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.

Dilution of [1-13C]leucine (Leu) and open-circuit calorimetry were used to determine the effects of diet and cold exposure on rates of plasma Leu turnover, Leu oxidation, and whole body protein synthesis (WBPS) in sheep. The experiment was designed as a crossover design for two 23-day periods. Six adult sheep were assigned to two dietary treatments, medium (Me-diet) and high (Hi-diet) intake, and were fed either 515 or 830 kJ/kg BW0·75 per day of metabolizable energy intake, respectively. The temperature in the chamber was changed from a thermoneutral environment (23°C) to a cold environment (2–4°C) for 5 days (the 18th to 23rd day of the experiment). Turnover rate of both plasma Leu and WBPS were greater (P<0·01) for the Hi-diet compared with the Me-diet and increased (P<0·01) during cold exposure. Leucine oxidation rate was numerically greater (P=0·10) for the Hi-diet compared with the Me-diet and increased (P=0·03) during cold exposure. No significant diet×environment interaction was detected in the rates of plasma Leu turnover, Leu oxidation or WBPS. It is concluded that plasma Leu kinetics and WBPS were influenced by intake level and increased during cold exposure, but the responses to cold exposure were not modified by intake level in sheep under the conditions of the present experiment.

Katuk leaves (Sauropus androgynus (L.) Merr.; KL) are widely consumed by breast-feeding Indonesian mothers as it has been reported to increase breast milk production. It is hypothesized that supplementing KL in diets might increase crude protein (CP) concentration and fibre digestibility in the diet. The KL had high CP and non-fibre carbohydrate concentrations (333 and 332 g/kg dry matter; DM, respectively), but low neutral detergent fibre assayed with heat, a stable amylase and expressed exclusive of residual ash (aNDFom; 200 g/kg DM). Fibre digestibility linearly increased with increasing of KL supplementation in low-quality hay (LQH) diets. The KL did not contain a considerable amount of tannins. In LQH diets, gas production after 24 h incubation (GP24) linearly increased with increasing of KL supplementation (P < 0.001). Meanwhile, GP24 linearly decreased with increasing of KL supplementation in medium- and high-quality hays (MQH and HQH; P < 0.001). Metabolizable energy tended to linearly increase in LQH diets, but tended to linearly decrease with increasing of KL supplementation in MQH and HQH diets (P = 0.078). Therefore, this study suggested that KL can be a potential supplement in the ruminant diet due to its abundant dietary proteins but low fibre concentration in its leaves. However, further studies (e.g. in vitro or in vivo) investigating other rumen parameters after incubation should be performed to validate how KL can be supplemented in the diet of ruminant livestock.

Digestibility trials were carried out with five individuals each of domesticated oryx, sheep and cattle, using three diets ranging from 12·5 to 7·4% crude protein. Feed intake, water consumption and urine production were measured.

Intakes of dry matter (as g/day or g/kg W0·75/day) did not differ between diets for any species. On a metabolic weight basis the sheep and oryx ate the same amount. The cattle ate more than the sheep of all three diets, and more than the oryx in two of the three.

For all three species, digestibility of dry matter, crude protein and crude fibre was lower when the lower quality food was given. On any single diet, significant differences in digestive efficiency for any diet component between species were few and small.

Total daily intakes of water (ml/kg W0·85/day) were lower for each species when eating the diet with the lowest protein content. On each diet total intakes were significantly different in the decreasing order cattle > sheep > oryx, in the mean ratio 3·3:l·7:10.

Urine production (ml/kg W0·85/day) varied slightly between diets for each species. On each diet the cattle produced significantly more urine than the sheep or oryx. The ratio of urine produced to water drunk decreased in the order oryx > cow > sheep, in the mean ratios 0·63, 0·34 and 0·27. Despite some interspecific differences in nitrogen concentration, there were few differences in the proportion of total excreted nitrogen that was lost through the urine.

Calculations of evaporative water loss showed that loss of water by this avenue was significantly less in oryx than in sheep or cattle, which did not differ significantly.

In the absence of any evidence of a more efficient digestion, the low metabolic intake of food by oryx suggests a low metabolic rate. The oryx's low water consumption and small evaporative loss are obvious adaptations to its desert habitat.

Vigorous cauliflower plants sometimes bear abnormally small curds, yet this common problem has received little recognition or attention from research workers. Curd size is often reduced towards the end of the harvesting period of a crop, and this is more marked if environmental conditions reduce mean curd size and lengthen the time to maturity. Small late curds may be a consequence of their slow growth rather than their late initiation. Cultivars differ in their tendency to produce plants with late maturity and small curds. This may not be due to genetic differences within cultivars. Moreover, breeding to eliminate or reduce this condition may not be possible without affecting overall maturity time and curd size.

A field experiment testing the effects of potassium and magnesium sulphates applied from 1960 to 1967 and sodium chloride applied in 1966 and 1967 on a range of crops (Bolton & Penny, 1968) was sown with ryegrass in 1967. Only basal N and P was given to all plots until 1971 when basal K was also applied. The experiment terminated in autumn 1974.

Grass yields were increased by K residues for 3·5 years but overall yields became small due to K deficiency. After giving basal K, residual K no longer increased yields but did slightly increase % K in the grass until the end of the experiment. Some residual K from the 1960–7 dressings was found in the sandy loam soil after the final harvest.

Magnesium fertilizer residues slightly increased grass yields in the 1967–70 period but not later. However, % Mg in the grass dry matter was increased by the residues for the whole 7·5 year period. Exchangeable Mg was also increased in soil sampled after the final harvest, especially in the 23–46 cm subsoil.

Sodium fertilizer residues increased grass yields until the basal K was applied, especially on plots without added K. Significant increases in % Na in the grass and Na uptakes were detectable in all years, i.e. up to 7·5 years after the last Na application. This finding is contrary to most accepted views on the longevity of Na fertilizer effects and could be important in areas where sodium deficiencies in cattle and sheep occur.

Increases in % Cl in the grass from the sodium chloride were only detectable in the first two cuts in the year following the final application.

Chamber sampling is a common method for measuring nitrous oxide (N2O) emissions from agricultural soils. However, for grazed pastures, the patchy nature of urine deposition results in very high levels of spatial variability in N2O emissions. In the present study, the behaviour of the sample mean was examined by simulating a large number (9999) of random N2O chamber samples under different assumptions regarding the underlying N2O distribution. Using sample sizes of up to 100 chambers, the Central Limit Theorem did not apply. The distribution of the sample mean was always right-skewed with a standard deviation varying between 12·5 and 135% of the true mean. However, the arithmetic mean was an unbiased estimator and the mean of the sample mean distribution was close to the true mean of the simulated N2O distribution. The properties of the sample mean distribution (variance, skewness) were affected significantly by the assumed distribution of the emission factor, but not by distribution of the urine patch concentration. The geometric mean was also investigated as a potential alternative estimator. However, although its distribution had lower variance, it was also biased. Two methods for bias correcting the mean were investigated. These methods reduced the bias, but at the cost of increasing the variance. Neither of the bias-corrected estimators were consistently better than the arithmetic mean in terms of skewness and variance. To improve the estimation of N2O emissions from a grazed pasture using chambers, techniques need to be developed to identify urine patch and non-urine patch areas before sampling.

In earlier studies, results from incubation experiments were combined with measurements of outflow rates of small particles from the rumen to predict the extent of degradation of dietary protein in vivo (Orskov & McDonald 1979). The degradability of a protein supplement was shown to decrease when fractional outflow rate increased (Orskov 1982). In a series of experiments, the factors affecting the fractional rates of outflow of dietary protein supplements from the rumen of sheep and lactating dairy cows were investigated (Agricultural Research Council 1984). In addition, outflow rate of soyabean meal from the rumen of dry and lactating Chios sheep and Damascus goats offered high concentrate diets was determined in recent studies (Hadjipanayiotou et al. 1988). Chromium-treated protein supplements were used to measure their outflow from the rumen using the marker concentration in faeces (Ørskov 1982). This paper reports outflow from the rumen of growing Chios lambs and Damascus kids offered concentrates ad libitum.

In dealing with fertility in sheep there are a number of initial difficulties. On the one hand, there is generally a lack of any uniform definition of such terms as ‘fertility’, ‘fecundity’ and ‘prolificacy’ (cf. Marshall & Hammond, 1947; Lush, 1938; Rice, 1942; Asdell, 1946; and others); on the other hand, investigators have been confronted with a real difficulty in procuring suitable information which would conform to the requirements of any single and adequate definition of fertility. Because of this, fertility figures have been calculated in different ways* and may differ by as much as 30%. The situation is at present so confused that reference to similar work, especially when the original papers are not available, or the terms not clearly denned, is often of dubious value if not altogether misleading. In the past the data analysed were mostly based on farmers' answers to questionnaires or on flock records. The limitations of such methods are only too obvious; yet it must be clearly realized that in commercial flocks there is no possibility of any basic departure from them, even though their accuracy could in many cases be improved. In other words, only such information is collected as the circumstances allow. This, for instance, may be the number of lambs docked per ewes put to ram in one flock and number of lambs docked per ewes lambed in another.

Trials were conducted during the summer seasons (1978 and 1979) at the Faculty of Agriculture, Elminia University, to evaluate the effect of some growth regulators on sex expression, sex ratio and yield production of snake cucumber. The results obtained showed that both sex expression and ratio could be modified with plant regulator sprays even under the long and high temperature conditions of Elminia governorate. All plant regulators induced the formation of the first female flower at lower nodes compared with the control. There was significant suppression of male flowers in plants sprayed with plant regulators. All the treatments gave an increase in total yield and improved fruit characters.

The performance of Suffolk cross-bred ewe lambs produced either by Suffolk crossbred ewes, 70–90% Suffolk (HS), or by Ossimi ewes, 35–45% Suffolk (LS), was investigated. Forty-three ewe lambs from both groups were available, and were given two different levels of feeding.

The LS ewe lambs showed, insignificantly, better growth performance than the HS group, and breed group differences increased with age. They also reached puberty earlier (305·4 v. 334·6 days for the HS ewe lambs). Using the HS breeding rams rather than the imported Suffolk ones, for improving lamb production from the local sheep flocks, is recommended.

The LS ewe lambs started their first breeding season 18 days earlier, and ended 34 days later, than the HS ewe lambs. Both cross-bred groups showed clear anoestrous periods of 225·4 and 202·2 days, respectively. The onset of their second breeding season was similar, on average 29 August. These figures are close to those of the purebred Suffolk ewes, and far away from the nonseasonal local parents.

Magnesium deficiency has been recognized to occur on acid (pH 5·5 or lower), sandy and highly leached soils or in soils whioh have received heavy application of fertilizers especially with materials which are lacking in magnesium or high in potassium (Berger, 1962; Foy & Barber, 1958). In addition to absolute deficiencies, induced forms can also occur, especially when K:Mg ratio in the soil exceeds 5:1 (Caldwell, Hooper & Little, 1968).

Percentages of soluble dry matter (S.D.M.), determined in expressed sap from the pith of kale stems by using a hand refractometer, were higher near the vascular bundles than in the centre of the pith and also varied from the top to the base of any one stem. Sampling errors were minimized by taking vertical borings midway between the vascular bundles and the pith centre and by taking two bores per stem (base and top). Inbred lines varied for mean S.D.M. Relative S.D.M. values for two inbred lines were maintained through wet and dry periods in the autumn, and values for fifty-eight inbred lines were significantly correlated in the successive years, one with a dry autumn and the other with a wet.

S.D.M. values were positively and significantly correlated with dry-matter percentage (D.M.) of the pith and with total water soluble carbohydrates (W.S.C). Close correlations were also found between S.D.M. and resistance to cold damage, both in the field and in freezing cabinets for inbred lines of marrow-stem kale and for other cultivars of Brassica oleracea. Although there are some exceptions to these correlations, the rapid method for determining S.D.M. should be very useful in screening breeding material for cold resistance. The combination of high percentage digestibility of the dry matter of stems and improved winter-hardiness can be achieved by selecting in addition for low fibre content using penetrometer tests.

The effects of changing plant density and nutrient supply on the yield of swedes were measured in nine experiments over 3 years. With small populations, a large nutrient supply was required to reach the maximal yield of roots, but with large plant populations the same nutrient rate depressed yield. This interaction is illustrated by a response surface, and reasons for it are discussed. The interaction is of limited importance in practice because it was small over the range of population and nutrient supply commonly used. Even with small populations, the compensation achieved by applying more fertilizer was uneconomic. On crops with large populations, such as swedes for human consumption, however, the normal recommended rate of fertilizer should not be exceeded because of loss of yield as well as increased cost. More fertilizer and greater plant density were needed to give maximal total yield (roots + tops) than of roots alone. Effects of nutrient supply and plant population on plant establishment and dry-matter content of the swedes are discussed.

Comparisons were made of the tuber yield and leaf morphology of three dihaploids, their chromosome-doubled derivatives and tetraploid parthenogenetic parents grown in a glasshouse at low, medium and high fertilizer levels. Differences in yield between the dihaploids and doubled dihaploids were not significant (P > 0·05) and responses to increases in fertilizer were similar. Leaf complexity showed generally large (usually significant, P< 0·05) increases when the fertilizer level was increased from medium to high. For the heterozygous tetraploid parents the tuber yield increased more than leaf complexity. Probably the dihaploids and doubled dihaploids utilized the additional fertilizer to increase foliage growth rather than tuber yield whereas the converse was the case for the tetraploid parents. There was no evidence that chromosome doubling resulted in changes in the response of dihaploid genotypes to changes in the fertilizer level.

In a 3-year study, maize (Zea mays L.) sown on 11 November or 1 December produced longer ears, higher grain yield per plant and greater grain yield per hectare than maize sown on 21 October. However, 100-kernel weight was greater when the crop was sown on 21 October and 11 November than on 1 December. There were no differences in yield characters or grain yield between cultivars or between row orientation. The sowing dates, maize cultivars and row direction had no influence on the number of ears per plant.

Various species of animals, ranging from ordinary laboratory rats to some high-grade beef and dairy cattle, have been imported from the temperate regions of the world to Nigeria in recent years. Most favoured are Large White pigs and this breed of livestock is proving to have very great potential in the livestock production industry in this part of the tropics. Temperate breeds of livestock when introduced to the tropics are said to decline in their general performance, owing partly to direct effects of high ambient temperatures(Yousef & Johnson, 1965). Some generalized statements have also been made on the adverse effects of tropical climate on growth though very little objective field experimental evidence exists (Williamson & Payne, 1978).

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.

The aims of this work were to determine the feasibility of using the incorporation of radio-labelled thymidine into fat cell DNA in vivo as an index of cell division in the adipose tissue of young pigs, and to distinguish between the processes of new cell synthesis and the ‘filling’ of existing ‘empty’ cells.

Five Large White pigs were given tritiated thymidine as follows: two animals were injected at 2 days of age, two at 9 days of age and one at 40 days of age. The animals were killed at different times after the injection and adipose tissue was removed from various sites. The tissue was separated, using collagenase, into ‘fat cell’ and ‘stromal cell’ fractions. The specific (radio)activity of DNA isolated from each fraction was measured.

Fat cell synthesis occurred rapidly in pigs aged between 2 and 40 days of age. It appeared that by 40 days of age the rate of synthesis declined in backfat such that the filling of pre-existing empty fat cells became a more important contributor to the increased mass of adipose tissue than the filling of newly synthesized cells.