Between 1980 and 1986, six field experiments were conducted to investigate the relations between planting density, total dry matter and pod yield of groundnut (Arachis hypogaea L. cv. TMV2) grown at different levels of irrigation and rainfall at two sites in central India. In general, the relationship between total dry matter and planting density for most treatments was well described by the function:

where W is the crop dry weight per unit ground area, wm is the maximum weight per plant, Wm is the maximum crop weight per unit ground area and P is the plant population. Because the harvest index, h, was constant for each treatment irrespective of plant population, a similar equation described the relationship between pod yield and planting density. When nine of the eleven treatments planted in a square (i.e. 1:1) arrangement were compared, the asymptotic value Wm varied between treatments depending on available soil water and atmospheric demand. To quantify the effects of plant and environmental factors on crop productivity, a ‘transpiration equivalent’ (ωw; (g/kg)/kPa), i.e. the product of the dry matter/water ratio and mean seasonal saturation deficit D, was used as a crop constant to calculate productivity at each site or season from a knowledge of seasonal rainfall and/or irrigation and soil water-holding capacity. Thus, total crop productivity, W'8, was calculated using the equation W'8 = ωwS/D where S (mm) is a soil supply term dependent on soil water-holding capacity and monthly values of rainfall and/or irrigation. When values for Wm and W'8 were plotted against each other, a linear regression was obtained with a slope = 1·02 (R2 = 0·78). The mean harvest index of 0·38 was used to predict pod yield from a knowledge of W'8. It was concluded that of all the climatic, soil and management factors that influence crop growth in semi-arid situations, it is the interaction between the supply of and demand for water that ultimately determines total productivity, pod yield and optimum plant population.

Dried spent hops possess a high absorptive capacity, and attention is drawn to its use as a “filler” to absorb such by-products as molasses and treacle.

The material possesses a high crude protein value and its ether extract is very high for a fibrous food, while the amount of crude fibre is the same as in good meadow hay. There is a high percentage of mineral matter present.

The digestibility of the material has been determined by feeding with hay chaff and linseed cake meal to three sheep. The spent hops were not readily eaten and could only be included in a ration in an amount equal to one-seventh of the dry weight of the total ration.

Its digestibility is low, a fifth of the crude protein and the nitrogenfree extractives, one-half of the ether extract, one-twentieth of the crude fibre and one-fifth of the total organic matter only being digestible. The production starch equivalent was 24.5.

1. A group of six lactating ewes, rotationally grazed a low-nitrogen treated plot (40 lb nitrogen applied in early March) and a similar group a highnitrogen treated plot (1001b nitrogen applied in early March and 60 lb at monthly intervals thereafter, all as Nitro-chalk) from mid-April to early July, and the concentrations of serum magnesium and calcium along with food intake and milk yields of the ewes were studied.

Diurnal variations in microbial protein nitrogen, total volatile fatty acids and ammonia were examined in two wethers fed once and twice daily with 0·4 kg of concentrateand 0·4 kg hay/day. The total protein nitrogen varied during the day from 76·9 to 130·2 mg/100 ml of rumen fluid. The greatest amount of protein nitrogen was noted immediately before feeding and the smallest 4 h after feeding. The protein nitrogen of rumen protozoa formed about 39·8–53·4% of total protein nitrogen in rumen fluid. Volatile fatty acids varied from 74·0 to 130·5 m-mol/1 of rumen fluid and ammonia from 187·0 to 305·6 mg/1. The higher concentration of total and protozoal protein nitrogen and of VFA was observed when animals were fed twice daily. The changing of feeding frequency from once to twice daily caused an increase of ammonia concentration in the rumen of only one wether. The results obtained are discussed.

Between March and August 1968 to 1970, Chlormadinone acetate (CAP), 10 mg/head/ day, was administered to 668 Zebu cows and heifers for oestrous cycle synchronization for 14, 12, or 9 days, the latter schedule supported by an injection of 5 mg estradiol valerate on day 2 to achieve luteolysis. Applied orally over a period of 14 days, CAP provided a reliable method for cycle synchronization. The severe anoestrous rate experienced in all herds reduced the overall percentage of synchronized animals. Fertility from insemination during the first synchronization period (day 2 to 10 after treatment) was slightly, yet insignificantly reduced, but was completely restored during the second synchronization period (day 20–30). Insemination only during this second synchronization period resulted in conception and pregnancy rates similar to those combined from the first and second synchronization period.

Of factors tested for influencing synchronization and fertility, presence or absence of penis-deviated teaser bulls (psycho-stimulation) had no effect on the percentage of animals synchronized, or on post-treatment fertility. In well-managed herds, the percentage of animals responding to treatment was predetermined by the number of animals already cycling, reflecting their phase of reproductive life. Levels of management had an important impact on the success of cycle synchronization combined with artificial insemination. Both methods are managerial tools for improvement of already good management. Their failure under insufficient management conditions has diagnostic value.

Possibilities and limits shown for oestrous cycle synchronization in Zebu cattle were similar to those reported in European cattle. Within these limits, CAP can be employed successfully as a means for cycle synchronization, providing sufficient synchronization and acceptable fertility and allowing economical use of artificial insemination.

Two calves (Aberdeen Angus and American Brahman) were used exposed to different combinations of wet- and dry-bulb temperatures in a psychromatric chamber at the Physiology Department of the University of Queensland. These animals were 7–8 months old when first exposed to heat.

Effect of various drugs affecting the sympathetic nervous system (adrenaline, noradrenaline, Dibenamine, Priscol, atropine and acetylcholine) on the rate of cutaneous evaporation in calves was tested. Cutaneous evaporation was measured by means of a capsule before and after the administration of these drugs.

Cutaneous evaporation increased with the introduction of adrenaline and was suppressed by the administration of Dibenamine. Noradrenaline and Priscol had no appreciable effect. Acetylcholine failed to stimulate sweating and atropine did not block the sweat glands.

Sweat glands of cattle were, therefore, found to be functional and their innervation adrenergic. Cattle use sweat to prevent body temperature from rising, yet the amount of sweat secreted is not large enough to allow cattle to maintain thermoneutrality at high air temperatures.

For straw incorporation, three crucial factors affect the soil microbial community and various enzyme activities: straw length, amount and burial depth. To analyse the individual and interactive effects of these three factors on the soil microbial community and various enzyme activities, 23 treatments with five levels of the three variables (straw length, amount and burial depth) were applied in a quadratic orthogonal rotation combination design. A comprehensive indicator was constructed that could represent soil microbial functional diversity and enzyme activity by determining the weights of measured indicators and using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The results indicated that the soil microbiological indicators have a higher criteria weight than soil enzyme activity indicators. The final weight orders of indicators were as follows: Shannon–Weaver > invertase > Shannon evenness > urease > catalase > McIntosh index > Simpson diversity > phosphatase. The soil comprehensive values constructed by the TOPSIS method are reliable. The optimal combination for the improvement of soil microbial functional diversity and enzyme activity was a straw length of 13–24 cm, burial depth of 10–17 cm and straw amount of 370–650 g/m2.

Growth and nutrient uptake by an upland rice variety, Agbede and a swamp rice variety, BG 79, were studied under four different soil moisture regimes (60, 80, 100% soil moisture saturation and flooding).

BG 79 (Swamp rice) ultimately attained greater mean total dry weight than Agbede (Upland rice), except in the flooding treatment, where the reverse applied. For both, 100% soil moisture saturation gave the greatest total dry weight increase, whereas the driest soil depressed dry-matter production: plants grown on soil maintained at 80% moisture saturation ultimately attained greater mean total dry weight than those grown on flooded soil. Flooded plants of the swamp rice outyielded plants grown on soil maintained at 80% moisture saturation, but the reverse applied to the upland rice.

Total leaf numbers were usually greater in BG 79 than in Agbede during the tillering and mid-vegetative stages. Increase in the soil moisture up to complete saturation increased the total leaf number in both varieties.

Mean leaf area was greater in Agbede than in BG 79 during the tillering and midvegetative stages. During these two periods of growth the 100% saturation treatment produced plants with the greatest leaf area, whereas 60% soil moisture saturation produced plants with the smallest leaf area in both varieties.

BG 79 had more shoots than Agbede. During tillering saturated and flooded soil encouraged the production of shoots in both varieties, but the driest soil prolonged the tillering period, especially in BG 79. Final shoot number tended to decrease with decreasing soil moisture. The percentage shoot mortality in Agbede was not significantly affected by soil moisture regimes, but BG 79 plants grown on the driest and saturated soil had significantly greater percentages of shoot mortality than flooded plants. In both varieties, plants grown on the driest soil had significantly greater percentage shoot mortality than those grown on soil maintained at 80% moisture saturation.

Mean Relative Leaf Growth Rate and Net Assimilation Rate were significantly faster in BG 79 than in Agbede variety, but the reverse applied with regard to Leaf Weight Ratio.

In both varieties flooded plants had the lowest concentration of manganese, especially during tillering. The small adsorption of Mn with flooding is attributed to a probable antagonism between iron and manganese.

In 1992 and 1993, eight rates of 15N-labelled fertilizer (0–245 kg ha−1) were applied to winter wheat growing on the Ropsley long term field trial where eight different N amounts had been applied annually since 1978. The fate of the labelled N in the crop and topsoil (0–23 cm) was determined at harvest in the year of 15N application and in the first and second residual years.

By harvest in the second residual year, 60–77% of the original labelled application had been recovered in the crop and topsoil with 23–40% lost. These losses virtually all occurred within the first two growing seasons; there was no significant loss during the second residual year. Significant changes in the 15N balance were observed at N applications in excess of the range 140–175 kg ha−1 which suggested a marked decrease in the efficiency of N use and an increase in residual labile N in the soil at harvest. At low N applications (<175 kg ha−1), a positive added nitrogen interaction (ANI) was observed: 40–50% of this was a residual ANI due to the short or long term effect of applying N fertilizer, and the remainder was probably an apparent ANI due to pool substitution in the immobilization process. At large N applications (>175 kg ha−1) a negative ANI was observed: large N applications resulted in a net suppression of soil N uptake due to substitution by fertilizer for a limited plant N demand.

In many nutritional experiments with cut pasture the voluntary intake and digestibility is determined with pen-fed sheep. However, the voluntary intakes of sheep are extremely variable, the between-animal coefficient of variation varying between 13·1% and 10·5% (Blaxter, Wainman & Wilson, 1961; Minson, Harris, Raymond & Milford, 1964). Thus each pasture cut must be fed to large numbers of animals if differences between pasture species and varieties are to be detected with significance. (Heaney, Pritchard & Pigden, 1968.)

Dry-matter intake (D.M.I.) from Panicum maximum(guinea grass) was studied in digestibility trials with Holstein and water buffalo bulls and in a feeding trial with lactating cows.

Differences in voluntary D.M.I. per unit body weight0·73 between the Holsteins and water buffaloes were not significant. Average D.M.I. for all bulls in all main trials was 2·16 kg per 100 kg B.W. Average D.M.I. by the lactating cows was 2·08 kg per 100 kg B.W., for all practical purposes the same as for the bulls.

D.M.I. was not related to stage of maturity or season of harvest of the guinea grass. Intakes of digestible protein, T.D.N., and digestible energy in different seasons and at different growth stages were related to the percentage of those nutrients in the grass.

Correlation coefficients were 0·68 between D.M.I. and B.W.0·73, 0·59 between D.M.I. and T.D.N. content, and 0·58 between D.M.I. and crude protein content, D.M.I. was not closely related to dry-matter content (r = 0·30) or crude fibre content (r= 0–01) of the guinea grass.

Nitroethane (NE), 2-nitroethanol (NEOH) and 2-nitro-1-propanol (NPOH) were investigated in order to determine their inhibitory effects on in vitro ruminal fermentation and methane (CH4) production of a hay-rich substrate (alfalfa hay: maize meal = 4:1, w/w). The rumen liquor collected from cannulated Holstein dairy cows was incubated at 39 °C for 72 h. The addition of NE, NEOH and NPOH slowed down the fermentation process and notably decreased molar CH4 proportion by 96.8, 96.4 and 35.0%, respectively. The abundance of total methanogen and methanogens from the order Methanobacteriales were all decreased with NE, NEOH and NPOH supplementation. Meanwhile, the nitrocompound addition reduced mcrA gene expression, coenzyme F420 and F430 contents. The correlation analysis showed that CH4 production was correlated positively with the population abundance of total methanogens, Methanobacteriales, mcrA gene expression, coenzyme contents of F420 and F430. The nitrocompound addition decreased acetate concentration and increased propionate and butyrate concentrations in the culture fluid. In summary, both NE and NEOH addition presented nearly the same inhibitory effectiveness on in vitro CH4 production; they were more effective than NPOH. The results of the current study provide evidence that NE, NEOH and NPOH can dramatically decrease methanogen population, mcrA gene expression and the coenzyme content of F420 and F430 in ruminal methanogenesis.

Twenty-six experiments were carried out in England and Wales from 1983 to 1985 to compare urea and ammonium nitrate (AN) as N top-dressing for cereals over the range 100–300 kg/ha N. Most of the experiments were sited on chalky or other soils of pH>7·0 where the greatest differences in effectiveness were expected.

The results showed that while relative N offtake in grain was 2·5% greater from AN, there was no difference in grain yield. Splitting the main N application increased N offtake from urea but not from AN. Overall, urea effectiveness from a single application at GS 31 increased with increasing rainfall on the day of application, but was not increased by subsequent rainfall. On chalk soils, urea effectiveness increased with increasing cumulative rainfall up to the fifth day after application. There was little effect of rainfall on urea effectiveness when the dressing was split. Although grain yield was unaffected by the type of fertilizer N applied, grain N concentration was usually less from urea.

The fertilizer N requirement for optimum yield (Nopt) wassimilar for both fertilizers. Splitting the main N application had no effect on yield or Nopt. We concludethat urea is a satisfactory source of N for cereals.

The effects of irrigation, nitrogen fertilizer, cutting three or six times per year and a combined pesticide treatment that included aldicarb, phorate, benomyl and methiocarb on ryegrass (Lolium perenne) cv. S.23, either alone or in mixtures with white clover (Trifolium repens) cvs S.I00 or Blanca, and on lucerne (Medicago sativa) cv. Vertus grown on a silty clay–loam at Rothamsted and a sandy loam at Woburn were studied in 1977–81.

Benefits from irrigation were greater for six-cut than three-cut swards, with pesticides than without, for ryegrass with clover S. 100 than ryegrass with Blanca and at Woburnthan at Rothamsted. Lucerne did not benefit.

Responses of ryegrass to fertilizer N were best fitted by the model y = a + b/1+cx+dx2; and those of ryegrass–clover by the model y = a+bx (where y = yield, x = amount of N; a, b, c and d are constants). Without N, yields of ryegrass–Blanca clover mixtures considerably exceeded those of ryegrass–S.100. The former gave yields equivalent to those of ryegrass given 270 kg N/ha at Rothamsted and 330 kg N/ha at Woburn.

Lucerne without irrigation, N or pesticides gave yields in excess of all other unirrigated crops, even when these received pesticides and maximum N. Yields from three cuts of ryegrass greatly exceeded those from six cuts but yields of ryegrass–Blanca were greater from the six-cut regime.

Pesticides substantially improved the yields of ryegrass and clover, whether grown separately or mixed, but not those of lucerne. Pesticides not only controlled pests and diseases but also increased the incidence of vesicular–arbuscular mycorrhizas. The relative magnitude of yields of the different swards at the two sites differed, depending on treatment with irrigation, N fertilizer and pesticides. Differences between sites were removed or reversed by appropriate combinations of treatments.

Ryegrass–Blanca given no N fertilizer and cut six times removed 300 kg N/ha, an amount that was increased by irrigation and decreased by less frequent cutting; ryegrass–S.100 clover contained less N. Removals of P and K. often exceeded 35 and 300 kg/ha, respectively, each year. Herbage containing Blanca clover had much more Ca than that containing S.100 but at comparable yields all swards contained similar amounts of Mg.

Correlations between various characteristics at each weight indicate that (i) a good percentage of lean is associated with increased bone, a larger eyemuscle area and, in particular, less backfat; (ii) the carcass conformation score for 260 lb. hogs has a high negative association with average backfat and this may be because the extreme amounts of fat on some these hogs adversely affected the balance of the carcass.

Visual scores or assessments made on the shoulder, ham, streak and on the carcass conformation bear no relationship to the proportionate weights or to the leanness of the respective parts of the carcass. They reflect only the requirements of the trade which are based on shape and are not substantiated by dissection. In nearly all cases, gilts achieve better scores than hogs. The back rasher score assessed on a good fat to lean ratio and a good eye muscle is much higher for gilts than for hogs and decreases as the slaughter weight increases. There is a positive association between back rasher score and the leanness of the back.

1. The relationship existing between the gross digestible energy content and the chemical composition of twenty-four silages has been studied with nine Cheviot wether lambs over a period of 8 months.

2. Silages were made from grassland herbage and varied widely in the chemical composition of the ingoing material.

3. Each silage was fed to a group of three lambs for a 10-day preliminary- and a 9-day collectionperiod. Faeces and urine were collected in metabolism crates.

4. The silages were analysed for volatile acids and bases, for proximate nutrients and for some of the more precise chemical constituents as suggested in the scheme of analysis of Ferguson (1948).

5. A close relationship existed between the gross digestible energy contents of the silages and the lignin (Ellis) content.

6. The most accurate prediction of gross digestible energy was obtained by taking into account the content of lignin (Ellis), cellulose (Crampton & Maynard) and crude protein, in the silage.

7. In the case of hays (Walker & Hepburn, 1955) no increase in the accuracy of predicting gross digestible energy was obtained by estimating the lignin and cellulose content, rather than crude fibre alone. However, with silages the results give support to the opinion of Mitchell (1942) and Schneider et al. (1951) that analysis for more precise chemical constituents will increase the accuracy of predicting digestibility.

8. Crude fibre and cellulose were not related in any fixed way with the digestibility of energy. Crude fibre itself was digested to some 80% compared with 62% in hays.

9. Metabolizable energy was closely related to digestible energy.

10. The starch equivalents of the silages were calculated by conventional methods and also from the content of gross digestible energy.

1. Herbage from pastures managed under the Intensive System of Grassland Management, and representing three to five weeks’ growth, from three centres in three seasons, was closely comparable with that obtained by other workers from “pasture cuts” at one- to three-weekly intervals from unmanured pastures, in respect of the chemical composition of its dry matter, which is, in fact, a concentrated feeding stuff of narrow nutritive ratio and low in fibre content.

2. The nutritive ratio is somewhat wider in a dry than in a wet season, but the average fibre content is not markedly different.

3. During the grazing season, drought or the early summer flush period produce some reduction in protein content and an increase in fibre content, with a recovery following the cessation of the drought or after the flush period respectively.

(1) A gasometric method for the determination of organic carbon in soils by the use of sulphuric-chromic acid mixtures at 100° C., as suggested by Watts in 1902, is described, and recommended for use in routine soil analysis.

(2) The method is compared with the Kjeldahl procedure recently introduced by Robinson, McLean and Williams, and is found to give results which are generally similar, though numerically slightly lower.

(3) The wet combustion method is somewhat simpler than the Kjeldahl method, but it has the disadvantage that nitrogen determinations cannot be made simultaneously, so that its usefulness in studies on soil organic matter is decidedly less.

The increase in dry weight of field lettuce from sowings made between March and August in 1973 and 1974 started exponentially but this did not persist throughout growth. Departures from exponential growth were most marked in the 10 days of growth prior to maturity and a logistic rather than an exponential curve gave a better overall fit to the data. The rates of increase in plant dry weight were similar from all sowings made between mid-May and early to mid-July, when air temperatures and total radiation during the growth period of these crops exceeded 11–12 °C and 250 mWh/cm2, respectively. Sowings made earlier than mid-May took longer to mature and in 1973 gave crops with lighter heads. Quadratic regressions of harvest date on sowing date gave good fits to data obtained in different years at different sites but separate equations were required for each site.

In two trials the effect on D.M. intake of applying flavouring agents to grass silage at feeding time was examined using a total of 89 British Friesian cows in mid to late lactation. The flavouring agent used in Expt 1 was Simax 100 (5 ml/cow per day), while in Expt 2 Palatol (20 ml/cow per day), molasses (0·7 kg D.M./cow per day) and molasses + Talin (0·7 kg D.M./cow per day) were added to both lowand high-quality grass silage.

Both Simax (significantly) and Palatol increased silage D.M. intake by an average 0·67 kg/day. The total D.M. intake of the cows fed the molasses and molasses + Talin was similar to that obtained by those receiving the silage treated with Simax and Palatol. However, in the case of the cows receiving the molasses and molasses + Talin, the increased D.M. intake was obtained mainly from the additional molasses and not by an increased silage intake. This result indicates a very low substitution rate for molasses.

Although D.M. intake was increased by the addition of flavouring agents, milk production remained unaltered because of the relatively late stage of lactation of the cows in both trials.