An experiment was conducted to examine the effect of ammonia treatment or soya-bean meal supplementation on rumen and lower tract digestion and urinary purine-derivative excretion in sheep given barley straw-based diets. Four wethers each fitted with simple rumen and duodenal cannulae were randomly allocated to four diets in a 4×4 Latin-square design. The diets were, untreated barley straw + molasses meal (diet 1), ammonia-treated barley straw + molasses meal (diet 2), untreated barley straw + soya-bean meal + molasses meal (diet 3) and ammonia-treated barley straw + soya-bean meal + molasses meal (diet 4). Dry-matter (DM) intake, total tract neutral- and acid-detergent fibre apparent digestibility and faecal nitrogen (N) output were higher for diets 2 and 4. Microbial protein yield, determined from total urinary purine-derivative excretion, was also high in sheep on diets 2 and 4. However, supplementation with soya-bean meal in diet 4 reduced DM and fibre digestion but increased intake and microbial synthesis. Despite the lower microbial protein synthesis for diet 3, total tract N digestion was high for the diet, an indication of higher nutrient absorption in the lower tract. The above results indicated that there was a substantial increase in rumen microbial N yield from ammoniated straw-based diets. However, not all the N was made available to the animals. Some of the microbial N absorbed in the lower tract may have been overestimated by the use of the purine derivative-microbial N evaluation method. On the other hand, when protein supplements were given the amount of microbial protein available to the ruminant through absorption in the lower tract may have been underestimated by urinary purine derivatives.

Acacia saligna and A. salicina phyllodes, harvested in autumn from young and mature trees, were fed as sole diets to goats (20·3 (s.d. 4·8) kg; no. = 16) and sheep (32·6 (s.d. 4·9) kg; no. = 16). Crude protein of phyllodes from mature trees was 111 g/kg dry matter (DM) and from young trees ranged between 121 and 132 g/kg DM. Condensed tannins and ash content were about twice as high in young trees as in old ones and gross energy was higher in old trees than in young ones. DM intakes by goats from both tree species were low: 24·8 and 13·7 g/kg M0·75 per day for mature and young trees, respectively. Corresponding intakes by sheep were 20·4 and 11·5 g/kg M0·75 per day. Metabolizable energy intakes were up to 125 and 99 kj/kg M0·75 per day for goats and sheep, respectively and were higher for phyllodes from mature trees than for young trees. Goats lost up to 219 glday and sheep up to 346 g/day and both species were in negative nitrogen balance. DM, organic matter and energy apparent digestibilities were low for all diets but were generally higher for goats than sheep. It is concluded that neither A. saligna nor A. salicina could be used as a sole food for small ruminants because of low intakes and negative nitrogen balances. This appears to be due to high tannin content.

A study was conducted to compare the effects of ammoniation and protein supplementation of barley straw on rumination behaviour of sheep. Four wethers were allocated to four diets offered ad libitum in a 4 × 4 Latin-square design. The diets were, untreated barley straw + molasses meal (diet 1), untreated barley straw + soya-bean meal + molasses meal (diet 2), ammonia-treated barley straw + molasses meal (diet 3) and ammonia-treated barley straw + soya-bean meal + molasses meal (diet 4). Animals were kept in metabolism crates throughout each 16-day experimental period and allowed free access to water and a mineralized salt lick. The first 11 days of each period were for adaptation to the harnesses and diets while the last 5 days were used for rumination studies. Animals given diets 3 and 4 had slower eating rates compared with those given diets 1 and 2. Rumination index and duration of each rumination period was lower for sheep consuming diets 3 and 4 than for those on diets 1 and 2 but not significantly so (P > 0·05). Rumination time per 100 g neutral-detergent fibre (NDF) intake was significantly lower (P < 0·01) for diets containing ammoniated straw. Animals given ammoniated straw diets also regurgitated fewer boluses per unit NDF intake than did those on untreated straw diets. The results showed that increased intake and digestibility, which is usually associated with ammoniated straws, was due to sheep doing less work per unit of time to break down straw for digestion. In this way, potentially digestible tissues within a given amount of straw is more readily exposed. The foregoing suggests that ammonia treatment results in less rumination so that ruminants given ammonia-treated straw diets do less work ruminating.

Carcass and eating quality characteristics of crossbred wether and female lambs sired by Charollais (C), Suffolk (S) and Texel (T) rams out of Mule ewes (Bluefaced Leicester ♂ × Scottish Blackface ♀ or Swaledale ♀J)were evaluated in a study carried out over a 3-year period in an upland flock. A total of 10 unrelated rams of each breed were used as sires. Lambs (no. = 280) were selected for slaughter at the same estimated subcutaneous fat level on four occasions within each year (i.e. at weaning in July and at approx. monthly intervals thereafter). Following slaughter, the left side of each carcass was physically dissected. A loin joint from lambs slaughtered in the 2nd and 3rd years of the study (no. = 184) was used to evaluate eating quality.

Suffolk-sired lambs were heavier at slaughter (S: 42·2; C: 41·0; T: 40·7 (s.e. 0·35) kg) but had similar killing-out proportions compared with the other two breeds (S: 444; C: 450; T: 452 (s.e. 26) g/kg). Texel-sired lambs had higher lean proportion (S: 543; C: 550; T: 567 (s.e. 4·4) g/kg) and lower total carcass fat proportion (S: 240; C: 242; T: 233 (s.e. 5·3) g/kg) compared with S and C sired lambs. Bone proportion was similar for C and T lambs but was higher for S (S: 199; C: 191; T: 191 (s.e. 2·1) g/kg). Lean: bone (S: 2·75; C: 2·90; T: 2·99 (s.e. 0·037)) and lean:fat (S: 2·38; C: 2·40; T: 2·54 (s.e. 0·034)) ratios were higher for T-sired lambs. Female lambs were lighter (40·4 v. 42·2 (s.e. 0·24) kg), and had proportionately more intermuscular fat than wethers (122 v.118 (s.e. 1·3) g/kg) but the sex differences for other tissue proportions were small. Carcass weights and total carcass fat proportions increased and lean proportions decreased across the four slaughter dates. There were no effects of breed or sex on eating quality. However, samples from lambs slaughtered at weaning were judged to be more tender than those slaughtered later in the season.

One hundred and twenty-six twin-bearing ewes were given either formic acid (FA) treated grass silage or grass/ molassed sugar-beet pulp (MSBP) silage in order to investigate factors affecting colostrum yield and quality and the efficiency of immunoglobulin (IgG) absorption. The experiment commenced on day 91 of pregnancy and the diets consisted ofFA-treated silage (Tl), FA-treated silage + soya-bean meal (SB) (72), MSBP silage (T3), MSBP silage + SB (T4), FA-treated silage + MSBP (T5), FA-treated silage + MSBP + SB (T6) or FA-treated silage + 150 g/kg of a crude protein concentrate (T7). Soya-bean meal was offered only in the last 3 weeks of pregnancy aiming for a total crude protein intake of220 g per ewe per day. Blood samples were taken from lambs in order to measure serum Ig concentrations. Ewes were milked at 1 h,10h and 18 h post lambing. Daily metabolizable energy intakes of 6·8, 11·4, 9·6, 12·8, 10·5, 13·7 and 14·7 (s.e. 0·58) M] per ewe were recorded for Tl to T7 respectively over the last 3 weeks of pregnancy. Respective crude protein intakes of 72, 213, 110, 225, 109, 215 and 175 (s.e. 5·64) g per ewe per day were recorded for Tl to T7 over the last 3 weeks of pregnancy. The addition of protein increased colostrum yield at 1 h (P < 0·01), 10 h (P < 0·01) and 18 h (P < 0·01) post lambing and total yield of colostrum to 18 h (P < 0·001). There was no significant response (P > 0·05) in colostrum production during the first 18 h following protein supplementation when the basic diet was FA-treated silage. There was no difference (P > 0·05) in colostrum production during the first 18 h between ewes offered MSBP treated silage or MSBP supplemented silage. Ewes offered FA-treated silage produced less colostrum during the first 18 h compared with ewes offered either MSBP treated or supplemented silage (P < 0·05). The production of colostral IgG during the first 18 h after parturition was related to the amount of colostrum produced; the greater the colostrum production the greater the Ig production. There was a significant quadratic relationship between the total amount of IgG ingested per kg lamb birth weight during the first 18 h and lamb serum IgG at 24 h (R2 = 0·4005; P < 0·0001). Lamb serum Ig level increased linearly with increasing colostrum IgG consumption up to 15 g/kg lamb birth weight. Proportionately about 0·17 of the IgG ingested was present in the lamb's circulation at 24 h. Ewe protein supplementation pre-lambing increased the lamb's efficiency to absorb colostral IgG (P < 0·05) during the first 24 h. In conclusion, the data show positive relationships between feeding regimes, colostrum production and IgG transfer.

Forty-eight Greyface wether lambs, aged about 6 months and weighing 32 kg on average were used. They were allocated to be treated, by subcutaneous implantation in the upper surface of the ear flap, with the naturally occurring steroids oestradiol-17β (O), testosterone (T) or the synthetically produced androgen trenbolone acetate (TA). Treatment groups were as follows: sham-implanted controls (C); 50 mg O (slow release formulation) (O); 40 mg TA (compressed pellets} (TA); 50 mg T (compressed pellets) (T); 15 mg O + 40 mg TA (TAO); 15 mg O + 50 mg T (TO). Combined implants were placed in close proximity under the skin of the same ear. The lambs were offered, to appetite, a good quality diet containing per kg dry matter (DM) an estimated 12-0 MJ metabolizable energy and 150 g crude protein. Comparisons were made for the main effects of O and the androgens T and TA. Main effects due to O were increased DM intake, live-weight gain (LWG) empty body weight (EBW), chilled carcass iveight (CCW), carcass crude protein (CP) deposition, plasma insulin concentrations and teat length with reductions recorded for the proportion but not weight of fat in the carcass, plasma urea and thyroxine concentrations. Treatment with androgens did not, on average, influence LWG or other indices of growth performance or carcass composition other than to produce significant increases in carcass phosphorus deposition and reduction in the depth of thorax. Significant increases in the iveight of penile tissue and reductions in teat length were recorded. There was evidence for a greater androgenic effect on penile tissue and anti-oestrogenic effect (on teat length) of TA compared with T at the concentrations used. TA also reduced the weight of the thymus gland, an effect reversed in the presence ofO.

Analysis of plasma taken from the vein contralateral to the site of implantation showed that O concentrations were reduced in the presence of TA and T, and that O had no effect on the concentrations of androgens measured. Concentrations ofT and 17 β-hydroxy-trenbolone in blood were of a similar order, which for T is typical of postpubertal entire male sheep.

The results suggest that O treatment was effective in promoting growth and carcass CP deposition which was not increased by T or TA, despite the presence of these androgens at biologically active concentrations in blood. This effect appears to differ from the additive effects frequently obtained for castrated male cattle.

Thirty-five mature Churra ewes, ranging in live weight from 30·3 to 52·6 kg and in body condition score from 1·25 to 4·00 were used to study the relationship between body condition score (BCS), live weight (LW) and body composition and fat distribution in ewes of this breed, which is one of the major sheep breeds of northern Spain. The procedure at slaughter and at subsequent dissection was designed to partition each body into two components, carcass and ‘non-carcass’. Right side carcasses and ‘non-carcass’ components were used to analyse the chemical composition. From the left side of the lumbar region a joint was cut and dissected into muscle, bone, subcutaneous and intermuscular fat. According to the results obtained, omental fat represented the highest proportion of total internal fat regardless of the level of fatness. Distribution of internal fat was similar to that observed in other milk production breeds. Regressions on LW explained more of the variation than those on BCS for individual internal fat depots and chemically determined ‘non-carcass’ fat. The prediction of total body fat afforded by LW was better than that provided by BCS. The subcutaneous and intermuscular fat depots in the lumbar joint were well correlated with BCS, carcass fat and total fat in the body, validating the use of this region for assessing BCS in Churra ewes. Nevertheless, the correlation coefficient with the omental depot was not statistically significant. The results of this study suggest that BCS was not as accurate for estimating body composition and fat depots in mature Churra ewes as has been shown previously in other breeds. The single most effective prediction index was LW. However, the utilization of both BCS and LW together provided more accurate estimations.

The genetic and economic efficiency of alternative selection schemes and breeding objectives for the Karagouniki dairy sheep in Greece was investigated by model calculations. Criteria of efficiency were the annual genetic gain for the aggregate breeding value, the profit per ewe in the population and the annual selection responses for single traits. The introduction of a two-tier selection scheme, where the recorded ewes are separated into a nucleus and a pre-nucleus, was found superior in both genetic and economic terms for a breeding objective comprising the traits milk yield and number of lambs weaned per ewe per annum. Highest rates for annual genetic gain and selection responses were obtained when the nucleus size was proportionately 0·05 of the population (200 000 ewes), the size of the test matings 0·50 to 0·60 of the size of the pre-nucleus unit (0·10 of the population) and the number of daughters per test ram 40. Opening the nucleus to replacement ewes from the lower tier did not affect positively the annual genetic gain and the selection responses. Furthermore, a breeding objective comprising the traits fat yield and number of lambs weaned per ewe and per annum was found very efficient in both genetic and economic terms while selection on growth and carcass traits did not seem to be justified.

Thirty Suffolk cross wether sheep aged about 12 months and weighing 57 kg on average were used. They had been given previously a high energy diet to produce a fat body condition and average condition score of 3·7. Animals were allocated to an initial slaughter group (IS) or to four dietary treatment groups (UL, UH, CL and CH) based on sugar-beet feed (L) or white-fish meal (H) supplemented with chopped straw and pelleted, without (UL and UH) or with (CL and CH) the β-adrenergic agonist cimaterol, to provide an estimated 20 g (L) or 130 g (H) rumen undegradable protein per kg dry matter (DM). The sheep were offered 0·3 kg of the appropriate pelleted diet in addition to 200 to 400 g of chopped barley straw to provide proportionately 0·7 of the estimated metabolizable energy requirement for maintenance and, where appropriate, 2·5 mg cimaterol per day. Comparisons were made for the main effects of dietary protein intake and cimaterol and interactions between dietary protein and cimaterol.

The animals on dietary treatments were slaughtered after 49 days. The animals exhibited variable reductions in live weight and weights of carcass and non-carcass components in comparison with the IS group and in response to restricted dietary energy intake. The only effect due to the elevated dietary protein provision was a smaller loss in live weight compared with the low protein diet. In contrast, compared with responses recorded in its absence, treatment with cimaterol resulted in significantly greater values for weights of cold carcass, cross-sectional area o/m. longissimus dorsi and weights of DM, crude protein and ash in the carcass with significantly smaller weights for raw fleece. In comparison with the IS group, significantly smaller changes due to cimaterol were recorded for the weights of carcass crude protein and ash. Cimaterol treatment significantly increased the weight loss of fat in the carcass and in the perirenal and retroperitoneal, but not omental, depots as components of fleece-free non-carcass fat which was also significantly reduced in total. Interactions suggested that losses in carcass weight and DM in the presence of cimaterol were less and gains in carcass protein and ash greater, on the high than on the low protein diet. The results suggest that under conditions of energy undernutrition cimaterol may induce smaller losses or larger gains in carcass but not non-carcass, crude protein at the expense of fat depletion in carcass and non-carcass fat depots.

During a 3-year period, from April 1991 to December 1993, in a flock with four lambing periods annually, faecal samples from lambs at weaning at the age of 3 months (no. = 1756), were examined for gastro-intestinal nematode eggs by the McMaster method. Faecal samples were also examined at the age of 9 (no. = 170), 12 (no. = 157), 15 (no. = 253) and 18 (no. = 85) months from the females only. From June to December 1993 packed cell volume (PCV) was also examined from lambs at weaning. Seven genotypes were used in this study.

The faecal egg counts were affected by genotype, birth season, type of birth and rearing, sex and age. First generation cross of Sumatra × Barbados Blackbelly had lowest eggs per g of faeces (EPG) followed by Sumatra, St Croix, Sumatra × St Croix Fl and F2 and Sumatra × Java Fat tail. Lambs born in February-March when rainfall was low had lower EPG (V < 0·05) than those born in May-June or August-September. The EPG of lambs born and reared singly were significantly lower (P < 0·001) than those born twin, triplet or quadruplet. Female lambs had lower EPG than male lambs (P < 0·001). The EPG of lambs at 3 months were higher than at 9, 12, 15 or 18 months (P < 0·001).

PCV was affected by genotype, sex, type of birth and rearing and season of birth. There was a positive correlation between PCV and weaning weight of lambs and a negative correlation between EPG and weaning weight. These results show that the crosses of St Croix and Barbados Blackbelly with local Sumatra sheep are at least as resistant or more resistant to gastro-intestinal nematodes than pure Sumatra breed and therefore these breeds can be used in cross breeding programmes to improve the body size of local Sumatra sheep.

After 14 h of confinement in a stationary trailer, sheep were found to have lost proportionately a mean of 0·057 of their body weight. Two experiments, one with a heterogeneous flock (28·6 to 93·2 kg body weight) and the other with a more homogeneous flock (32·4 to 46·6 kg) showed very little recovery of this loss after 1 h of ad libitum food and water. When offered familiar concentrates, sheep ate on average 1·2 kg per animal in the 1st h, water only being taken in quantity (>5·01 per animal) in the next 6 h. Hay was taken at a much lower rate (0·25 kg per animal) and less water drunk (1·51 per animal). Competitive social interactions were five times more frequent during hay feeding than during concentrate feeding. After 14 h of confinement a break of Ih is evidently insufficient for feeding and watering and could result in poor welfare. If concentrates are offered, the resulting water deficit will not be redressed within 1 h, resulting in a strong motivation to drink when no water is available. If hay is offered, the heightened level of competitive social interaction could also result in poor welfare.

Blood from 106 females (1 to 7 years old) of the Cambridge flock at the University of Wales, Bangor was analysed for 21 protein systems. Of the 11 polymorphic systems, haemoglobin protein (HBB) was found to be significantly associated with ovulation rate as measured by mean ovulation rate for all records per ewe. Mean ovulation rate for the HBB AA genotype was 1·25 ovulations higher than for the AB and BB genotypes (P < 0·001). The results suggest that a gene segregating in this breed is different from the Booroola (FecB) gene and that lambs of either sex can be screened at a young age for a major difference in ovulation rate.

A model is developed in which the metabolizable energy (ME) requirement for growth and maintenance of the foetus, uterus and udder are described explicitly for sheep. The efficiency of the use of ME for the growth of the products of conception (kp) is assumed to be the same as that for growth in non-pregnant animals. Using the results from the model to calculate the efficiency of the use of ME for conceptus growth (kc) in the conventional manner yields values with a similar magnitude and similar variation with food quality as those estimated experimentally. It is concluded that separately accounting for the growth and maintenance of the foetus, uterus and udder is preferable in models but unnecessary in feeding standards.

This paper describes a general framework which enables responses to selection for resistance to gastro-intestinal parasites in sheep to be stochastically modelled. The model incorporates between-animal variation for pasture intake, the proportion of larvae ingested from the pasture which survive to become adults, the fecundity of the mature worm, along with density-dependent control of this trait and the mortality rate of the worms. The between-animal variation for each component is partitioned into genetic, permanent and temporary environmental components which vary with age. Infection rates are estimated from existing pasture larval contamination and new contamination from infected animals. Using this framework, selection for reduced mean faecal egg count was practised, in silico, for a period of 10 years. Several general patterns emerged. First, a curvilinear response to selection was observed, with responses initially being large then declining over time. Mean faecal egg count declined from approximately 500 to 140 eggs per gin 10 years and worm burdens and pasture larval contamination showed similar patterns of response. The initial responses to selection were approximately 1·7 times that predicted by quantitative genetic theory because the epidemiology of the disease changed as the animals' genetic resistance improved. A method of partitioning selection responses into components due to the altered genotypes of the animals and components due to altered disease epidemiology is outlined. Secondly, the faecal egg count distribution became more aggregated, or skewed, as selection progressed. Thirdly, correlating pasture contamination levels across years (carry-over effects) resulted in even greater apparent responses to selection. Finally, regular anihelmintic treatment reduced mean faecal egg counts but did not alter the patterns of response to selection, indicating that selective breeding should be feasible under a variety of anthelmintic regimes.

The influence of pre-slaughter nutrition on the potency of foetal serum in cell culture was studied. Ewes carrying late-gestation foetuses (120-day gestation) were either fasted for 66 h (F), fasted for 66 h but drenched with Ketol, a propylene glycol preparation, (5 × 120 ml doses; FK), given food ad libitum (A), or given food ad libitum and drenched with Ketol (5 × 120 ml doses; AK). Following slaughter foetal blood was collected for the determination of potency in cell culture using industry-standard cell culture bioassays: cloning efficiency, plating efficiency and a 96 h cell proliferation assay. Foetal serum insulin-like growth factor (IGF) concentrations were also measured. Pre-slaughter fasting or drenching with Ketol had no effect on the potency of foetal serum in any of the cell culture bioassays. Fasting significantly lowered foetal plasma IGF-1 levels (F < 0·01). Foetal IGF-2 levels were unaffected by fasting or drenching with Ketol.

The effect of sex on the size and number of adipocytes and on the lipogenic enzyme activity in different fat depots in Lacha (L) and Rasa Aragonesa (RA) lambs was studied. Male and female L lambs were fed on ewe milk and were slaughtered at 25 and 24 days of age corresponding to 11·4 and 10·9 kg live weight (UN), respectively. Male and female RA lambs were weaned at 58 days (16·0 kg LW) and were then given concentrates and barley straw until slaughtered at 89 and 91 days of age corresponding to 24·5 and 23·1 kg LW, respectively. A number of parameters were studied in omental (OM), mesenteric (MES) and kidney knob and channel fat (KKCF) depots including the amount of fat, the number and size of adipocytes and the activity of the following enzymes: glycerol 3-phosphate dehydrogenase (G3PDH), fatty acid synthetase (FAS), glucose 6-phosphate dehydrogenase (G6PDH) and NADPmalate dehydrogenase (MD). In subcutaneous (SC) and intermuscular (IM) depots, all the former parameters except the adipocyte number were studied. Females of both breeds had higher amounts of adipose tissue than males in the internal fat depots (P < 0·05) as well as larger adipocytes, mainly in the KKCF (P < 0·05 andP < 0·001 for L and RA lambs, respectively) and OM (P < 0·05 in the RA lambs) depots. There were no differences between sexes in the number of adipocytes. The activity of the G3PDH enzyme was higher in females than in males in OM and SC depots (P < 0·01) in L lambs, and in KKCF, IM (P < 0·05), OM and MES (P < 0·001) depots in RA lambs. Thus, the sex effect on adiposity in both breeds studied involved a greater fattening of the females which was consistent with a greater hypertrophy and a higher G3PDH activity.

Data on Djallonke sheep collected from 1983 through 1992 on 29 participating farms of an open nucleus improvement programme and from the nucleus were analysed. Initial on-farm records on 14342 lambs and on-station records on 2551 ram lambs were edited down to 6605 for birth weight (BWT), 5857 for preselection (birth to 80 days) average daily gain (PSADG), 10417 for 80-day weight (WT80), 13054 for lamb survival at pre-selection, 1978 for 180 (WT180) and 849 for 365 (WT365) day weights. Year of birth, sire line, flock, month and season of birth had significant (at leastP < 0·05) effects on both on-farm and on-station weights and on lamb survival. Trait means were 2·2 (s.e. 0·02) kg for BWT, 69·6 (s.e. 1·26) g/day for PSADG, 9·1 (s.e. 0·05) kg for WT80, 19·7 (s.e. 0·24) kg for WT180 and 31·8 (s.e. 0·45) kg for WT365. Mean survival was 90 (s.e. 0·9) %. Single lambs were heavier at birth and at 80 days of age, grew faster to 80 days and were about 200 and 500 g heavier at 180 and 365 days respectively than multiple lambs. There was a large variation between flocks: flock means for WT80 varied from 6·4 to 12·0 kg (CV 0·21), with smaller flocks having generally the lowest means. Lambs born in the hot-rainy season had the heaviest birth and 80-day weights, whereas ram lambs born in the cool rainy and early hot-dry seasons had the heaviest 180- and 365-day weights. Lambs born during the cool months of July to October had the lowest survival rate. Multiplicative factors were found to be more appropriate for adjusting on-farm records for type of birth, management level, birth date, season of birth and ewe parity than additive adjustment factors.

Effects were studied on food intake and diet apparent digestibility of giving to goats once daily a basal diet rich in tannin from inclusion of leaves of Quercus calliprinos either supplemented with a high carbohydrate or a high protein food. Also interactions with polyethylene glycol (PEG) were investigated. The results of the present work confirmed our presumption that the content of tannin in some Mediterranean browse is so high that it may negatively affect the utilization of protein in supplementary foods. Neutralizing the tannins with once-daily provision of PEG proved to be an effective means of preventing the negative effect. Providing 10 g/day PEG to goats given Quercus calliprinos leaves ad libitum and supplemented with 300 g/day concentrates containing 160 g crude protein per kg DM increased digestible crude protein intake by 50 g/day. When the concentrate food was given to goats, leaf dry-matter intake decreased significantly (from 664 to 565 g/day) and the goats lost weight rapidly. Therefore, supplementing tannin-rich leaves with concentrate food is recommended only if done in combination with PEG. High protein supplementation increased leaf (from 664 to 844 g/day) and digestible protein intakes (from 4·8 to 92·3 g/day) but a considerable portion of the protein supplementation was wasted due to interaction with tannins. PEG may allow economies in the use of such high-cost foods due to the greater efficiency of protein utilization (digestible crude protein intake increased from 92·3 to 122 g/day) of the supplementary food and to increased intake and protein utilization of the basal leaf diet (from 844 to 1023 g/day).

Exploiting the ‘ram effect’ is an inexpensive alternative for out-of-season breeding in moderately seasonal breeds. For maximum efficacy in Corriedale sheep, oestrous ewes have to be introduced together with the teaser rams. Successful applications depend upon timely manipulation of the animals to induce oestrus in most ewes and to minimize the likelihood of successfully induced non-pregnant ewes returning to anoestrus during the mating period.

In the first of two experiments, the effects of two alternative ram: ewe ratios (1:6 or 1:12) and five different doses (0, 15, 30, 45 or 60 mg) of medroxy-progesterone acetate (MAP) applied in intravaginal sponges for 9 days were assessed on seasonally anovular adult Corriedale ewes. Control ewes (0 MAP) did not receive sponges, but were injected with 20 mg progesterone at ram introduction. A second experiment tested the efficacy of post-oestrus intravaginally applied MAP (30 mg; 7-day treatment starting on days 3 to 6 after oestrus) for improving reproductive variables of successfully induced ewes exposed to entire rams.

Proportions of ewes ovulating and ovulation rates (assessed through laparoscopy) did not differ significantly (P > 0·05) in ewes treated with various MAP doses (213/220 = 96·8% and 1·26 (s.e. 0·031) respectively) or injected with progesterone (56/58 = 96·6% and 1·21 (s.e. 0·058) respectively). The MAP content of the sponges did not affect (V > 0·05) the proportion of ewes ovulating (269/278), marked by the rams (197/213), returning to oestrus (81/197) or lambing among those not returning to first oestrus (87/119). More ewes were marked in the groups exposed to a higher ram percentage (79·7 to 70·6%; P < 0·001) but no other reproductive variable was affected by the ram: ewe ratio at ram introduction (P > 0·05). In the second experiment, post oestrus progestagen supplementation reduced the proportion of ewes returning to first oestrus from 27% to 16% (P < 0·05) but failed to improve lambing rate or the number of lambs born per ewe lambing. Thus, MAP doses as low as 0·25 of the commercial formulation (60 mg) induced oestrus in seasonally anovulatory Corriedale ewes exposed to rams and oestrous ewes. Increasing the ram: ewe ratio augmented the proportion of marked ewes but did not affect any other reproductive variable. Supplementing MAP after oestrus did not improve reproductive rate in Corriedale ewes induced to ovulate during the seasonal anoestrus.

The influence of types of roughage, barley straw (diet B) versus lucerne hay (diet L), on the patho-physiology of a T. congolense infection was compared in eight pairs of Scottish Blackface male twin lambs. One animal of each twin pair was infected and the other used as a pair-fed control. Voluntary food intake, body weight, digestive function, various blood haematological and biochemical measurements were made.

Voluntary organic matter intake decreased significantly after the T. congolense infection, the decrease being greater in the diet L group than in the diet B group lambs (P < 0·01). The apparent digestibility coefficients of crude protein and organic matter were significantly lower in the infected lambs (P < 0·01). Mean retention time of the roughage through the digestive tract in the animals given barley straw was significantly longer (P < 0·05) due to a lower rumen outflow rate constant (P < 0·01). Infection resulted in longer mean retention times (P < 0·01).

Packed cell volume (PCV) was significantly lower before infection in the animals given diet B (P < 0·01). After infection, diet (P < 0·01) and infection (P < 0·01) had an additive effect on PCV. The anaemia was both macrocytic (P < 0·05) and hypochromic (P < 0·01).

Diet B resulted in higher plasma cholesterol (P < 0·05), but lower plasma urea (P < 0·01) and albumin (P < 0·01) concentrations before infection than diet L. The T. congolense infection significantly lowered plasma cholesterol (P < 0·01) and increased plasma urea (P < 0·01) concentrations compared with the uninfected controls. Plasma albumin concentrations decreased, but were more affected by nutrition (P < 0·01) than by infection (P < 0·05).

It ivas concluded that the patho-physiological effects of the T. congolense infection in the Scottish Blackface lambs were affected by the type of roughage offered, but that these effects were additive rather than interactive to the effects of infection.