Pods of white lupin are characterized by a high proportion of pod walls in the pod mass at maturity. Genotypic variation in pod wall thickness at maturity and in proportion of pod walls has been described in this species. The objective of this study was to describe the pod and seed development in two ecotypes and one cultivar of spring-sown white lupin differing in proportion of pod walls, and to estimate the precise stage of development when the differences in pod wall dry matter among genotypes are first observed. The nitrogen content was also determined during the pod development of three genotypes. LA356, E084 and Lublanc were grown in the field in the UK and France in 1998 and 1999. The duration of pod and seed development was similar among genotypes and environmental conditions. Proportion of pod walls by dry weight at maturity were 0·21–0·23 for LA356, 0·27–0·28 for E084 and 0·30 for Lublanc. The ecotype with the lowest proportion of pod walls accumulated less dry matter in the pod walls than those with the highest proportion.

Variation in pod wall dry matter per seed between genotypes was observed early during the pod development (300°C days from flowering) and it was maintained during all pod development. No significant differences were observed for the total nitrogen content at maturity among genotypes with high and low proportion of pod walls.

Three animal manures cross-labelled with 15N in either the urine, faeces or straw fractions were prepared. After a storage period of 86 days when the manures were exposed to either composting or to anaerobic storage, portions of the manures were incubated in six differently textured soils with clay contents ranging from 11 to 45%. Evolved CO2-C was determined during a 266 day incubation and inorganic N and 15N in soil were measured at the termination of the incubation. The mineralization of C was analysed using first-order kinetics, and two C pools with fast (P1) and slow (P2) turnover rates were estimated. The total conversion of added C (Ps) was estimated as Ps=P1+P2.

The cumulated CO2 production was considerably higher from soils incubated with anaerobically stored manure compared with soils amended with composted manure. CO2 production levelled off after c. 60 days in the three sandier soils whereas CO2 continued to be produced throughout the incubation from the three soils with the highest clay content. More C was assigned to the easily decomposable P1 pool in the sandiest soils whereas the more recalcitrant P2 pool was larger in the soils with higher clay content. Because of the different relationships between soil texture and C pools, Ps ended up being similar for five of the six soils. When taking C losses during the preceding storage into account, the accumulated C losses during storage and after incubation in soil accounted for 60 and 54% of C initially present in the composted and anaerobically stored manure, respectively.

Net N mineralization which averaged 16% of applied organic N took place in all soils amended with composted manure. Soils with anaerobically stored manure showed net immobilization after the 266 days of incubation. The amount of N immobilized accounted for up to 30% of the inorganic N applied with the manure. As anaerobically stored manure generally loses less inorganic N during storage, it may contain more inorganic N than composted manure at the time of field application. Because of the immobilization that takes place after application of anaerobically stored manure to soil, the immediate levels of plant available N in soil may not be as different from soil supplied with composted manure as could be expected from the inorganic N content in the two types of manure. However, when considering the manure as a N resource, anaerobic storage is superior to composting.

Two studies were conducted at Massey University in 1998. Expt 1 investigated the combined use of n-alkanes and 13C techniques for the estimation of individual proportions and total intakes of herbage (H) and maize silage (MS) by dairy cows. Expt 2 measured the variation in the amount of MS consumed by individual cows fed as a group. In Expt 1, six dry Holstein–Friesian cows were kept indoors and fed a diet containing one of the following H[ratio ]MS ratios (dry matter basis)[ratio ]100[ratio ]0, 80[ratio ]20, 60[ratio ]40, 40[ratio ]60, 20[ratio ]80 or 10[ratio ]90 for 25 days. Cows were dosed with a slow-release capsule containing 8 g of dotriacontane (C32) and 8 g of hexatriacontane (C36). Intake estimates were based on individual faecal samples collected twice daily during two 5-day periods. In Expt 2 (grazing trial), 12 early-lactation cows were selected from a commercial herd of 48 autumn-calving cows and blocked into pairs according to milk yield, lactation length and lactation number in a complete block randomized design. Within each pair, cows were randomly assigned to two treatments: supplemented, S (4 kg MS DM per cow after the morning milking in feed troughs) or not supplemented, NS. Another eight cows were randomly selected from the rest of the herd to increase the number of individual estimations of H and MS intakes. Cows grazed perennial ryegrass-white clover pasture during the rest of the day. In Expt 1, H[ratio ]MS ratios were not accurately predicted by the odd-chained n-alkanes, but there was a strong linear relationship between the concentration of 13C in faeces and actual H: MS ratios in the diet. The 13C method was therefore combined with the n-alkanes, resulting in accurate estimations of H and MS intakes. In Expt 2, a large variation was observed among individual cows in their daily intakes of MS (range 0·94 to 5·09 kg DM per cow, coefficient of variation = 36%), but this variation in MS intake was not associated with milk yield (P > 0·05). The results indicate that the n-alkane and 13C techniques can be successfully combined to estimate the intake of MS and H of grazing cows supplemented as a group. Under the conditions of the present study, individual cows differ considerably in the amount of maize silage consumed per day, although the reasons for this are not clear.

Two sets of experiments were conducted on sandy loam soils at Anand, India during the rabi (winter) seasons of three years (1993/94–1995/96) to study the effects of farmyard manure, nitrogen, phosphorus and potash as well as the method and time of sowing and irrigation on the growth and yield of chicory. Application of farmyard manure and phosphorus had no beneficial effect, whereas the application of nitrogen at 100 kg/ha and potassium at 50 kg/ha increased yield by 12·09 and 3·33%, respectively, on a pooled basis. Crops sown either in rows 30 cm apart or broadcast performed equally well with respect to dry root yield. Sowing of chicory on 5 November gave the highest dry root yield. Delayed sowing significantly reduced the dry root yield. Scheduling irrigation at an irrigation water: cumulative pan evaporation ratio of 0·7 produced maximum dry root yield.

The production of NH+4-N following in vitro incubation of cattle urine was monitored for 24 h in the presence of ampicillin sodium salt (0, 32, 64, 128 mg/l), hydroquinone (0, 16·7, 33·4, 66·8 mg/l), wheat straw (0, 3·3, 6·6, 13·2 g/l) or spruce sawdust (0, 3·3, 6·6, 13·2 g/l) with (20 IU) or without urease. Each concentration of ampicillin, hydroquinone, wheat straw or spruce sawdust was tested in triplicate.

The equipment consisted of Woulff flasks containing 300 ml of a buffered solution (0·02 M; pH 7·50) with 1 ml of cattle urine. The cattle urine was characterized by measuring the main nitrogen contents, which were 6·52 mg total-N/ml, 5·96 mg urea-N/ml and 0·026 mg ammonium-N/ml. The initial pH of urine was 7·84. Ammonium and nitrate concentrations, and pH were monitored at zero- time and after 3, 6 and 24 h of incubation with the cattle urine.

The addition of urease to the flasks containing urine induced a significant increase in the production of ammonium-N, from 1·83 to 6·32 mg NH+4-N/flask after 24 h of incubation.

In the presence of urease, an inhibitory effect was recorded in NH+4-N production with ampicillin and spruce sawdust. In contrast, hydroquinone inhibited urease activity and wheat straw adsorbed the NH+4-N produced, both causing a dose-dependent relationship.

In the absence of urease, ampicillin, hydroquinone, wheat straw or spruce sawdust caused a dose- related decrease in NH+4-N production. However, the highest amounts of wheat straw (6·6 and 13·2 g/flask) exhibited a temporary increase in NH+4-N production during the first 6 h. This is probably due to a generation of extra NH+4-N as compared to the control flasks without straw. However, at 24 h, the situation paralleled the other materials.

Although pH increased approximately from 7·50 to 7·65 during the hydrolysis of urea in the presence of urease, no gaseous ammonia was volatilized into a 0·1 M HCl flask. Moreover, no increase in nitrate concentration was found during the incubation.

The present results suggest that ampicillin, hydroquinone and spruce sawdust could be used in order to reduce NH+4-N production from cattle urine. The NH+4-N already produced could probably be absorbed on wheat straw.

Despite numerous reports on the positive effects of vesicular arbuscular mycorrhizae (VAM) on plant growth in temperate soils, surprisingly little data exist on the importance of VAM for crop growth on acid sandy soils of West Africa. A pot experiment conducted with local genotypes of pearl millet (Pennisetum glaucum L.), sorghum (Sorghum bicolor L. Moench) and cowpea (Vigna unguiculata) with and without phosphorus (P) application in a sterilized sandy soil from a farmer's field in Niger showed large growth-enhancing effects of VAM. Phosphorus application led to 18- and 24-fold increases in pearl millet root and shoot dry matter independently of VAM, whereas the shoot and root dry matter of sorghum and cowpea depended largely on the interaction between P application and VAM. With P, VAM increased total uptake of P, K, Ca, Mg and Zn by 2·5- to 6-fold in sorghum and cowpea. On severely P deficient West African soils P application can lead to large increases in early root growth, a prerequisite for early mycorrhizal infection and a subsequent significant contribution of VAM to enhanced plant growth and nutrient uptake.

A pot experiment was carried out at Nahshala Farm, about 50 km from Al-Ain, UAE, during the 1998/99 growing seasons, using six halophytes: Spartina sp., Distichlis palmeri, Paspalum vaginatum, Juncus roemerianus, Salicornia bigelovii and Batis maritima, under two levels of leaching fraction, 0·25 and 0·50 and three levels of irrigation salinity, 10, 20 and 40 g/l. The objectives of the experiment were twofold: (1) to find out the optimum and threshold of saline water irrigation to keep salinity level down as much as possible in the soil using the leaching fraction technique; and (2) to study the response (growth and biomass production) of some halophytes to different levels of salinity. The experiment was conducted in triplicate with a split-plot design arranged in a randomized complete block. Results indicate that these halophyte species can be grown productively at a leaching fraction between 0·25 and 0·50 when salinity of the irrigation water is less than 20 g/l. At higher salinities, Salicornia bigelovii can grow and yield satisfactorily under these conditions, while the other species may require more frequent irrigation at higher leaching fractions. Some of these tested halophytes may be able to revegetate the salt-affected lands and be a potential source of forage in these harsh habitats. This study supports the idea of seawater agriculture by demonstrating the possibility of using some high salt-tolerant halophytes at relatively higher leaching fraction in order to maintain satisfactory yield production of such halophytes.

A model was developed to simulate tuber yield and water use of a potato crop by modifying and extending an existing water-use model. Empirical validation of the model was carried out with data from 37 crop-years of experiments on a wide range of cultivars at five sites within the UK (viz Silsoe, Gleadthorpe, Rothamsted, Woburn and Dundee). The study confirmed the validity of the model over a range of yields from 1·67 to 73·7 t/ha and under conditions from severely droughted to fully irrigated.

For welfare reasons, fattening pigs on organic farms are raised on deep litter in the open with simple, flexible climate tents for shelter. Within this system, the nitrogen (N) flow both during fattening of the pigs from 17 to 100 kg liveweight in winter and during composting of the deep litter from the enclosures in summer was studied. During the fattening period, the pigs were provided with barley straw at four daily rates (0·67, 1·21, 1·32 and 1·87 kg) per kg increase in liveweight. During the summer period, N balances from four enclosures receiving straw at around the 1·32 kg rate were examined. Temperatures in the deep litter mat and in the compost heap were determined, as well as concentrations of ammonia (NH3) and nitrous oxide (N2O) in the compost heaps. The temperature increased after 4 weeks to between 40 and 70 °C in the deep litter mats receiving > 1·21 kg straw; the highest temperatures were observed in the mats with the highest straw rate. Temperatures exceeded 50 °C in all compost heaps. In the deep litter mats and compost heaps the highest temperatures were recorded for the longest periods in the material containing the most straw. The initial concentration of NH3 in the gas phase of the compost heaps was > 10 mg NH3-N/m3, which dropped to zero within 1 month. After the NH3 concentration had fallen, the amount of N2O increased significantly for a period in the two heaps with 1·21 and 1·32 kg straw. Over 120 days in summer, an average of 16·3±6% N was lost from the four enclosures strawed at a rate of 1·32 kg (±0·2 kg) straw per kg increase in liveweight. During the winter 12–24% of the N excreted was lost during a fattening period of 119–134 days, and 15–42% of the N stored was lost during the following composting period of 143 days. In total, 29–54% of the N added to the deep litter mat in excretion and straw was lost during the fattening period (119–134 days) and subsequent storage (143 days). The lowest loss was recorded from deep litter strawed daily with 1·32 kg straw per kg increase in pig liveweight.

A series of experiments were carried out at 14 sites in the major arable areas of the UK, in the years 1993–94, 1994–95 and 1995–96 to determine the causes and extent of over-winter plant losses of two autumn-sown cultivars of white lupin (Lupinus albus L.).

Over the three seasons frost was the major cause of plant losses. Two mechanisms (one known and one not previously reported in the UK) of frost tolerance under field conditions were identified: (i) lignification of the root parenchyma early in the life of the seedling, and (ii) a large vernalization requirement of the main-stem apex, which delays stem elongation in older plants. A model was developed that could be used to predict the susceptibility of these lupin cultivars to the first severe frost of the winter using accumulated thermal time (above a base temperature of 3 °C).

The effect of sowing at the beginning or end of a sowing window, calculated to optimize plant architecture the following summer, therefore varied with the weather during the autumn/winter period. A combination of cool autumn weather and late sowing (outside of the sowing window) resulted in plant losses due to a lack of lignification of the root parenchyma. In unusually warm autumn conditions (1994–95 and 1995–96) plants sown at the beginning of the sowing window were well developed before the first frosts occurred, with consequent stem elongation and plant losses.

Although losses due to pests were not severe (c. 3 to 5 plants/m2), plants were attacked during the autumn by grey field slugs (Deroceras reticulatum Muller), bean seed flies (Delia platura Meigen), and probably thrips (Thrips angusticeps Uzel, Noctuidae), although this has not been confirmed. The fungal pathogens Fusarium spp. and Botrytis cinerea Pers. caused losses in conjunction with frost damage.

Near infrared spectroscopy (NIRS) is widely used in the flour milling industry for rapid determination of moisture and protein in wheat. However, these measurements give little indication of the nutritive value of wheat when fed to poultry or pigs. Accurate estimates of nutritive value require specialist facilities and are time-consuming and costly. Accordingly, prediction from chemical or NIRS measurements would be of some considerable benefit. In the current study 160 samples of wheat, representing 24 different varieties, were used to generate NIRS calibration equations for chemical, nutritive and agronomic characteristics. Predictions of chemical constituents in wheat were very accurate. Coefficients of determination (r2) were 0·94 for dry matter, 0·90 for crude protein, 0·97 for ash, 0·78 for starch and 0·98 for oil. True metabolizable energy in broiler chickens was predicted more accurately (r2 = 0·52 for adult birds, 0·74 for young birds) than apparent metabolizable energy (r2 = 0·45). Digestible energy (r2 = 0·17) and nitrogen digestibility (r = 0·22) in pigs were not predicted very accurately on a smaller subset (n = 33). Agronomic characteristics were predicted very accurately (r2 = 0·98 hardness, 0·80 bushel weight, 0·99 thousand-grain weight). Predictions of nutritive value of wheat from chemical or agronomic characteristics are very inaccurate, since coefficients of determination vary from zero to 0·25. It is concluded that NIRS can accurately estimate the chemical composition of wheat, but accurate prediction of nutritive value is reduced by animal variation. Nevertheless, NIRS is potentially more reliable for assessing nutritive value than chemical composition or agronomic characteristics.

An experiment was carried out to determine the effects of parasitic status and level of feeding motivation on the diet selected by sheep grazing perennial ryegrass/white clover swards. Twenty-four female Scottish Blackface weaned lambs were divided into four treatment groups each of six animals. Pre-grazing treatments were imposed to create two levels of feeding motivation, low (fed ad libitum) and high (0·60 of ad libitum diet) and two parasitic states, parasitized (daily dose of 2500 L3Ostertagia circumcincta) and non-parasitized. Each treatment group was placed in one of four 0·35 ha field plots and allowed to graze a mixed grass/clover sward. Mean clover height was manipulated pre-grazing by cutting so that it was less than the mean grass height. This maximized the probability that clover in the diet of sheep was due to selection. No fertilizer was added to the sward in order to ensure that the nitrogen content of the clover was higher than that of the grass. Each treatment group was rotated around the four plots on a daily basis for 2 weeks. Sheep with a high feeding motivation strongly and significantly selected clover and had a higher proportion of clover in their diet compared with sheep with low feeding motivation. Parasitic status had no significant effect on the diet selection of sheep; but the level of parasitic burden within parasitized sheep was positively correlated with the proportion of clover in the diet. Parasitized sheep spent less time grazing each day and had lower daily herbage intakes compared with non-parasitized sheep. This was a result of a reduction in the duration of feeding bouts and not a reduced number of bouts per day. Sheep with the higher feeding motivation had a greater number of feeding bouts per day and this resulted in those animals having a greater daily herbage intake. Level of feeding motivation had greater effects on the diet selection of sheep than parasitic status. Sheep with a high feeding motivation are able to select strongly for clover in their diet when there is low overall clover availability and are capable of dramatically affecting the species composition of a sward. This has implications to the maintenance of a desired grass/clover ratio in grazed swards.

The study examined the extent to which n-3 PUFA from different sources were biohydrogenated in the rumen and their effects on rumen microbial efficiency and whole tract nutrient digestibility. Four ruminally and duodenally cannulated wether lambs were used in a 4×4 Latin square design. Four iso-energetic and iso-nitrogenous diets based on dried grass were formulated to provide similar fat levels (60g/kg DM) from different sources; Megalac (palmitic acid: C16:0; Control), whole linseed (α-linolenic acid, C18:3n-3 ; Linseed) fish oil (eicosapentaenoic acid, C20:5n-3, EPA and docosahexaenoic acids C22:6n-3, DHA; Fish oil) and whole linseed plus fish oil providing equal amounts of oil (LinFish). Diets were offered at a rate of 1·2kg/day in 12 equal portions.

Total fatty acid intake was similar on all diets whilst duodenal fatty acid flow varied between 101, 94, 87 and 90% of dietary intake for animals fed the Control, Linseed, Fish oil and Linfish diets respectively. Duodenal flow of C18:3 n-3 in animals fed the Linseed diet was twice that of animals fed the Control diet (P < 0·01) whilst animals fed the Fish oil diet had a significantly greater flow of EPA and DHA than those fed any of the other dietary treatments. Duodenal flow of trans C18:1 in animals fed the Linfish diet was significantly greater than that in animals fed either Linseed, Fish oil or Control diets (P < 0·001). Biohydrogenation of C18:3n-3 was 80 to 93% in all diets whilst that of C20:5n-3 and C22:6n-3 was 72 to 79% in diets that contained fish oil or linseed and fish oil. Apparent fatty acid digestibility (duodenum to rectum) tended to be greater for unsaturated than saturated fatty acids whilst whole tract fatty acid digestibility (mouth to rectum) was significantly greater in animals fed diets containing fish oil (P0·05). All dietary n-3 PUFA sources decreased microbial protein synthesis and efficiency when expressed as either gN/kg organic matter (OM) apparently or truly degraded in the rumen. Additionally, the inclusion of fish oil increased the proportion of propionate in the rumen whilst depressing the rumen digestibility of OM and fibre (P < 0·01), but had no significant effect on whole tract OM or fibre digestibility.

A split-plot experiment was conducted in 1992 and 1993 at Mokwa in the southern Guinea savanna zone of Nigeria to determine the responses of maize yield components to infestation by parasitic weed Striga hermonthica (Del.) Benth. and identify the most important yield components under Striga parasitism. Infestation treatments (infested v. non-infested) and hybrids [9022-13 (highly tolerant), 8644-31 (moderately tolerant), 8321-21 (moderately susceptible) and 8338-1 (highly susceptible)] were the main and subplots, respectively.

Striga significantly reduced grain yield and all the yield components considered. Pre-flowering stress due to Striga parasitism was higher than post-flowering stress and resulted in higher reduction for ears per plant (44%) than reductions for other yield components (12–29%). The numbers of yield components for which the hybrids exhibited the highest percentage reduction increased with the degree of susceptibility to Striga. Thus, 8338-1, the highly susceptible hybrid, suffered more severe reductions in a larger number of yield components than the other hybrids. Number of ears per plant was a major yield component and accounted for an overwhelming proportion (R2 = 0·95) of the variation in grain yield under Striga. Reductions in maize grain yield and its components were more severe under the moisture stress that occurred in 1992.

The study examined the reliability of predicting faeces output of cattle from chromium oxide (Cr2O3) released from a device (CRD) inserted in the rumen. Sixteen steers were selected from four genotypes and were offered a diet of low quality pasture hay with a protein meal supplement. The steers were placed in metabolism crates which allowed for total collection of faeces over two 5-day periods, days 6–9 (period 1), and days 13–16 (period 2), of a 20-day extrusion cycle of the CRD. Three faeces samples were taken from each steer per rectum; grab samples in the a.m. and p.m. and a daily subsample, that is, a sample of each daily total collected output. Cr2O3 release rates were derived for each sampling regime (a.m., p.m. and daily from the Cr2O3 content of faeces). These derived rates were compared with the release rate specified by the supplier to determine differences and any bias associated with the sampling regimes. Release rates were also derived from the predicted expiry date calculated from plunger travel in the CRD. Organic matter digestibility of the diet was determined from measurements of feed intake and faeces output over the 4 days for each steer and from an in vitro technique on diet samples. Predicted forage intakes were estimated using the mean faeces output collected over 4 days in combination with either the in vivo or in vitro digestibility estimates. Correlations between actual forage intake and predicted forage intake for each method were calculated and the bias in predicted forage intake between methods was compared.

The daily data revealed significant effects of steer (and/or CRD) and sampling period on the estimated release rate of Cr2O3 from the CRD. However, whilst there was only a period effect on the release rate with p.m. sampling there was a linear decline in release rate with the a.m. sampling. The correlation between predicted and actual forage intake was greatly reduced when in vivo digestibility was replaced by in vitro digestibility.

The results of this study suggest that the CRD had release rates less than specified and therefore devices should be calibrated for both the animals and the pastures prior to use. Furthermore, faeces sampling should be restricted to <13 days post-dosing to minimize bias.

Acacia saligna, a leguminous tree, has a high crude protein content, remains green all year and can be grown in deserts using only runoff water. However, dry matter intake (DMI) by sheep and goats of A. saligna is low, presumably due to its high tannin content. It has been suggested that DMI could be increased by such methods as wilting of the forage and by neutralizing the negative effects of tannins by tannin-complexing agents. The purpose of this study was to determine DMI of supplementary A. saligna (phyllodes and small stems) by grazing sheep (∼ 50 kg) and goats (∼ 37 kg) when the animals were (1) offered wilted or fresh material (Expt 1); and (2) administered with polyethylene glycol (PEG), a tannin-binding agent (Expt 2). In this second experiment, there were three 14-day periods in which one group each of sheep and goats was on a regime of: No PEG–PEG–No PEG, whereas another group was on a regime of: No PEG–No PEG–PEG. In Expt 1, the DMI of A. saligna was statistically higher in goats than in sheep, but there was no difference in intake between fresh and wilted material. Average DMI of A. saligna, both fresh and wilted, was 124·1 g/day or 8·41 g/kg0·75 per day for goats and 94·1 g/day or 5·05 g/kg0·75 per day for sheep. Goats and sheep consuming fresh A. saligna gained more body mass than their respective controls; the difference was significantly greater in goats but not in sheep. In Expt 2, DMI of fresh A. saligna in the first period (before PEG) was 104·1 g/day or 7·16 g/kg0·75 per day for goats and 84·8 g/day or 4·51 g/kg0·75 per day for sheep. Administration of PEG during the second period resulted in an increase in DMI of 62% in goats and 83% in sheep. These animals maintained a high A. saligna intake in the third period when PEG was withdrawn. Goats and sheep that did not receive PEG in the second period had similar A. saligna intake as in the first period, but increased intake by 62% and 47%, respectively, with PEG in the third period. Overall, the two goat groups and two sheep groups consuming A. saligna lost less body mass than their respective controls; the difference was significantly less in sheep but not in goats. It was concluded that wilting A. saligna did not increase DMI. Administration of PEG increased A. saligna intake and the intake remained high after PEG was withdrawn. Offering A. saligna as a supplement had a positive effect on body mass change.

Experiments were conducted during 1992/93 and 1993/94 to determine the effect of different planting dates and dinocap applications on control of powdery mildew and yields of early and late maturing coriander cultivars. Early plantings resulted in lower overall disease severity values for both the cultivars, but the late maturing cultivar S-33 benefited more than RD-44, an early maturing cultivar. Early planting resulted in smaller increases in yield in RD-44 but provided considerable economic gains in S-33. Further, it was possible to achieve similar levels of control of powdery mildew and yields in coriander with fewer dinocap applications by early plantings of both the cultivars. Therefore, to reduce the fungicide inputs, it is important that emphasis should be placed on early plantings for managing powdery mildew especially in environments conducive for its development.

This study was carried out from September 1998 to August 1999, by conducting three experiments, one each in the monsoon, winter and summer seasons. The forage availability and botanical composition of native range were obtained. Five 3–4-year-old Kutchi males, weighing 50–55 kg, were used to determine total faecal output, and were observed to allow the diet selected to be sampled by the hand plucking method. Dry matter (DM) yield of range was highest during winter and lowest during monsoon, annual mean being 1611 kg DM/ha. Contribution of shrub foliage to total forage yield in monsoon, winter and summer was 3·81, 1·64 and 9·98%, respectively. Crude protein (CP) content (g/kg DM) of ground vegetation declined from 99 in monsoon to 72 in winter and 66 in summer, while that of top foliage remained similar in all the seasons (mean CP 142 g/kg). Goats consumed a diet of almost the same CP content (mean CP 137 g/kg) in all the seasons. Goats consumed 64·0, 54·0 and 55·9 g DM/kg W0·75/day, in monsoon, winter and summer (annual mean 58·0 g DM/kg W0·75 /day). DM and CP digestibility coefficients were higher in monsoon and summer (mean DM 0·595; CP 0·533) and decreased (P < 0·05) in winter (DM 0·485, CP 0·424). Neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility coefficients were highest in monsoon (NDF 0·542; ADF 0·446), and declined (P < 0·05) to 0·340 and 0·266 in winter and 0·415 and 0·326 in summer. Digestible crude protein (DCP) intake was almost similar in monsoon and summer (mean 4·6 g/kg W0·75 /day) and declined (P < 0·05) in winter (3·1 g/kg W0·75 /day), while metabolizable energy (ME) intake was higher in monsoon (0·90 MJ/kg W0·75 /day) and declined (P < 0·05) to 0·78 and 0·80 MJ/kg W0·75 /day, in winter and summer, respectively. Average body weight of goats in monsoon, winter and summer was 54·0, 54·6 and 56·5 kg, respectively (annual mean 55·0 kg). It is concluded that goats grazing on a semi-arid rangeland meet their DCP and ME requirement throughout the year.

The current experiment was conducted to study the effect of different doses of tannic acid, a hydrolysable tannin, on ruminal degradation and post-ruminal digestion of treated soya bean meals (SBM) in sheep. Samples of SBM were prepared by spraying 100 g SBM with 100 ml distilled water containing 0, 1, 5, 10, 15 or 25 g of commercial tannic acid (S0, STA1, STA2, STA3, STA4 and STA5, respectively). Three ruminally cannulated ewes, that had never consumed tannic acid previously, were used to determine in situ degradability of tannic acid-treated SBM. Intestinal digestibility of protein remaining after 16 h rumen incubation was estimated in vitro. Extent of rumen degradation of SBMs was significantly (P < 0·05) affected by the tannic acid treatment. All doses of tannic acid used in this experiment, even the lowest one (STA1), significantly decreased the extent of N degradation but only doses higher than that used to treat STA3 reduced the extent of DM degradation. This reduction in the extent of DM and N degradation was mainly due to a marked decrease in the immediately degradable fraction (a), which was observed in all treated SBM, and to a lower rate of degradation (c), observed in meals STA3, STA4 and STA5. Intestinal digestion of the non-degraded protein was decreased (P < 0·05) by treatment with the two highest doses of tannic acid (those used to treat meals STA4 and STA5). It was therefore concluded that tannic acid can exert a negative effect both on rumen degradation and on intestinal digestion of SBM, this effect being clearly dependent on the dose used to treat the SBM.

Data on 1468 pregnancies and 2356 newborn goat kids of six genetic groups under intensive management were utilized to determine some genetic and non-genetic factors affecting gestation length, and to assess the relationship between gestation length and survival of kids to 25 days of age. The study revealed significant (P < 0·01) effect of breed of dam, litter weight, breeding season and parity on gestation length. Number of kids born and sex of kids were not a significant source of variation affecting this trait. Granadina goats had the shortest gestation (149·0±0·31 days), whereas Toggenburg (151·7±0·28 days) and Alpine (151·4±0·46 days) had the longest. Litter weight and gestation period were related curvilinearly in summer and linearly in autumn. Gestation of goats bred in summer was 1 day longer (P < 0·01) than those mated in the autumn. There was a progressive reduction of gestation length as parity increased (151·3±0·24, 150·6±0·17 and 149·9±0·39 days for 1, 2·6 and > 7 kiddings, respectively). The mean survival rate of kids gestated < 148 days and 148–;152 days were 78±2 and 87±1, respectively, and these were significantly lower (P < 0·05) than the survival rate of kids gestated 152–156 days and > 156 days (94±1 and 95±2). In conclusion, prolonged gestation (152–160 days) in goats was beneficial because it resulted in heavier litters at birth and higher viability of neonatal kids.