Thirty-two weaned Kenana bull calves were adequately fed to maximize growth and serially slaughtered at predetermined live weights of approximately 100, 200, 300 and 400 kg. Eight animals were slaughtered at each slaughter point and slaughter data collected. Dressing-out percentage increased with the increase in slaughter weight but the increase was more marked between the first and the second slaughter points than between subsequent slaughter points. Kenana cattle compare favourably with Hereford, Hereford × Friesian, Friesian and Shorthorn × Ayrshire steers in dressing-out percentage; and are, apparently, superior to Jersey steers in that trait.

The model, y = axb, in the logarithmic form, was used to describe patterns of proportional weight increase of body components throughout the experimental period and in three arbitrary phases. The patterns of development which were demonstrated by some body components throughout the test period were not necessarily re-exhibited, in all stages, when development was considered in phases. These body components changed their patterns of proportional increase in weight as development proceeded.

Thirty-two weaned Kenana bull calves were adequately fed to maximize growth and serially slaughtered at predetermined live weights of 100, 200, 300 and 400 kg. Eight animals were slaughtered at each slaughter point and the left side of each carcass dissected into individual muscles, bone, fat, tendons and fascia. Individual muscles were grouped into nine muscle groups and the distribution of intermuscular fat was studied in four anatomical regions. Huxley's (1932) allometric equation was used to describe the development of carcass tissues.

Relative to overall carcass side growth, fat was the fastest developing tissue, followed by muscle and bone tissues in descending order. The muscles of neck + thorax and abdominal muscles exhibited the fastest rate of growth relative to overall total side muscle growth, and the distal muscles of both limbs exhibited the slowest rate of relative growth. Relative to the rate of side fat deposition throughout the experiment, subcutaneous fat was deposited at a faster rate than intermuscular or kidney + channel fat. Intermuscular fat was deposited at different rates in the anatomical regions of the carcass.

The development of muscle groups was further examined in three arbitrary phases of the test period and revealed significant differences between phases in the rate at which each muscle group developed. Similar changes in the intensity of the rate at which fat was deposited in the subcutaneous region and between the muscles of the carcass or sites were evident.

Kenana cattle compare favourably with foreign dairy and beef breeds of cattle in muscle:bone ratio. Further studies are needed to evaluate the efficiency of meat production from Kenana cattle under different systems of management.

As reported in Part 1 (Gaili & Nour, 1980) a study was conducted to investigate the development of body components in Kenana cattle and to evaluate the potential of the breed for meat production. This paper is an account of the data which were obtained on the development of carcass tissues.

The effect of different amounts of NaOH sprayed on whole grain on their digestibility by cattle was examined for barley, oats, maize and wheat. For all cereals the digestibility of fibre, dry matter and organic matter (OM) increased with increasing application of NaOH solution but responses were small at the highest levels used. The digestibility of OM was increased from 61 to 83% for barley, from 61 to 76% for oats, from 83 to 89% for maize and from 79 to 92% for wheat. The optimum amount of NaOH required differed between cereals, being about 3·0–3·5% for barley, 4·5–5·0% for oats, and 2·5–3·0% for maize and wheats. With oats, wheat and maize the digestibility was apparently increased more with NaOH treatment than by physical processing.

Three grasses and two legumes, each at two stages of maturity, were fed to three fistulated sheep and samples of the feed, and faeces and contents of the reticulo-rumen, abomasum and ileum were collected for the determination of particle size by wet sieving. Modulus of fineness (MF) was calculated for all particulate matter that failed to pass a 0·15 mm screen. Resistance to flow from the rumen of feed particles of different sizes was also calculated.

The mean MF of the reticulo-rumen contents was 2·56 compared with 5·72 for the feed. Material leaving the rumen and found in the abomasum had a MF of 1·67 and subsequent changes were small and not significant; ileum 1·63, faeces 1·80. Particles greater than 1·18 mm passed out of the reticulo-rumen although the quantity was small (1–3%). The resistance to flow of particles of different sizes from the reticulo-rumen was closely related to particle size with no difference between grasses and legumes or between young and mature forages.

It was concluded that in modelling the flow of particles from the reticulo-rumen a non-compartmentalized approach should be adopted, but if a simple two-compartment model is required then a critical sieve size of about 1·18 mm may be useful, since less than 5% of the particulate material is retained on this sieve size.

Analysis of seasonal growth and fruit production of American Upland Cotton (Gossypium hirsutum L.) with different combinations of leaf shapes and colours was made in 1970. Plants with the ‘okra’ leaf shape (LOLO) had a higher photosynthetic rate, number of green bolls, number of ‘squares’ (flowering buds) and flowers, dry weight of fruiting parts, fruiting index, harvest index (ratio of seed cotton to total biological yield), yield and lint percentage than plants with normal leaves.

There were no significant differences in specific leaf weight (SLW) due to leaf shape. There was no significant correlation between SLW and photosynthetic rates among biotypes. There were no significant differences in different characteristics measured regarding leaf colours.

Fresh and wilted silages (dry matter 169 and 359 g/kg; pH 4·00 and 5·09; lactic acid 165 and 34 g/kg D.M., respectively) were made from ryegrass and used in intake and metabolism experiments with cattle and sheep. Complete ruminant diet (CRD) was used as a control.

Voluntary dry-matter intake of the silages by wether sheep was not significantly different (70·7 and 69·1 g/kg W0·75 for fresh and wilted material, respectively) but was significantly higher (P < 0·001) for CRD (97·9 g/kg W0·76). With rumen-fistulated steers the voluntary intakes of dry matter for the fresh and wilted silages and CRD were 117·1, 105·7 and 130·4 g/kg W0·76, respectively, and were not significantly different. The digestibility of dry matter was significantly higher (P < 0·01) for the fresh and wilted silages (0·751 and 0·698, respectively) than for the CRD (0·608). When incubated in nylon bags in the rumen the silages rapidly lost nitrogen and only 0·2 and 0·3 of nitrogen of the fresh and wilted materials, respectively, remained after 1 h. Between 0·4 and 0·5 of the residual nitrogen in the silages was subsequently lost over a period of 24 h. The loss of the nitrogen of the CRD was much slower and 0·3 of the nitrogen remained after 24 h. The rate of loss of digestible cell wall constituents was similar for the fresh and wilted silages but was slower for the CRD. The silages gave similar rumen fermentation patterns (pH, total volatile fatty acids, acetic, propionic, butyric, valeric and hexanoic acids and ammonia concentrations) during the period following their consumption.

The palatability of the fresh and wilted silages, measured with rumen-fistulated sheep, was less than that of the CRD and a ruminal effect on intake was observed in the case of the silages.

The high intake of the fresh silage is noteworthy, as it casts grave doubt on the widely held view that fermentation acids, particularly lactate, are pre-eminent in governing the voluntary intakes of silages.

From the rapid loss of nitrogen from the silages in nylon bags in the rumen it is concluded that, to increase the utilization of nitrogen, it would be advantageous to reduce protein breakdown in the silo and to supplement silage with a readily available energy source.

The deposition of S in rainwater was measured at ten locations in central Kenya, monthly for 1 year (1977–8). Amounts deposited ranged from 1·58 to 3·81 (mean 2·47) kg S/ha. Concentrations ranged from 0·10 to 0·17 (mean 0·12) mg S/l rainwater. The washout factor (w) was 200 and the vertical deposition velocity (Vg) for dry deposition was 0·31 cm/sec. Two locations were affected by local anthropogenic emissions. The agricultural significance of these results is briefly discussed.

Lesion development and growth of Xanthomonas malvacearum (E. F. Smith) Dowson were followed in seedlings of different cultivars of cotton (Gossypium hirsutum L.) after inoculation of hypocotyls. There was a close relationship between numbers of the parasite and length of hypocotyl lesion. Disease development could be accurately determined by measurement of lesion length from 2 to 3 days after inoculation until growth of the parasite ceased. Growth patterns of the parasite in vivo took the form of a distinct period of exponential (phase 1) growth followed by relatively little, if any, further increase in numbers (phase 2 growth). The duration of phase 1 growth was related to host resistance and environmental factors.

Two methods for calculating the flow of digesta and its constituents from the concentrations of two markers, 51Cr-labelled chromium EDTA (51Cr-EDTA) and 103Ru-labelled ruthenium phenanthroline (103Ru-P), and digesta composition were compared in fistulated sheep fed once daily and in other fistulated sheep fed continuously. One method uses the marker concentrations to calculate the flow of whole digesta directly (double-marker) whereas the other uses the markers to calculate separately the flow of fluid and non-filtrable particles, the sum of which is digesta flow (two-marker).

When feed was given continuously, flow values calculated using the double-marker method and the two-marker method, which requires a correction to be made for nonideal behaviour of 51Cr-EDTA, did not differ. When feed was given once daily, the double-marker method consistently overestimated flow relative to the corrected twomarker method but the differences were extremely small (less than 0-8% for digesta flow and 0-5% for nitrogen flow). 51Cr-EDTA as a single marker slightly overestimated digesta flow (up to 2·3%) but grossly overestimated nitrogen flow (up to 22·5%); 103Ru-P as a single marker grossly underestimated both digesta flow (up to 30·5 %) and nitrogen flow (up to 23·1%).

It was concluded that the double-marker method is to be preferred when the diet is given continuously or frequently at fixed intervals. When the diet is given once daily, the two- and double-marker methods can be expected to give similar values. Single markers should not be used for estimating the flow of digesta and its constituents when samples are taken from a simple cannula.

Seven high-oil sunflower eultivars were grown in 1976 and 1977 at selected locations in Ghana, to evaluate the potential of sunflowers as an oil-seed crop for the lowland tropics. All eultivars flowered and matured earlier than observed under temperate conditions. Yields were between 75 and 1600 kg/ha at 9% moisture content. Oil contents ranged from 41 to 47% with a higher proportion of oleic acid (about 54%) than linoleic (about 38%). It is concluded that sunflower production is feasible and could become as important as that of existing annual oil seeds.

Progressive colonization of adventitious, seminal and lateral roots of wheat by Gaeumannomyces graminis var. triticiwas monitored for 18 days after direct inoculation of roots. Adventitious roots supported greater colonization by superficial runner hyphae above and below inoculation sites than did seminal roots due to more rapid establishment of colonization. Subsequent rates of superficial runner hyphal growth along the two types of root were not significantly different. In contrast with seminal and lateral roots, adventitious roots did not show any dark stelar discoloration during the period of observation. Both the rate of growth of superficial runner hyphae and of advance of dark stelar discoloration were substantially slower on lateral roots than on seminal roots. After an initial period of equal growth above and below inoculation sites, superficial runner hyphae grew more slowly below than above these sites on all three types of root.

Estimates of the energy contents of the foetuses, placentae, foetal fluids, empty uteri and maternal empty bodies at 88 and at 144 days of pregnancy were obtained from a comparative slaughter experiment on Finnish Landrace × Dorset Horn ewes. Over this period the mean daily intakes of metabolizable energy (ME) for ewes with twin, triplet or quadruplet foetuses were 11·2, 12·0 and 12·2 MJ respectively (low plane of feeding) or 14·4, 15·2 and 15·3 MJ (high plane of feeding), total numbers of ewes being 15, 23 and 7 respectively. The diet contained 8·2 MJ of ME and 153 g crude protein per kg dry matter. All six categories of ewe lost energy from maternal empty-body tissues between 88 and 144 days at mean daily rates of 2·7, 4·1 and 4·9 MJ (low plane) and 1·4, 2·7 and 3·6 MJ (high plane), according to litter size. Rates of energy deposition in the gravid uterus were 0·72, 0·93 and 1·07 MJ/day respectively, and were not affected by plane of nutrition. Estimates of heat production from these balance data were confirmed by direct measurements made on about half of the ewes.

Estimates of the gross efficiency of utilization for foetal growth of the combined energy from maternal tissue and from ME intake, after allowing for maternal main–tenance, were similar for each litter size but were 0·14 and 0·11 on the low and high planes of feeding respectively. Consideration of these together with other published observations suggested that efficiency of utilization of ME in pregnancy increases linearly with the ME concentration of the diet and at concentrations below 10 MJ/kg dry matter is less than the efficiency of utilization of energy derived from maternal tissue loss.

The average of 160 intercalving periods of 47 imported and 33 home–reared purebred Holsteins in western Nigeria during 1967–75 was 628( ± 45) days. The probable effects of seven variables including origin of cow, sex of calf, season of calving, age of cow at calving, parity, year of calving and calf birth weight were investigated through an intra-class linear regression model in which the first three factors were treated as qualitative and the last four as quantitative factors. Origin of cow, sex of calf and season of calving did not significantly affect calving interval. Effects of age at calving, parity, year of calving and calf birth weight were highly significant (P < 0·01) but individual effects adjusted for others were not quite significant. These four quantitative factors were, however, highly interrelated; simple correlations which varied between 0·33 and 0·86 were highly significant. Interactions between the two sets of factors were negligible.

The effects of direct drilling, shallow cultivation and ploughing on the growth of winter cereals (wheat and oats) are reported for the first 4 years of long-term experiments on two non-calcareous clay soils (stagnogleys), representative of soils occupying a large proportion of the cereal growing area of the U.K. These 4 years have been characterized by extreme contrasts in rainfall and wetness of the soil.

On a Lawford series soil, with 35% clay, although the treatments affected average grain yields none of the differences was large. With additional nitrogen fertilizer, the yield after direct drilling was significantly heavier by 6% than after ploughing. On the Denchworth series, with 50% clay, 4 year average yields were also similar after direct drilling and ploughing, but in individual years the treatments had large effects. In two wet years grain yields after direct drilling were 89 and 82% of those after ploughing, but in another year they exceeded by 16% those after ploughing, where lodging had restricted grain filling. In the unusually dry season of 1975–6 yields of winter wheat after direct drilling exceeded those after ploughing (by 14 and 6% on the Lawford and Denchworth soils respectively) and this was attributed to greater availability of water and deeper rooting in the spring. In a year of heavy wheat yields (1977–8) about 10t/ha was achieved on both soils irrespective of the method of cultivation. In this year, after prolonged wet soil conditions in winter, the response to additional nitrogen fertilizer was greater after direct drilling and shallow cultivation than after ploughing.

The concentration of nitrogen in the crops tended to be smaller throughout the growing season after direct drilling than after ploughing, especially on the Denchworth soil in the wettest season. The method of cultivation had no effect on the uptake of either phosphorus or potassium except on the heavier soil in the wettest year, when potassium uptake was restricted after direct drilling.

The results are discussed in relation to information on soil conditions and root growth also being obtained in these experiments.

Two poorly digested materials, barley straw and grass cell wall residues recovered from sheep faeces, were treated with sodium ethoxide, methoxide or hydroxide under various conditions and the effects on their digestibilities studied by the nylon bag technique in the sheep rumen.

Acetyl groups were removed during these treatments and the degree of deacetylation could be controlled by adjusting the amounts of reagents used, about 25 m-mole of base/g being required to produce the maximum effect. Sodium ethoxide in ethanol was the least effective of the reagents used: it did not remove acetyl groups from barley straw and left a larger proportion untouched in faeces cell walls than did sodium methoxide in methanol.

Irrespective of the reagent employed digestibility increased with the progress of deacetylation and the two processes reached a maximum together, but there was not a linear relation between acetyl content and digestibility. In the case of straw treated with sodium hydroxide there appeared to be a linear relationship between digestibility and the amount of reagent applied, up to 20 m-moles/g straw.

Phenolic ester groups were less susceptible to the reagents tested than acetyl groups. It is concluded that the action of the basic reagents is probably upon polysaccharides other than cellulose, that access to some regions of the cell walls may be limited by the solvent present, and that the linkages that restrict digestibility have a sensitivity to basic reagents similar to that of the acetyl ester groups present.

One hundred and seventy-seven female Ayrshire cattle from approximately 6 months to 6 years of age were sampled on one occasion to determine the concentrations in plasma of Cu, P, Ca, Mg, Na, K and glucose. Eighty-nine adults, either lactating or dry, were re-sampled 2 months later to estimate concentrations of ketone bodies and free fatty acids. The data were analysed to estimate the contributions of various factors to variation in the concentrations.

The combination of age and stage of pregnancy or lactation significantly affected variation in all the constituents although some of this variation was accounted for by milk yield. The concentrations of Cu, Mg, glucose and ketones were significantly affected by milk yield. The presence of ketone bodies in milk (recorded in relation to the first occasion of bleeding only) was associated with a significant increase in the plasma concentrations of Na and Mg and a significant decrease of K and Ca.

The herd comprised pairs of genetically related animals. However, the estimates of heritability had large standard errors and only those for P and Ca were significantly positive.

A tetraploid wheat breeding programme was initiated at the Plant Breeding Institute in 1970. Hexaploid × tetraploid wheat crosses were expected to contribute to the improvement of the tetraploid wheats but severe hybrid necrosis caused the death of the pentaploid Fxhybrid plants in most crosses. The genotypes of tetraploid wheat selections derived from crosses involving Rampton Rivet, a non-carrier of Neu were determined by test crossing to hexaploid wheat varieties which were known to carry the Neim allele. Similarly, hexaploid wheat selections which did not carry Ne2 were identified from crosses involving Maris Ranger by test crossing to durum selections which carried the Nef allele. By the careful choice of one parent, hexaploid x tetraploid wheat crosses were then made which avoided the hybrid necrosis problem. Segregation of the Ne% gene was as expected but selection for agronomic characters appeared to favour the retention of the dominant allele of the Ne1gene. Nevertheless, test crossing on a relatively small scale still identified many non-carriers.

Two genetic strains of white turkeys were reared together in a large flock under conditions allowing optimal growth from hatching to 20 weeks. Birds of both strains followed similar growth curves with males of both strains growing heavier than females. In one strain, however, the yield of breast meat as a proportion of live weight was greater in both males (287 v. 225 g/kg) and females (276 v. 201 g/kg). When expressed in ratio to breast width, maximum meat depth was greater in the strain which yielded the higher proportion of breast meat. However, with this index of breast plumpness, females scored higher than males in both strains (high yield, 0·45:1·00 v. 0·37:1·00; low yield, 0·33:1·00 v. 0·31:1·00). In the superficial anterior region of the pectoralis muscle in both strains and sexes, there were strong adenosine triphosphatase and weak succinate dehydrogenase reactions in nearly all muscle fibres. Differences in the radial growth of muscle fibres were found between the two strains and, by 20 weeks, birds of the lower yield strain had reached only 0·85 (males) or 0·82 (females) of the mean diameters attained in birds of the higher yielding strain.

In experiments on winter barley in 1975–6 and 1977–8 early or late sowing, full or half seed rate, nitrogen applied in March or April and tridemorph spray applied in autumn, early spring and late spring were assessed factorially in all combinations for their effects on mildew development, crop growth and grain yield.

Date of sowing had the biggest effect on yield. Early-sown crops (24 September 1975, 6 October 1977) greatly out-yielded the late-sown; by 79·8% in the first year and 53·9% in the second. Late sowing (6 November 1975, 2 November 1977) approximately halved plant emergence. Although late-sown plants developed more tillers, more grains per ear and larger grain this failed to compensate for the thinner stand.

Sowing at half seed rate did not decrease yield when compared with the crop sown at the full seed rate on the same date. In contemporaneous crops extra tillering and larger ears generally compensated for fewer plants.

The effect of date of applying N was variable. April N gave the best yield in the early· and late-sown crops in 1975–6 and in the late-sown crop in 1977–8. However, in the early-sown crop in the second year March N was best. Number of ears was increased in early-sown crops by March N but date of N application had no influence on number of ears in late-sown crops or on the number of grains per ear in any crop.

The winter of 1975–6 was mild and mildew developed on both early· and late-sown crops throughout their growth.

Single tridemorph sprays applied in autumn (14 November) to the early-sown crop or winter (25 February) to the late-sown crop or early spring (9 April) to both crops gave significant yield increases of 6·3–7·6%. Applying two sprays, one in autumn or winter plus one in early spring gave an increase equal to the sum of each applied separately. A late spring spray (14 May) had no significant effect on yield. The 1977–8 winter was colder and although mildew was moderate on the early-sown crop in autumn it was almost absent from this experiment after winter. Spraying failed to increase yield significantly.

Circadian variation in the apparent digestibility of diets having different physical characteristics was measured in samples taken from the terminal ileum using simple cannulae and marker ratios. Six pigs were used in three latin squares involving three iso-nitrogenous diets (30 g N/kg D.M.). Diet A was based on barley, weatings, soyabean meal and fish meal, diet B included barley, weatings and oats and diet C was purified. The allocation of diet provided 100 g D.M./kg Weg0·75/24 h and in each latin square a different pattern of feed intake was used; diets were given at intervals of either 1 or 12 h, or ad libitum.

Differences in the digestibility of the diets were consistently distinguished by the technique. The circadian variation in digestibility was related to the type of diet and could be modified by changing the number and distribution of feeds per day. The results show that an understanding of the variation associated with different diets and feeding methods is necessary for optimizing the strategy for sampling from the terminal ileum.