I am very honoured to be invited to give this Lecture. I knew John Hammond well, and am personally in his debt for the many kindnesses and considerations he extended to me early on in my career. He was, in more ways than one, a giant of a man, and it is most fitting that this Society should honour his memory by inviting special lectures in his honour, and especially on the 50th anniversary of the founding of the British Society of Animal Production (BSAP) in 1944.

An experiment was carried out to evaluate dairy performance and rumen fermentation from a forage-based diet supplemented with Lucaena leococephala (leucaena) and maize bran. Bos indicus (Ayrshire/Brown Swiss) х Bos taurus (Sahiwal) cattle were offered Pennisetum purpureum (napier grass) ad libitum either unsupplemented (N) or supplemented on a dry-matter (DM) basis with 1 kg (LL) or 2 kg leucaena (LH) or 2 kg leucaena together with 1 kg DM maize bran (LHM). Food intake, milk yield, diet apparent digestibility and nitrogen balance were measured using eight cows (mean live weight 384 (s.d. 41) kg in two 4х4 Latin squares. Rumen fermentation was measured using four rumen fistulated steers (mean live weight 352 (s.d. 12) kg in a 4 х 4 Latin square. Performance was recorded during the last 7 days of each 21-day experimental period. Supplementation increased food intake (6·3, 7·6, 7·9 and 8·7 kg DM per day; P < 0·01; s.e.d. 0·24) and milk yield (5·1, 5·4, 5·5 and 6·5 kg/day; P < 0·01; s.e.d. 0·28) for N, LL, LH and LHM respectively. Supplemented diets tended to be more digestible compared with napier grass as the sole food (organic matter apparent digestibility coefficients 0·54, 0·55, 0·57 and 0·57; s.e.d. 0·020; N, LL, LH and LHM, respectively) and N balance increased progressively with supplementation.

Supplementation progressively increased rumen ammonia-nitrogen concentrations in steers and the rate of rumen degradation of napier grass increased when leucaena (diets LL and LH) was offered. The results suggest that supplementation of napier grass with leucaena increased DM intake owing to increased ammonia concentrations and rates of napier degradation in the rumen. Supplementation of the forage diet with 1 kg DM maize bran did not significantly reduce the rumen degradation of napier grass and increased the molar proportions of propionate which may have increased the efficiency of utilization of metabolizable energy and therefore milk production.

The synchronization of eating, ruminating and idling activity by lactating dairy cows grazing a perennial ryegrass-white clover sward was studied. Synchronization was defined as the number of pairs of cows engaged in a particular activity as a proportion of the total possible number of pairs and was compared with random expectation using a kappa statistic. All three activities were significantly more synchronized than random expectation. This suggests that wherever possible individual cows should not be treated as replicates in grazing experiments.

Sixteen Finnish Ayrshire cows were used in a four period cyclic change-over experiment to evaluate eight concentrate supplements in a 2 × 2 × 2 factorial arrangement. Two concentrate energy sources (starchy and fibrous) were used, each given with two levels (0 and 180 g/kg on a dry-matter (DM) basis) ofrapeseed meal (RSM) and two levels (0 and 180g/kg on DM basis) of wet distillers' solubles (WDS). The starchy concentrate (S) comprised rolled barley and oats (1:1). For the cows given the fibrous concentrate (F), 600 g/kg of the grain mixture was replaced with a mixture of fibrous by-products. Grass silage was offered ad libitum and the supplements offered at a rate of 9 kg/day (fresh weight).

The cows offered F supplements consumed more silage DM than those offered S supplements (P < 0·01) but the difference in the total DM intake was smaller. The cows given S supplements produced slightly more milk than those given F supplement (26·5 v. 25·9 kg/day) but no differences were observed in the yield of milk constituents between the energy supplements. Replacing starch with fibre in the concentrate had no effect on the apparent digestibility of organic matter but tended to increase that of neutral-detergent fibre.

Including RSM in the supplement increased total DM intake (P<0·05) and led to increases in the yield of milk and milk constituents (P < 0·001 and P < 0·01). Diet apparent digestibility was not affected by RSM supplementation.

There were no significant interactions between concentrate energy source and RSM supplementation. Including WDS in the diet had no effect on food intake. Production responses to WDS supplementation varied with the concentrate energy source. WDS increased (at least P< 0·05) milk yield (1·0 kg/day) and the yields of fat (76 g/day) and protein (48 g/day) when given with the starchy concentrate. With the fibrous concentrate WDS had no effect on milk and protein yield, and decreased fat yield by 52 g/day (P < 0·05). The positive responses in the yields of milk fat and protein to RSM and WDS supplementation were almost additive with the starchy concentrate. Inclusion of WDS in the diet increased the apparent digestibility of organic matter and gross energy.

Weaning weights (or weight nearest to 205 days of age) from 8086 Mashona calves were collected from seven herds covering the period 1976 to 1988. Estimates of (co)variance components were obtained by restricted maximum likelihood using a derivative free algorithm and fitting an individual animal model. Estimates of direct additive heritability, maternal additive heritability, their correlation, total heritability and repeatability, obtained under two models were 0·243 and 0·281, 0·113 and 0·392, –0·282 and –0·269, 0·252 and 0·298, and 0·409 and 0·573, respectively. Trends within herd were estimated from the mean value of progeny born within a particular year. There were no significant trends in direct additive breeding values. A general decline in maternal breeding values was observed. Only one herd (herd 1) had a significant eroiyonmeYital freni (0·385 kg/year). It IMS emphftsilfiti that any future revision of the method used to improve the weaning weights of beef cattle should also improve their maternal breeding values.

Four diets, barley/proprietary protein concentrate (B/PC), barley/maize gluten (B/MG), barley/rapeseed meal (B/RSM) and wheat/'rapeseed meal (W/RSM) were formulated to contain 165 g crude protein and 13·0 MJ metabolizable energy per kg dry matter. In experiment 1, all four diets were offered ad libitum to Charolais × Friesian bulls from 187 kg live weight to slaughter at about 488 kg live weight. In experiment 2, the B/PC and B/RSM were offered ad libitum to Charolais × (Hereford × Friesian) bulls from 222 kg live weight to slaughter at about 491 kg live weight. There were no significant differences between treatments in daily live-weight gain, percentage fat and lean in the live animal, slaughter weight or days on experiment in either experiment. In experiment 1, the carcasses from bulls given B/PC were 14 kg heavier than carcasses from bulls given W/RSM (P<0·05), but only 10 and 7 kg heavier than from bulls given B/MG and B/RSM respectively (P<0·05). The killing-out proportion of bulls given B/PC was significantly greater (P<0·05) than bulls given B/RSM. In experiment 2, carcass weights were similar but the killing-out proportion of bulls given B/PC were again greater (P < 0·001). It is concluded that B/MG and B/RSM were as effective as B/PC as finishing diets and that wheat can be successfully substituted for barley, when offered with rapeseed meal.

The possibilities of using embryo transfer (ET) with in-vitro produced embryos as an alternative to artificial insemination (Al) for achieving pregnancy in commercial cattle, and improving the number and quality of calves produced were assessed using 157 multiparous, beefX. dairy suckling cows (mainly Hereford × Friesian) in three autumn and three spring-calving herds in Scotland. Within each herd, cows were allocated at random to (i) Al; or ET with in-vitro produced embryos, either (ii) singly (ET(s)), or (Hi) in pairs (ET(t)) to establish pregnancy. In-vitro produced embryos were derived from oocytes recovered from the ovaries of heifers with high-quality carcasses post slaughter. Semen from a single Simmental sire was used for in-vitro embryo -production and for Al across all herds. Following oestrous synchronization, Al cows were inseminated at 48 and 72 h after removal of the synchrony device. ET cows that had a palpatable corpus luteum received either one or two in-vitro produced embryos placed non-surgically in the ipsilateral uterine horn on day 7 after oestrous (oestrus = day 0). Pregnancy rate, calving rate and calving difficulty were monitored for all cows. Calf performance was monitored on the farms of origin from birth to purchase and thereafter at one finishing unit until slaughter. Animals were slaughtered at a prescribed level of body fatness and saleable meat yields determined.

Cows that received one in-vitro produced embryo gave birth to fewer calves than cows that were artificially inseminated or received two embryos (P < 0·01). Gestation length was longer for cows that gave birth to single ET calves (288 days; P < 0·01) than cows that gave birth to Al calves (285 days) or twin ET calves (284 days). Single ET calves were heaviest at birth (P < 0·01) and higher levels of assistance at calving were required for ET calves whether born as singles or twins. ET calves of both birth types grew more quickly (<1·00 kg/day; P<0·05) and produced larger carcasses (297 kg; P < 0·01) with higher yields of saleable meat (2207 kg; P < 0·01) than Al calves (0·92 kg/day; 281·7 kg; 206·3 kg respectively).

An experiment using twenty-five bulls aged between 1 and 1·5 years and weighing 117 to 209 kg was carried out to estimate voluntary dry-matter intake (DMI), digestible dry-matter intake (DDMI), dry-matter apparent digestibility (DMD) and growth rate when the bulls were given 18 foods available from smallholder dairy farms on the slopes of Mount Kilimanjaro, Tanzania. The animals were randomly allocated to five groups of five animals each. Foods were then randomly allocated to the five groups for four periods of 60 days each during which DMI was measured. A digestion trial was made at the completion of each measurement. Outflow rates of solids from the rumen were determined by giving the animals 200 g Cr-mordanted fibre of each food and grab faecal samples were obtained. Dry matter (DM) degradation characteristics of the foods were determined in sacco in the rumen of three Boran steers fed on guatemala grass and the water soluble fraction (A) was measured. DMI varied from 2·2 kg for banana pseudostem to 4·77 kg/day for urea-treated maize stover. DMD ranged from 549 for untreated maize stover to 767 g/kg DM for banana pseudostem and growth rate ranged from 72 for banana leaves to 275 glday for urea-treated maize stover. Potential degradability (defined by A + B) (where B is the insoluble fraction degradable with time) for the DM ranged from 617 g for banana leaves to 874 g/kg DM for banana pseudostem and the degradation rate (c) ranged from 0·0168 for banana leaves to 0·0440 per h for green maize stover. The separate use of degradation characteristics A, B and c in multiple regression to predict DMI, DDMI, and growth rates gave better results than when A + B or (A + B) + c were used. Multiple correlation coefficients between degradation characteristics and DMI, DDMI and group rate were r– 0·90, 0·93 and 0·93 respectively. The results indicate that DMI, DDMI and growth rates by cattle fed on crop residues and forages could be predicted well using the rumen degradation characteristics of the foods.

A comparison was made between two different finishing systems with Belgian Blue bulls. Two groups of bulls were grazed during an initial 140-day period and then finished indoors with concentrates. There were two stocking rates during the grazing period: a medium at six bulls per ha (MGFI) and a high at eight bulls per ha (HGFI). A third group of bulls was finished indoors on a concentrate diet during the whole finishing period (FI). The experiment was repeated over 2 years consecutively. The pasture which was grazed at the medium stocking rate was characterized by a higher sward height (P < 0·01), more refusals (P < 0·001), less Lolium perenne (P < 0·05) and more Trifolium repens (P<0·05) than that grazed at eight bulls per ha. The live-weight gain was 1·15 kg/day during the grazing period for the MGFI bulls and 1·00 kg/day when they were taken indoors. The increase in stocking rate reduced the gain at grass (1·00 kg/day, P < 0·001) and improved the gain indoors (1·24 v. 1·01 kg/day, P < 0·001). In the groups which were initially grazed when compared with the indoor system, the fattening period was longer (236·0 and 241·0 v. 186·9 days, P<0·01) and the live-weight gain lower (1·11 and 1·10 v. 1·44 kg/day, P < 0·001 for MGFI, HGFI and Fl respectively). The dressing proportion was greater also (P < 0·05), and there were higher concentrations of muscles (P < 0·05) and bones (P < 0·05) in the carcass of the bulls which were grazed initially. With these bulls, the lean meat was darker (P<0·05) and lost more water although there were no effects on the myoglobin content or on shear force. The net profit was in favour of the groups which were grazed.

The time spent under a shelter by eight grazing fattening bulls of the Belgian Blue breed in each of 3 years consecutively for a total of 48 days was recorded using a time-lapse recorder with infrared illumination.

During one grazing period, data were collected over 35 days (experiment 1). Observations were divided into 166 h with rain (20%) and 674 h without precipitation (80%). The average occupation rates were 15·4 (s.e. 29·1) % for the hours with rain and 4·5 (s.e. 14·8) % for the hours without precipitation (P < 0·001). The effect of intensity and duration of rain on the occupation rate was significant from 0·4 l/m2 or from 2 h.

Experiment 2 (13 days of observation) examined the influence of temperature and solar radiation on the use of shelter. The occupation rates were 21 (s.e. 23) % during the daylight hours (07.00 to 19.00 h), 6 (s.e. 8) % during the night (19.00 to 07.00 h) and 14 (s.e. 14) % during a 24-h period. The occupation rate between 07.00 and 19.00 h was significantly correlated to the mean daily temperature (r = 0·75), the maximum daily temperature (r — 0·86) and the direct solar radiation time (r 0·60). When the maximum daily temperature exceeded 20°C, the use of the shelter increased from 10 to 49% of the daylight hours.

There was no significant difference between the live-weight gains of animals from the observed group and those of other bulls on an adjacent pasture without shelter. Nevertheless, these observations suggest that a shelter may improve the welfare of grazing cattle.

Two groups each of six lambs of the fat-tailed Naeimi breed, well adapted to a semi-arid climate, were housed under semi-controlled temperature (43·2 to 43·8°C) with low relative humidity (<0·8). After a 1-week adaptation period, the first group (control) was injected subcutaneously with 1 ml vehicle solution of 40% ethanol in saline, twice daily at 08.00 and 17.00 hfor the 11-day experimental period. In the other group, each lamb was injected daily for 6 days with 0·18 mg/kg per day of the prolactin inhibitor, 2 bromo-a-ergocryptine (CB154) dissolved in the vehicle solution. Treatment during the next 5 days was as for the control animals. Rectal temperature (RT), respiratory rate (RR), water and food intakes were recorded before injections. Daily average data were used in the statistical analysis, except those of the 1st day of bromocryptine injection. Lambs of the control group were able to maintain their RT (39·5 (s.e. 0·04) °C) during heat exposure, but those treated with the bromocryptine could not (40·3 (s.e. 0·07) °C). However, the latter group continued to respire more rapidly (P < 0·01) after cessation of the CB154 treatment, reducing their body temperature slightly (39·9 (s.e. 0·06) °C). This shows that, following prolactin suppression, heat-stressed lambs were unable to regulate their body temperature despite their RR. Water intake did not change during bromocryptine treatment, but the ratio of water to dry-matter intake did increase due to lower food consumption. These results suggest that prolactin might have an important role in thermoregulation of the fat-tailed male sheep during elevated ambient temperature.

The effect of erythrocyte glutathione status and breed on the susceptibility of adult female sheep to the haemolytic anaemia caused by the brassica anti-metabolite dimethyl disulphide (DMDS) was determined in a factorial experiment. Within each breed (Scottish Blackface or Finnish Landrace), six sheep of low glutathione status (<30 mg/100 ml red blood cells (RBC)) and six sheep of high glutathione status (>70 mg/100 ml RBC) were dosed twice daily with DMDS for 35 days (25 mmol per head per day). All sheep developed a classic haemolytic anaemia within 2 weeks of the start of DMDS dosing. Weekly haemoglobin concentrations and packed cell volume values were not affected by breed or glutathione status. Heinz body numbers rose to a higher maximum in low glutathione animals but were not affected by breed. The results call into question the relationship between total erythrocyte glutathione concentration and the resistance of erythrocytes to oxidative damage.

The present experiment was undertaken to investigate adaptations to insulin action on metabolism during lactation by using plasma concentrations of β hydroxybutyrate (β OH) free fatty acids (FFA) and lactate (L) as indicators. The study included three groups each of four goats. One group was used at 12 to 31 days post partum (early lactation), one group at 98 to 143 days post partum (mid lactation) and one group at 1 year post partum (dry period). For a given physiological state, each goat was examined four times to study the effect of insulin infused for 2·5 h at two rates, medium (0·36 nmol/min) followed by high (1·79 nmol/min) in two protocols: under normal aminoacidaemia in study 1 followed by hyperaminoacidaemia in study 2. Appropriate amino acid infusions were used to blunt insulin-induced hypoaminoacidaemia under eukaliaemic and euglycaemic clamp conditions or to create hyperaminoacidaemia and maintain this state under insulin treatment. In the basal state βOH (P < 0·05), mid lactation) and FFA (P < 0·05 early lactation) were higher during lactation than in the dry period. Plasma L was unmodified. Insulin infusion always resulted in a decrease in βOH levels (P < 0·05). In both studies, the change in βOH concentration as a function of changes in plasma insulin (an index of insulin sensitivity) was greater during early lactation than in the dry period (P < 0·05); this was also the case of mid lactation in study 1. Insulin infusion decreased plasma FFA during early lactation and in the dry period in study 1 (P < 0·05), and there was a trend for insulin sensitivity to be greater during early lactation. In both studies insulin infusion did not affect plasma L in lactating goats whereas plasma L was increased in dry animals (P < 0·05). The results demonstrate that during early lactation, compared with the dry period, there is an increased ability of insulin to lower βOH and FFA concentrations. These effects were not altered by increasing plasma amino acid concentrations during insulin infusion.

Ovulation rate, embryo survival, lamb production, lamb survival and milk production of Awassi and BooroolaAwassi crossbred ewes, kept indoors, were compared. Awassi were non-carriers while Booroola × Awassi (F1) and about half of 3/4 Awassi-1/4 Booroola (BQ) ewes were heterozygous at the FecB gene. Mean ovulation rate increased by 1·5 to 1·6 corpora lutea per ewe ovulating and prolificacy by 0·7 lambs born per ewe lambing in Fj and BC1 (B+) ewes as compared with Awassi. Embryo survival rates in BC1 ewes with two, three and four ovulations were 0·83, 0·68 and 0·71, respectively. Lamb survival rates at 1 day of age were 0·93, 0·90 and 0·77 and average birth weight was 4·9, 4·0 and 3·0 kg for lambs born as singles, twins and triplets, respectively. Average milk production of the Awassi was 506 I per ewe per lactation. F1 and BC1 ewes produced respectively, proportionately 0·48 and 0·63 of the Awassi milk production and there was no significant difference in milk production between BC1,(B+) and BC1(++) ewes. The relatively low milk production of the Booroola Awassi crosses suggests that heterosis and recombination effects on milk production were negative. It is concluded that incorporation of the B allele per se can increase lamb production in the Awassi without affecting its milk production.

Stochastic simulation was used to compare the results of alternative breeding systems in a sheep population divided into 10 flocks of 120 ewes. The breeding systems compared were selection within closed flocks (CF), a closed nucleus system (CNS), an open nucleus system (ONS) and open nucleus systems with the selection of nucleus replacements being restricted to either nucleus born males (ONSRm) or nucleus born females (ONSRf). Selection was for a best linear unbiased prediction of breeding value for lamb live weight which had a heritability of 0·17. The open nucleus breeding systems (ONS, ONSRm, ONSRf) resulted in higher rates of genetic gain, more predictable selection responses and lower rates of inbreeding than either the closed nucleus system (CNS) or selection within closed flocks (CF). Initial genetic differences between flocks resulted in higher rates of genetic gain in the nucleus breeding systems due to the use of between flock genetic variance. In the ONS system up to 25% of nucleus sires and approximately 50% of nucleus dams were born in base flocks. Nevertheless if selection of either nucleus sires or dams was restricted to nucleus born animals there was very little change in genetic gain or rate of inbreeding.

Two studies, one using a trained taste panel and the other a consumer panel, were carried out to evaluate the eating quality of the Meishan breed. Entire male and female pigs of four genotypes: purebred Meishan (MS) and Large Wliite (LW) and the reciprocal crosses (MS♂ × LW ♀ and LW♂ × MS♀) were reared in single sex groups and given a commercial diet ad libitum from 35 kg live weight to slaughter at around 70 kg. For the taste panel, a loin joint was roasted under standard conditions and samples of fat and lean were presented to the panellists. There were no statistically significant differences between the genotypes for tenderness, juiciness, flavour, odour, incidence of boar taint or overall acceptability. Purebred Meishan samples had a higher incidence of abnormal odours but lower cooking losses and shear force values than the other three genotypes. Meat from gilts was judged to be significantly more tender and juicy, with a weaker pork flavour but a lower incidence of abnormal flavours and higher overall acceptability than that from boars. There were statistically significant interactions between genotype and sex for tenderness, abnormal odour and shear force which mainly involved the purebred Meishans and were of little practical significance. In the consumer study, loin chops and leg joints from purebred LW and the two crossbred genotypes were evaluated. Households received two samples of the same type of joint from the same sex in two separate distributions. Each household received an LW sample and a sample from one of the crossbred genotypes. In general, consumers found the appearance of the joints from the three genotypes to be equally acceptable. For eating quality, the within-household deviations of the crossbred compared with the LW suggested that MS♂ × LW♀ samples were considered to be of better eating quality, particularly for juiciness (deviation -0·71, s.e. 0·24, P < 0·01). In contrast, LW♂ × MS♀ samples were generally considered inferior, particularly in terms of juiciness (+ 0·59, s.e. 0·26, P < 0·05) and flavour (+0·63, s.e. 0·27, P < 0·05). However, the overall acceptability of both crossbreds was considered little different from the Large White. Overall, the results of this work suggest little benefit in eating quality for the Meishan under United Kingdom production conditions.

The aim was to investigate if selection of a balanced diet by growing and finishing pigs from foods differing in protein content is modified by the intrinsic nutrient and chemical properties of the high protein food ingredient offered. The treatments were as follows: a free-choice was offered between milled barley and either soya-bean meal (SBM) or low-glucosinolate rapeseed meal (RSM) or an equal mixture of SBM and RSM (SBM+RSM). In two further treatments (SBM/RSM and RSM/SBM) the protein supplements were changed when pigs reached 50 kg. These were compared with a control diet (CONT) formulated to provide 13-0 MJ digestible energy (DE) and 10 g lysine per kg and containing barley (680 g/kg), SBM (150 g/kg) and RSM (150 g/kg). A total of 72 pigs weighing about 30 kg were randomly allocated to the treatments in groups of six (three boars and three gilts). Pigs were slaughtered at about 90 kg and the chilled carcasses were assessed by measuring subcutaneous fat depths and cross-sections of the eye-muscle at the last rib. Responses from 30 to 90 kg on treatments CONT, SBM, RSM and SBM+RSM were, for food intake 2·57, 2·37, 2·21 and 247 (s.e. 0·08) kg/day (P < 0·05), for growth rate 0·93, 0·87, 0·70 and 0·82 (s.e. 0·05) kg/day (P < 0·05) and for food conversion 2·77, 2·72, 3·17 and 3·01 (s.e. 0·181) kg food per kg growth (P > 0·05) respectively. The amount of protein supplement selected in the diet from 30 to 90 kg on treatments SBM, RSM and SBM+RSM averaged 524, 495 and 483 (s.e.d. 64·9) g/kg respectively. With SBM this proportion decreased with increasing body weight (P < 0·01; R2 = 0·58). Changing RSM to SBM at 50 kg increased preference for the protein supplement and intake of SBM averaged 983 g/kg from 50 to 90 kg. On the other hand, switching from SBM to RSM increased preference for barley and intake of RSM averaged 572 g/kg. There were no significant differences in carcass quality but treatments RSM and SBM/RSM tended to produce increased fat depths. In conclusion, the use of RSM did not give a satisfactory level of -performance under the restricted free-choice feeding environment of this study. Preference and nutrient intake were adversely modified by RSM possibly due to the undesirable effects of antinutritive factors.

Male rabbits aged from 4 to 4·5 months were subjected to a 8L: 16D photoperiod for 4 weeks and were then split into two groups. One group of13 males was maintained at 8L: 16D (group 8). The other included 16 males and was submitted to 16L: 8D (group 16). Two successive ejaculates zvere collected and analysed once a week for 6 months. Animals from group 8 were sexually more active and ejaculated significantly larger volumes of semen than those from group 16. Performance of males from group 16 was better for all other measurements, whether these were qualitative (motility, percentage of live spermatozoa) or quantitative. Averages for the total number of spermatozoa and number of live spermatozoa per ejaculate were significantly greater in males submitted to 16L: 8D (509 and 408 v. 452 and 344 × 106 spermatozoa, respectively). However the testes of rabbits in group 8 had a significantly greater volume than those in group 16 (22·3 v. 17·4 cm3, P < 0·001). After the animals were slaughtered when 11 months of age, the volume and weight of the testes and the testis and epidydimis reserves did not differ significantly between groups. Under our experimental conditions, the sperm output of bucks exposed to 16 h of daylength was greater than that of bucks exposed to 8 h of daylength but in vivo and post-mortem measurements did not reflect this difference.

The aim of this trial was to determine the effects of a high winter feeding level on the performance of red deer calves from weaning to 15 months of age.

Two groups of 10 calves in each group were fed indoors from weaning to turn-out on good quality hay ad libitum. They received concentrates for 197 days, the first group (treatment H) ad libitum, and the second (treatment L) a daily quantity of 616 g dry matter (DM). At turn-out the two lots were grouped together for 149 days on natural pastures containing grass species characteristic of the area.

During the indoor period, treatment H calves consumed 2·5 times more concentrate than those in treatment L (272 v. 110 kg DM) and 2·8 times less hay (48 v. 234 kg DM). They weighed 19·6 kg more at turn-out (88·9 v. 69·3 kg). The difference in weight decreased to 8·8 kg at 15 months of age, but varied according to sex. This reduction of the weight gap between groups was due to the better adaptation of treatment L to pasture and to compensatory growth resulting from a higher grass intake after turn-out.

It is concluded that despite the good performance of treatment H animals in winter, a high energy level of feeding is only advantageous in certain cases. It is of benefit to animals that are to be slaughtered at 1 year of age and to lateborn calves, and can improve the frame development of females in their first breeding season.

A study was undertaken to ascertain the effect of pyridoxine in diets of varying protein to energy ratio (P: E) for Mediterranean gilthead seabream fry (Sparus aurata) with respect to protein utilization. Diets were formulated to provide three levels of added pyridoxine (0·5, 5·0 and 50·0 mg/kg), at two protein levels (320 or 470 g/kg) whilst maintaining a similar gross isocalorific profile at 20 MJ/kg. Feeding level was proportionately 0·02 of the fish body weight per day, resulting in the following effects after a 70-day feeding trial. Low P: E ratio diets (15 g/MJ) did not perform as well as high P: E diets (24 g/MJ), with respect to growth related indices. Higher inclusions of pyridoxine into diets of equal P: E ratios, caused elevations in food conversion efficiency, protein efficiency ratio and apparent net protein utilization. A marked improvement of growth rate concomitant with pyridoxine level only occurred in the high P: E diets. It was concluded that incremental additions of pyridoxine in the diet, increased the efficiency of protein utilization for all diets tested. However, the protein sparing effect oflipid was not achieved for the low protein diets indicating the relatively high requirement for protein in the growth of the juvenile seabream.