In a 3-year experiment on a sward of S. 23 perennial ryegrass 21 rates of nitrogen fertilizer ranging from 0 to 897 kg/ha were applied annually on plots cut three, five or ten times per year. The cutting dates within each frequency were decided on the basis of herbage growth stage. Four-parameter exponential curves fitted to the herbage yield data show that the pattern of response to nitrogen application in the five cuts per year treatment was markedly similar to that reported for a previous experiment (Reid, 1970). Alterations in the cutting frequency affected the pattern of dry-matter yield response to nitrogen, but not that of crude-protein yield response. The combined effects of cutting frequency and nitrogen rate are illustrated by response surfaces fitted to the dry-matter yield results using an extension of the equation for the curves fitted to the individual frequency results. These surfaces show that as the number of cuts per year was increased the total yield and the response to nitrogen decreased, but the response was maintained to an increasingly high nitrogen rate. The practical implications of the results are discussed in relation to intensive grazing managements for dairy cows.

Chemical imposition of water leachable germination inhibition was attempted as a means of overcoming wheat seedling wilting after insufficient rainfall. Effective inhibition in aqueous solutions was imposed by abscisic acid, coumarin and by two ethylene releasing preparations, Ethrel and Alsol. Germination inhibition caused by the latter two compounds was found to be associated with effects of the carriers, other than pH, and was not a result of ethylene gas liberation. As evidenced by tetrazolium staining the dormant seed possessed respiratory activity, and imposed germination inhibition, even to the extent of 75%, was not lethal. Rainfall simulation effected by 30 h H2O leaching with a 200 mm precipitation equivalent was ineffective for reversal of germination inhibition caused by abscisic acid and Alsol, limitedly effective in the case of Ethrel, while the coumarin-induced inhibition was relieved to a greater extent.

S. 24 perennial ryegrass harvested in June, and subsequently in September from the same sward was conserved by rapid freezing. The digestion of the carbohydrate and protein components of the two diets was investigated, using sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum and consuming daily 950 g of herbage dry matter.

The higher content of soluble carbohydrate and the lower content of protein in the spring-cut herbage compared with the autumn cut, led to a more efficient fermentation in the rumen with a higher yield of volatile fatty acids per mole of substrate degraded, a proportionately higher yield of propionic acid and a substantially greater net gain of protein between mouth and duodenum on the spring cut herbage. Consequently, the quantity and composition of the amino acids entering the small intestine, or being absorbed therein, were not significantly different, despite the higher protein content noted on the autumn herbage.

The total energy absorbed was markedly higher for the spring herbage (11·2 MJ/kg D.M.) compared with the autumn herbage (9·5) and the energy absorbed as protein from the two diets comprised 20 and 26% of total energy absorbed respectively.

The possible causal mechanisms within the rumen, and the subsequent effect of these on nutrient supply are discussed in relation to the well-established higher efficiency of use of metabolizable energy (ME) of spring-cut herbage compared with autumn cut herbage of similar apparent energy digestibility.

The effect on sward production of grazing by sheep during different periods of the winter and the effect of different dates of ceasing grazing in late winter-early spring were measured in field experiments by cuts during the spring and summer and by botanical analysis.

Winter and early spring grazing reduced herbage yield in April, May and June, but not subsequently. Nitrogenous fertilizer applied when grazing ceased approximately counterbalanced the reduction in yield due to grazing. The grazing treatments had little or no effect on botanical composition. The size of the reduction in yield due to grazing was such that it might reasonably be explained in terms of the date on which grazing ceased and the amount of photosynthetic tissue left at that date. The amount of yield added during a given period in the spring appeared to be very greatly affected by the amount of photosynthetic tissue present at the beginning of that period and it is suggested that this is a partially hidden cost of winter and early spring grazing which should be more fully researched.

The 32 combinations of applying or not applying nitrogenous fertilizer on five dates, with 6-week intervals between dates, during one treatment year were compared in three field experiments with Italian ryegrass (Lolium mvltiflorum). Phosphorus (P)and potassium (K) were applied at a uniform, high rate to all plots. All plots were harvested, by cutting, five times during the treatment year and once in May of the subsequent year.

Dry-matter yields and dry-matter yield responses to N were lower at the September and October harvests than at the May, June and July harvests. Where no N was applied 6 weeks before a harvest, N applied 12 weeks before that harvest generally increased yields of dry matter, N, P and K. On the other hand, where N was applied 6 weeks before a harvest, N applied 12 weeks before that harvest tended not to increase dry-matter yield and tended to reduce P and K yields. Applying 420 kg N/ha/year compared with nil approximately trebled the amounts of dry matter, P and K harvested in the treatment year. At the May harvest in the subsequent year dry-matter yield was increased by N applied in the treatment year, for all five application dates, although the previous autumn there had been no positive residual effect of the early applications. Apparent recovery of N was low compared with that recorded with Italian ryegrass in Cambridge. The content of N, as well as P and K, in herbage in May was reduced by the application of N the previous year. In the 1972 experiment the proportion of ‘stem’ in the harvested produce was markedly increased by N application. The size of this effect may have been associated with the rather small amount of soil N available. Applied N increased the number of tillers in the sward, but this effect appeared to be rather short-lived. A major reason for the positive effect of applied N on dry-matter yield, including the positive residual effect, appeared to be the increase in leaf blade length and probably sheath length due to N.

In a study of two coarse wool breeds (Awassi and Karadi) and their reciprocal crosses, data were obtained on the mean fibre length, mean fibre diameter, fibre type ratio, medullation and on the effect of some environmental factors on these traits. Reciprocal crosses showed intermediate values, in growth rate of fibres, percentages of fibre types and medullation, between those of the parental breeds. Sex exhibited a significant effect at weaning only, on fibre length. Heterosis in fibre length, at the two ages, was small and negative. Maternal influence on fibre length was small and not significant. Fibre length in Karadi sheep showed the highest frequency of bimodal distribution whereas Awassi showed the lowest. Awassi × Karadi was closer to Karadi and Karadi × Awassi had greater affinity to Awassi in the frequency of samples showing bimodal distribution.

Reciprocal crosses had larger diameter, at weaning, than those of the parental breeds. At 1 year of age they assumed an intermediate position between the pure bred parents.

At weaning, the two reciprocal crosses showed a highly significant heterosis in fibre diameter; its value decreased with advancing age and it showed no significant effect at 1 year of age.

Maternal influence on fibre diameter was very small and not significant.

Karadi × Awassi and Karadi samples had the highest percentage of samples showing bimodal distribution of fibre diameter.

Samples with bimodal distribution of both length and diameter, indicating two coats, had the highest frequency in Karadi followed by Karadi × Awassi; Awassi showed the lowest value.

Percentages of fine, coarse and kemp fibres were significantly affected by breed and age of dam. Type of birth showed a significant effect only on percentage of coarse fibres.

Karadi wool might be more suitable for carpet manufacturing. It excelled the other groups in the bimodal distribution of both length and diameter as well as in medullation. Cross-breeding increased the bimodality of fibre distribution.

Twenty-one two-row and 19 six-row barley cultivars, originating from the major barley growing areas, were compared in a duplicated experiment conducted under controlled environment conditions. Plants were grown in sand and supplied nitrate at two concentrations.

Number of leaves on the mainstem and leaf emergence rate both varied widely but there were no consistent differences between two- and six-row cultivars. The low nitrogen treatment led to significant reductions in number of leaves and emergence rates. As a result of these opposing effects the time of appearance of the flag leaf was not affected by treatment. The number of leaves unfolded was a linear function of time where nitrogen was supplied at high concentration but for plants supplied with low nitrogen, appearance of the third and fourth leaves was considerably delayed. Cultivars producing fewer leaves on the mainstem also showed faster leaf emergence and both these factors contributed to the earliness of a cultivar.

Low nitrogen treatments reduced number of spikelets per ear in both two-row and six-row barleys; this treatment also reduced the number of grain filled, although mean grain weight was not affected. Faster leaf emergence rates were associated with fewer spikelets per ear in both nitrogen treatments.

Since they are based on a relatively large number of cultivars it is likely that these results are general for barley. The importance of further detailed examination of apical development is indicated.

An experiment at Saxmundham, Suffolk, during 1974–6, tested late sprays of a liquid N-fertilizer (ammonium nitrate/urea) supplying 50 kg N/ha, and a broad spectrum fungicide (benomyl and maneb with mancozeb) on winter wheat given, 0, 50, 100 or 150 kg N/ha as ‘Nitro-Chalk’ (ammonium nitrate/calcium carbonate) in spring

Mildew (Erysiphe graminisf. sp. tritici) was most severe in 1974. It was increased by N and decreased by the fungicide in both 1974 and 1975, but was negligible in 1976. Septoria (S. nodorum) was very slight in 1974 and none was observed in 1976. It was much more severe in 1975, but was unaffected by the fungicide perhaps because this was applied too late.

Yield and N content, number of ears and leaf area index were determined during summer on samples taken from all plots given 100 or 150 kg N/ha in spring; each was larger with 150 than with 100 kg N/ha. The effects of the liquid N-fertilizer on yield and N content varied, but leaf area index was consistently increased. None was affected consistently by the fungicide.

Yields, percentages of N in, and amounts of N removed by grain and straw were greatly and consistently increased by each increment of ‘Nitro-Chalk’. Yields of grain were increased (average, 9%) by the liquid fertilizer in 1974 and 1975, and most where most ‘Nitro-Chalk’ had been given, but not in 1976 when the wheat ripened in July; however, both the percentage of N in and the amount of N removed by the grain were increased by the liquid fertilizer each year. The fungicide increased the response to the liquid N-fertilizer in 1974, but not in 1975 when Septoria was not controlled, nor in 1976 when leaf diseases were virtually absent.

The weight of 1000 grains was increased by each increment of ‘Nitro-Chalk’ in 1975 but only by the first one (50 kg N/ha) in 1974 and 1976; it was very slightly increased by the liquid fertilizer and by fungicide each year.

An experiment comparing the yield at various stages of continuous wheat growing on heavy land, using two varieties and two rates of application of nitrogenous fertilizer, is described and the results from 1963 to 1974 discussed.

The yield of the second wheat crop was substantially less than that of the first following oats which followed beans, but there were no consistent yield differences between the second and later crops.

The major disease present was eyespot, but the differences in yield between Cappelle-Desprez and Hybrid 46 were little affected as wheat growing continued.

Increasing nitrogen application from 63 to 126 kg N/ha did not reduce the differences between first and later wheat crops.

Experiments were made in a glasshouse and in the field to estimate the effect of weed competition on cowpea performance.

In the glasshouse experiment, plant height, number of nodes, green leaves, peduncles, weight of poda and seeds of cowpea were decreased by competition from Euphorbia heterophylla and the decrease was greater with increasing density of the weed associate. Generally cowpea did not respond to application of fertilizers. In the field experiment, competition from the natural weed flora affected the number of days to 50% flowering and yield components of the four cowpea varieties studied. The yield of the climbing variety, Dinner, was least affected by competition whilst the semi-erect variety, Ife brown, was the most affected.

Neem (Azadirachta indica A. Juss syn. Melia azadirachta Linn.) seed cake boiled with 8 g caustic soda/kg cake in 2·51 of water for 30 min yielded a product which was palatable to cattle unlike untreated neem seed cake which is bitter, foul smelling and wholly unpalatable to cattle.

Two experiments were made on calves to compare the performance of two groups of animals; one group (control) fed on a standard concentrate mixture consisting of 33% groundnut cake, 34% maize and 33% wheat bran and the second group (experimental) on 50% alkali-treated neem seed cake, 33% groundnut cake and 17% maize, the roughage being the same in both the groups.

The results showed that the dry-matter intake/100 kg body weight of the animals did not differ significantly (P > 0·05) between the two groups but digestibility of dry matter and total carbohydrates and the growth rate was significantly lower (P < 0·05) in the experimental group. The digestibility of crude protein and ether extract and the adjusted balances of nitrogen, calcium, phosphorus and sulphur remained similar (P > 0·05) in the two groups. The reduction of the growth rate in the experimental group could be accounted for by the lower total digestible nutrients (TDN) intake and there was no difference (P > 0·05) in the serum icteric index, blood inorganic phosphorus and serum alkaline phosphatase activity in the two groups.

It is concluded that alkali-treated neem seed cake has great potential as a cattle feed and alkali treatment removes either completely or very largely the toxic principles present in neem seed cake.

Soils at Rothamsted receive approximately 4 kg NH3-N/ha/year through dry deposition of atmospheric ammonia. The value is low compared with other nitrogen input processes and reflects the low concentrations of ammonia in the atmosphere. Rainfall is a major factor limiting dry deposition as it removes large amounts of ammonia from the atmosphere. Dry deposition of ammonia is a relatively unimportant source of combined soil nitrogen compared with other natural and artificial sources.

Winter wheat varieties of contrasting height were grown in a series of yield trials to investigate their response to nitrogen fertilizer. The treatments also included application of fungicides and the use of nets to prevent lodging. The varieties were ‘semidwarfs’ based on the Norin 10 genetic factor Rht2 or taller ‘conventional’ varieties, all well adapted to the U.K. environment. The average response of the semi-dwarf varieties was similar to the conventional and there were varietal differences within each group. There was a marked tendency for the newer varieties to be more responsive but the varietal differences were not consistent between trials, the occurrence of powdery mildew (Erysiphe graminis) being a major factor. When this disease was prevalent, response to nitrogen was greatest in resistant varieties and increased by application of fungicides. In farm practice the optimum rate of nitrogen application for a variety will depend on its physiological response, resistance to lodging and resistance to diseases if these are not controlled by fungicides. No evidence was obtained that the gene Rht2 necessarily confers a greater response to nitrogen.

A study of fruit set at different nodes was made in mung beans, Phaseolus aureus Roxb., under field conditions. Flowering commenced on the fourth node from the base and the percentage fruit set showed a gradual decrease from the fifth node upwards. Yield analysis was carried out for each of the fruiting nodes. When the leaf and inflorescences at a node are taken as a functional unit it is seen that there was a decrease in the ratio of leaf area to fruit and seed weights from the base of the plant upwards indicating that at the upper nodes particularly, some other plant parts also contribute to the photosynthate pool of the developing seeds.

A quantitative study of the dry matter, proteins and starch in the fruit wall and seeds of fruits at different stages of development was made. It showed that the rapid increase in dry matter, proteins and starch in the seeds at the later stages of development is compensated, in part, by a decrease of these components in the fruit wall. Histochemical studies of the fruit wall further supported these observations. This indicated the contribution of substrates by the fruit wall to the developing seeds.

Young steers with rumen and simple duodenal cannulas were given diets of approximately equal amounts of flaked maize and hay (A) or of flaked maize and straw supplemented with decorticated groundnut meal (DCGM) (B), fishmeal (C), heated soya-bean meal (D) or raw soya-bean meal (E) or of dried grass (F). A cow with rumen and re-entrant duodenal cannulas was given diets of hay and dairy cubes.

Some steers received doses of 32P-labelled inorganic phosphate twice daily with their concentrate feed. This led to small diurnal variations in inorganic P–32P specific activity but at similar daily sampling times the 32P specific activity in rumen bacterial nucleic acids reached a steady state after dosing for about 4 days. Contributions of microbial-N to non-ammonia-N (NA-N) entering the duodenum were then estimated by comparing nucleic acid 32P/NA-N ratios in related samples of rumen bacteria and duodenal contents. Similar estimates were made in these and other animals using α-, ε-diaminopimelic acid (DAP) and ribonucleic acid (RNA) as bacterial markers.

Estimates for steers given diets A, B, C and F based upon ‘32P-labelled RNA nucleotides’ were, on average, 85% of those based upon total RNA. The differences were attributed mainly to the latter being elevated by the presence of small amounts of dietary RNA. When RNA-based estimates of the proportion of microbial-N in NA-N in duodenal contents for these and other steers which were nearly free of protozoa were multiplied by 0·85 (‘adjusted RNA’) the values were, on average, similar to those based upon DAP. Similar estimates for the cow based upon ‘adjusted RNA’ measurements were, however, about twice those based upon DAP, probably because the cow contained a high protozoal population and the DAP based, method did not account for protozoal N.

For some steers total flows at the duodenum of organic matter (OM), microbial-N (mean based upon ‘adjusted RNA’ and DAP) and residual food N were estimated by reference to chromic oxide. Average values for g microbial-N synthesized/kg OM truly digested in the rumen for the different diets ranged from 15 to 22 (mean 20). Mean degradabilities of food N (residual food N at duodenum/N intake) were 0·57, 0·71, 0·71, 0·70 and 0·84 for diets A, B, C, D and E respectively. No differences between diets were significant at P < 0·05.

Total dry-matter yield of maize silage rose asymptotically as density was increased up to 17 plants/m2. Over the range 11–17 plants/m2, which is generally higher than is used in the U.K., the increase in yield was 1–1·6 t dry matter/ha which can justify the higher seed cost and although there was no adverse affect on time of maturity the risk of lodging increased at the highest density. During the harvest period whilst whole crop dry-matter percentage was rising from 23 to 28%, the ear dry-matter content rose steadily from 29 to 35%, whereas the leaf and stem dry-matter content remained essentially constant and only dried out at a later stage after a frost.

Caldera 535 had a higher leaf area index and net assimilation rate than the earlier variety Julia which it outyielded by 15%. The additional yield was mainly stem tissue and the greater vegetative production caused an 11-day delay in reaching the silage stage of maturity (25% crop D.M.). NO differences occurred between density treatments and varieties in the forage quality components considered, namely percentage drymatter digestibility, modified acid-detergent fibre, crude protein and ash. Thus in U.K. conditions, total dry-matter yield exerts an overriding influence on the yields per unit area of these quality constituents. This contrasts with reports from the U.S.A. in which a reduced grain/stover ratio adversely influences silage quality.

Removal of the whole ear (including husk and rachis) at an early stage in ear development resulted in a 50% reduction in the final dry-matter yield. In the earless plants, leaf area and net assimilation rate was lower, but the dry-matter content of the leaves and stem was considerably higher, and a marked purple coloration developed indicative of excess starch concentration. These results emphasize the need in maize silage not only for an adequate leaf canopy, best obtained early in the growing season by using high planting density and subsequently by using late maturing varieties, but also for sufficient sink capacity in the ear as well as in the stem fraction.

Blood and liver samples were taken from four fasted pregnant and five fasted non-pregnant Finnish Landrace × Dorset Horn ewes. The following metabolites were measured: adenine monophosphate (AMP), adenine diphosphate (ADP), adenine triphosphate (ATP), citrate, 2-oxoglutarate, phosphoenolpyruvate, pyruvate, lactate, 2-phosphoglycerate, 3-phosphoglycerate, α-glycerophosphate, malate, β-hydroxybutyrate, acetoacetate, glutamate, alanine and NAD+.

The effects of a 6-day fast on non-pregnant ewes were shown as significant reductions in the hepatic concentrations of 2-phosphoglycerate, alanine, NAD+ and ADP, together with significant increases in the hepatic concentrations of 3-hydroxybutyrate, malate and the ratio of 3-hydroxybutyrate:acetoacetate. In the blood there were significant reductions in the concentrations of urea, citrate and in the ratio of 3-hydroxybutyrate: acetoacetate.

Similar but more marked changes occurred in the late pregnant ewes, with additional significant reductions in the hepatic concentrations of citrate, ATP and the level of cell energy, and additional increases in the blood of the ratio of lactate: pyruvate and the concentrations of 3-hydroxybutyrate and 2-oxoglutarate. However, unlike the non-pregnant ewes no significant changes in either the plasma concentration of urea or the hepatic concentration of ADP were observed in the late pregnant ewes.

Studies on night-enclosed eland, oryx, buffalo and cattle in south eastern Kenya showed that the animals spent only a short time each day in the shade; the mean duration was not more than 2 h/day for any species.

All four species actively sought shade in the middle of the day. The time spent in the shade by the three indigenous species was significantly related to activity times and environmental heat load; that of cattle was not.

In general the time spent in the shade by the four species could be related to characteristics of their coat.

The captive animals at Galana spend less time in the shade than their free-living counterparts. This is thought to be partly due to the need of wild animals to reduce their total body water turnover rate and for captive animals to spend more time feeding during the day.

The inter-individual distances (IID) maintained by eland, oryx and cattle and the synchronization of the activity of these three species and buffalo were also studied.

Eland maintained the largest mean IID (13·7 m) while those for oryx (6·5 m) and cattle (4·0 m) were considerably less. Calculations showed that herds of 250 eland might occupy an area of approximately 5 ha, oryx 1 ha and cattle would occupy 0·5 ha. The IID of all three species were significantly related to activity and the IIDs of eland and oryx were significantly related to meteorological factors. The differences in the IIDs of the three species were thought to be due to differences in feeding strategies and the length of time for which cattle have been domesticated.

For all species feeding was well synchronized, but walking, idling and shade behaviour were not. Although only one activity was well synchronized it was the most time consuming one. The lack of synchrony in other activities did not pose a great problem in the management of the relatively small herds being studied. Lack of synchrony, however, might cause a problem if the size of the herds were substantially increased.

Using data from four field experiments, comparisons were made between the drymatter percentages of several varieties harvested at different times during the growing season.

There were negative quadratic relationships between tuber dry-matter percentage and tuber size in all varieties except Pentland Marble. The dry-matter percentage of particular tuber sizes varied according to the variety and the time of harvest. Failure to recognize the importance of tuber size and the time of harvest may easily distort differences in dry-matter percentage between varieties.

There were significant positive correlations between the number of tubers produced by each variety on 25 June and four different variables representing the dry-matter percentage of tubers harvested on 10 September. Varietal maturity, assessed as persistence of the foliage, was not significantly correlated with any tuber dry-matter percentage variable in September.

Seven-week-old White Rock males were exposed to step-wise increases in ambient temperatures from 7·7 to 37·7 °C in light and dark environments. Heart rate decreased with increasing ambient temperature with a quadratic slope (P ≤ 0·0001). Heart rate was lower during the dark period than during the light period (P ≤ 0·06). There was a positive linear correlation between heart rate and oxygen consumption (γ = 0·997) for ambient temperatures from 7·7 to 37·7 °C.

Body temperatures began to increase significantly when ambient temperature reached beyond 27·5 °C. The increases followed a quadratic slope (P ≤ 0·0001). Body temperatures during the light period were significantly higher than during the dark period (P ≤ 0·05).