Seven Wiltshire Horn rams were subjected to unilateral thoracic sympathectomy. Wool shedding was observed during the following 9 months. Fleece samples were collected on two occasions during winter from tattooed areas of skin on both the sympathectomized and unoperated sides. Skin samples were also taken from the sympathectomized and unoperated sides of the sheep during August and examined for catecholamine fluorescence using a fluorescence histochemical technique. While there was no difference in fleece casting between the sympathectomized and unoperated sides, there were increases in both wool growth and the number of brush end fibres on the sympathectomized side. Fluorescent histochemical evaluation of the skin samples revealed that the increases in shed fibres and wool growth were accompanied by a decrease in amine fluorescence in nonvascular tissue adjacent to the wool follicles.

Field studies on leaching a highly saline sandy loam soil having a shallow groundwater table showed that application of 150 mm water in two equal parts at 10 days interval had no distinct advantage over a single application of the whole amount. On the contrary, the surface-accumulated salts were displaced to a lesser extent and the salt peak remained at a shallower depth under split application, particularly during periods of high atmospheric evaporativity when the leached salts tended to move upward between successive water applications. A soil mulch created by shallow tillage reduced evaporation losses and curtailed upward movement of salts, resulting in nearly 10% increase in leaching efficiency. Significantly a small quantity of water (0·41 cm leaching water per unit soil depth) sufficed for 70% chloride removal, indicating that under the prevailing conditions a larger fraction of the pores contributed to the leaching process. A compact layer, having a bulk density of 1·69 g/cm3, at the soil surface, also appeared to be related to the higher leaching efficiency by maintaining a preponderance of unsaturated flow.

Soil instability, as measured by the dispersion ratios of the reclaimed salt-marsh soils of ca. 70 km2 of north Kent, was assessed on samples taken from 0–15, 35–50 and 70–85 cm depths from sites at the intersects of a 250 m square grid or along transects. The dispersion ratios were related to other soil properties including exchangeable sodium, potassium and magnesium percentages, organic carbon content, calcium carbonate content and electrical conductivity. The dispersion ratio correlates most closely with exchangeable sodium percentage and organic carbon content; weaker correlations exist with exchangeable potassium and calcium carbonate contents. Dispersion ratios rise sharply, i.e. reflect a marked increase in soil instability, when organic carbon content is less than 2·5% and calcium carbonate content is less than 2%. Magnesium has little effect on the dispersion ratio. The soil solution salt concentration (as expressed by electrical conductivity) is too low over much of the area to promote flocculation, and hence stability, of the soil clays.

The growth and water use of sugar beet affected by early (ED) and late (LD) drought was compared with that of irrigated (I) and unirrigated (NI) controls. Mobile shelters were used to exclude rain from ED plots during June and July, and LD plots during August and September, respectively, whereas outside these periods the ED and LD plots were irrigated as necessary.

The ED treatment affected the fibrous roots severely. Many of the roots in the top 60 cm of soil died and development of the root system below this depth was slow. Expansion of the leaf canopy slowed, radiation interception was reduced and the rate of water use fell from about 1·2 times to 0·6 times Penman potential transpiration rate. The LD treatment, which was imposed when the fibrous root system was already extensive, had little effect on the fibrous roots except in the top soil. The accessible soil water was quickly depleted and the resulting stress was accompanied by earlier senescence of leaves. The rate of converting intercepted light to crop dry matter was reduced in both treatments. However, the ED treatment was the most detrimental because the amount of light intercepted in the months of highest radiation was greatly reduced owing to the restricted leaf cover. The relative effects on growth are reflected in the final sugar yields which were 8·7, 10·5, 9·9 and 12·0 (±0·30) t/ha in the ED, LD, NI and I treatments respectively.

More of the deep soil water was used in the drought-affected plots (particularly LD) than in the irrigated controls. Maximum depths of water extraction were 140–150 cm in ED and I plots and > 170 cm in LD plots. The highest uptake rates per unit length of root (20–40 μl/cm per day) were measured in the deepest part of the root system. At all depths, uptake rates declined as the soil dried. After correcting for overestimated water use where necessary, the ratios of final dry matter and sugar yields respectively to season-long water use (June–October) were close to 1·4 and 0·8 t/ha per 25 mm for all four treatments.

By comparing growth rates of Brahman (B), Hereford × Shorthorn (HS), their reciprocal F1, hybrid (F1BX), their Fn hybrid (FnBX) and an F1 Charolais × Brahman hybrid (Fl CH x B) in environments that differed in their levels of stresses that affected growth, it was shown that heterosis for growth realized in any environment arose because of heterosis in its underlying determinants, namely growth potential and resistance to environmental stresses. Growth potential of the F1 BX was similar to that of the better parent (HS) whilst resistance to environmental stresses was similar to or approached that of the more resistant parent (B). This combination of high growth potential and high resistance to environmental stresses enabled the F1 BX to outgain both parents at all levels of environmental stress above zero. However, some or all of the heterosis in both growth potential and resistance to environmental stresses was lost in the Fn BX. Thus, although previous selection for increased live-weight gain should have favoured the Fn BX, they realized lower live-weight gains than the Fl BX in all environments and lower live-weight gains than the parental breeds in all but intermediate environments.

Because the breeds differed in both determinants of growth, the magnitude of estimates of heterosis for realized growth was dependent on the environment in which it was measured. A figure depicting this interaction was constructed.

Comparative estimates were also made of the rate of approach to sexual maturity of bulls of each breed. The F1 BX had similar values to the better parent (HS) for both scrotal circumference and plasma testosterone concentrations. However, the Fn BX had values that were intermediate to those of the parental breeds.

Generally, gains of the -F, CH × B exceeded those of all other breeds in all environments but their rate of approach to sexual maturity was slower than that of the F1 BX.

Two experiments were carried out to determine endogenous excretion of purine derivatives in steers and lambs, and to investigate the relationship between microbial nucleic acid input and urinary excretion of purine nitrogen.

The endogenous excretion of allantoin after conversion of hypoxanthine, xanthine and uric acid to allantoin, was calculated to be 72 and 26 mg/kg W0·75 per day in steers and lambs, respectively, when the dietary protein contained no nucleic acid nitrogen.

The excretion of purine derivatives increased linearly with increasing microbial nucleic acid input in lambs. The excretion of purine derivatives in excess of endogenous contribution was closely related to the theoretically expected values. The average recovery was calculated as 0·96 for one sheep and 1·0 for the other.

Fifteen treatments were applied in 1966 to Molinia caerulea dominant rough grazing on wet hill land at 305 m in mid-Wales. Improvement methods varied from controlled sheep grazing, application of lime, basic slag and nitrogen to the introduction of grasses and white clover with and without cultivations. Pasture productivity, feed quality and botanical composition were studied in the 4th, 9th, 14th and 18th harvest years. Controlled grazing increased D.M. production from 1·1 t/ha on the native vegetation to 3 t/ha in the 18th year. Application of lime, basic slag and 75 kg N/ha gave mean pasture production of 4·5 t D.M./ha which increased to 6·3 t D.M./ha on application of 290 kg N/ha per year. The quickest and greatest improvement was achieved by the introduction of grasses and clover following rotary cultivation or ploughing. At the lower N input these swards produced on average 6·3 t D.M./ha. Reseeds also showed the best response to 290 kg N with mean production on S. 23 perennial ryegrass (Lolium perenne L.) swards of 9·0 t D.M./ha. In vitro digestibility, crude protein and water-soluble carbohydrates were also highest on the reseeded swards.

Increased grazing eliminated Molinia before the 4th year and it was replaced by Nardus stricta and Festuca ovina. Subsequently, Agrostis tenuis replaced Nardus. On the swards given fertilizer the rate of botanical change was accelerated with the ingress of Poa spp., Holcus lanatus and Festuca rubra. The proportion of sown grass remained high on the seeded plots throughout the duration of the experiment but the white clover content was lower than expected and it virtually disappeared from most of the swards before the 18th year.

The results show the potential improvement possible on wet hill land. Given good fertilizer and grazing management, this improvement can be maintained for several years.

For many field-grown crops, including sugar beet, there is little information on the seasonal changes in leaf water potential and its components as the soil dries. Therefore, seasonal changes in leaf water, osmotic and turgor potentials of sugar beet were measured in two seasons, in crops that experienced differing degrees of soil moisture stress. In 1983 potentials of crops exposed to early and late droughts were compared with those of irrigated crops, and in 1984 measurements were made in a non-irrigated crop. In the irrigated crop the midday leaf water potential changed little during the season, except in response to fluctuating evaporative demand. In the drought and non-irrigated treatments there was a sharp fall in leaf water potential as soon as the soil water potential decreased. The size of the midday leaf water potential was primarily determined by soil dryness. However, the leaf water potential did not decrease below about — 1·5 MPa in either year. The leaf osmotic potential declined at the same time as the leaf water potential, but the extent to which this happened differed in the two years. Only in the 1984 non-irrigated crop did the osmotic potential continue to decrease as the soil dried, suggesting that osmotic adjustment had taken place in 1984 but not in 1983. Thus higher turgor was maintained in the 1984 crop than in the 1983 drought-affected crops. Some turgors were recorded as apparently negative in 1983.

Since the leaf water potential declined to a minimum of about — 1·5 MPa, the soil water potential minima were also about — 1·5 MPa. However, deeper soil was not dried to this extent, suggesting that the extra resistance for water uptake from deep soil was limiting or the rooting density was too low.

The pattern of recovery of leaf water potential overnight suggested that the rhizosphere resistance to water movement was small, even as the soil dried. However, measurement of stem water potentials in 1984 indicated that a significant resistance to water flow existed within the aerial part of sugar beet plants. This shows that the use of the water potential in leaves as an estimate of that in stems or roots can be misleading.

Elimination of the rumen anaerobic fungi from sheep fed chemically-treated barley straw diets resulted in elevated proportions of propionic acid in rumen liquor (from ca. 0·15 to 0·30). Subsequent inoculation of these sheep with a pure culture of fungus decreased propionate concentrations within 3 days to the levels observed in control animals that possessed abundant fungal populations throughout the experiment.

Confirmation that propionate itself was not responsible for the elimination of the fungi was provided by the results of a second experiment in which intraruminal infusions of propionic acid failed to reduce fungal growth or prevent recolonization in sheep previously rendered fungi-free.

In a third experiment with sheep fed untreated barley straw, monensin supplementation produced the well known elevation of propionate concentrations. However, this treatment also resulted in the elimination of rumen anaerobic fungi from the animals. The magnitude of the increased concentration of rumen propionic acid, resulting from the elimination of the anaerobic fungal flora, indicates an important role for the fungi in the fermentation of high-fibre diets. In addition, these findings indicate that the well known elevation of propionate levels produced by monensin may likewise be effected directly by removal of the rumen anaerobic fungi.

The effects of night enclosure and walking 3000 km on growing and breeding cattle were examined over an 8-month period. Walking consisted of an 8 h walk of 40 km every 3rd day and experimental cattle were enclosed each night for 11 h. In addition, all cattle were allowed water once every 3 days. In cattle which both walked and were enclosed, a reduction of nearly 40% in grazing time was recorded. This was associated with a depression of dry-matter intake of only 12%, suggesting an intensification of eating in response to a restriction of grazing time. The overall effects of walking and enclosing on productivity, as determined by adult weight loss, calf and weaner growth, calving percentage and birth weight, were negligible and masked by the greater effects of poor nutrition during the dry season which affected all the animals. It is concluded that the additional energetic requirements for walking are small and this is attributed to adaptation, fitness and a possible depression of metabolic rate. These factors may explain why the observed costs of walking were lower than those reported in the literature.

The effects of controlled grazing, application of N, P, K, Ca, and Mg and the introduction of grasses and white clover, with and without cultivations, on Molinia caerulea dominant rough hill grazing were studied over 19 years in mid-Wales. Nutrient concentration in, and uptake by, the herbage and changes in soil physical, chemical and biological characteristics were monitored periodically. Concentrations and uptake of N, P, K, Ca, Mg and Na were highest on the reseeded pastures. Nutrient balance sheets showed that the nutrients applied were most efficiently utilized on reseeded swards. They also highlighted the considerable losses of applied Ca and Mg that occurred.

Implications of the results are discussed in relation to both future agricultural use of such areas in the hills and the effects on the environment.

Two field experiments examined the effects of nitrogen fertilizer, irrigation frequency and three wheat varieties on the yield and quality of irrigated wheat on a heavy clay soil. In the first experiment, with irrigation supplied to all plots at mid-tillering and close to ear emergence, there were negative effects of nitrogen fertilizer on grain yield with the reverse occurring with grain protein. The variety Songlen had one of the highest grain yields combined with higher milling yields and flour protein. In the second experiment, yield was maximized with at least two irrigations, whilst increasing irrigation frequency reduced flour protein and dough development time. While WW15 gave the highest yields irrespective of nitrogen or irrigation treatments, this variety had the lowest flour protein. With only one irrigation or without irrigation, nitrogen fertilizer increased grain protein; more frequent irrigation reduced mean flour protein.

Efficiency of N contained in some modified urea fertilizers was studied for wetland rice grown in an alkaline, low organic matter Fatehpur loamy sand (Typic Ustipsamment) soil having an average percolation rate of 109 mm/day. In the four field experiments, sulphurcoated urea (SCU) produced significantly more rice grain than urea supergranules (USG) or divided applications of urea or ammonium sulphate. Application of SCU at 58 kg N/ha yielded as much rice grain as was produced by divided application of urea at 116 kg N/ha. The N uptake data suggested that SCU-N was more efficiently translated into grain yield than urea N. Granular (7-day release rate 19%) and forestry (7-day release rate 29%) grades of SCU were equally effective. However, application of half the N basally through SCU and the remaining half top dressed as urea failed to outyield all urea divided in three applications. The indigenous coated materials, rock-phosphate-coated urea and urea gypsum, also did not perform better than divided urea applications as these did not possess a 7-day release rate less than 95%. Urea supergranules placed in the reduced zone of the soil could not come to the level of divided application of urea or ammonium sulphate. The N uptake data indicated that USG-N was correspondingly inefficiently utilized by rice. When the deep placement aspect of USG was combined with slow-release properties of SCU in the form of sulphur-coated urea supergranules (SCUSG), the performance of this product was inferior even to the divided application of urea. Undissolved or partially dissolved granules of SCUSG could be recovered even after the harvest of the crop.

A method is described in which a liquid suspension of sheep faeces is used as an inoculum in the in vitro determination of digestibility of feedingstuffs for ruminants. The modified method was applied to 21 samples of grass, ten of lucerne, and a variety of other food materials. The results correlated closely (r = 0·98) with the in vivo digestibilities, and the relationship between in vitro and in vivo digestibilities was represented by the equation: in vivo digestibility = in vitro digestibility × 1·003.

Water influx, i.e. total water intake from water drunk and water obtained from food, was measured using tritiated water in six groups, each containing ten single comb White Leghorn (SCWL) hens, in which each group received decreasing amounts of dry matter (D.M.) in decrements of 10%. Group 1 received 101·2 g D.M./day, an amount normally offered these hens, group 2 received 92·4 g D.M./day, group 3 received 81·0 g D.M./day, group 4 received 70·4 g D.M./day, group 5 received 61·6 g D.M./day and group 6 received 52·8 g D.M./day. In the first 4 weeks, egg production remained relatively high in the restricted fed groups compared with group 1 and body mass declined rapidly (period I); in the second 4 weeks, egg production declined to a great extent but body mass remained constant (period II). The ratio of water influx to DMI remained constant in the two periods in hens with the same DMI but with different egg production. The linear regression of DMI and/or egg production on water influx were significant within each period. DMI explained 65% of the variation in water influx, egg production explained 30/55% of the variation, and both DMI and egg production explained 66/70% of the variation. Within each period, the regressions of DMI on water influx in hens with similar egg production were generally significant, and, in contrast, the regressions of egg production on water influx within each DMI were generally not significant. It was concluded that DMI was more important than egg production in affecting water influx in laying SCWL hens.

The moisture use pattern and efficiency (MUE) of four barley cultivars (two hulled and two hull-less) were studied when the crops were grown in winter under unirrigated conditions at Varanasi, India, with different rates of application of nitrogen fertilizer. Increase in moisture use with age of the crop due to vegetative growth was recorded. Influence of varieties on consumptive use of water was found to be negligible except in the 1st year between 65 days after sowing and after harvest of the crop, when differences were due to differences in duration of the crop growth and rainfall which was received at the time of maturity. The moisture mining capacity of the barley crop from the profile (up to 120 cm) was increased with increase in the rate of nitrogen application. MUE of barley cultivars closely paralleled the grain yields, being more with hulled cultivars than hull-less ones. Higher MUE of barley was observed in the 2nd than in the 1st year of experimentation because of a better distribution of rainfall and moisture availability at the time of sowing, which boosted yields. Nitrogen application increased both yield and MUE of barley.

The effect of including full-fat rapeseed (Brassica napus, cv. Jet Neuf) into diets for mature wether sheep was studied. A 4 × 4 latin square was carried out with diets containing 4% rapeseed oil in different physical forms: as intact seeds; as a mixture of rapeseed oil and rapeseed meal; or as an extruded rapeseed product. A control diet, containing rapeseed meal but no added oil, was also fed.

There was no effect of added oil on rumen fermentation or dietary fibre digestibility. Extrusion had the effect of lowering nutrient availability, both in the rumen and in the small intestine. Total nitrogen digestibility for the diet containing the extruded product was 5% lower than any other diet.

All diets produced apparent net gains between mouth and duodenum of ether extract; however, the diet containing dispersed oil and meal was the only one that did not show apparent synthesis of long-chain fatty acids in the forestomach. Apparent disappearances of fatty acids in the small intestine were highest, at 56 and 58 g/day respectively, for the diets containing the extruded product and the intact whole seeds. Extrusion had the effect of reducing apparent biohydrogenation of 18:1 in the forestomach.

The use of extruded rapeseed in this experiment showed little benefit over that of intact rapeseed, for sheep, owing to the lower digestion of nutrients for the heated supplement. The free-dispersal of rapeseed oil in the diet, however, may inhibit microbial synthesis in the rumen.

A 4 × 4 latin-square design experiment was carried out to determine the effects of increasing nitrogen (N) intake by feeding diets containing increasing amounts of fishmeal upon the digestion of organic matter (OM) and N by cattle equipped with rumen and duodenal cannulae. A basal diet (B) containing 600 g silage and 400 g ground barley/kg diet and three diets (BF1, BF2 and BF3) in which increasing amounts of the silage and barley basal diet were proportionately replaced by fishmeal were fed. The mean daily intakes of OM and N when each diet was fed were 4·29, 4·28, 4·22 and 4·20 kg OM and 90, 108, 125 and 143 g N for diets B, BF1, BF2 and BF3 respectively.

Neither the amounts of OM entering the small intestine nor those voided in the faeces were altered by the diets fed. Thus mean apparent OM digestibility for all the diets fed was 0·74 ± 0·007 and the proportion of digestible OM intake apparently digested in the rumen was 0·83±0·011.

Mean daily concentrations of ammonia N in the rumen were significantly (P <0·01) increased from 85 mg N/l (diet B) to 129 mg N/1 (diet BF3) as fishmeal intake increased.

The quantities of non-ammonia N (P <0·05) and of amino acid N (P <0·001) entering the small intestine were significantly increased as more fishmeal was added to the diets fed. As fishmeal intake increased apparent N digestibility was significantly (P <0·001) increased.

Neither the quantities of microbial N entering the small intestine daily nor the apparent efficiency of microbial N synthesis within the rumen were increased by the diets fed. The quantities of feed N entering the small intestine daily were significantly (P<0·01) increased as fishmeal intake increased; thus apparent feed N degradability in the rumen was significantly (P <0·05) decreased from 0·84 (diet B) to 0·73 (diet BF3) as fishmeal intake increased. Similarly, the rates of disappearance of N from each of the four barley or barley and fishmeal concentrates when incubated in the rumens of the cattle in porous synthetic fibre bags were decreased as the proportion of fishmeal in the concentrates increased. Thus, the rumen N degradability of the diets fed, when calculated from the rates of disappearance of N from porous synthetic fibre bags placed in the rumen, decreased as fishmeal intake increased.

As fishmeal intake increased the amino acid composition of duodenal digesta (expressed as g/kg determined amino acids) changed such that the content of arginine increased (P <0·01) and the content of isoleucine decreased (P <0·01). The concentrations of arginine (P <0·01), leucine and lysine (P <0·05) in blood plasma increased as fishmeal intake increased.

Adult Finn-cross ewes, pregnant from September matings, were kept under natural photoperiod (control, 30 animals) or with an additional exposure to a 1 h long. 300 lux light pulse, 16–17 h after an artificial dawn (light-pulse treatment, 32 ewes) for 2·5 months. After lambing, the supplementary light was discontinued and half of the ewes from each group were injected daily with 2 mg melatonin for an additional 2·5 months.

The light-pulse ewes produced heavier lambs and more milk, as can be deduced from the higher rate of growth of their lambs during the first 10 days of life, than the control animals. The light-pulse and/or melatonin treatments delayed the occurrence of the first post-partum ovulation and oestrus (which occurred in the untreated animals about 4 and 6 weeks, respectively, after lambing), by 1–3 weeks. However, more ewes exhibited oestrus and cyclic activity in the light-treated than in the other groups. The fertility in the light-treated group was, consequently, superior to that in the group kept under natural photoperiod, in spite of the similar lambing rate of the mated ewes of the different groups.

It is concluded that the light-pulse, but not the melatonin treatment, had a beneficial effect on the reproductive performance of the ewes, as measured by the weight of the newborn lambs, the milk production of the dams during the first 10 days post-partum, and the cyclic activity of the ewes after February lambing in Israel.

Two experiments were conducted on two varieties of Corchorus olitorius(‘NHCo 6’ and ‘NHCo 7’). The first one was on the effect of density of planting on their growth and development whilst the second was on the best planting ratio for Corchorus-tomato intercropping.

There was no significant difference in morphological characters of the two varieties. The maximum value of leaf area index for the two varieties was around 3. Maximum marketable and edible yields were obtained for the two varieties at 30 × 5 cm (666600 plants/ha) and the best time for harvesting was 44 days after sowing.

The best planting ratio for Corchorus-tomato intercrop was 2 rows of Corchorus and 1 row of tomato for maximum edible yield of Corchorus but for maximum economic returns, the best ratio was 1 row of Corchorus to 2 rows of tomato.