Blood samples were taken from 428 Friesian (Holstein) bulls on three occasions, on average at approximately 3-monthly intervals, between 3 and 15 months of age, and also from 214 of them on three occasions at 6-monthly intervals when they were between 2 and 6 years of age.The average concentrations of blood glucose and haemoglobin and of serum cholesterol, urea, albumin, globulin, inorganic phosphate, Ca, Mg, Na, K and Cu were calculated for each of these periods and correlated with improved contemporary comparisons of milk yield and quality.

Repeatability estimates were similar within each of the two periods but were lower when mean concentrations calculated between 3 and 15 months of age were compared with those between 2 and 6 years. The main exceptions were cholesterol (0·52) and Cu (0·54) for which repeatability estimates were similar to those derived within the above two periods. The constituents with the next highest levels of repeatability were magnesium (0·44), globulin (0·43) and inorganic phosphate (0·39), which were approximately 30% lower than those obtained within the two periods.

Correlations between blood concentrations and improved contemporary comparisons were negligible, indicating that it is not possible to use these blood constituents to predict the milk production potential of a bull's daughters.

Twenty-seven British Friesian heifer calves were housed as a group but fed individually barley-lucerne pellets according to a scale related to body weight. At 16 weeks and again at 31 weeks of age nine calves were implanted subcutaneously at the base of the ear with 300 mg trenbolone acetate (group T), nine calves were similarly implanted with 140 mg trenbolone acetate and 20 mg oestradiol-17/? (group TE) and the remaining nine calves were sham implanted (group C).

As a result of increased feed conversion ratios, body-weight gains were significantly greater in group T (0–80 kg/day) and group TE (0–87 kg/day) than in group C (0–72 kg/ day) during the 15 weeks following the second implant, but there was no significant difference between groups following the first implant.

Following both implants in groups T and TE the mean concentrations of urea and albumin in serum decreased, and that of globulin increased. The mean urea: creatinine ratio in the urine of animals in groups T and TE relative to that in group C also decreased.

The heifers were served by an Aberdeen Angus bull at the first and, when they occurred, subsequent oestruses. Following calving the mean milk yields in the first lactation in group T (641 kg in 96 days) and group TE (1993 in 212 days) was considerably lower than in group C (3636 kg in 293 days). The udder size in both groups of animals treated with the anabolic steroids was markedly reduced. It is concluded that despite an improvement in feed conversion ratios and body-weight gains, trenbolone acetate should not be administered to prepuberal heifers which will be retained for breeding and milk production.

Two field experiments with cotton were conducted over two growing seasons on calcareous, heavy to medium textured, alluvial soils, to study the influence of N and P fertilizer rates, the method of fertilizer placement and the time of N fertilizer application on cotton yield, product quality and fertilizer utilization.

Nitrogen application up to 50 kg/ha in the first experiment and up to 120 kg/ha in the second experiment increased seed cotton yield; higher nitrogen rates in the first experiment had an adverse effect on seed production due to abnormal rainfall which caused an intense vegetative growth and delayed the time of maturity.

Split application of N at sowing and at early flowering was slightly superior to a single application at sowing or to split applications at sowing, early flowering and initiation of fruiting. Addition of nitrogen during the flowering stage failed to influence cotton production significantly.

Banding P and N fertilizers increased plant height significantly, compared with the broadcasting method; placement methods, however, did not significantly affect seed yield.

Increasing amounts of N and P fertilizers had essentially no effect on lint quality.

The phosphate concentrations in the tops derived from fertilizer phosphate, were low ranging from 1–2 to 2–4 % of the P concentration in the tops and it was not affected by the different treatments.

The utilization coefficients of the nitrogen fertilizer sources by cotton were high, nitrate N being utilized much more efficiently than ammonium N.

The dry-matter digestibilities of 13 important herbaceous and browse forages from an arid rangeland in north-western Kenya were evaluated in a comparative in vitro trial using rumen fluid from indigenous sheep, goats, a camel, and Merino sheep kept at an agricultural laboratory. All inoculum donors had varied diets preceding the experiment, but little substantial difference was observed in the ability of each fluid to digest test materials. Tt was concluded that the Merino sheep inoculum provided an adequate substitute for inocula from indigenous animals for studies of the nutritional ecology of free-ranging livestock.

1. Two series of experiments designed to investigate the effects of delaying planting potato seed tubers after drawing ridges in preparation for planting and of consolidation of soil beneath seed tubers on the growth and yield of potatoes are described and the results discussed.

2. Delayed planting reduced the yield of saleable ware-size (> I¾ in.) tubers in one year by as much as 1.7 + 0.59 tons/acre, but had little effect in the other years, and it is argued that the effect was dependent on the tilth obtained in preparation for planting, the soil moisture content at the time the ridges were drawn, the amount of moisture lost during the delay period, and the rainfall after planting.

The relative uptake of phosphate, introduced as radioactive 32P into an Agrostis-Festuca hill land association in mid-Wales, was examined under two contrasting methods of cultivation: (i) complete cultivation, (ii) slot-seeding. Seedling plants of Lolium perenne S. 23 and Trifolium repens S. 184 were grown as pure stands and as binary mixtures with plants either 4 or 6 cm apart.

Relative uptake of phosphate was higher under complete cultivation and, in the binary mixtures, clover accounted for 26% of the uptake only. The percentage of phosphate removed by each of the species when grown in mixtures remained constant over cultivation treatments. The significance of the results to agronomic practice is discussed.

Recent studies on maize in Nigeria showed that the new ‘FARZ series’ of maize, which were specially bred for high yield, respond to high density treatments (Lucas, 1981; Remison & Lucas, 1982). The optimum maize grain yields were obtained by these workers at density treatments 6·6 and 5·3 plants/m2. Prior to the release of these varieties, optimum grain yields were obtained between 3·7 and 4·3 plants/m2 (Fayemi, 1963; Chinwuba, 1967).

A study was conducted to compare field crops and varieties grown at the Kufra Agricultural Project, Libya, and the Imperial Valley Field Station, El Centro, California. Lucerne (Medicago sativa L.), barley (Hordeum vulgare L.), wheat (Triticum octivum L.), sudangrass (Sorghum bicolor Moench) were grown at both locations in 1969–70.

Yield studies at Kufra, Libya, and the Imperial Valley Field Station indicated that the crop performances were equally well adapted at both locations. Lucerne yields were higher at Kufra, which may have been due to more moderate temperatures and less salt in soil and water at Kufra. Low yields in some of the other crops at Kufra such as wheat may be due to inexperience and inadequate fertilizers. Newly developed varieties for Imperial Valley should be adapted to the Kufra area.

The numbers of viable anaerobic proteolytic bacteria were determined from the caecal fluid of three ponies fed diets based on maize, oats or barley. In anaerobic conditions selected to promote the growth of those bacteria capable of utilizing protein, between 2 × 105 and 8 × 105 of viable anaerobic proteolytic bacteria/ml of caeoal fluid were observed. Time of sampling post feeding did not appear to affect the numbers observed. These numbers would appear adequate to make an important contribution to protein digestion.

To identify separate effects of gender, castration and exogenous oestrogen on growth, castrated lambs of both sexes and entire male lambs (n = 8) were implanted subcutaneously with three sizes of oestradiol-17β implants, or not implanted, and grazed on ryegrass and white clover pasture for 180 days. A group of non-implanted entire female lambs (n = 8) was run together with the others. Non-implanted entire male lambs grew faster, had heavier heads, less internal, non-carcass fat and more protein and less fat and water in the carcass than non-implanted entire females. In addition, they had higher 12th vertebral spine, thicker tibia, and heavier and larger humerus than entire female lambs. Castration of male lambs reduced live-weight gain, weight of head and content of protein in the carcass whereas it increased carcass fat content. In addition, it caused lengthening of cannon bones and reduced height of 12th vertebral spine and length of tibia. In females, gonadectomy increased height of 12th vertebral spine and diameter to length ratio of the radius. Oestradiol treatment increased live-weight gain, reduced total internal and carcass fat, and increased water and protein content of the carcass in gonadectomized animals of either sex, and increased weight of carcass and head in spayed ewe lambs. Oestradiol treatment inhibited longitudinal growth of cannon bones and stimulated that of vertebral column and ribs, but had little effect on the dimensions of limb bones apart from increasing their diameter. Oestradiol treatment had no effect on muscle length but increased muscle girth and weight, except for m. splenius in ram lambs where muscle weight was reduced. Effects of oestradiol on skeletal measurements in most cases were linearly related to dose of oestradiol. It was concluded that the variable effects of sex steroids on the skeleton were related to the differential pattern of skeletal maturation. In early maturing bones acceleration of the growth process by an exogenous sex steroid caused elongation to cease prematurely, whereas in late-maturing bones the acceleration effect on elongation did not result in premature cessation. This observation may explain the often contradictory reports in the literature on the effects of sex steroids on linear growth of bone.

The variations in fleece components over the body of the Blackface sheep are described. The differences amongst regions are relatively large and highly significant. The structural components—density, fibre type ratio and weight per unit area—are more variable than the fibre characteristics—weight, length and diameter. Fairly regular patterns are found which approximately correspond to those found in other breeds and there is evidence of significant animal by site interaction. It is concluded that neither fixed nor random site sampling can be regarded as ideal but that the best procedure would be single or multiple sampling in the mid-side region.

1. A digestibility trial is described using sheep fed on the product remaining after herbage leaf-protein extraction.

2. The material gave an analysis of 25.7% dry matter, 16.2% crude protein, 0.26% phosphorus, 1.26% potassium and 1.13% calcium.

3. The animals showed no loss in body weight during the feeding period.

4. The material was of low palatability, and the sheep consumed a maximum of 2½ lb. of dry matter per head daily.

5. The average digestibility coefficient of the dry matter was 52.1% and that of the crude protein 67.6%.

6. Nitrogen balance determinations indicated a sufficiency of protein in the feed.

7. The material barely supplied sufficient potassium and was inadequate in its supply of phosphorus and calcium.

Observations on the onset of the breeding season in a flock ofSouthdown ewes in subtropical Australia (latitude 27° S.) indicated that the mean date of onset during the years 1962-65 was 3 March, with annual means ranging from 11 February to 17 March. There was evidence that, under some circumstances, ovarian activity may be initiated before the summer solstice.

The onset of the breeding season was later in ewe lambs than in yearling and adult ewes and the mean age at puberty was 239 days.

A balance experiment was carried out using four young lactating goats in a Latin square design, fed with perennial ryegrass (Lolium perenne) from plots that had received 377 kg K/ha (diet 1); 63 kg K plus 377 kg Na/ha (diet 2); 188 kg K plus 188 kg Na/ha (diet 3) or no fertilizer (control diet 4).

The apparent availability of Mg was high in all the grass diets (0·355–0·469); it was significantly depressed (P < 0·05) when the intake of K was high (diet 1); but was not significantly different when a high intake of K was accompanied by a high intake of Na (diet 3).

There was a significantly lower (P < 0·05) apparent availability of Na in diet 4 and a significantly higher (P < 0·05) apparent availability of K in diet 3. There were no significant differences in the apparent availability of Ca.

The plasma Mg concentration was not significantly affected by any dietary treatment but did decrease temporarily when diets were changed.

There were no significant effects on mineral concentrations in the milk.

This study aims to determine the effects of dietary crude protein (CP) content of early-weaned calves; and the influence of flint maize processing methods on intake, total tract nutrient digestibilities and performance of Nellore heifer calves. Fifteen early-weaned Nellore female calves (4 ± 0.5 months; 108 ± 13.1 kg) were used. In phase 1, animals were fed one of the following diets for 112 days: 130, 145 or 160 g CP/kg dry matter (DM). In phase 2, animals received one of the two diets for 84 days: 0.60 dry ground maize grain, 0.30 whole-plant maize silage plus 0.10 mineral-protein supplement or 0.90 snaplage plus 0.10 mineral-protein supplement. In phase 1, intake and digestibility of dietary components were not affected (P > 0.05) by increasing dietary CP content. Daily total urinary nitrogen (N) and urinary urea N increased (P < 0.05) in response to increasing dietary CP content. Animal performance was not affected (P > 0.05) by dietary CP content. In phase 2, maize processing methods did not affect (P > 0.05) intake and digestibility of dietary components as well as animal performance, carcase characteristics and carcase composition. Therefore, based on the current experimental condition, we conclude that dietary CP concentrations of 130 g/kg DM can be indicated for early-weaned Nellore calves. However, more studies are recommended to validate this result and to evaluate concentrations below 130 g CP/kg DM for early-weaned Nellore calves. Moreover, snaplage could be used as an exclusive fibre and energy source for finishing cattle in feedlot.

Two studies were undertaken to evaluate the effects of cellulase and endoxylanase enzymes on the chemical composition and the fermentation characteristics of grass silage, using the gas production technique. Perennial ryegrass was ensiled in 1 litre glass containers for 90 days with cellulase (0·2 g/kg grass on fresh weight basis) and endoxylanase in the concentrations of 0·05 g/kg grass (Endox 0·05) and 0·2 g/kg grass (Endox 0·2). Subsequently, dried samples, ground through a 1 mm screen, were used in chemical analysis and gas production measurements. In Expt 1, the enzyme treatment significantly decreased silage NDF (P < 0·001), ADF (P < 0·001) and acetic acid (P < 0·01) concentrations and increased lactic acid (P < 0·001) production. In Expt 2, lower concentrations of NDF (P < 0·001) and ADF (P < 0·001) in treated silages resulted in increased sugar concentration (P < 0·001). In this experiment, butyric acid was detected. Addition of cellulase and Endox 0·05 enzymes did not alter silage digestibility. In both studies, cellulase and Endox 0·2 treatments tended to increase the rate of gas production within 10 hours of inoculation with rumen fluid whereas Endox 0·05 had no effect. The volume of gas produced was however greater for the untreated silage than for the enzyme-treated silage samples after 48 h of incubation. The strategy of applying cellulase and endoxylanase to the herbage in the ensiling process proved to be effective in modifying the chemical composition and increasing sugar concentration and the rate of gas production of the silages. Further research on the factors determining enzyme effectiveness is therefore suggested to elucidate the mechanisms leading to higher utilization of the released sugars.

Phenological development and its variation during reproductive growth have important effects on the yield and quality of forage grasses. In perennial ryegrass (Lolium perenne L.) genetic variation in heading date is well recognized, but there are no reliable studies about the variability in the length of the stem elongation phase. To determine the variation in phenological traits of single plants of perennial ryegrass genotypes, a field trial was conducted over three growing seasons (2011–2013) using plant material from eight different ecotype populations, sampled from old permanent grassland swards in Northern Germany. In addition to the phenological stages of jointing, heading and flowering, the critical phase of stem elongation was considered as a new phenological trait. It was hypothesized that the length of the critical phase between jointing and heading differs significantly among genotypes and thus offers a new tool for selecting for specific purposes, e.g. adaption to changing climatic conditions, cutting or grazing as well as yield and quality. The study revealed significant genotypic variation in the observed traits, which was highest for the critical phase (GCV = 0·21). Moderate heritability in jointing (h2 = 0·72) revealed a large environmental impact. In contrast, high heritability (h2 > 0·86) in heading, flowering and the critical phase imply a strong genetic effect. Moderate to high genotypic and phenotypic coefficients of correlation revealed a substantial linkage among the phenological traits. Results are discussed in the context of providing different approaches and strategies in forage crop production, especially with regard to regional weather conditions and future climate change. Significant differences among the tested ecotype populations indicate that existing diversity in permanent grassland can provide source material for further progress in grass breeding.

1. The availability of K in potassium metaphosphate was investigated in an experiment with large pots using a red sandy soil, low in exchangeable potassium. Potatoes were grown. The effects of potassium metaphosphate in three different granule sizes, applied at two rates, were compared with those of equivalent potassium chloride and potassium sulphate.

2. Characteristic deficiency symptoms appeared in plants receiving no K and the crop responded to K fertilizer in potassium concentration, yields of tubers, and dry matter, and starch concentrations.

3. Potassium metaphosphate, regardless of granule size and of application rate, was as effective as potassium chloride and potassium sulphate in giving normal development of potato plants, high potassium uptake in the foliage, and yield of tubers.

Using microbiological methods, thiamin, riboflavin and niacin have been determined in individual milk samples taken from a number of ewes at intervals during their lactation. Although considerable individual variations were found, the average values of 0.67μg./ml. for thiamin, 5.68μg./ml. for riboflavin and 4.80μg./ml. for niacin in New Zealand ewes' milk are somewhat higher than those reported by overseas workers. No lactational effects are apparent from the results presented.