ALBERT

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.

Description: SummaryDuring 3 years the distribution of pests on ten crops of winter rape and two of spring rape, and the damage they caused, has been determined.During immigration the adults of all pests infested crop edges more than crop centres, particularly on large crops, irrespective of the presence of wind breaks. The proportion of M. aeneus and G. assimilis at the crop edge gradually diminished as they moved further into the crop, and their larvae and pods with C. assimilis emergence holes were more evenly distributed over the crops than the adults. Damage by M. aeneus was not the only cause of podless stalks. The larvae of D. brassicae were largely confined to the edges of crops; split pods were largely but not solely confined to the edges.In winter rape crops correlations were found between the percentage of podless stalks per plant and the number of M. aeneus present, and the percentage of pods infested with C. assimilis larvae and the adult C. assimilis population. In two fields infested with D. brassicae the diminution in the proportion of split pods from crop edge to crop centre was positively correlated with diminution in the number of adult D. brassicae.

Description: SummaryIn 16 experiments with field beans at Rothamsted, Woburn and Saxmundham between 1969 and 1976, seed-bed applications to the soil of dieldrin or γ-HCH were used to control subsequent infestations of the roots by larvae of Sitona lineatus. Rates of between 1·12 and 4·48 kg a.i./ha were used. Larval populations on untreated plots plots were variable, but 70–80% control was usually given by rates of 2·24–4·48 kg a.i./ha. Insecticides nearly always increased yields, the mean increase for all treatments being 0·15 t/ha, but a maximum yield response of over 0·5t/ha was achieved. It is suggested that the importance of S. lineatua larvae as pests of field beans in Britain has been under-rated.

Description: SummaryNumerous dwarf bean accessions were screened for resistance to three strains of bean common mosaic virus (BCMV). Many lines were resistant to a strain of BCMV isolated at Wellesbourne (NVRS) and the Dutch NL4 strain, but only a few lines showed resistance or tolerance to the Dutch NL3 strain. The NVRS strain was found to belong to BCMV Group IVa.Hybridization experiments showed that resistance to the NVRS strain of BCMV in the dry bean cvs Seafarer and Aurora was controlled by a dominant gene and that in Seafarer this was probably the dominant I gene originally found in Corbett Refugee.

Description: SummaryThree experiments carried out in 3 years (1973–5) which examined the effects of length of sprouting period and temperature of sprouting on growth and yield of three early potato varieties are described. In Home Guard in 1973 at the earliest harvests, tuber yields increased with increase in length and temperature of sprouting period. At later harvests tuber yields decreased with increase in sprouting period especially at the higher temperature (13 rather than 8 °C) and increasing the temperature of sprouting reduced tuber yield. In 1974 length of sprouting period had few effects on yield at any harvest and increasing the temperature increased yields only at the first harvest. In Vanessa cold storage at 3 °C prior to entry to sprouting temperatures induced an earlier onset of sprout growth than continuous exposure to temperatures conducive to sprout growth. Long sprouting periods produced less sprout growth and at the earliest harvest lower tuber yields than all except the shortest period. Judged from the onset of sprout growth increases in length and temperature of sprouting generally increased tuber yields especially at early harvests. In Pentland Javelin sprout growth was very slow and tuber yields at early harvests decreased at both sprouting temperatures if sprouting began after mid-November. At later harvests effects of both factors were small.The implications of differences in the effects of sprouting periods according to variety and, in Home Guard, season, are discussed in relation to the provision of the most desirable sprouting environment and to variety testing. The similarity in the effects of lengthening the sprouting period and of increasing the temperature of sprouting suggest that temperature is the major causal factor in sprout growth and its effect on field growth. Sprouting periods may therefore be measured most accurately by accumulated day degrees 〉 0 °C and a close relationship between such a scale and tuber yields is demonstrated. The relevance of such scales for advice to growers is discussed.Tuber growth rates for Vanessa and to a lesser extent Home Guard in 1974 were extremely high, in excess of 10 t/ha/week for Vanessa. These high rates were associated with high levels of radiation received by coastal sites in May and June and are discussed in relation to the canopy structure of the varieties.

Description: SummarySoil air was sampled daily at depths of 5, 10, 20 and 30 cm in fallow and cropped plots, which had either been rolled or cultivated. Carbon dioxide was measured by gas chromatography.Carbon dioxide concentrations were greater in the cropped than in the fallow plots. The rolled plots were wetter than the cultivated plots and carbon dioxide concentrations were also greater.In the fallow plots, carbon dioxide was correlated with soil temperature but variations in soil moisture content had little immediate effect.In the cropped plots, temperature effects were overshadowed by the response to irrigation which immediately increased the carbon dioxide concentration. These increases were attributed to enhanced root respiration, rather than to restricted diffusion or increased microbial activity.

Description: SummaryElectromyographic (EMG) activity, electroencephalographic (EEG) activity, heat production (H), respiration rate (RR), and body temperature (TB) of unacclimatized chickens were measured during periods of light and darkness at ambient temperatures (Ta) between 7·7 and 37·7 °C. The difference between pectoral muscle and abdomen temperature was less than 0·1 °C over the entire temperature range. Body temperature increased (P ≤ O·l) when Ta was above 27·5 °C and was higher in the light than in the dark (P ≤ 0·05). Respiration rate decreased significantly with increasing Ta. The decrease, however, was not as great during the dark (P ≤ 0·05) as during the light period (P s£ 001). Heat production decreased (P ≤ 0·01) with increasing Ta up to Ta = 22·3 °C. There was no significant difference between heat production during the light period and that during the dark period. EMG amplitude declined (P ≤ 0·01) with increasing Ta up to 27·5 °C in the light and 22·3 °C in the dark and was higher (P ≤ 0·05) in the light than in the dark. Mean frequency of EMG activity was independent of light and Ta. The percentage of low-frequency EEG activity in the dark did not change significantly over the entire Ta range, but in the light it decreased as Ta increased above 25·7 °C (P ≤ 0·05). The percentage of high-frequency EEG activity appeared as a mirror image of low-frequency activity. Overall results indicated a thermoneutral zone between 32·2 and 37·7 °C in the light and between 27·5 and 37·7 °C in the dark.

Description: Several investigations (Shaw & Norton, 1906; Darnell & Copeland, 1936; Kimberley, 1976) have reported no appreciable loss of nutrients of unbroken grain voided by cattle. Although the chemical composition of voided whole grain may be similar to the grain as fed, losses in grain dry matter ranging from 10 to 26% for cereal grains passing through the alimentary tract of steers have been measured (Toland, 1976, 1978a, 6). In one of these studies (Toland, 19786) the disappearance of grain dry matter of whole oats and wheat in nylon bags suspended in the rumen for 48 h was approximately 20 and 35 % respectively. Further analyses of this dry matter remaining in the nylon bags for 48 and 96 h of incubation would indicate which components of the grain were being broken down in rumen fermentation. This report provides information on the differential loss of the fibre and starch components of the grain dry matter from incubation in nylon bags for the two varieties each of oats and wheat and for an additional cereal grain, triticale.

Description: SummaryThe relationship has been investigated between the yield of oil-seed rape (Brassica napus L.) plants and (a) the proportion of podless stalks, (b) the proportion of pods infested by seed weevil larvae and (c) the effect of removing a proportion of buds and pods. Plants compensated for damage and, although late removal of buds or pods sometimes caused greater yield loss than early removal, only plants with more than 60% podless stalks or buds removed had diminished yields. The numbers of podless stalks per plant increased with plant size. Removal of 60 % of a plant's pods caused no yield loss; in the field a maximum infestation of only 25% of the plant's pods with seed weevil larvae occurred. The results are discussed in relation to damage by pollen beetles (Meligethes aeneus Fab.) and seed weevils (Ceutorhynch.ua ossimilis Payk.)

Description: SummaryOat straw, timothy straw and two field-cured hays (43·8, 47·3, 52·0 and 56·0% organic matter digestibility (OMD) and 0·56, 0·75, 1·00 and 1·41% N respectively) were fed ad libitum together with 0, 235, 470 and 705 g D.M. of rolled barley to 5-year-old North Country Cheviot wethers in four 4x4 Latin square designs (Expt 1). In an attendant study (Expt 2) of conditions with in the rumen four rumen fistulated wethers were offered daily 0, 200, 400 and 600 g D.M. of rolled barley with ad libitum hay (54·3% OMD, 1·45% N), also following a Latin square design.The voluntary intake of two of the hays (54·3 and 56·0% OMD) decreased progressively as the barley increased. Intakes of the other roughages were slightly increased when the lowest amount of barley was fed. For each roughage total organic-matter intake and the OMD of the ration increased progressively with increasing amount of barley consumed. No associative effects of barley on the OMD of the roughages were demonstrated. The acid-detergent fibre (ADF) digestibility of diets comprising the highest amount of barley with the oat straw and the field-cured hay of lowest N content were significantly lower than that of the respective all-roughage feeds. In Expt 2 the intake of increasing amounts of barley significantly reduced rumen pH, the molar proportion of acetic acid and the disappearance of hay and hay ADF from terylene bags within the rumen, while volatile fatty acid concentration and the molar proportion of butyric acid increased.Multiple regressions were obtained relating the change in roughage intake to the amount of barley fed and the digestibility and chemical composition of the roughages. The equation with the least error, explaining 88% of the variation, was Y= 30·561 — 0·615C — 21·453N±3·69, where Y is the change in roughage intake as a percentage of the intake of roughage fed alone, Cis barley intake as g OM/W0·73 and N is the nitrogen content of the roughage.

Description: Quantitative information concerning preejaculation sexual preparation of bulls was published some years ago by Collins, Bratton & Henderson (1951), who concluded that about 40% more motile sperm could be obtained by imposing one false mount before ejaculation. It had been suggested that one false mount in bulls is essentially as efficient as two such attempts in terms of sperm output (Branton, D'Arensbourg & Johnston, 1952). More recently Hafs, Knisely & Desjardins (1962) have shown that bulls given a planned 5 min sexual preparation yielded 30% more sperm than those given no preparation. Similarly 10 min preparation resulted in a 12% increase in sperm output when compared with a 5 min preparation. These authors also showed that zero, one, two or three false mounts significantly affected motile sperm output.

Description: SUMMARYThree field experiments at the University of Nottingham, in 1976, 1977 and 1978, examined whether a growth retardant chemical, ancymidol, could be used to restrict stem extension, delay the onset of lodging and thereby increase the seed yield of S. 24 perennial ryegrass. Applications of ancymidol increased seed yield by up to 60% by increasing number of seeds per unit area, although this was associated with a delay in the onset of lodging in 1977 and 1978 only. Application of ancymidol increased the percentage of the total above-ground crop dry matter harvested as seed, but it was not possible to relate this to the growth of the crop between anthesis and harvest.

Description: SUMMARYSamples of soya-bean meal, groundnut meal, sunflower meal and fish meal were incubated in nylon bags in the rumens of sheep receiving either whole barley or dried grass. For the vegetable sources of protein the rate of disappearance of protein was greater when they were incubated in the rumens of sheep receiving dried grass than in sheep receiving whole barley. The rate of disappearance of fish meal did not vary between sheep fed whole barley or dried grass.Rate of outflow of protein particles from the rumen was determined by rendering the protein supplement totally indigestible by a treatment with sodium dichromate. The rate of outflow was greatest with sheep receiving dried grass and increased with increasing feeding level.The mathematical expressions of degradation rate and outflow rate were combined to give the total amount of protein degraded in the rumen for the grass and barley diets at two levels of feeding.The amino acid composition of residues left in the nylon bags after 9 h of incubation were shown to be almost identical to the amino acid composition of the original protein supplement, indicating that the composition of the amino acid in the undegraded protein entering the abomasum essentially resembled that of the supplements.

Description: SUMMARYNineteen NP experiments were carried out with wheat and barley mostly in the Mesaoria plain of Cyprus over the period 1968–78. The fields were fallowed over the season preceding the experiments. Rainfall ranged from 68 to 405 mm. Kyperounda, a tall durum wheat, Pitic 62, a semi-dwarf aestivum wheat, and Athenais barley were the test varieties. No yield was obtained when rainfall was below 100 mm. Athenais barley consistently outyielded the wheat varieties, particularly Kyperounda, by up to 200% presumably because of earlier heading, which helpedthe crop to escape drought to a certain extent.Kyperounda wheat and Athenais barley mostly responded to 35 kg N/ha but Pitic 62 benefited from up to 70 kg N/ha. Fertilizer N not taken up in a year of extremely low rainfall remained in the soil and was available to the following crop.Response to P was more marked when rainfall was below 250 mm being linear over the rates tested (highest rate 26 kg P/ha). Athenais barley responded to P more than the other varieties. Bicarbonate-soluble soil P was between 1 and 10 mg/kg.Since rainfall is unpredictable it is recommended that 20–40 kg N/ha be applied atseeding together with 13–26 kg P/ha. A similar amount of N should be top dressed in late January. The higher amount refers to the semi-dwarf Pitic 62 wheat and could be increased further if the December-January rainfall, which normally constitutes 40% of the total, is high. These rates refer to crops grown after fallow. For continuous growing the rates would probably have to be increased.

Description: SUMMARYAn analysis has been made of the reproductive performance of Red Sokoto goat of Nigeria. Data are based on records of 140 kiddings from 96 does. Age at first kidding was 435 ± 18·9 days. The mean litter size at first kidding was 1·45. Prolificacy increased with parity, the kidding percentages from first to third parities being 141, 186 and 200 respectively. Doe weight was significantly correlated with litter size (r = – 0·27). Repeatabilities of litter size per doe kidding and of litter weight were negative. Heritability of litter size was 0·08 ± 0·02. Birth weights were low, the mean weight of kids during the 3 years ranging from 1·48 to 1·64 kg. Doe weight was related to litter weight in a manner such that litter weight as a proportion of doe weight tended to decline as doe weight increased. The ratio of litter weights of singles to twins at any given weight of the doe was 100:180. Kid mortality by 3 months of age was 30·8 %. Mortality among twins was only slightly higher than singles. However, mortality in kids born in multiple births (triplets and quadruplets) was much higher. Birth weights of surviving kids were significantly higher than of those that died.

Description: SUMMARYDuring summer the morning (08.00 h) to afternoon (15.00 h) increases in rectal temperature, respiratory rate and pulse rate of free grazing Marwari and Magra sheep (rams) of the desert areas of north-western India were compared with those of Corriedale rams, which are being imported into India to improve the productivity of local stock through cross-breeding. Basal (morning) values for all three measurements were similar in the three breeds. While the afternoon values in respect of all three characters were significantly higher than the morning values in all the breeds, the increases were greatest in the Corriedales.

Description: SUMMARYThe relationships between the number of stems per tuber and tuber characters measured before planting were studied using a wide range of tuber weights of the varieties Désirée and Maris Piper. The effects of the storage temperature of the seed tubers and the site of growth on these relationships were then investigated over 3 years.Linear relationships between the numbers of stems per tuber and tuber weight accounted for more of the variation in numbers of stems than linear relationships established using tuber shape or sprout measurements. The linear relationships had positive slopes and intercepts, showing that small seed tubers produce more stems per unit weight than large seed tubers. There was little evidence of non-linear effects.On average over all treatments, using ten plant samples, single linear relationships between above-ground stems and tuber weight accounted for 64 % of the variation in above-ground stems with D6sire'e and 58 % with Maris Piper. When separate regression lines were fitted for each treatment the best models in each variety accounted for about 86 % of the variation in above-ground stems. The best model with Désirée had parallel lines showing that the advantage, in terms of stem production, of small seed over large seed increases in environments favouring stem development. The relationships for each treatment are used to show how the stem density established can vary when planting tubers at the recommended spacing.Seed tubers of comparable weight, planted at different sites, gave different numbers of stems suggesting that the optimum spacing may vary from one site to another.It is suggested that breeding varieties for yield stability might be aided by selectingfor low variation in the relationship between the number of stems per tuber and tuber weight.

Description: The practical value of obtaining estimates of general combining ability (GCA) from data accumulated in a breeding programme has been discussed by Gilbert (1967). In this study use has been made of data collected during the course of screening potato breeding material, derived from Solanum vernei Bitt. et Wittm., for resistance to the white potato cyst nematode, Qlobodera pallida (Stone) Mulvey & Stone, to assess the relative contributions of GCA and specific combining ability (SCA) by the procedure described by England (1974) which is based on Gilbert's (1967) method.

Description: As a nitrogen fertilizer for vegetable production in Britain ammonia has been used mainly for bruasels sprouts (Page, Tatham & Wood, 1974; Page, 1975a; Page, Wood & Case, 1976), and leeks (Page & Williams, 1977). These crops with long growing seasons allow considerable latitude in time of application of the ammonia. Summer and autumn maturing cauliflowers have not only a short growing season, but also have a physiological control of curd formation which appears to be insensitive to nitrogen supply (Salter, 1969; Salter & Fradgley, 1969). They are also usually transplanted into the field, and the root system is therefore restricted for at least part of the growing season. It is therefore desirable to know if the roots would reach the injected nitrogen in time, as, until the ammonia becomes nitrified, nitrogen movement in the soil is small (Page, 19756). Thus, time of application of the ammonia was considered likely to be important.

Description: SUMMARYA small-plot experiment on sandy loam soil at Woburn tested the effects of subsoiling by hand and of incorporating a large dressing of P and K fertilizer into the subsoil.Ths treatments were applied once in 1973 and their effects were assessed from 1974 to 1977 on the yields of, and N, P, K uptakes by, barley, potatoes, wheat and sugar beet grown in rotation. All crops were present each year and all plots received annual seedbed dressings of N, P and K appropriate to the crop. Dolomitic limestone was applied once in the rotation. The effects of the treatments on P soluble in 0·5 M-NaHCO3 and exchangeable K in surface and subsoils were measured.Subsoiling alone increased the 4-year mean yield of wheat by 21%, of barley by 24% and of sugar from sugar beet by 11%. Mean yield of potatoes was unaffected.Incorporating P and K into the subsoil increased the mean yield of potatoes by 16% and further increased mean yield, in addition to the effect of subsoiling, of barley by 20% and of sugar by 4%. Mean yield of wheat was not further affected.

Description: SUMMARYA Kenya Highland maize was planted at three altitudes, 1268, 1890 and 2250 m. Development rate, dry-matter accumulation and leaf area production were recorded during vegetative growth, together with grain formation and dry-matter accumulation in the primary cob. Rainfall, insolation, soil and air temperatures were continuously recorded at all sites. Maize developed faster at low warm altitudes, the rate being dependent on soil and air temperature. During vegetative growth, this relationship could be satisfactorily explained by an integrated temperature, but during the reproductive phase, some allowance had to be made for over optimal temperatures at low warm altitudes. Altitude had little effect on crop leaf area at any particular development stage, but leaf area production rates were closely related to leaf emergence rates. Before establishment of complete ground cover, large differences in dry-matter accumulation rates were observed which appeared related to rate of leaf area production. Once full ground cover was established, crop growth rates became much more similar. Potential number of grains per embryonic primary cob was greatest at low altitudes, but the final number of grains per cob at harvest was greatest at high altitudes. Rate of increase of grain weight was constant and very similar at all sites until growth stopped abruptly at 69, 83 and 96 days after tasselling at low, medium and high altitudes respectively. Rate of accumulation and partition of total dry matter in the primary cobs was similar at all sites, but owing to greater duration of development at high altitudes, dry matter per cob increased with altitude. Large yield differences were found at harvest, yield decreasing with decreasing altitude. Yield differences were mainly due to variations in number of grains per plant, although grain size also contributed. In this and other trials it was shown that the number of grains per plant at harvest was closely related to the mean thermal growth rate (expressed in units of g/plant/growing degree day) during the grain site initiation period.

Description: Great Britain relies heavily on imported food and Cantell (1977) has estimated that within urban areas there are over 100000 ha of dormant land (i.e. derelict and awaiting development) for which the most fundamentally valuable temporary use is growing food, since such land, Cantell claims, could yield 25 million tonnes of potatoes or 4 million tonnes of carrots annually. The national waiting list for allotments exceeds 100000 and, according to Thorpe (1969), vegetables are grown on nearly all (98·3%) urban allotments. Underlying the case for encouraging the agricultural or horticultural use of dormant land is the supposition that, once cleared of junk, urban soils differ little in potential quality from farmland. But this is not necessarily so: Purves & Mackenzie (1970) have reported that vegetables grown in Scottish urban soils were contaminated by trace metals as have Warren, Delavault & Fletcher (1971) in Canada, Beavington (1973) in Australia and Davies (1978) in England. Lead, is one of the commonest urban pollutants and many countries set limits on the concentration permitted in food. In Great Britain the present limit is 2 mg/kg (fresh weight) but it is planned to reduce this to 1 mg/kg.

Description: SUMMARYExperiments, conducted over 3 years, investigated the effect of all combinations of two storage periods at low temperature (0 or 2 °C) and two storage periods at 10 °C on the sprout growth, numbers of stems per tuber, foliage development and subsequent tuber yield of the two maincrop varieties Maris Piper and Désirée.Although the number of day-degrees accumulated during sprouting was the same for all treatment combinations, there were large effects of treatments on the number of sproutlets per tuber and the total sprout length per tuber. However, there was no effect on the number of stems per tuber, foliage development or saleable ware yield inany year.

Description: SUMMARYThis paper presents an iterative analysis of incomplete variety × environment tables. The analysis estimates potential differences in the sensitivity of varieties to environment effect. It is noted that the technique allows unequal weighting of data, and the special case of a complete table is discussed.

Description: SummaryWhen experiments are conducted on two crops in association significance tests are available for judging whether treatments are having different effects or not. If, however, differences are established, it becomes necessary to assess the various treatments in agronomic, dietetic or economic terms. Graphical methods are here advanced to aid such assessment, special attention being given to (a) the stability of recommendations when the monetary or other values of the two crops change from season to season, (b) the measurement of yield advantage of mixtures over pure stands, and (c) the maximization of yield when it is desired to produce the two crops in specified proportions. The relationship to competition experiments is discussed.

Description: SUMMARYThe use of soil water by six grasses (perennial ryegrass, cocksfoot, timothy, rough stalked meadow grass (RSMG), tall fescue and Italian ryegrass) was measured over 2 years. The swards were cut either at 3-week (C3) or 6-week (C6) intervals. In both years the maximum soil water deficit attained under C6 was greater than under C3. Following several of the cuts from C6 there was a marked, although temporary, reduction in the rate of water uptake.An extended dry period in the second harvest year revealed substantial differences in the total water used and in the patterns of uptake from the soil profile by the grasses. Effective depths of utilization of water under treatment C6 were: RSMG, 40 cm; timothy, 70 cm; cocksfoot, 70 cm; perennial ryegrass, 80 cm; tall fescue 〉 100 cm. This order of depth of utilization corresponded with the order of yields obtained during drought conditions. An examination of the root systems of four grasses also showed that, particularly under treatment C6, roots of tall fescue were more numerous at depth than those of timothy, cocksfoot or perennial ryegrass, and under this treatment it showed its greatest tolerance to dry conditions. Drought tolerance in these grasses appears largely determined by the volume of soil exploited by the roots for water.

Description: SummaryForage maize was harvested on three occasions from three genotypes (Inra 200, LG11 and Anjou 210), grown at three plant densities (5·0, 9·8 and 13·5 plants/m2). Three replicate silos were filled with 8 kg fresh crop per treatment, sealed, and stored for 100 days.Crops from all treatments fermented to give predominantly lactic acid, low values for pH (average 3·9, range 3·7–4·1), with no butyric acid. Apparent loss of watersoluble carbohydrates during storage appeared to be directly related to their content at harvest.Genotype and plant density had relatively little effect on the composition of the silage, or on digestibility in vitro. Later harvest was reflected in increased contents of dry matter and starch, and in restricted fermentation. The content of digestible organic matter in the D.M. was decreased by later harvest.

Description: SummaryTwo field experiments were conducted at Aberystwyth on simulated swards of S. 23 perennial ryegrass which were cut one or more times between August and January. The further effect of cutting in early spring was also examined.The weight of harvestable herbage produced in spring was found to be much less from plots which had been cut frequently in autumn and winter, and was also reduced when the final cutting date was progressively delayed.The principal effect of later and more frequent cutting in autumn on developmental morphology was a dramatic reduction in the length of leaves produced subsequently. This effect persisted well into the spring period. Numbers of tillers and leaves were much less affected. Thus a greater bulk of herbage was present in spring on autumnrested swards. Production of new tillers in spring was, however, encouraged by greater levels of prior utilization, including cutting in March.Total herbage yields from the different defoliation systems up to and including different harvesting dates in spring were very similar, but contained a higher percentage of dead material when autumn growth had been allowed to accumulate for longer periods. Under these systems considerable numbers of leaves were formed but died without being harvested. Tiller survival at low temperatures was poorer in swards left undefoliated after the end of August.

Description: SummaryThe relation between the ratio of the natural 12C and 13C isotopes of carbon in the feed and resultant faeces of animals was studied to develop a technique for estimating the proportion of C3 species (tropical legumes) and C4 species (tropical grasses) selected by grazing animals.In general, theδ13C values (see text for definition) of faeces from rabbits, sheep, goats and cattle were lower (more negative) than those of the corresponding feeds by from 0·4 to 2·0. This was possibly due to contamination in the gut by tissues or fluids with lower δ13C values. When C4 and C3 feeds were alternated, cattle took about a week to fully achieve the new level (δ13C of – 28·7 on the C3 feed and – 13·1 on the C4 feed) in the faeces. This time lag is associated with the time taken for the feed to move through the digestive tract.When mixed C3 and C4 feeds were fed to rabbits, sheep, goats and cattle there was a negative linear relation between percentage legume (C3) in the feed and the δ13C of the faeces (P 〈 0·01). A decrease in one unit in the δ13C value was associated with an increase of 7·0–8·5% legume in the diet.Estimation of the percentage legume in the feed from the δ13C value of the faeces and of the C3 and C4 components of the diet, resulted in a consistent over estimation of the legume component because the faeces had lower values than the corresponding feeds. This bias was removed if the prediction was based on the δ13C of the feeds minus 1 unit; the legume percentage in the diets of the sheep, goats and cattle could then be estimated with a precision of about ± 5%.Differences in digestibility between the C3 and C4 components greatly bias the estimations. This bias in the diets fed to rabbits was effectively removed by using in vitro organic matter digestibility values of the two components to correct for the differences. Legume percentage in the diet could then be estimated with a RSD of ± 3%.Advantages and disadvantages compared with alternative methods of estimating the diet of grazing animals are discussed.

Description: SummaryTwelve 6–8 months old male Barbados Blackbelly lambs were used in a 4 × 4 latin square experiment with three replicates to study the utilization of diets made from local by-products and containing 64, 93, 125 or 143 g crude protein/kg D. M.Both dry-matter (mean 750·1 g/day) and digestible-energy (mean 6·2 MJ DE/day) intakes, and their digestibility coefficients increased, though not significantly, with increasing dietary protein concentration. However, nitrogen digestibility, urinary-nitrogen output and nitrogen retention all increased significantly (P 〈 0·01) with increasing dietary protein concentration.Metabolic faecal nitrogen and endogenous urinary nitrogen derived from the intercept of significant regressions of nitrogen intake against urine and faecal nitrogen outputs were 5·07 g/kg dry matter eaten and 3·46 g/day (0·35 kg W0·75) respectively. The diets had a mean biological value of 73·6%. The digestible crude protein requirements for maintenance were (g/day) 29·0, 38·4 and 26·6 when estimated from nitrogen retention, factorially and from live-weight performance respectively.

Description: The incidence of oestrus in pregnant ewes has been reported previously by Williams et al. (1956) and Bichard et al. (1974). However, their investigations were not designed specifically to study such a phenomenon and the number of animals employed was small. None of the factors affecting oestrus occurrence was investigated. Under experimental conditions, vasectomized or aproned rams are sometimes used after the removal of fertile rams to detect embryonic failure in pregnant ewes. It is of interest to check on the validity of this method. This study was carried out to obtain an estimate of the incidence of oestrus in early pregnancy using relatively large numbers of fat-tailed Barki and imported Hungarian Merino ewes and to investigate the effect of year, breed of ewe and age of ewe on its occurrence.

Description: SummaryThe birthcoat of coarse wool Barki lambs was investigated at the age of 1–1·5 months. Lambs were covered when they were 2 months old to study kemp succession, and some other adult fleece traits, at the age of 16 months in relation to the birthcoat fibre type arrays. Samples were taken from three dorsal and three lateral positions. The average halo hair grade was 5·45% and the coarse fibre type array, plateau, contributed 64·7% of the birthcoat arrays, the rest were of the less coarse, saddle, type. Halo hair grade and fibre type arrays showed an antero-posterior gradient, increasing in score and coarseness posteriorly.All halo hairs, 41·9% of super sickles and 22·6% of hairy tip curly tip fibres were shed as first generation kemp (G1 Curly tip and histerotrich fibres shed the least and they contributed the majority of the total persistent fibres. When pre-curly tip fibres increased in the birthcoat samples, that was followed by more kemp in the adult fleece.The average G1% kemp was 4·43. Kemp decreased in subsequent generations, values were 34·50 and 8·37 for G2/G1% and G1/%, respectively. G1%, and G2/G1% kemp showed a general trend of an increase towards posterior positions; the shoulder position was an exception to that.Coarse birthcoat fibre type arrays, plateau, were followed by more kemp in G1% and in successive generations than were the less coarse, saddle, arrays. High values of G2/G1% kemp were followed by significantly high G3/G1% kemp. Within animals, there was a significant correlation (P 〈 0·01) between halo hair grade and G1% kemp.Staple length showed a tendency to increase towards posterior positions and females showed slightly longer staples than those of males. A slight trend of decrease in staple length was observed following the less coarse array, saddle, as compared with that which followed the coarse array, plateau.For selection against kemp at an early stage, though birthcoat halo hair grade was positively correlated with G1% kemp, a high halo hair grade is essential for the lamb's early survival, hence fibre type arrays should be considered in selection. Less coarse birthcoat arrays, saddle in the present material, and a high, within array, curly tip: pre-curly tip ratio would be preferrable.

Description: SummaryMilk yield of 2-year-old Scottish Blackface and of East Friesland × Scottish Blackface ewes rearing single or twin lambs was estimated by the oxytocin method on 1 day each week up to the 14th week of lactation. Both groups of ewes had been reared from birth under good nutritional conditions. They were housed in individual pens from mid-pregnancy and offered a liberal ration of a pelleted concentrate food until parturition. Similar food was offered ad libitum during lactation.The cross-bred ewes rearing singles or twins produced significantly more milk in the first 12 weeks (181 and 258 kg respectively) than did pure Blackface ewes in the same period (144 and 208 kg respectively). The pattern of lactation differed between breeds. Cross-bred ewes attained higher maximum yields between the second and sixth weeks (2·37 and 3·32 kg/day, respectively, for single- and twin-suckled ewes) than did the Blackface ewes (1·97 and 2·88 kg/day). The yield from the cross-breds was sustained at a higher level throughout lactation. In the third 4-week period cross-bred ewes rearing single and twin lambs produced 116 and 92%, respectively, of their yield in the first 4 weeks whilst Blackface ewes produced 87 and 65%, respectively.In the sixth week of lactation the milk produced by the two breed groups was similar in quality (mean value of solids-not-fat 11·04% and fat 5·48%) but by the 11th week the fat percentage of milk produced by Blackface ewes had increased significantly to 7·34% whereas that of the cross-breds had remained almost unchanged.Single-suckled ewes gained weight throughout lactation but twin-suckled ewes remained relatively constant. Lambs reared as singles by cross-bred or Blackface ewes reached a mean live weight of 36·2 and 35·0 kg at 102 days of age, respectively, compared with 33·6 and 30·1 kg for twin lambs. Food intake of all ewes increased until the fifth or sixth week of lactation.

Description: SummaryThree techniques, lamb-suckling and test-weighing, hand- or machine-milking following administration of oxytocin, and measurements of body-water turnover, used for the estimation of milk yield in suckled sheep are discussed in relation to sources of error and comparability of estimates.Results are presented from an experiment in which the lamb-suckling and the oxytocin techniques were compared. The mean daily milk production of Scottish Blackface and East Friesland × Scottish Blackface ewes suckling single and twin lambs was measured by both methods at weekly intervals for 6 weeks. All ewes were well nourished to ensure full expression of milking capacity. Additional information from a similar experiment on Merino ewes is also presented.The oxytocin method gave higher estimates of mean daily milk yield in the first week of lactation, especially in the groups of ewes rearing single lambs and in the Blackface breed. By the second week in most groups and the third week in all groups there were no significant differences between estimates made by the two methods and the relative values of the estimates were not affected by level of milk production, number of lambs suckled or genotype of ewe and lamb.

Description: SummaryMn, Fe, Cu and Zn were determined in topsoil and herbage samples from sites in North West Pembrokeshire. Means and ranges for these elements are given and the distribution is shown throughout the sampled area.There are no clear relationships between the total amounts of these elements in the soils and the amounts found in herbage but it is shown that soil drainage strongly influences both soil and plant concentrations, and pH has a strong influence on Mn concentrations in soils and plants.Seasonal variation in plant uptake of these elements is discussed and the effect of soil contamination of herbage, especially on Fe content. It is hoped that data from this area can be used as a guide to the range of values found for Mn, Fe, Cu and Zn in soils and herbage of an area relatively unpolluted from industrial sources for comparison with more polluted regions.

Description: SummaryA series of irrigation experiments was done at Rothamsted where the soil is a flinty silty clay loam over flinty clay. The results are compared with those obtained by Penman (1962, 1970, 1971) at Woburn where the soil is a loamy sand over sand. The limiting deficits, Di, above which irrigation increased yields, were about 2·5 times greater at Rothamsted than at Woburn; this ratio approximates to the ratio of the water-holding capacities of the soils (– 0·1 to – 15 bar) to a depth of 1 m. The limiting deficits at Rothamsted were 80 mm for spring-sown field beans, 84 mm for main-crop potatoes, 100 mm for spring barley and 140 mm for spring and winter wheat. The responses to irrigation were not determined accurately as there were few years with a large response for any crop. However, the evidence is that the maximum response that could be expected for potatoes was 0·19 t/ha/mm water, and for grain dry matter of beans 0·006 t/ha/mm. The figure for potatoes agrees with that obtained by Penman at Woburn; the response of beans was much smaller at Rothamsted, partly because of severe attacks of broad bean stain virus.

Description: SummaryThis paper describes the comparative semen characteristics (volume, motility, sperm density, number of sperms, percentage live and abnormal sperms) of Corriedale (exotic) and Marwari and Jaisalmeri (indigenous) rams during the summer and rainy seasons under the arid conditions of Jodhpur, in northwestern India. Except for sperm density, the semen of indigenous animals was superior to that of the Corriedale, although the differences recorded were not of a magnitude to cause the Corriedale sheep to be considered reproductively ineffective under hot arid conditions, if managed properly. The present findings do not conform to the earlier views of the prevalence of ‘summer sterility’ in Corriedale rams observed under hot humid conditions but there appears to be a negative relationship between semen quality and atmospheric humidity. The Corriedale sheep are recommended for improving the sheep sector in the desert areas of Rajasthan.

Description: SummaryProximal colons taken from foetal and newly born lambs have been shown to actively transport methionine from lumen to blood when incubated under in vitroconditions. The lumen to blood flux of methionine, measured across foetal and early post-natal colons was approximately 25 and 15 times greater than the blood to lumen flux, each flux being determined in the presence of 1 mM methionine.The ability of the colon to transport methionine decreased with age, there being no net transport across the colon of a 26-day-old lamb. The post-natal disappearance of this transport function appeared to be roughly exponential with a half-time of approximately 2 days.The short-circuit currents and open-circuit voltages, measured across proximal colons of lambs of different ages, remained stable throughout incubation. The transtissue electrical resistance of colons taken from 9- and 16-day-old lambs was approximately double that recorded across colons taken from younger animals.These results are discussed both in relation to what is already known concerning amino acid transport in the neonatal pig colon and in relation to what their possible physiological significance might be to normal post-natal development in lambs.

Description: SummaryIn 1974 and 1975 certified Scottish seed tubers were multiplied at four sites of different altitude which had different mean soil temperatures. The progeny tubers were subsequently grown to produce a ware crop at Wellesbourne in 1975 and 1976. In 1975, the effects of the site of seed production on sprout growth and tuber yield of the ware crop were small though there was an indication of a negative relationship between total tuber yield and the temperature at each site. In 1976 the effect of the site of seed production was more marked. The total sprout length per tuber of both the varieties used was greatest from the hottest site and least from the coolest site. In the field the final yield of both varieties was lowest from the hottest site and greatest from the coolest site of seed production. There was no indication that the effect of the site of seed production on tuber yield occurred as a result of differences in stem density.

Description: SummaryAdult sheep, unweaned and mature weaned calves have been examined by metabolic studies for sodium balance. The ratio of sodium input/output was near unity with only a very small amount of the ingested sodium salt being retained. A positive sodium balance was always present, with excess sodium salt being excreted. The main channel of sodium excretion was the kidney, although when sodium intake was increased the sodium content of the faeces showed a proportional increase. Unweaned calves, a few days old, were quite able to excrete excess sodium salts in concentrated urine.There was a clear difference in preference for sodium salts over water, between weaned calves allowed access to sodium salts while being fed milk, and weaned calves denied sodium salts at the milk feeding stage. Sodium-naive calves showed a marked preference for sodium salt solutions while the sodium-experienced calves showed at best an indifference and sometimes even an aversion. With continued access to sodium salts the volume ingested declined steadily in both groups but food intake remained constant.In both calves and sheep the preference for sodium salts showed considerable variation between animals. The evidence from parallel metabolic studies suggests that this variation indicates that salt intake is controlled by some mechanism, possibly in the central nervous system, which is activated by dynamic sodium metabolism. Our experimental results confirm that ruminants have a well developed salt taste but predilection for sodium salts could be a biochemical manifestation rather than a hedonic propensity.

Description: SummaryDuring 3 years a total of ten crops of winter rape and two crops of spring rape were sampled for insect pests and pest damage once or twice a week from the green bud stage to just before harvest. The most common pests were Meligethes aeneusFab., and Ceutorhynchus assimilisPayk.; the former was usually the more numerous, especially on spring rape crops. Ceutorhynchus quadridensPanz. and Dasyneura brassicaeWinn. were less abundant. C. assimilisand M. aeneus immigrated to winter rape crops when temperatures exceeded 15 °C. Maximum infestation of M. aeneus occurred either at the green bud stage, or when flowering began or at full flower depending on temperature; maximum infestation of G. assimilis occurred during flowering, which varied in time from mid to late May. In response to changing temperatures successive waves of immigration sometimes occurred. Immigration to spring rape occurred at green bud stage.The two methods used for sampling pests, sweep nets and water traps, gave different results. Water trap collections primarily reflected pest flight, and were not necessarily related to the pest population on the crop.Ovary maturation of M. aeneus occurred between their emergence from hibernation and migration to winter rape. They began laying 3 weeks after their arrival on winter rape but immediately they arrived on spring rape. The proportion of male to female M. aeneus present on crops was variable. C. assimilis fed for 3–4 weeks after their arrival on winter rape before their ovaries developed and they mated.On both winter and spring rape the number of M. aeneus declined during flowering and that of C. assimilis declined while pods were maturing. Their decline on winter rape was associated with their emigration to new host plants. New generation M. aeneus emerged before winter and spring rape were harvested, and new generation C. assimilis emerged before spring rape but not winter rape was harvested.The implications of these findings are discussed in relation to pest control.

Description: SummaryOats, clover, beans (Vicia) and maize were tested as ‘break crops’ in three experiments on land cropped frequently with wheat or barley. Barley was used as a ‘no-break’ control treatment. Test crops were winter wheat followed by spring barley; they received N-fertilizer at four rates. After barley wheat had much take-all (Gaeumannomyces graminis var. tritici); all the break crops decreased the take-all effectively and equally. Other soil-borne diseases were unimportant. N-fertilizer required for best yields was less, by 100 kg N/ha after clover and by 50 kg after beans, or maize, than after barley or oats. Best yields after oats, beans, clover were respectively I·O, 1·2, 1·4 t/ha better than after barley. Differences in take-all explain much of these effects. Ploughed-in trefoil did not affect take-all but gave small increases in yield. Percentage N in wheat grain was increased by fertilizer-N; it was greater after barley, maize or clover than after oats. Effects on the following barley, except those of N-fertilizer, were small.

Description: SUMMARYThe jaws of 481 adult culled ewes were examined visually and radiographically for dental abnormality and changes in skeletal structure; the findings were correlated with ante-mortem body condition score and breed. Only two ewes had normal buccal morphology; the remainder of the sample showed a range of abnormalities which included loose and missing teeth, gingival hypertrophy, food-filled gingival pockets, ridging and shearing of the occlusal surfaces. There was a general loss of bone structure. Dental abnormality was not strongly correlated with breed but showed a significant relationship with radiographic assessment of bone density. Body condition did not appear to be adversely affected by dental disease. Skull dimensions and dental pad position were strongly associated with breed. The state of the incisor teeth alone was a poor indicator of cheek tooth condition.

Description: Copper, lead and zinc ores have been mined in past years in many western counties of Great Britain leaving a legacy of extensive soil contamination. A survey of north-east Clwyd (Davies & Roberts, 1978) revealed that in the Halkyn Mountain area some 171 km2 of land are contaminated by lead and 69 km2 by cadmium (including 13 km2 containing from 10 to 540 mg Cd/kg soil). The Mendip Hills of Somerset are an ancient leadzinc mining area similar in many ways to Halkyn Mountain and, after some reconnaissance sampling in 1972 and 1974, a trace element survey was initiated in 1977. Topsoil samples (174) were collected on an approximately regular 2×2 km grid from a 600 km8 area of north Somerset including the Mendips (B. E. Davies and R. C. Ginnever, unpublished results). This survey revealed that the Mendips were generally contaminated by cadmium, lead and zinc. Highest soil lead values were found near Wells (11 g/kg) and Charterhouse (73 and 80 g/kg) but in the case of cadmium the survey revealed that some 2 km2 of land around the village of Shipham contained values exceeding 10 mg Cd/kg. Preparatory to detailed investigations planned for 1979 a reconnaissance survey of soils and vegetables from the village was made. Meanwhile, the Department of the Environment announced the results of another (independent) survey which also demonstrated that Shipham possessed a considerable cadmium problem (e.g. McGinty, 1979). A full account of our survey of north Somerset will be published and this paper presents the results from the reconnaissance of Shipham.

Description: SUMMARYIn field trials made in 1977, the synthetic pyrethroids Deois and Permethrin offered better protection to cowpea flowers and pods but the crop did not outyield that treated with Nuvacron in grain production. Further evaluation of Decis and Permethrin in 1978 showed that the relationships between rate and insect damage, and yield were curvilinear. On the early crop, Decis at 15 g a.i./ha and lOga.i./ha reduced insect damage to flowers and pods, respectively, below the control but yield differences were not significant from 5 to 50 g. Four or five applications of Decis were most effective in reducing insect damage, but yields obtained from them were not better than that from one application. Permethrin at 12·5 g a.i./ha reduced insect damage below the control but produced grain yield which was significantly lower than 25 g and above.On the late crop, Permethrin was effective from 5 to 25 g in reducing insect damage and providing increased grain yield. One application of Decis was sufficient to reduce pod damage and increase grain yield over the control, but appreciable yields were obtained from the three and four application regimes.A cost/benefit analysis of insecticide application shows that the synthetic pyrethroids compared favourably with Nuvacron. In 1978, two and three applications of Decis gave the highest net returns on the early and late season crops, respectively. Decis appeared most economical at 10 g on the early crop while Permethrin was most rewarding at 62·5 g in the early crop and 10 g in the late crop. The seasonal differences in weather are discussed in relation to the performance of the crop.

Description: SUMMARYThe feasibility of measuring lysine and protein nitrogen in barley using an infra-red reflectance analyser was examined. This is a very rapid technique, requiring no manipulative skills, and measuring several components simultaneously using milled grains. The results show that this instrument is sensitive to changes in lysine and protein nitrogen and can be calibrated to measure these components to a high degree of accuracy. It is shown that the gross morphological and biochemical abnormalities of high lysine mutants do not affect these measurements, indicating that this method is suitable for the rapid screening of material from breeding programmes designed to improve the lysine content of barley proteins.

Description: SUMMARYRoot growth of rice (Oryza saliva L.) is frequentlyinhibited by an adverse physical environment resulting from high moisture stress and strength of soilunder upland conditions, and the effects are often reflected in poor performance of the crop. This necessitates a critical understanding of rice root growth under varying soil physical conditions.The growth responses of the rice root system to the interaction between moisture regime and bulk density of soil as well as to the induced soil physical characteristics were assessed under controlled glasshouse conditions. Four moisture regimes: 0 (M1), 0–20 (M2), 0–350(M3), and 350–10000 (M4) mb, were superimposed on low, medium and high bulk density treatments in clay, loam and sandy loam soils. The soil physical environment was characterized by measurements of moisture distribution, penetrationenergy and oxygen diffusion rate in soils as functions of depth.A low moisture stress of 20 mb in low density soils favoured rice root growth. In low density soils, even though the number of roots at the base (proximal end) was maximum under M1, the depth of penetration, volume and dry weight of root were significantly more underM2 than under M1; M3 and M4. Irrespective of bulk density, even though oxygen diffusion rates in soils under M3 and M4 were greater than those under M1 and M2, the number of roots at the base, volume and dry weight of the root system decreased under M3 and M4 owing to low moisture content and high penetration energy in the surface layer (0–5 cm) of all the soil types. Lower moisture content and higher penetration energy at higher bulk densities of the soil types significantly reduced the root growth and especially the depth of penetration.

Description: SUMMARYThe associations between yield, nitrogen and soluble-carbohydrate concentration within S. 23 perennial ryegrass were investigated at three levels of nitrogen application. Controlled growth room conditions were used.The simple correlation between yield and nitrogen concentration was negative at the low rate of nitrogen application, not present at the intermediate rate of nitrogen and positive though not significant at the high rate of nitrogen. Yield and soluble-carbohydrate concentration were only correlated (positively) at the low nitrogen rate.At low nitrogen there were ‘efficient’ genotypes with relatively high yield and low nitrogen concentration. ‘Inefficient’ genotypes had relatively low yields and high nitrogen concentration. The majority of genotypes were neither markedly efficient or inefficient. The efficient genotypes at low nitrogen maintained their yield advantage at higher nitrogen levels with average nitrogen concentration and high numbers of tillers. Inefficient genotypes remained relatively stable in yield, numbers of tillers and nitrogen concentration.Partial correlation indicated an underlying high degree of dependence between yield, nitrogen and soluble-carbohydrate concentration at all nitrogen levels. The association of yield and nitrogen concentration showed a similar trend over nitrogen levels to that obtained using simple correlation. Yield and soluble-carbohydrate concentration were positively related, and nitrogen and soluble-carbohydrate concentration inversely related, when the effects of the remaining attribute were eliminated.Data extracted from Lee et al. (1977) confirmed that yield and nitrogen concentration for varieties under field conditions varied with level of nitrogen application in a similar manner to genotypes in the controlled growth room. The variety (Melle) could be characterized as being particularly efficient.Both sets of results indicate that selection for high yield of nitrogen in herbage can best be achieved through selection for yield alone.

Description: SUMMARYVicia faba cv. Minden was planted at densities ranging from 6 to 98 plants/m2. Nitrogen was applied to the soil as split dressings or as a foliar spray. CO2 concentration in the canopy was increased in some plots to 0·22% for 3 weeks during the early pod-filling stage.Yield and number of seeds per plant varied inversely with plant spacing between 9 and 98 plants/m2. Mean seed weight increased up to 13 plants/m2 and then remained constant between 13 and 98 plants/m2. Yield/ha was unaffected by plant density above 18 plants/m2.Application of 200 kg N/ha as ‘Nitro-Chalk’ (mixture of NH4NO3 and CaCO3) to the soil as split dressings did not affect yield or its components but 80 kg N/ha as urea applied in four foliar sprays increased yield by 361 kg/ha (8·6%). Recovery of the labelled nitrogen in the grain varied from 28% when applied during vegetative growth to 8% when applied in the reproductive phase and 15% in the foliar spray.The highest yield (5·12 t/ha) was obtained by supplementary CO2. The results suggest that there is no advantage in applying fertilizer nitrogen to well-nodulated spring beans.

Description: SUMMARYFour experiments were conducted to examine the extent to which some sampling procedures may bias the estimation of the nutritive value of herbage consumed by cattle which have been fistulated at the oesophagus.In one experiment the nitrogen, sulphur and calcium contents (g/100 g organic matter (OM)) and organic matter digestibilities (OMD %) of 15 herbage samples were determined and compared with those of extrusa collectedfrom Hereford cattle fistulated at the oesophagus. The extrusa samples were analysed both as total extrusa, which included saliva, and as extrusa which had been squeezed through muslin and the solid and liquid fractions separated. The herbage samples covered a wide range of nutritive values (0·78–4·92 g N/lOOg OM; 0·08–0·27 g S/100 g OM; 0·17–1·43 g Ca/100 g OM and 34·4–85·7% OMD).It was concluded that satisfactory estimates of nitrogen, sulphur and calcium contents and digestibility of herbage prehended by cattle can be made from oesophageal fistula extrusa and that the precisions of the estimates will not be increased if extrusa are separated into solid and liquid fractions immediately following collection. Corrections are not necessary for estimates of herbage sulphur, calcium and digestibility made from total extrusa but may be necessary for nitrogen values in excess of 2·74 g N/100 g OM. If extrusa are squeezed it is necessary to apply correction factors for nitrogen and sulphur but not calcium or digestibility.In the other experiments three factors were examined in relation to the nitrogen content and digestibility of extrusa. They were the effects of (i) previous grazing experience of the pasture (ii) fasting for 0, 3, 6 and 23 h prior to sample collection and (iii) collection of extrusa during the morning or afternoon.It was concluded that the lack of previous grazing experience of apasture or the length of a pre-collection fast up to 23 h will not significantly bias the estimation of the nutritive value of extrusa, but that it is preferable to collect extrusa samples from cattle in the morning and that sampling on rainy days should be avoided.

Description: There are extensive areas in Scotland and other parts of Britain where, because of low soil cobalt status, the cobalt concentration of pasture herbage is below the 0–1 /fg/g D.M. regarded as the requirement for grazing ruminants (Agricultural Research Council, 1965). A common method of overcoming the effects of cobalt deficiency in livestock occurring within these areas is to apply cobalt sulphate to the pasture. Following work carried out by Stewart, Mitchell & Stewart (1941, 1942) and Stewart etal.(1946) the standard recommended application of cobalt sulphate for pasture has remained at 2 kg/ha for many years, an application generally expected to last for 3–5 years. However, in South East Scotland there are doubts about the adequacy of such treatment which has led to a reappraisal. Significant increases in uptake of cobalt by herbage following applications to land at this rate are not always observed and sometimes there is no appreciable increase in ‘available’ soil cobalt as determined by acetic acid extraction.

Description: SUMMARYBetween 1972 and 1976 a series of 15 trials was carried out at various climatically favoured sites throughout Scotland to assess the potential of new hybrid maize varieties of European origin under Scottish conditions. No meaningful differences were found between varieties in respect of dry-matter yield or maturity.Seed rates ranged from 100 to 200 × 103 seeds/ha giving final stands from 40 to 194 × 103 plants/ha. Regression analyses for the variety Dekalb 202 included in 54 treatments indicated that the relationship between plant population density and dry-matter yield was partly linear with an important quadratic function, suggesting an optimum of 179 × 103 (± 80 × 103) plants/ha. Plant population density accounted for 65·9% (P 〈 0·01) of the variance in dry-matter yield but was not significantly related to dry-matter content.Climatic variation between years had no overriding influence on growth and development. Dry-matter production for the variety Dekalb 202 sown in mid-May ranged from 2·86 (1972) to 14·54 t/ha (1975) with associated dry-matter contents of 15·1 and 24·1% respectively. In a few instances slightly higher dry-matter contents (maximum 28·6%) from mid-May sowings were associated with lower yields.Neither date of sowing nor accumulated temperature to harvest measured as Ontario Heat Units was significantly related to yield but date of sowing accounted for 29·5% (P 〈 0·01) of the variance in dry-matter content. Accumulated Ontario Units at harvest were not significantly related to dry-matter content.An interesting relationship between dry-matter yield and the date on which the crop had received 1379 Ontario Units was found. This relationship may be useful in selecting sites at which maize may be grown or to predict maximum potential final yield in any given season.

Description: SUMMARYThe Rothamsted ley–arable experiments were on two fields with similar soils but with contrasting previous cropping: old grass on Highfield, old arable on Fosters field. Damage by take-all (Qaeumannomyces graminis var. tritici) occurred sooner in successive wheat crops grown after a lucerne ley and arable sequence (LU) than after a grass-clover ley and arable sequence (LC). On Highfield the difference was consistent and large, it occurred as soon as a second wheat crop was grown and resulted in wheat yielding 1 t/ha less after the LU than after the LC sequence. This difference did not persist in the next wheat crop where take-all was prevalent after both sequences. On Fosters field take-all developed more slowly and differences between sequences were mostly smaller.Wheat seedling bio-assay of soil cores from the LU and LC sequences showed that little take-all fungus persisted through the leys and that soils were much infested after a first wheat crop in the LU sequence on Highfield, but not in the LC sequence on Highfield or in either sequence on Fosters field. Microscopic examination of roots from assay seedlings and from field plants showed that Phialophora radicicola var. graminicola (PRG) was most common in soils where take-all developed slowly, but our results did not show if this was a causal relationship. The occurrence of much PRG in the LU sequence on Fosters conflicts with previous reports which associate large populations of this fungus only with grassland soils.

Description: SUMMARYEight varieties of spring barley differing in their morphology and resistance to lodging were grown in a trial as main plots which were split for seven treatments: a natural control (C), a control with plots which were mechanically supported (S) and four artificially induced lodging treatments: permanent early lodging (PEL); temporary early lodging (TEL); permanent late lodging (PLL) and temporary late lodging (TLL). The seventh treatment (GR) was an application of the growth regulator BAS 09800W. In comparison with S, treatments PEL, TEL, PLL and TLL reduced grain yield by 38–1, 24–8, 22–0 and 13–9 % respectively. Natural lodging in C plots reduced the yield of the two weakest strawed varieties, Guilden and Jupiter, by 8 and 10% respectively in comparison with treatment S. Yields (C) of these two varieties were increased by GR which had no effect on the yield of other varieties, but reduced grain size in some cases. Treatment GR significantly reduced but did not eliminate natural lodging in weaker strawed varieties and reduced the length of the top four internodes. Lodging reduced grain size in terms of 1000–grain weight and sieving fractions and increased the content of husk and protein. Lodging susceptibility was positively correlated with plant height but showed no clear relationship with the number of vascular bundles, stem diameter, wall thickness, or with the content of lignin, cellulose and hemicellulose in the basal internodes. Lodging resistance appeared to be closely associated with short basal internodes.

Description: SUMMARYDissection data for 1006 pig carcasses taken from the first 2 years of the Meat and Livestock Commission's (MLC) Commercial Pig Evaluation (CPE) were used to examine the relationships between carcass components and carcass weight over the growth period from 46 to 92 kg carcass weight. Alternative models were tested and parameters examined for different genotypes (pigs from different companies in CPE), sexes (barrows and gilts), feeding regimens (ad libitumand restricted feeding) and years.Generally, linear allometry provided an acceptable description of carcass development, although some curvilinearity was indicated for the head, kidneys, rump back joint, M. psoas and total dissected lean. Growth coefficients conformed to the generally accepted pattern of carcass development in pigs. Using linear allometry, proportional weight increases were comparable for all genotypes and sexes, but dissected fat increased relatively faster on the restricted feeding regimen.At a constant carcass weight of 66·5 kg, all tissue weights and the weights of primary components and most joints differed by genotype. The ratio of carcass lean weights for the two extreme genotypes was 1·04; comparable ratios for carcass fat weights were 1·13 (restricted-fed pigs) and 1·07 (ad libitum-fed pigs).Significant differences were recorded between sexes and between feeding regimens, largely reflecting differences in fatness. Some important year differences were also found.

Description: SUMMARYTwenty-seven British Friesian heifer calves were housed as a group but fed individually barley-lucerne pellets according to a scale related to body weight. At 16 weeks and again at 31 weeks of age nine calves were implanted subcutaneously at the base of the ear with 300 mg trenbolone acetate (group T), nine calves were similarly implanted with 140 mg trenbolone acetate and 20 mg oestradiol-17/? (group TE) and the remaining nine calves were sham implanted (group C).As a result of increased feed conversion ratios, body-weight gains were significantly greater in group T (0–80 kg/day) and group TE (0–87 kg/day) than in group C (0–72 kg/ day) during the 15 weeks following the second implant, but there was no significant difference between groups following the first implant.Following both implants in groups T and TE the mean concentrations of urea and albumin in serum decreased, and that of globulin increased. The mean urea: creatinine ratio in the urine of animals in groups T and TE relative to that in group C also decreased.The heifers were served by an Aberdeen Angus bull at the first and, when they occurred, subsequent oestruses. Following calving the mean milk yields in the first lactation in group T (641 kg in 96 days) and group TE (1993 in 212 days) was considerably lower than in group C (3636 kg in 293 days). The udder size in both groups of animals treated with the anabolic steroids was markedly reduced. It is concluded that despite an improvement in feed conversion ratios and body-weight gains, trenbolone acetate should not be administered to prepuberal heifers which will be retained for breeding and milk production.

Description: SUMMARYThe phosphorus status of five Nigerian coastal plain sands was evaluated by determining the relative abundance of the various P forms and the P adsorption capacities of the soils. Total P ranged from 4460 to 1129 mg/kg. Organic P had a range of 23–232 mg/kg and formed below 30% of total P in four of the profiles but above 50% in the hydromorphic Otegbo profile. The relative distribution of the various inorganic forms was in the increasing order of residual P, active P and occluded P, except in the Onne profile in which the residual P was relatively the least abundant. The relative distribution of the active P forms was in the decreasing order of Fe-P, Al-P and Ca-P.The adsorption capacity varied widely among the soils. The amount adsorbed from the addition of 150 mg/100 g of soil ranged from 40–2 to 86–2 mg/100 g and was related to the clay content. The adsorption at 0–3 mg/1 P in equilibrium solution ranged from 19 to 265 mg/kg. The subsoils generally adsorbed more P than the surface soils. The P requirements of the soils estimated from the sorption capacities were in the low and medium ranges.