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.

Root interactions between populations of Lolium perenne, Dactylis glomerata, Holcus lanatus and Anthoxanthum odoratum collected from fertilized and unfertilized plots of the Park Grass Experiment were investigated at two levels of NPK over a period of 3 years.

The root competitive abilities of species were dependent on fertilizer applications and changed with time. For example, L. perenne was more competitive at high nutrient application and during the early stages of the experiment. On the other hand, the root competitive ability of H. lanatus was greatest on unfertilized soil and increased with time. The large effect of root interaction on plant yield and the effects of fertilizer application on this, may be regarded as evidence of competition for one or more of the elements, N, P and K. H. lanatus, the most aggressive species, was more competitive on the unfertilized soil (NIL) than on the fertilized soil (NPK). However, this could not be confirmed by chemical analysis of plant material; there was no conclusive evidence that aggressive species contained higher concentrations of these nutrients when grown in mixtures with less aggressive species. The possibility of allelopathy, the production of toxins by one plant which inhibit the growth of another, cannot be precluded.

The root competitive ability of species and populations was not positively correlated with the yield of species and populations in pure stand. Indeed, negative correlation was found especially on unfertilized soil. In this case varieties or species with a low yield in pure stand were highly successful root competitors in mixtures, while those with high yield in pure culture were poor root competitors.

The present study deals with the reproductive performance of an imported Suffolk flock and the cross-bred ewes resulting from upgrading the local Ossimi sheep with the Suffolk. A total of 1738 ewe records were available for the study.

No significant difference was found between Suffolk and Ossimi ewes in conception rate or proportion of multiple births. However, the Ossimi ewes (mated to Suffolk rams) weaned 25 more lambs per 100 ewes lambing than the imported ewes. The cross-bred ewes were of better reproductive performance than both pure-breds. The best Suffolk cross-bred ewes were those of 40–49 % Suffolk breeding. They weaned 21 more lambs per 100 ewes run with the rams than the local ewes. Reproductive performance of the cross-bred ewes declined with increasing Suffolk genotype above this proportion.

Under the prevailing sub-tropical conditions, the Suffolk ewes have an anoestrous period of 200 days from late January to late July or August; the local ewes showed oestrous activity throughout the year, but with some irregularity.

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.

Hay was fed to an in vitro continuous culture of the rumen microbial population and to sheep kept in metabolism cages, and the effects of potassium chlorate addition on the rumen fermentation were studied. The compound was given for 8 days in vitro and for either 3 or 8 days in vivo.

Potassium chlorate addition in vitro (13·7 mg/g hay D.M.) depressed the production of CH4 and acetate, had little effect on propionate production and caused a small increase in the production of n-butyrate and n-valerate. The treatment also depressed cellulose digestion and the concentration of DNA in fermentor liquor, but increased the CO2:CH4 ratio in fermentor gas.

When given in vivo for 8 days at 6·7 mg/g hay D.M., potassium chlorate progressively depressed total VFA concentration in rumen fluid, had no effect on VFA molar proportions but caused a small increase in the CO2:CH4 ratio in rumen gas. When administered in vivo for 3 days at 14·4–15·3 mg/g hay D.M. the treatment increased the molar proportions of propionate and depressed those of acetate in rumen fluid without affecting total VFA concentration. There were considerable differences between animals in propionate response, and the maximum responses were generally obtained 2–5 days after dosing had ceased. Potassium chlorate addition also caused a temporary reduction in appetite with some sheep.

It was concluded that potassium chlorate was toxic to the rumen microbial population when given for 8 days, but that large doses given over 3 days could be used to increase the ratio of propionic acid relative to acetic and butyric acids produced from the rumen fermentation.

Lamb and fattening performance and carcass quality of Suffolk x local Ossimi cross-bred lambs are discussed. 1369 cross-bred lamb records over the period from 1957 to 1970 were available for the study. The lambs of 50–59% Suffolk were the best cross-bred group with an advantage of 7–7, 14–2 and 17–1% over the native Ossimi lambs in birth weight, 120-day and yearling body weights, respectively. Generally, lamb performance declined as the Suffolk breeding was increased. However, breed groups variation was not statistically significant, except for birth weight.

Seventy-one weaned male lambs, 4 months of age, from three breed groups: 70–90% Suffolk, 35–45% Suffolk and local Ossimi, were fattened for 16 weeks using two levels of feeding. The two Suffolk cross-bred groups gained slightly more body weight than the local Ossimi. After 8 weeks of fattening, the 35–45% Suffolk lambs gained significantly more weight than the local lambs. However, the local lambs were more efficient in converting food to live-weight gain.

The carcass quality of the Suffolk cross-bred lambs was better than the local lambs, and the advantage was greater for the high Suffolk breeding group.

When cowpea plants were grown in large pots under simulated tropical conditions, and were dependent on either symbiotic fixation or inorganic N for their total nitrogen requirements, short periods of waterlogging had adverse effects on vegetative growth and seed production. The effects of waterlogging were more acute as plants experienced stress at progressively earlier stages of development. In plants depending either on biologically fixed N or inorganic N, waterlogging before flowering reduced vegetative growth by about 50%. Although some compensation in vegetative growth occurred during the reproductive development of nodulated plants, seed yields in both cases were still 48% less than in unstressed plants. Depending on the stage of plant development, treatment effects were mediated largely through changes in branch, peduncle and flower production and/or abortion, which contributed directly to variations in the number of pods retained to maturity. Inorganic nitrogen stimulated vegetative growth but did not significantly improve seed yield compared with effectively nodulated plants.

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.

The effect of herbage allowance on the intake and performance of Scottish Half bred ewes with twin lambs was investigated over the first 16 weeks of lactation. Herbage allowances were defined as g herbage D.M./kg live weight (LW)/day, and were maintained by provision of fresh areas of ungrazed sward each day.

Herbage allowances in the range 25–120 g D.M./kg LW/day were offered on an area of perennial ryegrass (Lolium perenne cv. S. 23). Parturition was synchronized and ewes and lambs were turned out to pasture 1 day after lambing.

Measurements were made of the herbage intake, live-weight change and milk yield of ewes, of lamb growth rates and of the herbage intake of lambs from 10 weeks of age.

Herbage allowance had a significant linear effect on intakes of grass by ewes and lambs. The highest intakes by the ewes were achieved during the second week, and were in the range 23–43 g OM/kg LW/day. Intakes declined, as lactation proceeded, to 19–29 g OM/kg LW/day at week 12. Intakes of lambs were similar in weeks 10 and 12 and were in the range 17–24 g OM/kg LW/day. Allowance had a significant effect on live-weight change of the ewes after the first month and upon final body condition.

There was no effect of allowance on milk yield until week 6. Mean milk yields were 2·3 kg/day at day 14, 1·0–1·5 kg/day at day 42 and 0·7–1·1 kg/day at day 84. There was a positive effect of allowance on growth rates of the lambs after the first month. Mean overall growth rates to 84 days of age were 175–243 g/day.

Four diets were fed to two Friesian bull calves fitted with re-entrant duodenal cannulae. The diets contained no poultry litter (diet 0); 30% poultry litter (diet 30 D); 50% poultry litter (diet 50 D) or 30% poultry litter which had been ensiled at 45% moisture content for 3 weeks (diet 30 W). The total flow of digesta from the abomasum was measured over four 24 h periods for each diet.

The flow of dry matter and organic matter to the duodenum was similar on all four diets but the percentage of apparent digestion occurring in the stomach was higher when the diets containing poultry litter were fed.

Less nitrogen was digested in the hind gut on diet 30 W than the other three diets. Greater amounts of the nitrogen ingested and also of the nitrogen flowing to the duodenum were apparently digested in the hind gut on the diet containing no poultry litter. Microbial protein synthesized/100 g organic matter apparently digested in the stomachs was lowest when the calves were fed the 30 W diet.

The results obtained in these experiments were then used to evaluate the results of growth trials previously reported.

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.

In order to investigate the characteristics of inverted cassava plantings, seven-node cuttings were planted upright or inverted, and such that four nodes of each cutting were within the soil in a glasshouse. They were observed for 7 weeks. The inverted cuttings sprouted less rapidly, but the percentage of the cuttings which eventually sprouted was not decreased. The inverted cuttings produced more sprouts than the upright ones, and a greater percentage of their sprouts were produced below ground than for the upright cuttings. At 5 and 7 weeks, the total leaf area per cutting was less for the inverted cuttings. The number of leaves per cutting did not differ between the treatments.

In a field experiment comparing upright and inverted stem pieces, field emergence and tubering were slower in the inverted cuttings. Yield per plant and per unit area was significantly lower for the inverted cuttings. In the upright planting, most of the tubers originated at the lowest extremity of the cutting and formed a compact bunch there. For the inverted planting, most of the tubers arose from the shallower-lying submerged nodes, but the tubers did not form a compact bunch. The inverted planting had a lower percentage of its tubers lying along the ridge. In a few of the inverted plantings, but not in the upright, the bases of some stems became tuberous. The treatments did not differ with respect to mean tuber length, radius of spread of the tuber tip, and the number of major stems per plant.

Two sheep, with and without ciliate protozoa, were fed on a wood-pulp cellulose, corn starch, soya-bean protein diet and the microbiological and chemical characteristics of the rumen ingesta of both sheep were studied. The purified diet led to a simplified rumen flora enabling some deductions to be made about the interactions of the principal bacterial species and their interactions with the protozoa in relationship to the biochemical analysis of the rumen. Ammonia concentrations were similarly low in each animal. Total volatile fatty acid concentrations were higher in the faunated sheep though the proportion of propionic acid was highest in the unfaunated sheep. Cellulose digestion in the faunated rumen was about twice that in the unfaunated one. Total bacterial concentrations in the unfaunated rumen were over twice those in the faunated rumen, but the numbers of cellulolytic bacteria were higher in the latter while the numbers of amylolytic bacteria were higher in the unfaunated rumen. The principal species of bacteria differed in the two rumens.

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.

Long-term undernutritional stress is often a feature of sheep and beef cattle production, but has only become a major feature of dairy cattle husbandry in the United Kingdom in recent winters when food was short and expensive. An experiment was carried out to study the effects of long-term underfeeding during pregnancy and early lactation on some blood constituents, milk yield and composition and body weight of dairy cattle. Two groups of cattle were fed at 60 and 40% of the estimated requirements for maintenance and pregnancy or lactation for 13 weeks before and 13 weeks after calving, and one group was fed at the maintenance level only for the same period. A control group was fed at 100% of estimated requirements for this period. All groups were subsequently fed at the control level for a further 24 weeks.

The experiment showed that cows undergoing long-term nutritional deprivation were able to maintain concentrations of blood constituents within narrow limits; the concentrations of such constituents as glucose or non-esterifled fatty acid did not reflect energy deficit or surplus. The animals remained clinically healthy during the underfeeding and recovery periods. The results suggest that debility occurring under field conditions in association with reduced food supply may be due to a multiplicity of factors or to severe imbalance of specific nutrients, rather than to energy or protein deficit alone.

There was a difference in efficiency of utilization of energy of 19% between cows in the most severely underfed groups which maintained lactation and those which were not able to maintain lactation. There was evidence that this difference in efficiency was detectable within a few weeks of the start of the period of reduced nutrition. Animals which were less affected in the early stages of food deprivation were also those which maintained the advantage through the deprivation and recovery periods.

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.

The use of non-radioactive ruthenium phenanthroline (Ru-P) and chromium EDTA (Cr-EDTA) as dual phase markers of digesta flow was examined and compared with chromium sesquioxide (Cr2O3) in conjunction with spot samples of digesta collected from T-shaped cannulae situated in the proximal duodenum of weaned calves.

In vitro estimates of organic matter digestibility indicated that on a cubed barley diet, Ru-P exhibited toxic effects at concentrations on 2·2 × 10–5 M and above. No such effects were noted with Cr-EDTA. Subsequently satisfactory infusion rates of 12 mg Ru and 280 mg Cr/kg dry-matter intake were established.

Daily flows of organic matter, starch, nitrogen, fibre, sodium and potassium at the proximal duodenum were calculated by the dual phase marker system and by Cr2O3, and regression equations relating these two for each dietary component were calculated. Examination of the intercepts revealed that they all differed significantly from zero (P < 0·05) whilst all the regression coefficients were significantly different from unity (P < 0·05), thus indicating that Cr2O3 underestimated nutrient flows at low flow rates and overestimated them at high flow rates relative to the corresponding estimates based on Ru-P plus Cr-EDTA.

The efficiency of utilization of the energy of the food by growing pigs of the Large White breed was measured. Ten diets had a digestible energy varying from 75·3 ± 0·91 to 85·7 + 0·81% and a metabolizable energy from 72·3± ·92 to 83·4±0·64% of the gross energy. Net energy was 85·2±3·20% of the metabolizable energy (ME).

Regression calculations resulted in the following estimates: a maintenance requirement of 151 kcal ME for growing pigs weighing 9–58 kg and efficiencies of 66·7 and 100% for the utilization of ME for protein and fat accretion, respectively.

Feeding regime (ad libitum or restricted at about 80% ad libitum) did not influence food utilization.

In this paper we present a series of resolvable incomplete block designs suitable for variety trials with any number of varieties v in the range 20 ≤v ≤ 100. These designs usefully supplement existing square and rectangular lattices. They are not necessarily optimal in the sense of having smallest possible variances but their efficiencies are known to be high.

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).