The 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.

The 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.

A 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.

Seed 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.

Information on the total dry-matter intake (TDMI), concentrates supplied (C), live weight (LW), week of lactation (WL), milk yield (MY) and composition, quality of forage fed to, and parities of, 385 cows from five different sources were assembled to develop appetite prediction equations. The equations were based on multiple regression and least squares constants and were calculated using the data from each source and the data pooled from all sources. The major factors affecting total dry-matter intake (TDMI) were C, LW, WL and MY and for the pooled data these factors explained 73–76% (R2) of the total variation in TDMI. The predictive values of some of the equations were tested against independent sets of data and for groups of cows and individual cows, the equations predicted TDMI within ±1·1 and 1·6 kg, respectively. The application of the equations in the field is discussed and some suggestions made for increasing the R2 of future appetite equations.

An 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.

Between 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.

A 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.

During 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.

The results of observations begun in 1973 and of disease surveys carried out on winter oil-seed rape crops on ten farms in Hertfordshire and Bedfordshire between 1975 and 1978 are reported. The major diseases encountered in the surveys, namely downy mildew (Peronospora parasitica (FT.) Tull.), canker (Leptosphaeria maculans (Desm.) Ces. & de Not.), light leafspot or scorch (Pyrenopeziza brassicae Sutton & Rawlinson) and grey mould (Botrytis cinerea Fr.) are discussed in relation to diseases of rape grown elsewhere and the results of experiments on disease control reported. Symptoms of virus infection and root disease were rare.

Early (before stem extension) use of two applications of benomyl (1·2 kg a.i./ha) decreased the incidence and severity of light leaf spot and canker and increased yield by up to 33%. Benomyl plus thiram seed treatment (5 and l·5ga.i./kg) was less effective than a benomyl foliar spray. In field experiments differences in severity of light leaf spot and canker explained a substantial part of variation in yield but downy mildew did notaccount for further variation.

Four 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.

Experiments, 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.

A 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.

Vicia 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.

A 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.

Samples 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.

The 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.

Three 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.

Under 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.

Experiments 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.