Individual dry matter intakes were measured using four groups of 16 ewes, indoors or at sparse winter grazing. In periods of varying duration (14 to 35 days) the ewe groups received 14 feedblock supplements competitively, eight trough supplements competitively or two feedblock supplements individually. In each period hay was available ad libitum. All supplements contained chromic oxide and individual supplement intakes were estimated by total faecal collection. Individual hay and total dry-matter intakes were estimated by faecal apportionment according to indigestibility of dietary components.

Metabolizable energy content (0·81 × digestible energy) of the feedblocks ranged from 7·9 to 9·2 MJ/kg dry matter compared with a value of 13·0 MJ metabolizable energy/kg dry matter for concentrates. The variation in individual supplement intake was large, irrespective of type of supplement. However the mean coefficient of intake variation for 14 feedblock supplements (0·56) significantly (P < 0·05) exceeded that (0·39) for eight trough supplements at equivalent mean dry-matter intakes.

Thus, ‘free-access’ feedblocks did not allow a more uniform supplementation than trough supplements. Supplement intake variation was higher outdoors and increased as total feedblock intake reduced.

The variation in individual hay and total dry-matter intake was lower, and generally independent of that for the supplements. Mean coefficient of variation of 0·24 and 0·22 were obtained for hay and total dry matter, respectively, based on 22 collections with competitively fed sheep.

Total daily metabolizable energy intakes of individual ewes outdoors ranged from 5 to 22 MJ per collection.

Experiment was conducted to evaluate the effect of weaning age on growth performance, feed intake, feed efficiency (FE) and blood metabolites in Nili-Ravi male buffalo (Bubalus bubalis) calves. Twenty-four male buffalo calves were assigned to one of the three treatment groups: continuous milk feeding (CMF), limited milk feeding (LMF) and early weaning (EW), and weaned off milk at 12, 10 and 8 weeks of age, respectively. For the first 3 days after birth, calves in all three treatments were fed colostrum, and were then moved to individual milk feeding at 10% of BW for the next 6 weeks. Thereafter, the provision of milk to the CMF group was gradually tapered to zero through week 12, using week 6 intakes as a base. The LMF calves were fed milk at 7.5%, 5.0%, 3.5%, and 1.5% of BW during weeks 7 to 10, respectively. Lastly, calves in the EW group were fed milk at 5.0% and 2.5% of BW at weeks 7 and 8, respectively. Calf starter (CS) feed was also provided ad libitum from weeks 2 to 12 and individual intakes were recorded on a daily basis. Blood samples were taken from weeks 6 to 12, on a weekly basis; whereas, the BW, heart girth, withers height and hip width were measured at the start of experiment and later on a weekly basis. Weight gain, average daily gain, and body measurements were the same across all three groups. Milk intake was lower (P < 0.05), whereas CS intake was greater (P < 0.05) in the EW calves compared with the other treatment groups. Dry matter intake was greater (P < 0.05) in the EW and LMF calves compared with the CMF calves. The FE was greater (P < 0.05) in the CMF calves compared with the LMF and EW treatment groups. Blood glucose concentration was similar among the treatments; however, blood urea nitrogen was greater (P < 0.05) in the EW calves compared with the CMF and LMF groups. Plasma concentration of non-esterified fatty acids was higher (P < 0.05) in the EW calves compared with the CMF calves. In light of these results, it is evident that buffalo calves can be successfully weaned as early as 8 weeks of age without negatively affecting their growth performance.

1. Measurements of digestible energy intake, live growth and carcass measurements were conducted with 96 individually housed pigs (48 male and 48 female) given the same diet at four feeding levels (ad libitum; Agricultural Research Council daily digestible energy intake (C); C–12·5%; and C–25% daily digestible energy intake. The pigs were slaughtered at one of six live weights (45, 60, 75, 90, 105, 120 kg).

2. Prediction equations of average daily live-weight gain and introscope P2 backfat thickness on the hot carcass (hot P2) were developed as functions of average daily digestible energy intake for males and females at varying live weights. The relationships found were 20·8 g live-weight gain per MJ digestible energy intake and 0·81 mm hot P2 backfat thickness per MJ digestible energy intake from 25 to 90 kg live weight.

3. Compared with feeding level C, C –25% produced no difference in feed conversion ratio, reduced shoulder maximum, mid-back and loin minimum backfat thickness by 6–8 mm (14–4%), 4–2 mm (168%) and 4–1 mm (17–5%) respectively (P<0·01) and increased eye-muscle area by 2908mm2 (10·9%).

4. Compared with females, males reached slaughter weight 9·4 days earlier, increased daily live-weight gain by 64g, increased feed conversion ratio by 0·3, had 1·6mm less hot P2 backfat thickness, had less backfat at all mid-line positions and showed no difference in eye-muscle area.

The sweating rate of N'Dama cattle was found to show a significant stepwise increase from 10.00 h to 14.00 h (P ><0·01).

Among breeds, the sweating rates (mg/10 cm2 per 5 min) in White Fulani and N'Dama cattle were similar (100·8 to 118·3), but were significantly higher than for N'Dama × German Brown (74·4), German Brown (62·6) and Friesian (56·7) cattle (P<0·10).

Sweating rate was significantly higher for the neck and midside (90·0 to 93·3) than for other sites (75·1 to 80·0) (P<0·05).

Genetic parameters were estimated using uni- and bi-variate random regression models for weight, eye-muscle depth and fat depth measures between 60 and 360 days of age. Each trait was measured up to five times in 50-day intervals following weaning on approximately 4000 Australian Poll Dorset Sheep. The model accounted for rearing type, dam age, management group and age of recording. The model used for analysing weight included quadratic, orthogonal polynomials for direct genetic and environmental effects, a linear polynomial for maternal genetic effects and heterogeneous error variance across ages. The fat and muscle analysis used linear orthogonal polynomials for direct genetic and environmental effects and heterogeneous error variance. Throughout the 300-day trajectory heritability for weight traits ranged from 0·20 to 0·31, while heritability for fat depth ranged from 0·24 to 0·34 and heritability for eye-muscle depth ranged from 0·24 to 0·40. Genetic correlations between repeated measures of the same trait at different ages were positive and declined as the age interval increased, to minimum values of 0·60, 0·31 and 0·50 for weight, fat and muscle respectively between 60 and 360 days of age. Genetic correlations between weight and fat and weight and eye muscle were moderate to high (0·6 to 0·8) and positive but decreased slightly with age. The genetic correlations between fat and muscle were moderate to high (0·5 to 0·7) throughout the 300-day trajectory. In all cases, the estimates produced in this study were reasonably consistent with the limited number of studies that exist in the reported literature. This study demonstrated the relationships that exist between repeated measures of weight, fat and muscle measures over time, which is of interest to prime lamb producers looking to select for specific breeding objectives or market end points requiring precise weight, fat and muscle combinations at certain ages.

Holstein-Friesian steer beef production is renowned globally as a secondary product of the milk industry. Grass feeding is a common practice in raising Holstein steers because of its low cost. Furthermore, grass feeding is an alternative way to produce beef with a balanced n-6 to n-3 fatty acids (FAs) ratio. However, the performance and meat quality of Holstein-Friesian cattle is more likely to depend on a high-quality diet. The aim of this study was to observe whether feeding two mixed diets; a corn-based total mixed ration (TMR) with winter ryegrass (Lolium perenne) or flaxseed oil-supplemented pellets with reed canary grass haylage (n-3 mix) provided benefits on carcass weight, meat quality and FA composition compared with cattle fed with reed canary grass (Phalaris arundinacea) haylage alone. In all, 15 21-month-old Holstein-Friesian steers were randomly assigned to three group pens, were allowed free access to water and were fed different experimental diets for 150 days. Blood samples were taken a week before slaughter. Carcass weight and meat quality were evaluated after slaughter. Plasma lipid levels and aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), creatine kinase (CK) and alkaline phosphatase (ALP) activities were determined. Diet did not affect plasma triglyceride levels and GGT activity. Plasma cholesterol levels, including low-density and high-density lipoproteins, were higher in both mixed-diet groups than in the haylae group. The highest activities of plasma AST, CK and ALP were observed in the haylage group, followed by n-3 mix and TMR groups, respectively. Carcass weight was lower in the haylage group than in the other groups and no differences were found between the TMR and n-3 mix groups. Although the n-3 mix-fed and haylage-fed beef provided lower n-6 to n-3 FAs ratio than TMR-fed beef, the roasted beef obtained from the TMR group was more acceptable with better overall meat physicochemical properties and sensory scores. According to daily cost, carcass weight and n-6 to n-3 FAs ratio, the finishing diet containing flaxseed oil-supplemented pellets and reed canary grass haylage at the as-fed ratio of 40 : 60 could be beneficial for the production of n-3-enriched beef.

In 1972 a comparison was made between rotational creep grazing (R—8 paddocks) and set stocking (S—2 paddocks) for ewes and their twin lambs at 3 stocking rates viz. 20 (H), 17 (M) and 14 (L) ewes/ha.

The herbage intakes/kg live weight of the R ewes were similar to those of the S ewes in period 1 (c. 7th week of lactation) but higher i n period 2 (c. 10th week of lactation). The intakes of the lambs were not affected by the grazing management in periods 3 or 5, but in period 4 the R lambs had a higher intake than those on S. The overall lamb growth rates were also higher on R compared with S. The carcass outputs (net of supplementary feed) were higher for any R treatment compared with any S treatment being 453, 451 and 427 for R and 419, 379 and 380 for S at the H, M and L stocking rates respectively.

There is a global imperative to reduce phosphorous (P) excretion from pig systems. In this study, a previously validated deterministic model was modified to be stochastic, in order to investigate the consequences of different management strategies on P excretion by a group of growing pigs. The model predicts P digestion, retention and excretion from feed composition and growth parameters that describe a specified pig phenotype. Stochasticity was achieved by introducing random variation in the latter. The strategies investigated were: (1) changing feed composition frequently in order to match more closely pig digestible P (digP) requirements to feed composition (phase feeding) and (2) grouping pigs into light and heavy groups and feeding each group according to the requirements of their group average BW (sorting). Phase feeding reduced P excretion as the number of feeding phases increased. The effect was most pronounced as feeding phases increased from 1 to 2, with a 7.5% decrease achieved; the increase in phases from 2 to 3 was associated with a further 2.0% reduction. Similarly, the effect was more pronounced when the feed targeted the population requirements for digP at the average BW of the first third, rather than the average requirements at the mid-point BW of each feeding sequence plan. Increasing the number of feeding phases increased the percentage of pigs that met their digP requirements during the early stages of growth and reduced the percentage of pigs that were supplied <85% of their digP requirements at any stage of their growth; the latter may have welfare implications. Sorting of pigs reduced P excretion to a lesser extent; the reduction was greater as the percentage of pigs in the light group increased from 10% to 30% (from 1.5% to 3.0% reduction, respectively). This resulted from an increase in the P excreted by the light group, accompanied by a decrease in the P excreted by the remaining pigs. Sorting increased the percentage of light pigs that met their dig P requirements, but only slightly decreased the percentage of heavy pigs that met these requirements at any point of their growth. Exactly the converse was the case as far as the percentage of pigs that were supplied <85% of their digP requirements were concerned. The developed model is flexible and can be used to investigate the effectiveness of other management strategies in reducing P excretion from groups of pigs, including precision livestock feeding.

The objective of the study was to assess the post-weaning growth response of Sahiwal calves reared on four different pre-weaning dietary regimens. The four diets were: (a) whole cow's milk, starter ration (SR; CP = 20%, total digestible nutrients (TDN) = 72%) and Berseem hay (H; Egyptian clover; CP = 21%, TDN = 63%); (b) whole cow's milk + H; (c) milk replacer (MR; reconstituted to supplier specification; Sprayfo®) + SR + H; and (d) MR + H. The protein and fat percentages of reconstituted MR were 2.22 and 1.84, respectively. Milk or MR were fed at the rate of 10% of the calves’ body weight (BW) until 56 days of age, and then withdrawn gradually until weaned completely by 84 days of age. The average initial BW of calves in groups A, B, C and D were 56.3 ± 1.0, 47.5 ± 1.0, 40.4 ± 1.0 and 30.3 ± 1.0 kg, respectively. Initially, there were 12 calves in each group with six of each sex; however, one male calf died from each of groups B and C and were not replaced. During the post-weaning period, 13 to 24 weeks, the calves were fed a single total mixed ration ad libitum based on maize, canola meal, wheat straw and molasses containing 16% CP and 70% TDN. Daily feed intake and weekly BW gains were recorded. The data were analyzed by MIXED model analysis procedures using the statistical program SAS. The intake of calves as percent of their BW, feed conversion ratio and cost per kg of BW gain were not different (P > 0.05) across treatments. The daily gain at 24 weeks of age for the pre-weaning treatments A, B, C and D were 746 ± 33, 660 ± 33, 654 ± 33 and 527 ± 33 g/day and the final liveweights of calves were 119 ± 4.2, 102 ± 4.2, 95 ± 4.2 and 75 ± 4.2 kg, respectively. Gains were influenced significantly (P < 0.05) by pre-weaning treatments. The calves fed MR and H only during the pre-weaning period were unable to catch up post weaning with calves on other dietary treatments. The calves fed whole milk from birth at the rate of 10% of liveweight together with concentrates had higher weaning weight and superior growth rate post weaning as well. Thus, pre-weaning feeding was important for higher weaning weights and superior growth rates post weaning.

For centuries, the humid West African coastal country of Benin attracts cattle herders from neighboring Sahelian countries such as Niger, Burkina Faso and Nigeria. Each year, several thousands of cattle are trekked over hundreds of kilometers to Benin following established and non-established transhumance corridors. This cross-border mobility has been shown to play an important role in ensuring the productivity of the transhumant herds through adequate late dry season access to pastoral resources. Yet, its effects on the traditional agro-pastoral production systems that are encountered along the routes in Benin have never been explicitly investigated. Therefore, we collected socio-economic household data, herd characteristics and management data from 104 resident herders and 38 transhumant herders in 2 vegetation zones of Benin. To determine whether or not the proximity to transhumance corridors affects sedentary production systems, characteristics of cattle herds and farmers’ management practices were compared between villages close to (within a 25 km buffer) and far from (outside a 25 km buffer) transhumance corridors within and between vegetation zones using non-parametric statistical tests. Existing relationships between resident and transhumant herders were also identified and characterized. Subsequently, herd characteristics and management practices were compared between resident herders having relationships with transhumant herders and those without. Herd sizes of resident herders living close to transhumance corridors were larger (P < 0.01) than those of their counterparts living far away. Also, proximity to transhumance corridors had positive effects on herd management practices. The relationships between resident and transhumant herders were governed by a variety of interests including encampment/manuring contracts, exploitation of grazing lands and watering points, trading and bartering of cattle. This exchange of cattle is an important driver of change in the breed composition of local herds and represents an opportunity for resident herders to enhance their herds’ productivity through crossbreeding. However, the mere replacement or indiscriminate crossbreeding of local cattle breeds with those kept by transhumant herders threatens the sustainability of the traditional resident herding systems by increasing the risk of genetic erosion and loss of valuable adaptive traits in indigenous animal genetic resources.

Developing countries are experiencing an increase in total demand for livestock commodities, as populations and per capita demands increase. Increased production is therefore required to meet this demand and maintain food security. Production increases will lead to proportionate increases in greenhouse gas (GHG) emissions unless offset by reductions in the emissions intensity (Ei) (i.e. the amount of GHG emitted per kg of commodity produced) of livestock production. It is therefore important to identify measures that can increase production whilst reducing Ei cost-effectively. This paper seeks to do this for smallholder agro-pastoral cattle systems in Senegal; ranging from low input to semi-intensified, they are representative of a large proportion of the national cattle production. Specifically, it identifies a shortlist of mitigation measures with potential for application to the various herd systems and estimates their GHG emissions abatement potential (using the Global Livestock Environmental Assessment Model) and cost-effectiveness. Limitations and future requirements are identified and discussed. This paper demonstrates that the Ei of meat and milk from livestock systems in a developing region can be reduced through measures that would also benefit food security, many of which are likely to be cost-beneficial. The ability to make such quantification can assist future sustainable development efforts.

Eight hundred and ninety-eight records of the interval between calving and conception (service period) of 349 Hariana cows, the progeny of 79 sires, were analysed by fitting constants for the effects of year, month of calving, calving sequence, sex of the calf, weight of the cow at calving and weight of the calf at birth. The average service period was 272·7 days with a coefficient of variability of 50·7%.

The service period was longest after the first calving. Animals calving in the months of February to August had a longer service period than those calving during the months of September to January. Heavier cows tended to have a shorter service period. Sex of the calf, calving sequence and birth weight of the calf did not affect this trait significantly.

Heritability of service period estimated from the paternal half-sib correlation using repeated records was 0·06 ± 0·018 and repeatability was 0·250 ± 0·039. It seems likely therefore that a shortening of the service period may not be possible through direct selection.

Forty-five piglets were used to study the effects of feeding diets containing 153, 239 or 321 g crude protein per kg dry matter between 1·8 and 6·5 kg live weight, and low and high protein diets subsequent to 6·5 kg live weight on growth performance, body composition and the cellularity of skeletal muscle to 45 kg live weight.

Reducing dietary crude protein between 1·8 and 6·5 kg live weight depressed growth performance and at 6·5 kg live weight increased body fat content but reduced body protein, body water and the weight and DNA content of the adductor muscle. The effects of dietary protein content before 6·5 kg live weight on body composition at the latter weight were still evident in pigs killed at 11·5 kg live weight whilst the differences in muscle DNA persisted to 45 kg live weight.

On the lower protein treatment subsequent to 6·5 kg live weight there was a tendency for pigs given the lowest protein diet before 6-5 kg live weight to exhibit better growth performance and deposit protein at a faster rate than those given the higher protein diets. However, these responses were reversed on the higher protein treatment subsequent to 6·5 kg live weight.

The effects of dietary protein content subsequent to 6·5 kg live weight on growth performance, body composition and the cellularity of muscle tissue were qualitatively the same as those for the live-weight phase 1·8 to 6·5 kg.

The nutritive value of banana by-products (leaves, pseudostems and raceme stems) for goats was studied by rumen degradability and in vitro digestibility techniques, voluntary intake and maintenance trials. Banana by-products had both a relatively low degradability and digestibility, with derived metabolizable energy content (MJ ME per kg dry matter (DM)) of 6·54 for leaves, 6·66 for pseudostems and 8·24 for raceme stems. Daily voluntary intake (g DM per kg M0·75) was 66·4 for leaves, 19·3 for pseudostems, and 15·3 for raceme stems. On these results, pseudostems and raceme stems would provide less than 0·30 of maintenance ME needs of goats. However, rations based only on banana leaves should meet more than 0·85 of the maintenance energy needs.

In the present study, the effect of type of stunning (electrical v. gas) and the gas mixtures in a modified atmosphere (MA) packing system (MA-A: 30% CO2 + 70% O2; MA-B: 30% CO2 + 69.3% N2 + 0.7% CO; MA-C: 40% CO2 + 60% N2) on light lamb meat quality, obtained by 20 males of Manchego Spanish breed, was evaluated at 7, 14 and 21 days post packing. For all ageing times, gas-stunned groups reached the highest pH (P < 0.001) and shear force (SF) values (P < 0.05), and at 21 days, water losses were highest; in contrast, meat colour coordinates were lower (P < 0.001). In general, MA-B showed the highest stability for colour coordinates whereas the lowest tenderness (high SF) was found on MA-A. In this study, the gas mixture with a low carbon monoxide level (MA-B) promoted a higher colour stability and good tenderness, in comparison to the other two blends. In contrast, the conventional packaging system (type A, high oxygen levels) had a reduced tenderness and major colour instability.

Prices of protein-rich foods increased dramatically in the summer of 1973. This caused considerable concern amongst BSAP members and a meeting of 36 scientists involved in studies of protein or allied aspects of nutrition was convened by the BSAP and held at the NIRD. The objective was to provide a statement of present knowledge on the protein requirements of the dairy cow. The Chairman of the day-long meeting was Dr C. C. Balch. A vigorous and wide-spanning discussion took place and while a definitive statement of quantitative requirements for protein was not produced, in compensation for this the state of the present knowledge on protein was revealed, so that it may be hoped that further studies will be prompted by these findings. This paper and the following one present respectively the minutes and an interpretation of the discussion.

The digestive microbiota plays a decisive role in shaping and preserving health throughout life. Rabbit younglings are born with a sterile digestive tract but then it gets progressively colonised by the microbiota of the nursing mother, by entering in contact with or ingesting the maternal droppings present in the nest. Here we posit that (i) offspring survival and (ii) lifespan of female rabbits are linked to how diverse their microbiota are. To test the hypothesis that maternal microbiota evolves in females having had different levels of offspring survival in their lifetime, we obtained 216 hard faecal samples from 75 female rabbits at ages 19.6, 31.6, 62.6 and 77.6 weeks. The annual mean offspring survival (MOS) at 64 days was calculated for each female then crossed against three alpha-diversity indexes (operational taxonomic units (OTUs), inverse Simpson index and Shannon index). Age was also analysed against these three parameters. The alpha-diversity indexes of the female faecal microbiota did not correlate with MOS, but they did decrease with age (e.g. from 712 OTUs at age 19.6 weeks to 444 OTUs at 77.6 weeks; P < 0.05). The age effect was also found in beta-diversity non-metric multidimensional scaling plots using the Bray–Curtis dissimilarity index and the unweighted UniFrac index but not for MOS. The ability of the microbiota composition from the faecal samples of young females (19.6 weeks old) to predict their lifespan was also evaluated. After subdividing the initial population into two classes (females that weaned a maximum of three litters and females living longer), we found no clear distinction between these two classes. To our knowledge, this is the first long-term study to characterise the gut microbiota of adult female rabbits through their reproductive life, thus laying foundations for using the gut microbiota data and its influence in studies on adult rabbits.

Many fibre sources can help the adaptation of piglets at weaning, improving the growth. In this study, the effects of a dietary crude fibre concentrate (CFC) on piglet’s growth was investigated. From 31 to 51 days of age, 108 weaned piglets (D×(Lw×L)), had access to two isofibrous, isoenergetic and isonitrogenous diets, supplemented with 1% of CFC (CFC group) or not (control (CON) group). From days 52 to 64 all piglets received the same starter diet. During the dietary treatment period the CFC group showed higher average daily gain, average daily feed intake and feed efficiency (P<0.001) than CON group. At 64 days of age, BW was higher in CFC group compared with CON group (P<0.001). Blood samples were collected at days 31, 38, 45 and 52 of age. From days 31 to 52 significant differences in the somatotropic axis between groups were observed. In particular, growth hormone levels were higher only at the end of the 1st week of dietary treatment (P<0.05) in CFC group animals compared with CON group animals. The IGF-I trend was similar between groups even if the IGF-I levels were higher in the CFC group than CON group 1 week after starting treatment (P<0.01). The IGF-binding protein 3 (IGFBP-3) levels were higher in the first 2 weeks of dietary treatment and lower in the 3rd week in CON group compared with CFC group (P<0.01). Specifically, the IGFBP-3 profile was consistent with that of IGF-I in CFC group but not in CON group. At the same time, an increase of leptin in CFC compared with CON group was observed (P<0.05). Piglets fed the CFC diet showed a lower diarrhoea incidence (P<0.05) and a lower number of antibiotic interventions (P<0.05) than CON diet from 31 to 51 days of age. Pig-major acute-phase protein plasma level (P<0.01) and interleukin-6 gene expression (P<0.05) were higher in CON group than CFC group at the end of 1st week of dietary treatment. In conclusion, this study showed that CFC diet influences the hormones related to energy balance enhancing the welfare and growth of piglets. Furthermore, the increase in feed intake during 3 weeks of dietary treatment improved the feed efficiency over the entire post-weaning period.

Three experiments were carried out in which plasma cortisol concentrations were measured hourly in lambs treated with various anabolic steroids. In the first experiment, female lambs were implanted with trenbolone acetate (TBA) and plasma cortisol was measured for 24-h periods 4 weeks after implantation and 1 week after reimplantation. Plasma cortisol levels were unaltered 4 weeks after treatment, but were found to be significantly lower 1 week after retreatment. On this occasion, peak concentrations of cortisol after ACTH challenge were also reduced by TBA. In the second experiment, female lambs were implanted with a mixture of TBA and oestradiol and plasma cortisol measured 1 and 4 weeks later. Results were similar to the first experiment although the reduction in plasma cortisol was less. In the third experiment, castrated male lambs were implanted with either TBA, TBA plus oestradiol or a long-acting oestradiol implant. In this experiment, only oestradiol affected plasma cortisol levels, causing a large elevation. All three treatments stimulated growth. Measurement of bound and free cortisol concentration in the third experiment indicated that oestradiol treatment tended to increase the proportion of cortisol present in the free form.

These results suggest that an inhibition of cortisol secretion may be important in the anabolic response of female sheep to TBA. In the male, however, cortisol concentrations are naturally lower and are not further reduced by TBA treatment.

Plasma insulin concentrations were also measured in the castrated males. Neither TBA nor the combined implant altered insulin levels, but oestrogen treatment resulted in a small increase in insulin. The diurnal pattern of plasma insulin closely paralleled that of cortisol.