Eighteen multiparous Holstein-Friesian cows were offered grass silage ad libitum and 3,6 or 9 kg dry matter per day of concentrates. Triplicate milk samples were taken at each of two daily milkings over a 28-day period and analysed for fat protein and lactose concentration. Milk yield and fat concentration were more variable than protein and lactose concentrations both between animals and between days. Sampling variation was small for all component concentrations. The main source of variation for all traits was time of milking (morning or afternoon) followed by variation between cows and by day-to-day variation. There was little linear trend with time in the data due to cows being close to peak yield. There was no evidence of cyclical variation over time for any trait. Mean weekly or monthly yields and concentrations were better predicted using samples from four rather than from two consecutive milkings but there was no further advantage from using six samples.

Eighty calves of both sexes, 4 months of age, of two lines, differing in genetic merit for fat plus protein production by 70 kg per 305-day lactation, were given one of four diets differing in protein content to give an estimated range of protein intakes from 299 to 530 g/day. After 21 days the calves were fasted for 72 h. Samples of blood were taken before and after feeding in the morning and afternoon prior to fasting, seven further samples were taken throughout the fast and five samples were taken ranging from 0·5 to 7·5 h after food was re-introduced. The samples were analysed for concentrations of urea, free fatty acids (FFA), glucose, triglyceride and f5-hydroxybutyrate.

No association between metabolite concentrations and predicted breeding value (PBV) were found at any stage of the trial except for the effect of feeding on FFA concentration, the rate of increase of FFA during the fast and its ultimate concentration. These associations with FFA depended on the sex of the calf and were either absent or less marked in males. The results strengthen the possibility that FFA concentrations during fasting are related to PBV in females, and that sexual dimorphism may explain differing conclusions amongst previous trials.

The magnitude of the estimate of coheritability of urea concentration during fasting with PBV, pooled across experiments, is reduced from -0·193 to -0·066 (s.e. 0·037) by inclusion of these results. However, heterogeneity between experiments is evident and remains to be explained. This suggests that urea concentrations are not consistent predictors of genetic merit and cannot be considered to be reliable for use in practice.

An experiment was carried out to evaluate the effects of forage type and level of concentrate supplementation on forage intake, diet digestibility and milk production. Twenty-four crossbred cows (Bos taurus × Bos indicus), in early lactation, were allocated to the following six dietary treatments: native grass hay (H) or oat-vetch hay (OV), offered ad libitum, and supplemented with either 0, 2·5 or 5·0 kg per cow per day of a wheat-middling-based concentrate. A four-period, partially balanced, change-over design was used and the treatments were arranged as a 2 × 3 factorial.

The daily dry-matter (DM) intake was 640 g (P < 0·001) higher with cows on (H) diets compared with those on OV diets. However, OV diets were more digestible (0·675 v. 0·566, P < 0·001) resulting in 800 g higher (P < 0·05) daily intake of digestible DM. The daily milk yield was 1·24 kg higher (P < 0·001) for cows on OV diets compared with H diets. Milk fat concentration was higher (P < 0·05), but milk protein concentration was lower (P < 0·001) with H diets. The rates of rumen degradation of DM and nitrogen of OV were higher than of H for all incubation periods; similarly the values of the rate constant of DM and nitrogen were greater for OV than for H.

The daily DM intake increased by 3·72 kg/day (P < 0·001), when the amount of concentrate increased from 0 to 5·0 kg/day, indicating a minor substitution of basal forage by concentrate. The apparent DM digestibilities of the diets were higher when the diets were supplemented with concentrates. The milk yield increased linearly (P < 0·001), when the level of concentrate supplement increased from 0 to 5 kg, resulting in 0·52 kg more milk per day per kg additional concentrate given.

Forty-five Friesian × zebu crossbred calves (4 days old) were used to evaluate the effect of feeding different levels of whole milk and weaning at different ages. A total of 252 I whole milk offered over 12 weeks was compared with a feeding level of 134 I milk offered over 8 weeks. Water given ad libitum was also compared with allowing access to water once daily. The calves were penned and fed individually. The average daily gain of the calves weaned at 12 weeks was 464 g compared with 378 g for the calves weaned at 8 weeks of age and allowed access to water once daily and 422 g for the calves weaned at 8 weeks and given water a d libitum. Feeding extra milk and weaning at 12 weeks decreased the intake of concentrates and significantly (P < 0·05) increased live-weight gain. Allowing ad libitum access to water was associated with an increase in concentrate intake but this was not reflected in a significant increase in animal performance.

An experiment was conducted to measure the response of spring-born suckled calves to supplementary feeding when they grazed, with their dams, on swards of different heights in the autumn. Two swards were maintained at mean heights of either 5·8 cm or 9·0 cm, and calves were offered 0, 0·76 or 1 -51 kg organic matter (OM) per day of a commercially available supplement for a period of 60 days until weaning. Supplement intakes by the calves grazing the taller sward increased throughout the 60-day period, but did not exceed 0·75 kg OM per day. There was no response in terms of calf live-weight gain to the provision of supplement on the sward maintained at 9·0 cm. On the shorter sward, intake of supplement increased at a greater rate and reached 0·75 kg OM within 3 weeks. Maximum intake by those calves offered 1·51 kg supplement OM per day was 1·25 kg OM per day. The provision of supplementary feeding when mean sward height was 5·8 cm resulted in a significant increase in calf live-weight gain (P < 0·05), although supplementary feeding did not fully compensate for the reduction in milk and herbage intakes because of partial substitution of supplement for herbage. During the winter after weaning the calves that had previously grazed the shorter sward showed increased live-weight gain compared with those that had previously grazed the taller sward but prior supplementary feeding was without significant effect in this group.

During clinical investigation of a commercial herd it was found that intake of supplemented poultry litter (PL) by beef cows at >10 kg/day, was associated with severe cachexia and a mortality rate of between 10 and 20% of cows. Postmortem analysis of 40 fresh carcasses and elevated serum levels of cholesterol, bilirubin, alkaline phosphatase, glutamic oxaloacetic transaminase and sorbitol dehydrogenase in cachetic cows indicated that the cows suffered severe liver damage. The interrelationship between liver damage and PL intake was subsequently investigated in three groups of 20 beef cows each, consuming 0, 3 and 10 kg PL respectively. As determined by the serum indices, intake of 3 kg PL seemed to be sufficient to cause liver damage, although these cows appeared healthy.

In another experiment, six beef cows were stall-fed a diet giving separate access to PL and wheat straw. PL intakes were 3·1,4·7 and 6·0 kg/day. Ruminal ammonia concentration was three to five times higher than the estimate of that required for maximal fermentation in the rumen. The high pH values (6·81 to 6·97) found are optimal for absorption of ammonia from the rumen. The combination of excess absorption of ammonia from the gut and low metabolizable energy intake might have been the cause of liver damage.

Friesian steer calves born in August were reared from 3 to 7 months of age on silage alone (S) or on silage and concentrates to supply metabolizable energy (ME) in the proportion of 0·5: 0·5 (55) or 0·1: 0·9 (19). The mixed diets were either offered to appetite (55A and 19A) or restricted to provide the same energy intake as the S group (55R and 19R). The cattle were then grazed for a 6-month period as a single group. During the winter the S, 55R and 19R groups had similar live-weight gains. Despite having the highest nitrogen intakes the S group deposited less protein, but more fat than the other two groups. There were no significant differences within A or R groups, but the A groups had higher live weights, empty-body weights and carcass weights than the R groups and had more fat and less protein per kg empty body weight at turn-out to grazing.

Compensatory growth was exhibited by the S, 55R and 19R groups during the grazing season. It arose because of differences in intake and not because of differences in the energy content of the gain. Intake was inversely related to the level of fat per kg empty body weight at the start of grazing. There was no evidence that the nature of the diet in winter had an effect on subsequent herbage intake.

It was concluded that diet per se in winter had no residual effect on intake at grazing, but that it did have direct and residual effects on the relative deposition of fat and protein which could lead to an association between the level of fat in the empty body and intake. Inefficient use of nitrogen from silages with moderate fermentation characteristics was also demonstrated.

The response of finishing Blackface lambs (mean initial live weight 29·6 kg) to shearing and level of concentrate supplementation on a silage-based diet was examined in two experiments. Silage intake decreased as concentrate level increased at mean rate of 0·13 and 0·26 g silage dry matter (DM) per g concentrate DM, in experiments 1 and 2 respectively, with no significant differences between unshorn and shorn lambs. Lambs gained 36, 97, 135, 193 and 224 g/day (s.e. 9·1; P < 0·001) in experiment 1 and 97,133,170,185 and 222 g/day (s.e. 9·9; P < 0·001) in experiment 2 when 0, 200, 400, 600 g/day and concentrate ad libitum were offered respectively. Shearing increased silage DM intake from a mean of 0·50 to 0·56 kg/day (s.e. 0·016; P < 0·05) in experiment 1, and from 0·80 to 0·90 kg/day (s.e. 0·013; P < 0·001) in experiment 2. There was no interaction between shearing and the level of concentrate offered. Despite higher DM intakes by shorn lambs, their live-weight gains were lower than those of unshorn lambs. Gains of unshorn and shorn lambs averaged 153 and 120 g/day (s.e. 5·8; P < 0·001) in experiment 1 and 162 and 161 g/day (s.e. 5·7; P > 0·05) in experiment 2 respectively. This appears to have resulted because shorn lambs could not fully compensate for their increased energy requirements after shearing, by increasing their DM intake. Shearing did not significantly influence carcass characteristics.

It was calculated that with lambs gaining 150 g/day, concentrate requirement was increased from 286 to 335 g/day and total DM intake from 965 to 1107 g/day as a result of shearing.

Lactation curves for several dairy traits in sheep were studied. Data were collected from seven pure breeds, three synthetic breeds and twelve single breed crosses in a 5-year milking trial. Wood's lactation model (yn = anbe-cn) was used to describe the lactation curves. Actual and fitted lactation curves had the same shape within each trait except for proportion of lactose. Correlations between actual and fitted lactation curves ranged from 0·92 to 0·99 for all traits except lactose (0·24). There was no apparent explanation for the low correlation for lactose content. It was concluded that the algebraic formula can be used to obtain estimates of parameters for sheep lactation curves. However, some caution should be exercised in extending results to proportion of lactose in the milk.

Crossbred groups had higher total milk production than pure and synthetic breeds. Lactation curves for crossbred ewes, grouped by breed of sire, had a similar pattern. Finnsheep and Rambouillet-sired crossbred ewes produced proportionately 0·23 more milk than ewes sired by Dorset and Lincoln rams. Breed differences in total milk production were observed among the pure breeds. The Suffolk breed was superior in milk production. All breeds, except the Romanov, followed a similar pattern for lactation curves. The Romanov breed produced milk at a relatively low but consistent level throughout the lactation trial.

Seventy-eight Beulah (BH) and 78 Welsh Mountain (WM) wether lambs (mature live weights (MLW) 60 and 70 kg respectively), were used to investigate genotypic differences in performance and compensatory growth during the post-weaning period. After an initial slaughter of 12 of each breed, a complete straw-based pelleted diet (122 g crude protein and 10·4 Mj metabolizable energy per kg dry matter (DM)) was offered ad libitum to a further 29 of each which were slaughtered at a range of live weights between proportionately 0·35 andl -00 of ML W. As well as these groups undergoing normal growth (NG), the remaining lambs were given the same diet at a level sufficient to maintain constant live weight (LW) for 3 months. Eight of each breed were then slaughtered and the remaining 29 of each offered the diet ad libitum for a period of post-restricted growth (PRG); these 29 were also slaughtered between 0·35 and 1·00 of MLW. During the periods of ad libitum food supply, voluntary food intake was greater in BH than WM lambs (BH: 38·3, WM: 35·3 g DM per kg LW, P < 0·01) and during PRG as compared with NG although this result was due to a response only in WM lambs (NG - BH: 38·0, PRG-BH: 38·5, NG - WM: 33·3, PRG - WM: 37·2 g DM per kg LW, breed × pattern of food supply interaction, P < 0·05). Daily live-weight gain (LWG) was greater during PRG than NG in both breeds (NG: 3·15, PRG: 4·80 g/kg LWper day, P < 0·05). This effect was greatest in the first 8 weeks of growth but persisted into the period 16 weeks to maturity. WM lambs had overall slightly leaner carcasses and a lower proportion of protein in the fleece-free empty body than BH when compared at the same proportion of MLW; particularly during PRG. The protein in the carcass-weight gain (CWG) was greater in WM lambs during PRG than during NG (NG: 98, PRG: 123 g/kg, P < 0·05), but did not differ significantly in BH (NG: 106, PRG: 118 g/kg). The proportion of fat in CWG was concomitantly smaller during PRG. There are thus breed differences in the performance and carcass composition of lambs during compensatory growth. Genotypes to be finished by continuous feeding or a regimen incorporating food restriction should be carefully chosen for date offinishing in relation to desired carcass composition.

The effects on reproductive performance offeeding supplements to ewes grazing predominantly perennial ryegrass swards before and during mating which started in mid November were examined with approximately 200 Scottish Blackface ewes in each of three experiments. In two experiments, ewes were offered no supplement (C), 600 g barley (S(B)) or 500 g barley + 100 g white-fish meal (S(B + FM)) per head per day from 3 weeks before until 3 weeks after the start of the mating period. Ewes in experiment 1 were grazed on different areas and in experiment 2 were rotated around these areas on a 12-day cycle. Initial herbage allowance in both experiments was 40 to 50 kg organic matter per ewe and stocking rates ranged from 10 to 14 ewes per ha. Ewes in experiment 3 were rotated around the same areas on a 10-day cycle at a stocking rate of 18 ewes per ha and offered either no supplement (C) or 600 g barley (S(B)) per head per day when live weight started to decrease or sward height declined to 3·5 cm, whichever occurred first. Both of these occurred shortly after the start of mating. Sward height fell from mid October and throughout November and was between 3 and 4 cm at the start of mating in all experiments.

There were no differences in response to the (S(B)) and (S(B + FM)) treatments in live weight, body condition or reproductive performance in experiments 1 and 2 and the effects of supplementation were examined with these treatments pooled.

Supplementation had very little effect on live weight, resulting in higher values only in experiment 1 but did produce higher body condition in all experiments. This occurred by the start of mating in experiment 1 but not until mid December in experiment 3 and early January in experiment 2.

A significant increase in the number of lambs born per ewe lambing was obtained from supplementation when the data from experiments 1 and 2 were combined (P < 0·05). There was no response in reproductive performance to supplementation in experiment 3. It was concluded that supplementation in the pre-mating period can improve reproductive performance when sward height declines from 6 to 3·5 cm but that supplementation in the post-mating period may not, even when the sward height is below 3·5 cm.

The effects of feeding supplements in relation to sward height in the autumn on the reproductive performance of ewes grazing predominantly perennial ryegrass swards were studied in four experiments with three genotypes. Treatments in which either no supplements were given or supplements were offered according to the height of the sward were compared when ewes were grazed on swards which were managed to decline in height from > 5 cm to 2·5 cm either before or after mating. At a sward height of < 3·5 cm, 400 g ground and pelleted barley was offered per head per day; at < 3·0 cm, 700 g was offered; and, at < 2·5 cm, hay was offered in addition to the barley. Responses to these treatments were compared with that of a treatment in which a sward was maintained at > 5 cm. Sward heights were controlled by varying stocking rate. In experiment 1, with 305 Scottish Blackface ewes, supplementation was not necessary until after the start of the mating period. In experiment 2, with 200 Brecknock Cheviot ewes, the supplementation protocol was examined on swards declining in height either before or after a synchronized mating. Experiment 3 repeated experiment 2 with 200 Beulah Speckled-face ewes and experiment 4 repeated only the pre-mating phase of experiment 3 with 195 Beulah Speckled-face ewes.

In experiment 1, ovulation, ova loss and potential lambing rates were determined from the number of corpora lutea and viable embryos at slaughter at 8 to 10 weeks after the start of mating in 103 ewes and lambing rate was determined from the number of lambs at lambing in the remaining 202 ewes. In experiments 2, 3 and 4, ovulation, ova loss and potential lambing rates were determined from the number of corpora lutea and viable embryos at slaughter at return to service or at 4 weeks after a synchronized first mating.

Grazing a sward declining in height below 3·5 cm in the pre-mating period significantly reduced ewe live weight, body condition and reproductive performance, particularly in the relatively prolific Beulah Speckled-face breed, compared with grazing a sward maintained at > 5 cm. Supplementation at the levels offered overcame some of the effects of the lower sward height treatment in the pre-mating period but did not compensate fully. Grazing a sward declining in height below 3·5 cm in the post-mating period, although reducing ewe live weight and body condition, had little effect on reproductive performance, compared with that achieved on a sward maintained above 4 cm. Supplementation at the levels offered at the lower sward height during the post-mating period produced no increase in overall reproductive performance and had a negative effect on some reproductive parameters.

An in vivo digestibility trial was conducted by feeding sheep the leaves, fruits and twigs of Atriplex barclayana in a proportion roughly equivalent to that eaten by sheep grazing freely in Atriplex plantations. Four treatments were imposed on each of four sheep in a 4 × 4 Latin-square experimental design: Atriplex offered alone or with 100, 200 or 300 g/day tapioca meal.

The mean apparent digestibility of the Atriplex dry matter (DM) and organic matter (OM) consumed were 0·59 and 0·56, respectively. Addition of tapioca to the Atriplex in the diet did not improve these digestibility coefficients. The low OM content of 760 g/kg together with its digestibility of 0·56 resulted in the Atriplex having a low metabolizable energy concentration of 6·28 MJ per kg DM. The in vitro apparent DM digestibility of Atriplex was approximately 0·09 higher than the in vivo apparent digestibility.

The mean nitrogen concentration of the Atriplex DM was 16·6 g/kg, and its apparent digestibility 0·73, which was not improved by the addition of tapioca to the diet. Nitrogen retention of the sheep eating only Atriplex was proportionately 0·17 of the nitrogen intake. The addition of 300 g tapioca improved nitrogen retention to 0·27 but was not significantly different from the other treatments.

Water intake and urine excreted were as high as 14 and 12 I/day respectively, for an Atriplex DM intake of about 1300 g/day. During the experiment the sheep only maintained live weight, despite daily intakes of up to 1200 g Atriplex DM and up to 300 g tapioca.

Patterns of milk production and circulating blood metabolite and hormone concentrations were determined throughout a 14-week lactation in groups of 10 twin-rearing East Friesland EF) and Scottish Blackface (SBF) ewes. All ewes were offered, ad libitum, a pelleted diet throughout the experiment and milk yields were measured weekly. Pooled blood samples (six samples, 20-min intervals), collected before feeding, on 1 day of each week, were assayed for plasma glucose, non-esterfied fatty acids, 3-hydroxybutyrate (3-OHB), albumin, total protein, insulin, growth hormone (GH), cortisol, prolactin, thyroxine (T4), and triiodothyronine (T3). At weeks 2, 4,10, and 14, samples were collected at 20-min intervals for 8 h and assayed individually for plasma insulin, GH, cortisol, and prolactin. Mean daily intakes and milk yields of ewes were similar in the two breeds. Mean pre-feeding concentrations of most blood metabolites during the experiment were also similar in ewes of the two breeds but SBF ewes had higher plasma concentrations of 3-OHB (0·67 v. 0·43 mmol/l; P < 0·01) and total protein (73·2 v. 66·4 g/l; P < 0·001). SBF ewes had higher overall mean concentrations of insulin (9·53 v. 4·36 mU/l; P < 0·001), cortisol (7·59 v. 573 μg/l; P < 0·05), prolactin (457·1 v. 316·1 μg/l; P < 0·05), and T3 (1.32 v. 1·12 μg/l; P < 0·001). GH and T4 profiles were similar in the two breeds. Following the daily introduction of fresh food, there were significant increases in concentration of insulin (P < 0·001) and cortisol (P < 0·01) while there was a decrease in mean concentrations of GH (P < 0·001) and prolactin (P < 0·01). There were significant interactions between breed and feeding effects on insulin, GH, cortisol and prolactin concentrations. Patterns of milk production in ewes of these breeds were associated with changes in insulimGH ratios both before and after feeding which may be of a causal nature.

The effect of including full-fat Colombian rice polishings, at 250 or 500 g/kg dry matter (DM) or defatted Colombian rice polishings (at 500 g/kg DM) on the fermentation of a basal diet of dried grass and medium-quality hay, in the rumen simulation technique (Rusitec), was investigated. With diets which contained 0, 0·25, 0·50 full-fat or 0·50 defatted, proportions of rice polishing, values for pH were depressed (7·22, 7·19, 7·11, 7·06 (s.e.d. 0·05)) and total volatile fatty acid concentrations were increased (52·8, 52·5, 75·5, 754 (s.e.d. 2·1) mmol/l) at the high levels of inclusion of rice polishings. Concentrations of ammonia (130, 140, 228, 209 (s.e, d. 64) mg/l) and total bacterial numbers (2·32, 2·70, 3·55, 442 (s.e.d. 0·82) × 108 per ml) were elevated by rice polishings inclusion. Numbers of cellulolytic bacteria (2·52, 1·74, 1·84, 2·10 (s.e.d. 0·60) × 106 per ml) and protozoa (19·8, 16·2, 15·8, 22·2 (s.e.d. 1·51) × 103 per ml were depressed (the latter significantly P < 0·01) by the inclusion offull-fat, but not by defatted, rice polishings.

Two experiments were carried out with weaned piglets from 8 to 25 kg live weight in order to determine the dietary amino acid content necessary for maximum growth. Six diets based on wheat, soya-bean meal, soya-bean oil and free amino acids were compared in each experiment. Essential amino acids were in the same relative proportion for all diets: (methionine + cystine)/lysine = 0·60 to 0·65; threonine/lysine = 0·65; tryptophan/lysine = 0·19. The range of amino acid content was 9·53 to 12·52 g lysine per kg in the first experiment and 11·34 to 15·94 g lysine per kg in the second experiment. The number of piglets used per diet was 136 (20 pens) and 106 (16 pens) in respectively the first and the second experiment. The relationship between either dietary lysine content or daily lysine intake and growth rate was quadratic and significant. Dietary lysine content and daily lysine intake which enable maximum growth were calculated according to this model. Dietary lysine contents were 15·5 and 14·9 g/kg for the first 3 weeks (8 to 17 kg) and for the overall post-weaning period (8 to 25 kg) respectively. Daily lysine intakes were 10·6 and 13·3 g/day respectively for the same two periods. Reasons for these values being higher than those currently cited are discussed.

The experiment examined the effect of breed, diet and sex on pig performance and carcass quality. Eight sires of the Duroc and Large White breeds each produced four experimental litters. Two boar and two female pigs from each litter were reared under standard conditions to 38 kg and then one of each sex was allocated to each of two finishing diets. These were cereal-based diets with and without 16 g/kg soya oil. Following slaughter at 80 kg, loin chops taken from half of the pigs (two litters per sire) were subjected to detailed investigation of physical, chemical and organoleptic characteristics. Lifetime live-weight gain was similar for both breeds but Duroc-sired pigs had greater voluntary food intakes and poorer food conversion efficiencies in the finishing stage. They also had greater killing-out proportions (775 v. 755 g/kg, P < 0·001) and backfat thickness at slaughter (284 v. 27·2 mm at P1 + P3, P < 0·05). Fat firmness measured by penetrometer at 4°C was lower in Duroc-sired pigs (738 v. 792 units, P < 0·001). The proportion of extractable intramuscular lipid was greater in chops from Duroc-sired pigs (13·8 v. 10·4 g/kg, P < 0·001). There were no significant effects of breed or diet on the eating quality of the grilled chops as assessed by a trained taste panel and a consumer panel.

Two experiments were conducted to elucidate the effects of intra-muscular injection of oestradiol within 1 min of birth (experiment 1) or within 4h of birth (experiment 2) on piglet activity, growth and pre-weaning survival rate. In experiment 1, 248 piglets (25 litters) were alternately injected within litter at birth with either 1 ml peanut oil/saline solution or 0·1 mg oestradiol benzoate in this carrier solution. The subsequent behaviour, growth and survival of these piglets were recorded. Experiment 2 used 38 litters (385 piglets), these being treated by litter with either of the same two treatments as soon after birth as they were found (approx. range 0 to 4 h). Piglet survival data were collected from this field trial. Oestradiol treatment significantly reduced the intervals from birth to reaching the udder (596 v. 740 s, P < 0·05) and from birth to first sucking (1060 v. 1497 s, P < 0·01) relative to control piglets in experiment 1. Treatment had no significant effect on pre-weaning growth rate (experiment 1), but did tend to reduce early postnatal mortality rate in both experiment 1 (7·2 v. 2·4% for control and oestradiol-treated piglets respectively) and experiment 2 (13·0 v. 10·2% for control and oestradiol-treated piglets respectively). It is concluded that oestradiol treatment at, or soon after, birth induces short-term hyperactivity in piglets. This may subsequently be reflected in an improvement in pre-weaning survival rate of piglets, although further data are required to confirm this conclusion.

An experiment was carried out for 4 weeks in early spring with 20 Friesian cows in their 6th month of lactation. Treatments were associated with grazing intensity of Persian clover (Trifolium resupinatum) such that daily pasture intakes ranged from 10·0 to 19·5 kg dry matter (DM) per cow. The marginal return to extra feeding obtained over the whole range of grazing treatments averaged only 0·4 kg milk for each additional kg DM of Persian clover eaten. This was very low considering the quality of the diet on offer (0·73 digestibility in vitro). It is suggested that a leaf fungal disease may have been implicated; this is discussed.

Ease of handling (time to enter and exit scales and dip, and temperament scores) and flight distance were studied in Bos indicus and Bos taurus cattle and their crossbreds. At one research station (LS), 20 cows and 20 female calves, each of N'dama and West African Shorthorn (WASH) cattle were used. At another research station (BRS), 15 cows each of N'dama, Holstein and their crossbreds (NH) were used for the study. In addition a further 20 cows and 20 female calves of the N'dama breed were studied at BRS for comparison with the N'dama at LS. There were no significant differences in ease of handling and flight distance between N'dama and WASH and between N'dama at LS and at BRS. There were significant differences between N'dama, Holstein and NH cows in ease of handling and flight distance. Cows took a shorter time to enter but generally a longer time to exit a scale, had a shorter flight distance and a lower temperament score (P < 0·01) than calves.