. The relation was also linear for buffalo although they excreted less urinary allantoin than cattle at the same level of digestible dry matter intake. It is postulated that the relationship arises because of the contribution that degraded microbial nucleic acids make to the excreted allantoin in the urine of cattle.

Description: SummaryA number of studies on sodium hydroxide treatment of rice hulls and straw are reported. Alkali levels ranged from 0 to 100 g NaOH/100 g for hulls and from 0 to 50 g NaOH/100 g for straw.Effects of prior grinding, prior irradiation with gamma rays (0–50 Mrads), alkali reaction time (0–24 h), neutralization of excess residual alkali with acids, and rinsing effects were studied in terms of increased salt (ash) content, test material solubility in water and in vitro and in vivo (terylene bag) fermentation.Moderate increases in solubility and digestibility of straw followed irradiation but not for hulls. Major increases were found for irradiated straw further treated with alkali but hulls were little affected by 5 g NaOH/100 g D.M. except at the 50 Mrad level. Nutrient fortification of inocula media did not help dissimilation. Grinding had little effect on degradation of alkali-treated hulls. Straw responses were greater than for hulls.Alkali treatment removed encrusting silica and lignin from rice hulls and increased in vitro and in vivo digestibility. Above levels of 12·5 g NaOH/100 g dry matter in vitro digestibility was depressed unless residual alkali was neutralized. Alkali-treated hulls were reduced in silica content better by rinsing or by no neutralization and no rinsing: neutralization or neutralization followed by rinsing were less effective. Lignin was best removed by alkali or alkali and acid without rinsing. Alkali reaction time on hulls was not critical, but alkali concentration was.Animal trials indicated useful intake and digestive responses to alkali-treated rice hulls. Raw rice hulls were rejected by sheep.When fed in a mixed diet with lucerne chaff (40% whole rice hull, 60% lucerne chaff) daily voluntary intake of rice hull dry matter was 345 g (nil NaOH); 361 g (10 g NaOH/ 100 g rice hull); 193 g (20 g NaOH/100 g rice hull) with apparent dry-matter digestibility values for the hulls of 20%, 41% and 51% respectively.

Description: SummaryS. 24 perennial ryegrass, containing 2·9 g nitrogen/100 g D.M.〉, was conserved by freezing (to represent the fresh material) or by drying. Three dehydration treatments were imposed, comprising low temperature (inlet temperature 145 °C) high temperature (inlet temperature 900 °C) or oven drying (100 °C for 18 h) and in addition part of the high temperature dried grass was treated with formalin (1 g/100 g crude protein) prior to feeding.The digestion of the energy and nitrogen components of all diets was investigated using sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum.Dehydration and formalin of the grass reduced nitrogen solubility and apparent energy and nitrogen (P 〈 0·001) digestibilities but led to increased quantities of nitrogen entering the small intestine (P 〈 0·01) compared with the frozen diet. A significant relationship describing nitrogen transformations was established: Y = 165–1·13X (r = –0·98, P 〈 0·001), where Y is g nitrogen entering the small intestine per 100 g N consumed and X is dietary nitrogen solubility. All dried diets showed increased losses of nitrogen within the small intestine compared with the frozen diet, the largest values being observed on the oven-dried and formalin-treated diets.Neither total VFA production within the rumen nor overall cellulose digestibility was influenced by dehydration, but on the formalin-treated diet there was a marked shift of cellulose digestion from the rumen to the caecum and colon compared with the other diets, associated presumably with the large reduction in protein solubility on this diet.Dehydration improved the efficiency of conversion of ruminally digested energy to VFA energy within the rumen, and in relation to the nature of the total absorbed nutrients a significant relationship was established:Y = 30·97–0·22X (r = –0·98; P 〈 0·001),where Y is g digestible crude protein lost in the total intestines per 100 g digestible organic matter intake and X is dietary nitrogen solubility.

Description: SummaryFourteen Friesian and 13 Angus steers, grown at pasture, were selected so that their carcass weights fell evenly throughout the range 200–300 kg. The right half of each carcass was dissected into muscle, fat, bone and fascia and tendon, and the left half boned-out and fat trimmed into retail cuts. A step-wise multiple regression procedure, including a pseudovariable for breeds, was used to compare compositional components on a common weight basis.Angus, at the lower end of the live-weight range, had heavier empty bodies than Friesians; at the heavier end of the live-weight range, this was reversed. This relationship between live weight and empty body weight was due to variation between breeds in the weight of contents in the fore stomachs but not the intestines.When compared at either the same live weight or the same empty body weight, Angus had more hot carcass than the Friesians (8·0 and 8·4 kg, respectively). There was no difference between breeds in loss of carcass weight in the 24 h post-slaughter.There was no breed difference in weight of blood, head, kidney and channel fat, kidneys, liver, diaphragm, heart, lungs, tail or fore-stomachs, when compared at the same offal weight. The feet and intestines were, respectively, 0·55 and 2·43 kg heavier for Friesians than for Angus at the same offal weight, but the pizzle was 0·11 kg lighter. Hide weight was greater in the Angus at all offal weights, with the difference between breeds being 0·016% of (offal weight).There was no difference between breeds in the weight of muscle or the weight of fascia and tendon when compared at the same dissected side weight; however, the Angus had 4·8 kg more fat and 3·0 kg less bone than the Friesians at the same dissected side weight.When compared at the same muscle weight the Friesians had 1·04 kg more proximal hind-limb muscles, 0·30 kg more proximal fore limb muscles, but 0·74 kg less abdominal muscles than the Angus. At all dissected muscle weights the Angus had a greater weight of muscles of the neck and thorax, and this difference increased with increasing weight of dissected muscle. The Friesians also had 1·52% more of their muscle as ‘expensive muscle’. There were no breed differences in the distribution of any other muscle groups.There was no breed difference in the distribution of dissected fat between subcutaneous and intermuscular depots when these were the only fat depots considered. However, when kidney and channel fat was included in the total dissectable fat of the carcass, Friesians had 22·4 % more kidney and channel fat, the same weight of intermuscular fat and less subcutaneous fat than the Angus at the same total dissected fat weight.Friesians tended to have more of their bone weight in their legs (humerus, femur, tibiar–tarsus, radius–ulnar–carpus) and Angus more in their thoracic region (thoracic vertebrae and ribs, scapular and sternum-costal cartilages).At the same retail side weights there was no difference between breeds in the weight of fat-trimmed, boned-out, retail cuts; however, the Friesians had 3·3 kg more retail bone than Angus, but 2·3 kg less fat trim and 0·46 kg less sausage mince.There was no difference between breeds in the distribution of retail bone or of fattrimmed, boned-out cuts between the forequarter and hindquarter. However, the Friesians had 13·2 % more fat trim in the hindquarter. Friesians had 0·27 kg more retail cuts located in the rump but 0·80 kg less in the loin, when compared at the same weight of retail cuts. Also, the Friesians had more of their retail cuts as topside, thick flank and foreshin. There were no other differences between breeds in the distribution of retail cuts.

Description: SummaryTwenty experiments between 1970 and 1974 tested the effect of spring applications of all combinations of five amounts of potassium (0–333 kg K/ha) and two amounts of sodium (0, 150 kg Na/ha) on sugar-beet yield, profitability and the amount of K and Na in the crop in mid-summer. The experiments were in commercial sugar-beet crops where soils contained little exchangeable potassium, most having less than 100 mg K/l in top soil. On average, sugar yield was greatest when 150 kg Na/ha plus 167 kg K was used, the fertilizer increasing yield by 0·71 t/ha. Response to this combination of K and Na fertilizers was 1·45, 0·57 and 0·22 t sugar/ha when the soil contained less than 60, 61–120 and more than 120 mg K/l respectively.From results of earlier experiments, it was thought that response to even a large amount of K without Na would be less than to Na without K because usually there is insufficient rainfall in the spring for maximum response to K. In fact, 333 kg K/ha increased yield by about the same amount as Na, probably because a large proportion of these experiments were made in wetter-than-average springs.The concentration of K in dried tops and roots in mid-summer increased linearly with soils containing from 40 to 120 mg K/l but when there was more K in the soil the concentration of K in the plants did not increase further. By contrast, the concentration of Na in plants did not reach a similar plateau. Whole plants in mid-summer contained between 128 and 251 kg K/ha and 42–102 kg Na/ha, depending on the fertilizer treatment. Recovery of applied K varied from 90% when small amounts were used on fields containing least K to about 20% when large amounts were given on fields containing moderate amounts. Recovery of Na varied from about 50 to 23%.The comparison of the financial return from using K alone or K plus Na showed that Na was essential for maximum profit. On average, the most profitable dressing of K gave a return of £14/ha whereas K plus Na gave up to £46/ha. On fields with least K, the corresponding results were £50 and £115/ha respectively. In relation to soil K, the most profitable application was 150 kg Na/ha plus about 150 kg K/ha on soils with 60 mg K/l or less, and 150 kg Na/ha plus about 75 kg K/ha on most other soils.

Description: SummaryExperiments made over a period of 3 years (1971–73) at Pantnagar, India, on the effect of plant density and spatial arrangement of a hybrid variety of maize (Ganga 2) and a local cultivar (Rudrapur) indicated that a density of (at least) 75000 plants/ha is necessary to obtain maximum grain yield. With increasing density from 25000 to 75000 plants/ha the date when 75 % of plants were silking was delayed 2–5 days and the percentage of barren plants increased from 1·7 to 28·7. In dense stands, grain yield of the hybrid variety was less affected by increasing row width from 60 to 90 cm than it was in the local cultivar.The average increase in yield with narrow (60 cm) row width as compared with wider (75 cm) row width was 6.8 % and it is argued that, in the context of the national need for increased food production, this increase cannot be overlooked.

Description: SummaryThe effect of a single injection of 100 μg prostaglandin analogue Cloprostenol, during the luteal phase of the oestrous cycle was examined for synchronization of oestrus, time of ovulation and embryonic viability in ewes.Following injection of Cloprostenol alone, 84% of ewes were detected in oestrus 29–48 h later. Pretreatment with PMSG increased the proportion of ewes in oestrus within 36 h. In these ewes 38% had begun ovulating 30 h after the onset of oestrus and by 36 h 87% had begun ovulating. Normal embryos of 8-cells to blastocysts were obtained from ewes given PMSG and Cloprostenol, and on transfer to recipient ewes, treated with Cloprostenol, all recipient ewes produced lambs.It is concluded that injection of 100 μg Cloprostenol is an efficient method of synchronizing oestrus in ewes and that normal embryonic development would be expected in mated ewes following this treatment.

Description: SummaryPot experiments in which cowpea and hyacinth bean were grown at 15–45% soil moisture showed that nodulation, nitrogen fixation and plant growth were poor at 15%. The weights of nodules and plants were lower in January (winter) than in June (summer). In June cowpea was more tolerant of dry conditions giving good nodulation at 25–35% whereas hyacinth bean required 35–45%.Under field conditions the number and dry weight of nodules were affected by the irrigation interval whereas plant growth was affected by the amount of water applied. Applying 75 mm depth of water every 7 days gave the best combination of nodulation and plant growth.

Description: Untimely ploughing and rotavation of a silt loam soil was found to increase bulk density, and mechanical resistance to a needle penetrometer probe, and to reduce air porosity. These effects were not found deeper than 8 cm, although measurements with a 13 mm field penetrometer probe indicated some increase in mechanical resistance down to 30 cm. The effect of untimely cultivations on soil conditions was small when compared with the effect of loosening by hand digging. This treatment reduced substantially the bulk density and mechanical resistance; it increased air porosity and moisture content of the subsoil. Although measurements of mechanical resistance with the laboratory penetrometer were 2·4 times those of the field penetrometer, there was nevertheless good correlation between measurements.

Description: SummaryFour groups of eight lambs, 4 months of age and reared parasite-free from birth, were used to investigate the effect of the intestinal parasite Trichostrongylus colubriformis on the intake and efficiency of utilization of food, using balance trial and comparative slaughter techniques. One group (CI) was killed initially as control. Two further groups (ALC and ALI) were offered ad libitum a complete ruminant diet. The ALI group was dosed orally each day for 14 weeks with 2500 infective larvae. Sheep in a further group (PF) were individually paired to members of the ALI group, and given the same amount of food as their pair. Balances of nitrogen, Ca and P and the digestibility of dry matter and energy were determined for the ALI and PF groups during weeks 6–7 and 12–13 and after 98 days of infection the sheep were killed. The bodies of these and the CI and ALC sheep were analysed for water, fat, nitrogen, Ca and P contents.Parasitism reduced food intake over the whole experiment by 9%, but had no effect on the digestibility of energy or nitrogen. At the first trial the N balances of the ALI group were inferior to those of the PF group due to increased urinary N excretion, but there was no difference at the second trial. Ca and P balances of the ALI group tended to be inferior to those of the PF group at both trials. The weight gain of the ALI sheep was only 50 % of that of the PF sheep with the same digestible energy and protein intakes. The protein content of the gain in empty body weight of the ALI sheep was 80 g/kg compared with 112 and 124g/kg in the ALC and PF groups, respectively. Possible causes of the poor protein anabolism are discussed.The gross efficiency of utilization of metabolizable energy for growth was calculated to be 13·3 % in the ALI sheep, compared with 26·2 and 24·2 % respectively, in the ALC and PF groups. It was not possible to determine whether this was due to change in maintenance requirement or in efficiency of fattening.The Ca and P content of the skeletons of the ALC and PF sheep increased by 55 % during the 98-day period, while no net change occurred in the ALI sheep. It was concluded that this was caused by an induced mineral deficiency resulting from parasitic damage in the small intestine.

Description: SummaryA series of five metabolism trials was made to determine apparent nitrogen digestibility and metabolizable energy (ME) contents of protein rich feedingstuffs. The mean nitrogen digestibilities of fish meal, groundnut, mustard, sesame and cottonseed cakes were 66, 69, 68, 57 and 40%, respectively. Corresponding values for metabolizable energy values were 1820, 2460, 2330, 1870 and 1530 kcal/kg, respectively. The metabolizable energy contents of coconut cake, niger cake and blood meal were 1190, 2360 and 2190 kcal/kg, respectively. The quantity of protein, its digestibility and crude fibre content in the cakes are the prime factors for this trend in MB. Simple and multiple regression equations were derived from biologically assayed metabolizable energy and chemically analysed energy-yielding nutrient contents of the feedingstuffs. The simple regression equation is:ME kcal/kg = 32·95 (% crude protein + % ether extract × 2·25+ % available carbohydrate)–29·20.The multiple regression equation is:ME kcal/kg = 370·29 + (24·47 × % crude protein)+ (65·77 × % ether extract)+ (44·07 × % available carbohydrate)- (8·15 × % crude fibre).The correlation coefficients of simple and multiple regression equations were 0·72 and 0·73, respectively, indicating that there is very little advantage for prediction in using the multiple regression equation. The usefulness of the equation for routine checking of poultry feeds for ME is apparent since the nutrients required to predict metabolizable energy can be analysed within a short period of time.

Description: SummaryMidas, a barley variety very susceptible to brown rust (Puccinia hordei), and two less susceptible varieties (Julia and Mazurka) were given three amounts of nitrogen (50, 100 or 150 kgN/ha) either at sowing (in March), in May, or half at each time. Benodanil sprays were applied to one half of each plot in June and again in July to control brown rust. Brown rust became more severe in 1973 than in 1974 and was most severe on Midas with 150kgN/ha. In 1973, there was most brown rust where all or part of the nitrogen was applied in May, but in 1974 there was least brown rust where all the nitrogen was applied in May, probably because dry weather limited its uptake.In 1973, when ample rain fell in spring and summer, grain yield was increased more by nitrogen given in May than in March, especially when benodanil was given. In 1974, little rain fell until July and then March nitrogen increased grain yield most whether or not benodanil was given. Top dressing of N (in May) produced a smaller straw yield than seed-bed dressing did in each year.Benodanil spray much decreased brown rust and increased yield of grain, but not of straw; the increase was greater in 1973 than in 1974, when brown rust was less abundant. Benodanil increased yields of all varieties, but that of the rust susceptible variety, Midas, most. Benodanil increased grain yield more, as more N was given to the barley, and more with N given in May than in March. It increased the amount of N removed by the barley grain, but not by the straw.

Description: SUMMARYPenned Romney wether sheep were fed ad libitum diets of untreated silage and hay made from the same pasture (Expt 1), untreated silage (Expt 2), and high quality fresh pasture (Expt 3). Voluntary intake and wool growth were measured. In each experiment half of the sheep were given intraperitoneal injections three times per week which supplied the equivalent of 1·03 g DL-methionine/day.Relative to silage in Expt 1, hay increased voluntary dry matter intake, depressed apparent nitrogen digestibility and increased wool growth. Methionine supplementation increased voluntary intake and wool growth with animals fed on hay or silage in Expt 1 and with those fed on silage in Expt 2, but had no effect on either variate with the diet of fresh pasture.Wool sulphur content, measured in Expts 2 and 3, was increased by methionine supplementation, and it was calculated that 34 and 15% respectively of the sulphur administered as methionine was recovered in the wool.The effects produced by methionine supplementation in this work are compared with those produced from different forms of post-ruminal amino acid supplementation in sheep fed a variety of diets. Factorial estimates of the requirements for sulphur of sheep and cattle in different physiological states have been calculated, and are discussed in relation to results of trials involving supplementation with sulphur-containing amino acids.

Description: SummaryA dynamic model has been derived to predict the day-to-day changes in the growth and nutrient composition of crops grown in the field with different levels of nitrogen and potassium fertilizer. Equations are included in the model to represent processes such as re-distribution of nutrients down the soil profile after rain or evapotranspiration, transformations between the various forms of potassium, transport of potassium ions through the soil to the roots and the dependence of growth and nutrient uptake on incoming radiation, plant composition, and soil water stress.The model was tested by using it to forecast the responses of a test crop, cabbage, to fertilizers in four separate field experiments at WeUesbourne. From data describing the initial soil conditions and weights of the plant, the soil and crop characteristics and the daily weather conditions, the model correctly predicted the pattern of responses in each experiment, although, in some instances the absolute values of the theoretical and experimental yields differed somewhat. Of special significance was the ability of the model to forecast the effects of different weather conditions on crop response and the interactions between the effects of N and K fertilizers on the growth and chemical composition of plants.

Description: SUMMARYChopped barley straw was fed ad libitum to penned Romney wether sheep. Supplements of urea, ground wheat grain + urea, lucerne hay and autumn saved pasture (ASP) were given for five periods each of 3 weeks using a 5 × 5 Latin square design. The latter three supplements supplied similar amounts of nitrogen and approximately 20% of the energy required for maintenance.The concentration of ammonia in the rumen fluid of sheep fed the basal straw diet was low and was increased by all the supplements. The concentration of total volatile fatty acids (VFA) in rumen fluid was unaffected by supplementation with urea, but was increased by the three supplements of nitrogen and energy. Differences in VFA molar proportions between treatments were small.Sheep offered straw alone had a digestible energy (DE) intake of 69% of maintenance and showed a weight loss of 121 g/day. Supplementation with urea had no effect upon apparent energy digestibility (42%) or voluntary intake, but significantly reduced the rate of live-weight loss. The lucerne hay and ASP supplements also had no effect upon straw consumption, but increased total DE intake to 87% of maintenance due to the additional energy provided by the supplements, and reduced live-weight loss. Supplementation with wheat + urea increased the estimated amount of digestible organic matter derived from straw by 8·5%, increasing DE intake to 94% of maintenance and reducing live-weight loss to 18 g/day.Averaged over all five groups of animals, straw intake increased by 9% in the second period of feeding and then gradually decreased with time, reaching a value in period 5 which was similar to period 1.

Description: SUMMARYThe experiment described was carried out to compare the effects of some combinations of dietary ingredients which were within the bounds of current commercial use but which differed in their lipid characteristics.The four dietary treatments used were either low or high in lipid content with a high or low proportion of unsaturated fatty acids in that lipid. Fourteen pigs (seven gilts and seven barrows) were assigned at random to each dietary treatment. The major dietary constituents were barley × wheat × dried skim milk (treatment 1), barley × wheat × soyabean meal (treatment 2), barley + wheat + dried skim milk × tallow (treatment 3) and barley × wheat × maize × fish meal (treatment 4).Production performances were satisfactory on treatments 1, 3 and 4. The pigs on treatment 2 ate less food, grew more slowly, had poorer feed conversion ratios and fatter carcasses than the animals on the other treatments; the reason for the poor performance on this diet is not clear.Comparison of the fatty acid compositions of the backfat triglycerides and the dietary lipid shows that the dietary lipid had little effect on the backfat lipid characteristics; only in the case of linoleic acid was there a dietary-induced effect on the amount of this fatty acid in the backfat triglycerides of pigs on treatment 4.Treatment 4 which produced the backfat with the greatest linoleic acid content also produced the softest backfat. The subjective fat scores of the carcasses of pigs fed the other diets were not related to the fatty acid compositions of the backfat triglycerides or the monoene/saturated fatty acid ratio.These results are discussed in relation to the effects of diet and triglyceride structure on pig backfat lipid characteristics.

Description: SUMMARYThree buffalo calves and four Holstein x Hariana cross-bred calves of 4–6 months of age were fed for 21 weeks either on a normal protein ration according to National Research Council (1966) standard or 25% below or above it. The scheme of feeding was as follows:Blood urea was determined every week from 6th to 21st week except in 10th, 14th and 15th week. When the animals attained the age of 15–17 months, their blood urea was again determined.Blood urea of buffalo calves was found to be significantly higher than that of cow calves under similar conditions of feeding from 4 to 11 months of age. This difference disappeared at 15–17 months of age. Probable causes for this difference between species are discussed. Blood urea in both species tended to increase on high protein and decrease on low protein rations.

Description: SUMMARYMeasurements of O2 consumption (Vo2), CO2 production (VCO2) evaporative water loss and rectal temperature (Tr) have been made and metabolic heat production (H), evaporative heat loss (—E) and respiratory quotient (RQ) calculated with individual and groups of 1-day-old chicks at constant ambient temperatures (To) in the range 20—43 °C and 80 or 20% relative humidity (R.H.).Minimal metabolism (10·7 kJ/kgJ/h) occurred at 35 °C.One-day-old chicks act as heterotherms outside the zone of minimal metabolism since neither H nor —E are sufficiently developed mechanisms to maintain homeothermy.Huddling allows chicks to maintain a higher TT at a lower H per unit metabolic body size.Reducing E.H. from 80 to 20% raised the upper temperature survival limit (UTSL) from 41·5 to 43 °C.Panting was initiated when Ta = 38 °C and Tr was between 39·5 and 39·9 °C.

Description: SUMMARYThe percentage of natural cross pollination was estimated in the Alexandria area (Egypt) in two sites near and far from an apiary. The Egyptian cotton variety Giza 45 and the glandless strain Bahtim 110, as a marker parent, were used during three growing seasons. The average natural crossing within the square of the marker parent were 3·54 and 0·34% near and far from the apiary respectively. For the plants around the square of pollen source, however, the average of natural crossing was 0·56% near the apiary, while it was 0·21% far from the apiary. The natural crossing steadily decreased as the distance from the marker variety increased.

Description: SUMMARYCarcass data for 424 castrated male lambs, comprising seven breed-type groups, were used toevaluate a series of linear measurements, subjective scores and the lean content of sample joints as predictors of percentage lean in carcass. The groups represented the main types of British lamb and mean carcass weights ranged from 12·8 kg (Welsh Mountain) to 20·8 kg (Lowland Longwool). Lambswere selected from commercial abattoirs to cover the ranges of fatness and conformation normally found in practice within each group. The pooled within-group S.D. for percentage lean was 3·70 and theoverall S.D. (ignoring groups) was 3·96.Predictors were compared in terms of precision and the stability of their prediction equations. Of the characteristics measured on the intact carcass, subjective scoring of external fatness gave the most precise prediction both within groups and overall (R.S.D.within = 2·82, B.S.D.overall = 3·17). Fat thickness over the eye muscle (0) was the best predictor among those taken on the quartered carcass (R.S.D.within = 2·76, R.S.D.overall =3·00). The most precise individual predictors were percentage lean in the best end neck and shoulder joints (R.S.D.within = 1·51 and 1·59 respectively). Among pairs of predictors not involving dissection, the combination of C and percentage kidney knob and channel fat in the side gave the most precise prediction (R.S.D.within = 2.51, R.S.D.overall = 2·68). The stability of the prediction equations between groups tended to increase with the precision of the predictors. Among the more precise predictors, the equation for percentage lean in the leg was a notable exception, being particularly variable from one group to another.

Description: SUMMARYThe grazing feed intake of four ¾ Brahman and four purebred Hereford steers was measured on four occasions during 12 months while they grazed improved pastures in a cool temperate environment. When pen fed roughage diets, the excretion pattern of chromic oxide and faecal nitrogen–digestibility relationships were also investigated in these animals.There were no breed differences in the relative recovery of Cr2O3 in the faeces when bulking 10.00 and 17.00 h samples nor were there breed differences in the faecal nitrogen–digestibility regression obtained. However, although there were large discrepancies between feed intake and live-weight change when measured in different seasons, the Herefords had the higher feed intake on each occasion while breed differences in live-weight change were non-significant.

Description: SUMMARYThe residues from a continuous millet–maize rotation, grown at two levels of phosphate and two levels of nitrogen fertilization, were either burned and the ash incorporated; chopped and incorporated unburned; or completely removed. After 3 years, differences in soil organic matter were small and largely non-significant, but the ash treatment had minimized the general fall in soil pH, and the ash and the unburned residue treatments had both conserved topsoil exchangeable K and Mg, which, where the residues had been removed, had declined by 44 and 12%, respectively. Fertilizer effects were also significant; single superphosphate had increased exchangeable Ca and lessened the fall in soil pH; calcium ammonium nitrate had depleted exchangeable Mg generally and had lowered pH and exchangeable Ca particularly where unburned residues had been returned.A balance sheet of soil cations (0–30 cm), drawn up from soil and crop analyses and known fertilizer inputs shows, first, that whereas the calcium added in single superphosphate increased the exchangeable reserves of this nutrient, that added as calcium ammonium nitrate did not and must be presumed lost by leaching; secondly, the decline in exchangeable K where residues were removed was much less than the total crop removal, indicating a probable substantial release from non-exchangeable form.In the fourth season, treatment-induced soil differences, in particular the ratios between exchangeable cations, significantly affected the chemical composition of the maize test crop but not its final yield.

Description: SUMMARYLettuce obeys the Shinozaki–Kira relationship in which the reciprocal of plant weight is linearly related to plant density. The intercept (a) represents the reciprocal of the weight of an isolated plant and the slope (b) represents the reciprocal of yield/unit area at high densities (the ‘ceiling yield’). This work examines the time course of (a) and (b) in an ‘ideal environment’ in which water and nutrients are non-limiting, and the light/temperature regime is constant.Two pot experiments are described: the first showed that the growth of isolated lettuces follows a logistic expression, which can therefore be substituted for a–1 in the Shinozaki-Kira equation. It was then hypothesized that b–1, the ‘ceiling yield’ would be constant over time. This was confirmed by the second experiment, giving the equationw–1t = w–10 e1–kt × w–1max × bd,in which wt is mean plant weight at time t, w0 and wmax are the initial and final weights of isolated plants, k is the early relative growth rate of such plants, b–1 is the constant ceiling yield, and d is the plant density.Two examples of the use of the equation are given: one shows how it predicts the interaction between seed size and plant density within a species (subterranean clover): the other illustrates how it can be used to explain why lettuce growth appears to be log-linear against time whereas cereal growth is more nearly just linear.

Description: SUMMARYThe results of experiments in which Navy beans (cv. Purley King) were precision drilled at the beginning, middle and end of May in 1972, 1973 and 1974 suggest that the optimum time to sow is mid-May when soil temperatures at 10 cm depth have reached 12–13 °C. Earlier sowing usually led to a reduced plant stand and low yields whilst in 1972 and 1974, two exceptionally cool years, later sowing resulted in lower yields following a reduction in 1000-seed weight.Despite contrasting weather conditions acceptable yields of seed were obtained in all 3 years from mid-May sowings although cool wet conditions in the autumn of 1974 curtailed drying of the seeds below 30% moisture content. Accumulated temperatures (Ontario units) were successfully used to predict stages in crop development and the data used to demarcate the areas in England most suitable for Navy-bean production.

Description: SUMMARYGas liquid chromatography was used to investigate the influence of several T, S and unclassified cytoplasms on the fatty acid composition of oil from A632 and CrS4HLA maize seeds. The fatty acid compositions of the A632 and CrS4HLA seeds differed markedly from each other with respect to oleic and linoleic acids but were stable within each seed line with respect to all sixteen of the cytoplasms tested.

Description: SUMMARYThe effect of stage of harvesting on dry-matter (D.M.) yield and chemical composition of barley, wheat and the legumes common vetch (F. sativa), woollypod vetch (F. dasycarpa) and fodder peas (P. sativum) were studied in Cyprus under low rainfall conditions in a series of trials sown in four successive years. Cereals were harvested at the beginning of heading, 50% heading and the milk stage of grain, and legumes at three stages from preflowering to full pod formation, D.M., protein and digestible D.M. yields and percentage D.M. content increased with age, whereas percentage protein content and D.M. digestibility declined. Under moisture stress conditions before and during the harvesting period D.M. yields did not increase significantly with age. Protein content of cereals under low rainfall conditions was higher than that of cereals grown in the U.K. under higher N fertilization levels. Rainfall conditions affected drastically the performance of both cereals and legumes. However, average yields were satisfactory; the barley variety 628 gave 8·98 t/ha, the highest D.M. yield among all cereal and legume varieties.

Description: SUMMARYThe effect of soil salinity (ECe range 2–9 mmhos/cm) on the growth of and ion uptake by barley, sugar beet and broad beans (crops increasingly sensitive to salinity) was investigated in a glasshouse experiment.Barley and sugar-beet yields benefited from the added Na in the soil but broad beans were always adversely affected. Changes in growth and ion uptake are discussed in terms of Na:K synergism and antagonism.Sodium:potassium antagonism was observed in barley just after germination, and in sugar beet throughout growth, but not in barley at other growth stages nor in broad beans. Greater Na uptake promoted increases in dry-matter yields of all plant parts with barley and sugar beet, indicating that Na played a specific role in their metabolism. In sugar-beet roots, sugar concentrations and dry-matter yields increased with added Na by half as much more than without added Na, suggesting that Na is an essential nutrient.We conclude from our experiments that the effects of salinity caused by Na salts when water is not limiting, is related not only to plant species but also to their stages of growth.

Description: SUMMARYThe effect of six intervals between harvests and three levels of N application on the proportion and yield of green leaf, dead leaf, ‘stem’ and inflorescence was studied in four ryegrass (Lolium) varieties during a 30-week period in the first harvest year in a field experiment. In one variety, S.23, the ‘stem’ was divided into true stem, leaf sheath, unemerged leaf and unemerged inflorescence.There was a bigger yield of ‘stem’ and a bigger total herbage yield response to doubling the interval between harvests in S.321 and S.22 than in S.23 and S.24.In the absence, but not generally in the presence, of applied N, S.321 outyielded the other varieties. S.24 was particularly responsive to applied N, especially in terms of green leaf yield.There was a large positive effect on yield of doubling the interval (from 3, 4 or 5 weeks to 6, 8 or 10 weeks respectively) during the main period of stem development. During the subsequent period, however, doubling the interval produced very little extra yield of total herbage and reduced green leaf yield substantially.The percentage increase in yield due to the application of N progressively decreased as the interval was increased.Maximum net production of green leaf was obtained by harvesting every 4 or 5 weeks for most of the season, extending to 6 weeks at the end. Harvesting every 3 weeks, by comparison, resulted in a slightly lower annual green leaf yield, but with a distinctly higher proportion of green leaf in the crop.Applied N generally had little effect on the proportion of crop fractions, but reduced the proportion of green leaf and increased that of' stem' in S.23 and S.24 at the August and September harvests.

Description: It has been observed that there is an appreciable from the beginning of flowering till its completion percentage of flower shedding in pulse crops but and the total number of flowers shed was calculated, reliable data are lacking. Preliminary studies were, At maturity, the number of full-size pods per plant therefore, vindertaken to collect information on the was counted and the percentage of flowers shed extent of flower shedding in some kharif (rainy was calculated, season) pulses.

Description: SUMMARYUnder experimentally controlled nutritional levels, using Hereford, Hereford x Dairy Shorthorn, Dairy Shorthorn and Friesian breed-types, 288 animals were studied for age of eruption of the four pairs of front permanent teeth. Standard deviations are similar to those of other reports on Bos taunts. Breed differences were negligible and there is no evidence of heterosis. Lower nutritional levels delayed and higher levels advanced eruption. This effect had a maximum difference of 72 days if the differential nutrition was applied in calfhood. Differential nutrition later produced a smaller effect. It is concluded that in practice, the age of teeth eruption cannot be used to determine accurately the previous nutritional status of individual animals.

Description: In an earlier paper (Little, McLean & Winter, 1977) we reported a technique for the measurement of the phosphorus content of the diet consumed bygrazing cattle, which recently has been used successfully to measure the dietary intake of phosphorus by sheep grazing Mitchell grass (Astrebla spp.) pastures in western Queensland (Beale & McMeniman, 1978). In this technique, phosphorus of salivary origin is distinguished from that of plant origin in samples extruded by oesophageally nstulated animals by prior labelling of salivary phosphorus with the isotope 32P following the intravenous infusion of Na2H32PO4. The difference in specific activity between saliva and extruded bolus is used as the basis of the calculation of the phosphorus content of consumed herbage. Oesophageally nstulated animals may graze experimental pastures for an hour or more while samples are collected from them. It is important to have an accurate measure of saliva speoific activity, representative of that secreted during the grazing period; therefore, application of the technique is facilitated if the rate of change in saliva specific activity during collection periods is slow and linear.

Description: SUMMARYA laboratory incubation study followed by a field experiment was made in a silty clay loam soil (pH 6·9) at Pantnagar, India, on the effectiveness of ordinary urea, coated urea (sulphur and shellac-coated), urea-isobutyraldehyde condensation product (isobutylidenediurea, IBDU) and urea blended with nitrification inhibitor AM (2- amino-4 chloro-6-methylpyrimidine) and neem (a non-edible oil seed obtained from Azadirachta indica) cake. Whereas untreated urea and IBDU hydrolysed rapidly leaving no trace of urea-N after 2 weeks, sulphur-coated urea mineralized quite slowly and retained urea-N for as long as 4 weeks after incubation. Urea blended with neem cake was intermediate. Of all the materials tested, sulphur-coated urea showed maximum nitrification inhibition. A combination of one third sulphur-coated urea at planting + two thirds ordinary urea 30 days later yielded 12·3% more maize grain than ordinary urea in the same proportion at the same times of application.

Description: SUMMARYField experiments at Sutton Bonington between 1970 and 1974 tested how crop yields were affected by hand weeding at different stages in the life of early- and latesown crops. Losses where weeds were never controlled ranged from 95% where tallgrowing Chenopodium album L. predominated to 50% when Stellaria media (L.) Vill. and Tripleurospermum maritimum L.) Koch ssp. inodorum Hyl ex. Vaarama (T. inodorum) were most involved.In five of the seven crops examined the latest date (X) at which weeding had to commence to prevent irreversible effects on growth and yield and the earliest date at which weeding could cease without yield loss (Y) coincided. For late March/early April sowings this occurred 6 weeks after crop emergence, while for late April/early May sowings in which events were more rapid the same stage was reached 4 weeks after emergence. For an early-sown crop in 1973, when rainfall was frequent and heavy and C. album prolific, X preceded Y with an interval of 4 weeks between the two dates (4–8 weeks after crop emergence, mid-May to mid-June). In complete contrast for a late-sown crop in 1974, when the weather was exceptionally dry and C. album virtually absent, Y preceded X and a single weeding at any time between 2 and 8 weeks after emergence would have prevented yield loss.Sugar beet had generally reached the late singling stage (4–6 true leaves) by the time weeding must have commenced. During the next 6 weeks, final yield was depressed by 120–150kg/ha (1·;5%) with each day that weeds were allowed to remain. However, leaf production continued throughout the season and the crop was capable of recovering from early checks caused by weed competition. It proved possible for crops whose weights were depressed by 25–30% when first weeded to recover completely by harvest.

Description: SUMMARYExperiments testing the effects on leafless peas of aldicarb, triazophos and a mixture of benomyl with zineb, were made on clay-with-flints soil at Rothamsted and on sandy loam at Woburn in 1977 and 1978.The crop was shown to be susceptible to a wide range of pests and pathogens including the pea and bean weevil Sitona lineatus, the migratory nematode genera Pratylenchus, Tylenchorhynchus and Tylenchus, the pea moth Cydia nigricana, the aphids Acyrihosiphon pisum and Macrosiphum euphorbiae, the bean leaf roll and pea enation mosaic viruses and the powdery mildew fungus Erysiphe polygoni.The mean yield of the four experiments when none of the treatments was applied was 3·6 t grain/ha, increased to 4·3 t/ha when all were applied. Aldicarb had the largest effect and increased mean yield at Rothamsted by 0·3 t/ha, attributed mainly to control of S. lineatus, and by 0·8 t/ha at Woburn attributed to control of S. lineatus and perhaps also to migratory nematodes, particularly Tylenchorhynchus. Triazophos and benomyl plus zineb did not individually increase yield but at Woburn when both aldicarb and triazophos were applied benomyl plus zineb increased mean yield by 0·7 t/ha.All crops lodged severely, irrespective of treatment but perhaps because of experimental conditions. We suggest that susceptibility to lodging under field-scale conditions requires further study.

Description: SUMMARYA series of laboratory silages were prepared and opened after 2, 20, 60 and 150 days. The silages were made without any additive and with formaldehyde, formic acid, hexanoic acid, benzoic acid or sulphuric acid. The cellulose, hemicellulose, acetyl, alkali-labile phenolic acids and core lignin were determined in all silages as well as the composition of the hemicelluloses. In all the silages, the core lignin remained unchanged while the cellulose content only decreased by up to 5%. Large losses of acetyl residues and alkali-labile phenolic acids were observed in all the silages and losses of 10–20% of the hemicelluloses were found. The losses of hemicellulose were not uniform. The arabinose side chains were preferentially cleaved relative to the xylose residues. It was shown that part of the loss of carbohydrate could have been caused by the acidic conditions in the silage as well as by microbial activity. The silages made using the acidic additives with the highest pKa values lost the greatest proportion of carbohydrate. The implications of these results on rumen activity are discussed.

Description: SUMMARYThe results of 84 experiments with six levels of nitrogen were used to investigateresponse curves relating the dry-matter yield of grass herbage to fertilizer nitrogen. Of the five curves tested, the inverse quadratic represented the relationship well, although no one curve fitted best on all experiments.

Description: SUMMARYA study of the birthcoat and its relation to kemp succession in the adult fleece of coarse-wool Awassi and Hamdani sheep was carried out, as an aid to early selection. Lambs were covered, at the age of 2 months up to 15 months, by fixing patches of canvas on six body positions.Both Awassi and Hamdani birthcoats had high halo hair grades. The animals played the dominant role in affecting different traits of the birthcoat which indicated the importance of genetic factors in further development of the birthcoat. The birthcoat of both types of lambs showed only coarse (plateau) and less coarse (saddle) fibre type arrays.Hamdani had more kemp as Gt and G2 (first and second generations respectively) than Awassi sheep. The shed Gx following the different fibre type arrays, showed some overlapping between plateau and saddle. The same arrays of the birthcoat behaved differently on the different positions, where generally the anterior positions had less kemp than those posteriorly. Percentages of shed fibres were 100, 17·14, 2·38 and 0·35 of halo hairs, super sickles, sickles and chalky curly tips respectively in Awassi. Corresponding figures were 100, 29·26, 5·87 and 7·73 in Hamdani. In Awassi, halo hairs, of the birthcoat, showed a relatively high correlation (P 〈 0·01) with G1 kemp on the hip and britch. Within saddle array, in Awassi, the correlation between halo hairs and Gx kemp showed the highest values (P 〈 0·01), whereas in Hamdani the correlation between super sickles in the birthcoat and G2 kemp showed medium values (P 〈 0·05).Selection of high halo hair grade lambs, in the birthcoat, that have saddle arrays, with high percentage of sickle fibres in Awassi and with low percentage of super sickles in Hamdani, would result in low percentages of kemp in the adult fleece. High halo hair grades would be necessary for early survival of lambs.

Description: SUMMARYThe electrical potential difference between exuding sap of detopped sunflower plants and rooting media containing different NH4 ion concentrations was measured, together with the Na and K concentrations in root tissue and their fluxes in the xylem exudate. It was found that adding NH4 ions to the medium made the electrical potential difference less negative with respect to the external solution and decreased the water conductivity of roots. Moreover, fewer K and Na ions were transported to the xylem sap and the K concentration in root tissue after 3 h had decreased whereas that of Na had increased. These results suggest that the sunflower root acts as an efficient accumulator for Na rather than simply as a barrier to Na transport. It is suggested that NH4 ions caused a decrease in charge separation across one of the barriers where Na is actively transported so that adding NH4 ions to the medium increased Na accumulation in root cells. This barrier may have been at the symplast.

Description: SUMMARYThe purpose of this work was to determine the relative importance of mass flow and diffusion in supplying nutrients to wheat plants and to calculate nutrient uptake rates by roots (inflow). Winter wheat was grown in the field and measurements of plant Na, K, Ca, Mg, P, S and N contents, root length, plant water uptake and soil solution concentration made at regular intervals during growth. The apparent contribution of mass flow to plant uptake of nutrients between mid- April and mid-June was greater than the measured plant uptake for sodium, calcium, magnesium and sulphur (14, 9, 2 and 4 times respectively); however, only 50 % of the measured plant uptake of nitrogen and potassium and 5% of the phosphorus was supplied in this way. There were some 7 day periods when mass flow was able to supply the measured uptake of nitrogen and potassium, and it is possible that for these nutrients the importance of mass flow and diffusion may change during growth. Mean inflows (uptake in mol/cm root/sec) were calculated from sowing until mid- June. Inflow decreased for all nutrients from high initial values to low values during the winter and rose again in mid-April and May before falling in June. The increase in inflow in mid-April was concomitant with increased shoot growth but the precise factors controlling plant demand for nutrients and uptake in the field are still ill-defined.

Description: SUMMARYVarietal differences in resistance to non-aggressive chocolate spot infection were detected in the field, although complete resistance was not observed. Following artificial inoculation under growth-room conditions, a parent–offspring regression of disease scores for the heterogeneous stock Chivers was estimated as 0·51 ± 0·24, and although this cannot be regarded as a reliable heritability estimate, it demonstrates a degree of additive genetic control. An F2 diallel cross, under field conditions, indicated resistance to be controlled mainly by dominant alleles within a system of partial dominance. Detached-leaf tests indicated that within virtually complete dominance systems, dominant alleles facilitate fungal penetration and induce a hypersensitive response within the leaf. Control of further lesion development was indicated to be effected by a virtually complete additive system.

Description: SUMMARYSeed treatments and methods of sowing sugar beet were tested in the laboratory and in field trials in 1975, 1976 and 1977 on a range of soil types including a sand, several loams and a peat.‘Advancing’ the seed by controlled imbibition of water followed by drying before sowing, gave 2–3 % more emergence. Seedlings appeared 3–4 days earlier and were up to 50 % heavier at the four to six leaf stage, but by final harvest yields of sugar per unit area were similar from advanced and untreated seed. ‘Priming’ in osmotic solutions of salts or polyethylene glycol, to bring all seeds to the point of germination, before drying back and sowing gave inconsistent effects in the field with emergence percentage frequently being below that of the control. Steeping seed in water, aimed at removing germination inhibitors, improved germination and reduced the time to, and duration of, germination when tested in the laboratory but gave poorer results than the untreated control in the field. ‘Chitting’ the seed in the laboratory greatly improved emergence characteristics but treatment effects in the field were very variable. Chitted seeds were sown in carrier gels in the field to try to protect the radicles from damage but seedling establishment was no better from fluid drilling than from normal dry seed sown ‘raw’ or pelleted in clay, even when only chitted seeds were put into the fluid. Possible reasons for this are discussed.Fluid-drilled seeds consistently gave quicker emergence and larger seedlings. Even when these were 30–50 % heavier, differences had usually become negligible by the end of the average 230 days long growing season, so that sugar yields were not consistently affected by the treatments tested.

Description: SUMMARYGrowth and nitrogen fixation of three cultivars of Phaseolus vulgaris L., inoculated with strain CIAT 161 of R. phaseoli, were compared at day-night temperatures of 36–25, 30–20 and 26–15 °C.Temperature affected the duration and magnitude of N2 (C2H2) fixation. Maximum fixation increased from 33·8 μmol C2H4 produced/plant/h at 35–25 °C to 73·0 μmol C2H4 produced/plant/h at 25–15 °C, but the peak in fixation was increasingly delayed as growth temperature was reduced. In the 25–15 °C treatment this delay in the onset of fixation led to decreasing leaf nitrogen concentrations and visible N-deficiency symptoms at the 28 day harvest.Varietal differences in response to temperature were not marked, though one cultivar achieved greater nodule development at 35–25 °C than the others. This earlyflowering cultivar again appeared weak in N2 (C2H2) fixation with low specific nodule activity at all temperatures studied.Results are related to bean production in Latin America, and to the possible need for ‘starter’ nitrogen in the cooler bean-producing regions.

Description: SUMMARYResistance to bean common mosaic virus in the cultivars Seafarer and Aurora from the U.S.A. is controlled by the dominant gene I originally found in the cv. Corbett Refugee.

Description: SUMMARYIn a preliminary laboratory experiment in Iran, not reported here, 5 out of 30 plant materials incorporated into a highly calcareous soil had a positive effect on increasing the DTPA- (diethylenetriaminepentaacetic acid)-extractable Fe and all except one significantly increased the vegetative growth of sorghum. The plant materials included Lawsonia inermis L., Malva silvestris L., Zyzyphus nummularia Wak. and Lavandula carnopifolia L. A glasshouse study was repeated with two California soils pretreated with 0·5% Fe2O3 to determine if these organic materials have practical value in making Fe available to plants. A calcareous, Fe-deficient Hacienda (fine-loamy, mixed, thermic aquic natrargid) and a non-calcareous Yolo (fine-silty, mixed, non-acid, thermic typic xerothents). The previously mentioned organic materials and Laminaria saccharina L. (Lamour) were incorporated into the soils at two rates, 15000 and 20000μg/g, as air dry and in ash form. An adequate supply of major and micronutrients other than Fe was ensured. Other treatments included 5 μg Fe/g as FeSO4, Fe-138 chelate and control. All of the plant materials with the exception of L. carnopifolia significantly increased dry-matter yield and Fe, Zn, Cu and Mn uptake by sorghum in the Hacienda soil. In the Yolo soil the above were not significant. Thin-layer chromatography of the extracts of the plant materials revealed the presence of significant quantities of phenolic substances.

Description: SUMMARYIn a field experiment on the effects of drought on spring barley the crop was protected from rain by automatic rain shelters. Various plots received irrigation at different times to give a range of drought treatments from full irrigation to no irrigation between emergence and harvest. The foliage area, light interception, stomatal resistance and leaf photosynthesis rate of five treatments were measured throughout the growing season, and a mathematical model has related the computed whole canopy photosynthesis to the measured total dry-matter yields at harvest. Hence, it was possible to estimate tha independent influences of drought on radiation interception, efficiency of use of intercepted radiation, and respiration. The analysis shows that for all treatments the decrease of intercepted radiation was the major factor in reducing yield, and it accounted for a loss of 30–40% for treatments that were stressed from the beginning of the season, and of 10–20% for treatments that were stressed after mid-May. Stomatal closure caused a reduction of up to 11% in daily photosynthesis, and the maximum effect was on plants that acquired a large leaf area before being stressed. However, the effect of stomatal closure integrated over the whole season was only 6% or less. Our measurements of internal resistance to carbon dioxide transfer were not precise enough to show significant differences between treatments; but increases of internal resistance, caused by stress, may have contributed to loss of yield.

Description: SUMMARYExperiments in 1976 and 1977, in south-east Scotland, with sunflower (cv. Fransol) examined the effects of bitumen mulch applied after sowing, date and depth of sowing on emergence, flowering and yield. Bitumen mulch increased soil temperatures in April and May by 1–4·5 °C resulting in earlier emergence (6–7 days), more complete emergence under adverse conditions of early and deep sowing, and earlier flowering (2–5 days). Delaying sowing from 7 April to 5 May reduced emergence time and time from sowing to first anthesis. Larger seedlings, having an increased leaf area, resulted from bitumen mulching and early sowing.In the laboratory, increasing temperatures from 5 to 20 °C reduced the average germination time by 0·75 days for each increase of 5 °C. Germination percentage was not affected by temperature over this range.Average seed yields and oil content were markedly different in 1976 and 1977; 2·22 t/ha and 44·7% for 1976 and 0·95 t/ha and 36·9% for 1977. Bitumen mulch and sowing depth had no effect on seed yield or oil content but delaying sowing until 5 May reduced both. Lower seed yields in 1977 resulted from fewer and smaller seeds. Infection of the seed heads with grey mould (Botrytis cinerea) after flowering was high in both years.

Description: SUMMARYThree methods of controlling swede mildew were compared. Mildew infection was reduced by delayed sowing but yields from later sown plots were seriously reduced. Infection was reduced but not eliminated on resistant varieties. Highly effective chemical control was achieved with the fungicide Persulon, which showed both eradicant and protective properties. The yield differences between a genetically resistant and a susceptible variety were eliminated when Persulon was used.

Description: SUMMARYMale and female (Suffolk × (Finnish Landraee × Dorset Horn)) lambs were used in three experiments to examine the replacement of milk by undried and dried fish protein hydrolysates (FPH), a mixture of lard and coconut fat, and partially hydrolysed starch (Protamyl 110). The animals received the experimental diets from 1 week of age in Expts 1 and 2, and from 4 weeks of age in Expt 3. They were given the diets in eight equal feeds (i.e. every 3 h) from an automated teat bar system. The level of feeding was 1·046 MJ/kg0−76/day. Experiments 1 and 2 lasted for 35 days, during which live-weight gain and food conversion ratios were recorded and at the end the digestibility of N, dry matter and starch was determined. Experiment 3 consisted of three small digestibility trials.In Expt 1, the replacement of milk protein with undried FPH and of milk fat with lard plus coconut fat had no significant effects on live-weight gain, food conversion ratio or nutrient digestibility. Somewhat lower gains for the lambs given the FPH than those given milk protein were observed during the first 15 days of the experiment. Apparent digestibility of milk protein and milk fat was 95 and 99% while that of PFH and lard plus coconut fat was 94 and 96% respectively. The replacement of milk fat with lard and coconut fat caused some reduction in live-weight gains and nutrient digestibility. Lactose was completely replaced by protamyl both in diets based on milk protein or FPH with no effect on live-weight gains or food conversion ratio.Apparent digestibility of fish protein was not affected by the drying process. Fat digestibility of diets containing undried or dried FPH ranged from 46 to 98% according to the type of emulsifier used. The results are discussed in relation to published data concerning the problems associated with the use of fish protein in milk replacers.

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

Description: SUMMARYAn experiment was carried out to study the composition of the mixture of rumen short-chain fatty acids and the clearance rate of the rumen liquid phase in sheep given diets of dried grass, high-nitrogen hay, low-nitrogen hay and barley straw. Differences between diets in clearance rate were not significant (P 〉 0·05) and differences between diets in the composition of the mixture of rumen acids were small. There were substantial variations in clearance rate between individual sheep but this was not associated with variations in the pattern of fermentation and the correlation between the proportion of propionic acid and the clearance rate in the rumen was low (r = –0·23).In a second experiment sheep receiving a moderate-quality hay were given intravenous injections of atropine sulphate which resulted in significant increases in rumen volume (P 〈 0·01) and significant reductions in ruminal clearance rate (P 〈 0·05). These were accompanied by significant increases in the numbers of protozoa (P 〈 0·05) and bacteria (P 〈 0·05) in the rumen but the composition of the mixture of rumen short-chain fatty acids was unchanged.It is concluded that there is little possibility through alteration of ruminal clearance rate, for manipulation of rumen fermentation pattern in sheep receiving diets of moderate- or poor-quality forages.

Description: SUMMARYAn experiment has been made using adult lactating cows in a randomized block design to study the effectiveness of basing feeding during the first 20 weeks of lactation on yield predicted from that obtained during the 8–12th days of lactation. Cows were classified as high yielding (HY) or low yielding (LY). The levels of feeding were identical within each yield group during the first 8 weeks of lactation but during the 9th to the 20th week two different levels of concentrate feed (HP and LP) were used. Over the 20-week period concentrates were offered in two or five daily feeds. Thus the effect of two levels and two frequencies of feeding on feed intake, milk yield and composition, and on live-weight change were studied.Cows in the HY group achieved a mean daily peak yield 2·6 kg higher than predicted while those in the LY group achieved the predicted mean peak daily yield. There was no significant effect of level of feeding on the 20-week milk yield but there was a significant effect on the yield of the LYLP class in weeks 9–20. Frequency of feeding had no significant effect on yield in either high-low-yielding cows. There was no significant effect of level of feeding on milk composition but low-yielding cows gave milk with a higher fat percentage than high-yielding cows. Five-times-a-day feeding also produced milk with a higher fat percentage than twice-a-day feeding.Live-weight changes were small and the largest variation was recorded in highyielding cows.The number of days from calving to first service was not significantly different for the two yield groups but there was a significant effect of level of feeding.

Description: SUMMARYBecause of environmental and economic constraints, we need to determine the effects of nitrogen fertilizer application on nutrient availability and fertilizer recovery, especially in regions of limited rainfall. This study was conducted to provide information on effects of N rate on yields and N recovery by standard and semi-dwarf spring wheats (Triticum aestivum L.) sown at two dates.Ammonium nitrate was applied to spring wheat at rates up to 272 kg N/ha each year for 4 consecutive years. Only grain was removed from the plot at harvest. Wheat types did not differ in grain yields, but these yields were significantly reduced in 2 of 4 years by late sowing. Average grain yields for late sowing were greatest at 34 kg N/ha, but yields for early sowing approached maximum at the 68 kg N for semi-dwarf wheat and 136 kg N/ha for the standard wheat.Semi-dwarf wheat was lower than standard wheat in grain and flour protein concentration and baking absorption. Late sowing (May 30) reduced test weights, flour yield and baking absorption, but increased wheat protein concentration as compared with early sowing (April 30). Leaching of fertilizer N below the 90 cm depth ranged from 152 to 378 kg/ha at the 272 kg N/ha/year rate, and was greater for the late than for the early sowing. Fertilizer N that could be accounted for averaged 87 and 82% for early and late seeding respectively. Water-use efficiency was reduced by late sowing.Soil-water extraction by wheat to the 120 cm depth was greater for high N rates.These 4-year results showed that semi-dwarf and standard wheats had only slight differences in total grain production. Also, for efficient use of applied fertilizer and available soil water, wheat should be sown in the spring as soon as soil and weather conditions permit.

Description: SummaryThree experiments were carried out to study the effect of replacing milk carbohydrates and part of the milk fat in milk with partially hydrolysed starch (Protamyl 110). Male and female cross-bred lambs (Suffolk × (Finnish Landrace × Dorset Horn)) were used in these experiments. They were weaned from their dams after having received colostrum at 1–2 days of age. The experimental diets were given at room temperature, in eight aliquots, at 3-h intervals through an automated feeding unit. The level of feeding was 1·05 MJ/kg0·75 live weight/day.In the first experiment, the diets were formulated to contain 28, 17 and 55% of their gross energy as protein, carbohydrate and fat respectively. Diet 1 contained glucose, while diets 2, 3 and 4 had 33, 67 and 100% of glucose respectively replaced by Protamyl. There were no significant differences in growth rate and food utilization between levels of starch inclusion.In Expt 2, the maximum Protamyl that could be incorporated in lamb milk replacers was examined. Four experimental diets were prepared so that 17 and 55; 25 and 47; 33 and 39; and 41 and 31% of their gross energy was supplied by Protamyl or butter fat respectively. It was found that up to 33% of the gross energy of the diet (41% of the dry matter) could be replaced with Protamyl without adverse effects on lamb performance. When the level of inclusions was increased to 41% of the gross energy (49% of the dry matter), lamb performance was depressed, particularly during the first 15 days of the experiment.In Expt 3, a direct comparison was made between Protamyl and lactose. The two diets used were similar in composition to diets 1 and 4 in Expt 1, except that lactose was used as a control instead of glucose. There were no differences in growth rate or food utilization as a result of replacing lactose with Protamyl.The results are discussed in relation to the development of carbohydrases in new born ruminants.

Description: SummaryPerkins & Jinks's (1971) analysis was used to detect and measure the interactions between the environment and the additive, dominance and epistatic effects of the genes for final plant height, spike length, 100-grain weight and yield per plant in three barley (Hordeum vulgare) triple test crosses (DL 3 × IB 226, DL 3 × Jyoti and Jyoti × P 113) raised in two environments (normal irrigation and no irrigation). The j- and I- type epistasis was more sensitive to environmental differences than the i-type epistasis. Similarly, additive gene action responded more to the different environments than did the dominance action of the genes.

Description: SummaryFour young lambs fitted with cannulas at the pylorus and at the ileo-caecal junction were used to study the effects of weaning on digesta flow and mineral absorption. Prior to weaning when milk alone was fed the small intestine was the major site for dry matter disappearance and for the absorption of Ca, P, Na and K. Both the small and the large intestine were, however, important sites for Mg absorption at this time.After weaning, when the lambs were fed a concentrate diet, at least two-thirds of the digested dry matter disappeared within the reticulo-rumen. The small intestine, however, still remained the major site for the absorption of Ca, P, Na and K. Most Mg absorption, in contrast, now occurred anterior to the pylorus and it would appear that the move from hindgut to foregut as a site for Mg absorption was directly associated with the introduction of dry feed and the development of fermentative digestion within the reticulo-rumen.Both before and after weaning the faeces was the major route for the excretion of Ca surplus to requirement and the faeces also became increasingly important as a pathway for P and Mg excretion once dry feed was given. The urine, in contrast, was consistently the major pathway for the excretion of Na and K.

Description: SummaryTwo experiments with growing pigs showed that the addition of L-lysine hydrochloride to diets limiting in lysine content raised not only N retention but also true N digestibility as a percentage of the diet. The change achieved in amino acid balance had no consistent effect upon ED (digestible energy, kJ/g diet) and therefore the experiment did not support the hypothesis that non-linear changes in dietary ED, resulting from ingredient substitutions, could be attributed to associated changes in amino acid balance.

Description: Although sheep combat thermal stress mainly by panting, a sizeable amount (40%) of total evaporative heat loss, is from sources other than panting (Hales & Brown, 1974). The frequency of sporadic discharge of sweat glands increases with increase in ambient temperature and is accompanied by a decline in respiration rate (Bligh, 1961). The wool coat can reduce evaporative cooling but sweating may have cooling value in sheep breeds with open fleeces (Rai, Singh & More, 1978). In sheep, the number and size of the sweat glands (Waites & Voglmayr, 1962) and the quantum of sweat production in a particular time period (Ghoshal et al. 1977) varies in different body regions. In view of the possible significance of surface evaporative cooling, thermal sweating in different body regions of sheep was investigated.

Description: SummaryThe numbers of viable anaerobic proteolytic bacteria were determined from the caecal fluid of three ponies fed diets based on maize, oats or barley. In anaerobic conditions selected to promote the growth of those bacteria capable of utilizing protein, between 2 × 105 and 8 × 105 of viable anaerobic proteolytic bacteria/ml of caeoal fluid were observed. Time of sampling post feeding did not appear to affect the numbers observed. These numbers would appear adequate to make an important contribution to protein digestion.

Description: SummaryThe results of 83 experiments with nine levels of nitrogen and six experiments with seven levels were used to investigate models of the response of spring barley to nitrogen. Of the eight models tested, the inverse quadratic, Greenwood's modification of the inverse linear and two intersecting straight lines represented the yield/fertilizer relationship well, although no one model fitted best at every site.The three models differed little in their average predicted optimal yields, but a slightly smaller average optimal dressing was predicted from two straight lines.

Description: SummaryTwenty-four lactating Jersey cows, grazing a 3-week regrowth of nitrogen-fertilized Chloris gayana cv. Pioneer pastures selected a diet containing 18% crude protein and were given 0, 2 or 4 kg/day of fresh Leucaena leucocephala or 250 g/day of formal-casein. The effect of the treatments on milk production was measured in a 4 × 4 latin-square design experiment with experimental periods of 14 days.Mean milk yield of unsupplemented cows was 9·6 kg/day, 10·1 kg/day when cows were supplemented with formal-casein and 10·3 kg/day when fed 2 or 4 kg Leucaena/day. Yields of solids-not-fat, protein, casein, butterfat and short and medium-chain (C4–C16) fatty acids in milk fat were higher when cows were fed supplements (P 〈 0·01). Intake of digestible organic matter was lowest on the unsupplemented diets although feed in excess of 40 kg D.M./cow/day was offered and cows had little difficulty harvesting feed with a mean bite size of 350 mg organic matter/bite and mean grazing time of 507 min/24 h.It was concluded that a tropical grass diet containing 18% crude protein was deficient in protein for lactating cows and that small quantities of the legume Leucaena can alleviate such a deficiency.

Description: SummaryScreening methods were devised to select cowpea genotypes with resistance to yield loss oaused by larvae of Maruca testulalis (Lepidoptera, Pyralidae). More emphasis was placed on flower damage than on pod damage. One hundred and forty genotypes of wild and cultivated cowpeas and four of related Vigna speoies were screened in the first year; 25 of these were selected for rescreening in the second year. Resistance to flower damage was assessed by the ratio of number of pods under unsprayed conditions to number of pods under sprayed conditions and resistance to overall post-flowering damage by ratio of seed yield under unsprayed conditions to seed yield under sprayed conditions. The absolute numbers of pods and seed yields from unsprayed plots were also taken into account. Several genotypes of moderate resistance and one of high resistance were located among cultivars of different origins.It is suggested that the empirical approach to the search for insect resistance, particularly the comparison of unprotected with protected yields, has great potential, especially for seriously damaged crops.

Description: SummaryThe shape of the lactation curve of Sahiwal cows was estimated by fitting a gamma function to 2034 lactations made by 681 cows at two farms in Indo-Gangetic plains of Northern India. The persistency of lactation yield was estimated by three methods: P1, the coefficient of variation among weekly yields; P2, ratio of lactation yield to peak yield, and P3, from the gamma function.The gamma function fitted to the weekly yields explained 75·9% of the variation. A least-squares analysis of different traits associated with lactation curve shape indicated significant influence of parity, period and season of calving on the lactation curve. The lactation yield, peak yield and daily yield up to the peak were highest for winter calvers, while persistency was highest for monsoon calvers. The milk yield traits showed an increase up to the second or third lactation, while the persistency decreased from the first to eighth lactation with increase in parity order. The lactation curve was also more flat in the first lactation than later. The lactation yield and persistency increased with increase in age at calving independent of parity order. The lactation yield, peak yield, persistency and daily yield up to the peak were positively correlated with service period, lactation length and calving interval.The heritability and repeatability estimates of different traits, genetic and phenotypic correlations of lactation milk yield with different persistency measures indicated that P2 is a better measure of persistency. The peak yield could be used as a criterion of selection in early lactation to bring about improvement in lactation yield and persistency.

Description: SUMMARYThe variation in the sodium, potassium, calcium, magnesium, zinc, iron, manganese, copper, phosphorus and nitrogen concentrations in autumn regrowth herbage across a perennial ryegrass (Lolium perenne) pasture has been measured. The regrowth resulting from urine return by sheep to a pasture takes the form of an ‘island’ of herbage in which nitrogen (27%) and potassium (28%) are significantly higher than, and calcium (20%), magnesium (10%), phosphorus (24%), and manganese (40%) are significantly lower than in the surrounding herbage. Because of the selective grazing behaviour of sheep the possible implications for animal health of this pattern of element composition across a pasture are discussed.

Description: SummaryThe effects of farmyard manure (FYM) and P and K fertilizers on soil properties were studied at the end of a 3-year (1972–5) field experiment at New Delhi, India. Each year a crop of rice and wheat was grown. FYM was applied at 0 or 15 t/ha, phosphorus at 0, 30 and 60 kg P2O5/ha and potassium at 0 or 60 kg K2O/ha. Treatments included application of manure and fertilizer to rice or wheat alone or to both the crops. FYM application increased organic C, total N and available K and P in the soil, the effects being greater when both rice and wheat received FYM. Application of FYM slightly decreased the soil pH. Phosphorus and potassium fertilizer increased available P and K in the soil, respectively.

Description: SummaryA combination of a mineral balance and a radioisotope technique has been used to study the effect of increased intakes of dietary calcium and phosphorus on the Ca and P metabolism of mature, Ca-replete wether sheep. Between Ca intakes of 40 and 100 mg/ day per kg body weight Ca absorption remained constant at a level just sufficient to supply maintenance requirements. Above 100 mg/day per kg body weight, however, absorption increased in direct relation to intake. It is suggested that the increased absorption occurred by diffusion and that at lower Ca intakes, increased diffusion was offset by a corresponding decrease, until it reached a negligible level, in the rate of active absorption.In spite of the fact that the wethers were already Ca-replete, the increased Ca absorption resulted in increased Ca retention and not as might have been expected in increased excretion. Increased retention was brought about by a decrease in the rate of bone resorption and bone accretion remained constant. Maximum retention occurred when bone resorption ceased and it was equal to the rate of bone accretion. It was only when retention of Ca reached a maximum that further increases in absorption resulted in increased excretion of Ca into urine and intestine. P retention was also increased with increased Ca and P intakes and probably occurred as a result of the increased Ca retention.The relevence of these findings to the control of parturient paresis (milk fever) in the dairy cow by dietary manipulation is discussed.

Description: SummaryExperiments were carried out on oil-seed rape, variety Zollerngold, to determine the effects on flower and pod development when (1) the supply of carbon assimilates was reduced by shading or leaf removal at different stages of development or (2) the supply of assimilates to the more apically positioned flowers or pods on the terminal raceme was increased by removing 15 of the most basal flowers or pods.A decrease in the production of carbon assimilates led to fewer flowers and pods developing to maturity and when the stress continued over most of the period of pod development the pods were smaller and had fewer seeds which were also lighter in weight.Removal of the 15 basal flowers or pods led to more of the apically positioned flowers developing into mature pods and the other pods becoming heavier with bigger husks, heavier seeds and sometimes a greater number of seeds.The results of a shading experiment in a controlled environment cabinet suggest that stresses in the supply of carbon assimilates around the time of anthesis are particularly harmful since in addition to reducing the number of pods which develop they appear to restrict the capacity for compensatory growth in the pods that remain when the supply returns to normal.

Description: SummaryA total of 146 nulliparous gilts at two centres were assigned to lactation lengths of 10, 25 or 40 days and maintained on the same weaning regime for up to five parities.The interval between weaning and conception tended to be shorter for the 40-day treatment with little difference between the 10- and 25-day treatments. The data from all parities were pooled on the basis of an assumed herd structure giving the number of litters produced per sow per year aa 2·63, 2·37 and 2·18 for the 10-, 25- and 40-day treatments respectively.The number of pigs born alive per litter remained more or less static with successive parities on the 10-day treatment but increased on the 40-day treatment with differences between treatment s reaching or approaching significance in parities 4 and 5. Although this trend was reflected in the number of pigs weane d per litter, the differences between lactation treatments were non-significant as a result of higher post-natal mortality in the larger litters of the longer lactating sows.Consequently sows on the 10-day treatment reared the highest number of pigs per year, 22·4 compared with 20·2 and 19·8 for 25- and 40-day lactations respectively.Data are also presented on changes in sow live weight.A high culling rate and an extended interval betwee n weaning and conception were experienced at one centre in parity 1. The possible reasons and effect on subsequent litter size are discussed.

Description: SummaryThe body weight and fleece weight of Marwari and Magra sheep (rams) of the desert areas of north-western India are compared with those of Corriedale rams, which are being imported into India for improving the productivity of the local stock through cross-breeding. All three breeds showed marked seasonal fluctuation in their body weight. While the Corriedales lost more body weight than the indigenous breeds during peak summer, they appeared to endure the relatively poor winter pasture conditions somewhat better. Between July and October, with the availability of lush monsoonal pasture, all three breeds increased in body weight.The greasy fleece weight of Corriedale rams was nearly double that of indigenous rams. The potential of the Corriedale ram for improving the productivity of the local stock is discussed.

Description: SummaryPiglets in litters, paired according to farrowing date, were redistributed during the first day after birth according to two schemes. In scheme AC–BD, one sow of the pair received the heaviest and the third heaviest quarters of the combined litters (based on weight post partum), while the other sow received the second heaviest and the lightest quarters. In scheme AB–CD, one sow received the heavier half, and the other the lighter half of the piglets. After 3 weeks under scheme AB–CD, the weight difference between the second and third quarters had become reversed, while under scheme AC–BD the difference was preserved. There was no evidence of a corresponding interaction in the selection of anterior or posterior teats. The rank correlation of the piglets' initial weight and suckling position was low for most sows. No marked differences were observed between fostered and unfostered piglets in the weight measures or suckling position. It is concluded that the growth of the piglets was influenced by the relative size of their litter-mates after redistribution, but that little of the effect could be explained by competition for the anterior teats.