In a 2 × 2 factorial experiment, half of each of two groups of ewes in high (20 ewes) or low body condition (20 ewes) were subjected to procedures designed to simulate normal management and climatic stresses, and the effects of these treatments on ovulation rate, embryo survival and endocrine status were investigated.

The mean ovulation rate of ewes in the high condition group was significantly higher than that of ewes in the low condition group (1·8 v. 11) (P < 0·001). Embryo survival rates were unaffected. Neither ovulation rate nor embryo survival were affected by stressful treatments.

Circulating follicle stimulating hormone, luteinizing hormone and prolactin levels were recorded in the peri-ovulatory period. Mean circulating follicle stimulating hormone levels were similar in three of the treatment groups but were generally lower in ewes in the low condition/stressed group. This difference was significant in some of the sampling periods. Neither basal levels of luteinizing hormone nor the size of the pre-ovulatory luteinizing hormone surge were significantly affected by level of body condition or stress but the surge began earlier in ewes in the low condition groups. The difference in timing was not, however, related to ovulation rate. Circulating prolactin levels were consistently and often significantly lower in ewes in poor condition (P < 0·05). Levels were not significantly affected by stress.

While ovulation rate was affected by body condition, the recorded progesterone profiles during the first 2 weeks after mating suggest that luteal function was not affected by any of the treatments applied.

One hundred and five Hereford heifers were reared on varying amounts of the same diet of grain and hay to grow at either high (H: 0·91 kg/day), medium (M: 0·67 kg/day) or low (L: 0·55 kg/day) rates between 2 and 8 months of age. Between 8 and 14 months, intake was restricted for half of the H heifers (HL: 0·14 kg gain per day), ad libitum for half of the L heifers (LH: 0·97 kg gain per day) and moderate for all other heifers (HM: 0·57; MM: 0·58; LM: 0·55 kg gain per day). These treatments resulted in a range of live weights at 8 (weaning) and 14 (premating) months commonly seen in commercial production. Heifers were mated with Hereford bulls at 14 months of age and subsequently grazed at pasture. Milk yields (I/day) at 30 days post partum and the 240·day sex-adjusted calf weaning weights (kg) for HM, HL, MM, LH and LM heifers in the first lactation were 4·1, 218; 4·9, 236; 4·3, 221; 5·7, 241; and 6·3, 259 respectively (P < 0·01). Calves from HM and MM cows were significantly smaller and leaner than those weaned by LM cows. Milk yields 30 days post partum and 200·day sex-adjusted calf weaning weights for the second lactation averaged: HM, 5·2 and 202; HL, 6·8 and 217; MM, 7·0 and 222; LH, 6·6 and 219; and LM, 7·0 and 229, respectively; and for the third lactation: 5·1 and 211; 6·5 and 225; 7·2 and 223; 7·4 and 230; and 7·6 and 237, respectively. The continued lower milk yield of HM cows (P < 0·05) was offset by a trend (NS) to higher fertility and lower calfmortality, particularly in the 1st and 2nd years of production. Over the three lactations studied, the number of calves weaned per opportunity and the total actual weight (kg) of calves weaned per cow kept averaged: HM, 0·86 and 573; HL, 0·66 and 465; MM, 0·68 and 466; LH, 0·70 and 512; and LM, 0·67 and 507, respectively.

The high growth rates commonly achieved by autumn-born Hereford heifers under commercial grazing conditions may reduce their subsequent milk-yield potential. This potential appears to be more sensitive to level of nutrition before 8 months of age than between 8 and 14 months.

1. Eighteen litters of piglets were weaned at 14 days of age and reared for a further 3 weeks at environmental temperatures of 18, 23 or 28°C. At each environmental temperature three levels of feeding were used. The changes in body composition of the piglets were studied by the comparative slaughter procedure, littermates being analysed at birth, and at 14, 22 and 36 days of age. For comparison, the bodies of suckled piglets of similar weights and ages were also analysed.

2. In the 2 to 3 day period following weaning, body weight decreased, with the greatest reduction being 0·28 (s.e. 002) kg at 18°C. Following this, body weight gain was dependent on both environmental temperature and level of feeding, although at any given level of food intake there was little difference between the values at 23 or 28°C.

3. There were marked changes in the chemical composition of the carcass in relation to the different temperature/feeding level combinations. The most variable component was fat. In the period following weaning there was considerable mobilization of fat, especially at the lower temperatures and feeding levels. The fat content of the early weaned piglets at 36 days of age (68 to 103 g/kg) was significantly less than that of the suckled piglets (169 g/kg) (P < 0·01). The decreases in fat content were accompanied by increases in the dry-matter content of the carcass.

4. The protein content of the carcass remained relatively independent of the different treatments, ranging from 140 to 164 g/kg for the early-weaned piglets, compared with 139 g/kg for those that had suckled their mothers.

5. The differences in the growth and body composition of the early-weaned piglet are discussed in relation to an inadequate food intake following weaning, to changes in nutrient supply and to variations in the climatic environment.

Data for a total of 3715 cattle from four sources were used to examine the relative importance of live weight at slaughter, and visual assessments of carcass conformation and subcutaneous fat cover, as predictors of killing out. The sources were the Meat and Livestock Commission's beef breed evaluation programme (1689 steers of different breeds and crosses), the beef demonstration unit at the National Agricultural Centre, Stoneleigh (814 commercial dairy-bred cattle), an East Anglian abattoir (405 commercial cattle) and the Milk Marketing Board's Warren Farm (807 dairy-bred steers by different sire breeds). An assessment of live body conformation was also examined as a predictor in the Warren Farm data.

Carcass conformation provided a more precise prediction of killing out than did either live weight or subcutaneous fat score. Regression coefficients in the different groups ranged from 5·4 to 12·0 g/kg for each increase in conformation class (six-point scale). The live conformation assessment was a less precise predictor (within sire breed residual s.d. = 17·7 g/kg) than the carcass assessment (15·6 g/kg).

A comparison was undertaken of 92 Canadian Holstein × British Friesian (HF) and 93 British Friesian (F), autumn born, male calves on three typical United Kingdom production systems. These were: intensive barley beef system (BB); a grass/cereal 18-month system (18m); and 24-month forage system (24m). Calves were brought in from a variety of farms. HF calves were heavier on arrival (43·1 v. 40.7 kg ***). The calves were the progeny of 27 Canadian Holstein and 43 British Friesian sires, and all out of British Friesian dams. They were castrated and reared conventionally to 100 kg before being allocated to treatment. Slaughter was undertaken when subjective handling suggested that the carcass would classify as fat-class 2 on the Meat and Livestock Commission classification scheme (equivalent to European Economic Community fat-class 3), provided that a minimum live weight (BB, 380 kg; 18m/24m, 420 kg) was achieved. There were no differences between breeds in daily live-weight gain on any system. Other results, HF first, follow. At slaughter, HF were both older (BB, 362 v. 342 days **; 18m, 591 v. 558 days ***; 24m, 716 v. 673 days ***) and heavier (BB, 413 v. 395 kg ***; 18m, 486 v. 469 kg NS; 24m, 531 v. 496 kg ***). Efficiency of food conversion, measured on the BB system only, was not significantly different (5·83 v. 5·84).

Barley straw was treated with anhydrous ammonia, sodium hydroxide, ammonia plus sodium hydroxide, sulphuric acid or ammonia plus sulphuric acid to study the effect on the digestibility of straw and the degradability of the straw in the rumen of sheep.

In experiment 1 four wethers fitted with rumen cannulae were given ammonia-treated straw to appetite and were used for measuring the dry- and organic-matter degradability of straw in the rumen after different in sacco incubation times. The organic-matter degradability (g/kg) after 48 h in sacco incubation was 459, 603, 576 and 660 for control, ammonia, sodium hydroxide and ammonia plus sodium hydroxide-treated straw respectively. Each treatment improved the degradability significantly (P < 0·01). The effect of ammonia plus sodium hydroxide treatment on rumen degradability of straw was additive (P < 0·05).

In experiment 2 the treated straws studied in experiment 1 were given to four wethers in a 4 × 4 Latin-square design, to measure the voluntary intake, digestibility, water consumption and urine excretion. The digestibility (g/kg) and daily intake of digestible organic matter (g/kg M0·75 per day) were 554, 12·5; 628, 24·7; 653, 19·7; and 668, 24·3 for the control, ammonia, sodium hydroxide and ammonia plus sodium hydroxide-treated straws, respectively. Intake of ammonia-treated straw was significantly greater than for sodium hydroxide-treated straw (P < 0·01). The water consumption and urine excretion by sheep were increased significantly by sodium hydroxide and ammonia plus sodium hydroxide treatments (P < 0·01).

In experiment 3, either straw or ammonia-treated straw were treated with 20, 40 and 60 g sulphuric acid (200 ml/1 solution per kg). The degradability of the acid-treated straws was measured using three wethers fitted with cannulae and given ammonia-treated straw to appetite. The dry-matter degradabilities (g/kg) after 48 h in sacco incubation were 52·0, 53·9, 58·7 and 67·4 for the control, and 20, 40 and 60 g acid per kg treatments, whereas the values were 61·3, 60·4, 68·4 and 69·4 for the ammonia-treated straw, and 20, 40 and 60 g acid per kg treatments respectively. There was a significant effect of acid treatment and ammonia treatment on dry-matter degradability.

1. Measurements of heat loss, energy and nitrogen balance were made on 18 groups of piglets weaned at 2 weeks, at environmental temperatures of 18, 23 and 28°C, and at three levels of feeding at each temperature.

2. From the experimental results, values of heat loss, energy retention, protein and fat deposition were derived for each temperature, at each of the three levels of metabolizable energy (kJ/kg M0·75 per day) intake: 550 (1·0MEm), 825 (1·5MEm) and 1100 (2·0MEm). The lowest of these levels was the calculated thermoneutral maintenance energy requirement (MEm).

3. From the results the following deductions were made, (a) Heat loss varies with both environmental temperature and metabolizable energy intake, and at an intake of 2·0MEm is minimal between 23 and 28°C. Energy retention varies in an inverse manner to heat-loss, and at 1·0MEm is negative at all environmental temperatures below 28°C. (b) Protein and fat deposition increase significantly with increase in metabolizable energy intake (P < 0·05), with fat deposition being more dependent on temperature than protein deposition. The mean increase in protein deposition per 1°C increase in environmental temperature is 2·05 kJ/kg M0·75 per day. Fat deposition is negative at all temperatures at l·0MEm; at l·5MEm it is zero at 23°C and negative at temperatures below this.

4. Critical temperature was calculated to decrease from 26·9°C at l·0MEm to 23·9°C at 2·0MEm.

5. The efficiency of energy utilization (k) was 0·58 at 18°C, 0·81 at 23°C and 0·74 at 28°C. The corresponding values of the maintenance energy requirements were 739, 615 and 550 kJ/kg M0·75 per day. Estimates of the energetic efficiency of protein deposition (kp) of 0·60 to 0·65, and of fat deposition (k/) of 0·82 to 0·86, were determined at 23 and 28°C.

1. Eight diets of similar energy content, ranging in crude protein concentration from 95 to 256 g/kg, were given at either 2·5 or 3·2 times the energy level for maintenance to entire male pigs growing from 45 to 90 kg live weight.

2. Growth rate improved with increase in feeding level and with increasing dietary crude protein up to 164 g/kg (P < 0·05). The food conversion ratio improved with each increase in dietary CP up to 186 and 164 g/kg on the lower and higher feeding treatments, respectively (P < 0·05). It was also improved with increase in level of feeding of the lower-protein diets but deteriorated with increase in level of intake of the higher-protein diets (P < 005).

3. Rate of protein deposition improved with increasing dietary crude protein up to 186 and 164 g/kg on the lower and higher feeding treatments, respectively (P < 005). The results showed that, for pigs given diets deficient in crude protein, rate of protein deposition was linearly related to protein intake (P < 0·001) but independent of energy intake. For pigs given a diet adequate in crude protein, rate of protein deposition was related to energy intake and independent of crude protein intake.

4. Body fat content at 90 kg decreased with increasing dietary crude protein up to 210 and 164 g/kg on the lower and higher feeding treatments, respectively (P < 0·05), and was increased by raising the level of intake of the higher-crude protein diets (P < 0·05). However, the influence of feeding level on body fat diminished as dietary crude protein was reduced.

Four experiments with sheep fitted with rumen cannulae were conducted to investigate whether the rate of digestion of ammonia-treated straw, estimated as disappearance of dry matter from nylon bags in the rumen, might be increased by supplements of either soya bean meal, sucrose or sugar beet pulp at a level of 0·1, or by increasing the concentrations of dietary soluble micro and macro minerals.

There were no differences among treatments in rate and extent of digestion of straw due to supplementations.

In another experiment, the effect of increasing the proportion of molassed sugar beet pulp or rolled barley on rate of digestion of ammonia-treated straw was investigated. A greater proportion of sugar beet pulp (0·45) could be included in the diet before the rate of digestion was decreased in comparison with rolled barley (0·35).

Assuming that the digestibility of the sugar beet pulp and the rolled barley was not changed by the increasing proportion in the diet, it could be calculated that the digestibility of straw was reduced from 0·538 with straw alone to 0·403 with the sugar beet pulp and to 0·218 with the rolled barley supplement when the supplements were included at a level of 0·70.

A comparison was undertaken of 85 Holstein × Friesian (HF) and 84 Friesian (F) steer carcasses that had been produced on three production systems. These were: intensive barley beef (BB); grass/cereal 18 month; and 24 month forage system. On each system, HF steers were heavier at slaughter (over all systems, 476·5 v. 453·3 kg ***) and had a lower killing-out proportion (512 v. 521 g/kg ***), which resulted in higher carcass weights (243·5 v. 235·9 kg **). Steers were slaughtered on reaching a standard degree of finish (equivalent to European Economic Community fat-class 3), provided that they had attained a minimum live weight. There were no significant differences in carcass fat class (3·23 v. 3·35) but HF had poorer carcass conformation classification (2·62 v. 3·21 ***). Of the HF carcasses, 60·4% were rejected on conformation for Beef Premium Scheme payments and only 29·0% of the F carcasses were rejected (P < 0·001): a considerable and unmerited financial penalty. Objective carcass measurements showed HF to have longer sides (1257 v. 1233 mm ***), longer legs (812 v. 790 mm ***) and deeper forequarters (420 v. 402 mm ***). These differences remained when dressed carcass weight and sample-joint fat proportion were taken as covariates. Comparison of the weight-adjusted carcasses showed the HF to have reduced rump (P < 0·001) and loin thickness (P < 0·05). No other consistent effects were seen for carcass measurements, subjective scores or colour attributes. Dissection of the 7th t o 9th rib joint, as a predictor of carcass composition, revealed no significant overall differences in proportions (g/kg) of muscle (571 v. 567), bone (219 v. 219) or fat (206 v. 212). The implications of carcass value of the above findings are discussed.

Thirty-six British Saanen female kids, born between either 20 March and 6 April (E) or 10 April and 16 June (L), were reared under three different patterns of lighting — a constant 18-h light: 6-h dark (C); or a weekly step-wise reduction from 18-h to 10-h light: 14-h dark over 10 weeks, commencing at either 6 (R6) or 10 (R10) weeks of age. Vasectomized males were used to test for oestrus; blood samples were collected to determine plasma progesterone concentration. Thirty-three goats attained puberty; all but two kids showed oestrus at first ovulation. The mean ( ± s.d.) age and live weight at puberty were 174·6 (± 4·1) and 141·7 (± 4·3) days (P < 0·001), and 28·6 (± 0·9) and 22·8 (± 1·0) kg (P < 0·001), for E and L treatments, respectively. For R6, R10 and C treatments, the ages and weights wer e 151·6 (± 4·7), 160·4 (± 5·2) and 164·7 (± 4·9) days (NS), respectively, and 24·5 (± 1·1), 25·3 (± 1·2) and 27·8 (± 1·1) kg (NS), respectively. A significant date of birth × lighting-pattern treatment interaction was found for date at puberty (P < 0·001), with puberty occurring earlier for E than L kids only when a reduction in daylength occurred. Puberty occurred earlier on R6 than R10 treatments only for L kids.

Rectal temperatures of cattle grazed near the tropic of Capricorn in central Queensland were studied. The cattle were of Bos indicus, B. taurus and crossbred lines, and were represented by over 200 growing heifers in each of 2 years and some supplementary groups.

Rectal temperatures were loge normally distributed when they were expressed as deviations from a basal temperature of 38°C. They were significantly repeatable, but were more highly repeatable when herd mean temperature was above 39·5°C. The heritability estimate was 0·33 (P < 0·01).

The mean phenotypic regression of growth rate on rectal temperature, within breed groups, was 0·04 (s.e. 0·006) kg/day per °C (r = 0·3, P < 0·01) over the entire growth period from birth to 18 months of age but greater during warmer seasons. The estimated genetic correlation was insignificant in one group of heifers but −0·86 (s.e. 0·17) in the other.

The evidence of favourable and possible unfavourable responses to selection of cattle for low rectal temperature in warm environments is discussed.

A factorial experiment was conducted with 80 first-litter sows and involved two levels of feeding during lactation (ad libitum or 2·0 kg/day), and two levels of feeding between weaning and mating (4·0 or 1·5 kg/day).

Average lactation length was 32·2 days. Sows given 2·0 kg/day during lactation lost more backfat (6·3 v. 0·9 mm; P < 0·05) and more live weight (36·8 v. 9·1 kg; P < 0·05) during lactation than sows fed ad libitum and whose average daily food intake was 4·47 kg. Sows receiving 20 kg/day during lactation took longer to return to oestrus after weaning. Within 8 days of weaning more sows fed ad libitum during lactation ovulated (0·90 v. 0·40; x2 = 20·0; P < 0·001) and exhibited oestrus (0·78 v. 0·38; x2 = 12·8; P < 0·001) than sows whose food intake throughout lactation was restricted. Ovulation rate, subsequent litter size and embryonic mortality were not significantly affected by feeding level during lactation.

Post-weaning feeding level did not affect the interval between weaning and oestrus. However, sows receiving 4·0 kg/day between weaning and mating had higher ovulation rates (14·8 v. 13·0; P < 0·05) and a greater litter size (10·0 v. 8·8; P < 0·1) at the subsequent farrowing.

Data on 1542 Damascus kids, collected from 1977 to 1981, were used to study environmental and genetic factors influencing pre-weaning and post-weaning growth traits of kids. Season of birth, type of birth, sex of kid and dam lactation number were the environmental factors investigated. Phenotypic and genetic parameters were estimated from paternal half-sib correlations. The average sire family size was 17·2 kids. Single kids were heavier at birth, at weaning and at 140 days of age than twins or other multiples (P < 0·01). Male kids were heavier (P < 0·01) and grew faster (P < 0·01) than female kids from birth to 140 days of age (4·7 and 4·2 at birth, and 29·2 and 24·6 kg at 140 days, respectively). Dam lactation number significantly affected pre-weaning growth, but had no effect on the post-weaning growth rate of kids.

Heritabilities for birth, weaning and 140-day weights, and pre-weaning and post-weaning growth rate, were 0·31 (s.e. 0·08), 0·27 (s.e. 0·07), 0·21 (s.e. 0·07), 0·16 (s.e. 0·06) and 0·22 (s.e. 0·07), respectively. Genetic correlations were mostly high and all positive, especially between weaning weight and 140-day weight (0·82 (s.e. 0·08)), and pre-weaning growth rate and 140-day weight (0·80 (s.e. 0·10)). The corresponding phenotypic correlations were also high and positive (0·71 and 0·67, respectively). No genetic antagonisms were found among the characters studied. Response to selection for post-weaning growth should be effective.

A study was made of weaning weights in a beef herd, using a rotational crossbreeding system including the Boran breed (zebu) and two temperate beef breeds (Devon and Limousin), and a seasonal calving period spanning the onset of the rains.

Significant sources of variation in calf weaning weights were crossbred type, age at weaning, sex, dam's age, season of birth, year and a year × crossbred type interaction (all P < 0·001).

The adjusted mean weaning weight was 203 kg. Weaners sired by a temperate bull were generally 1·08 times the weight of those sired by a zebu bull. Steers were 1·06 times the weight of heifers. Marked increases in weaning weights occurred as dams increased in age from 3 to 6 years and slight increases continued up to 9 years of age. Weaners born to 9-year-old cows were 1·09 times the weight of those from first calvers.

Alternative methods for investigating the effect of season of birth were examined and the final choice was a covariate for time from birth to the onset of the rains. Calves born in the earliest part of the calving period were approximately 1·14 times the weight of those born just after the onset of the rains.

A factorial experiment involving high (53·1 to 59·5 MJ) and low (25·4 to 27·1 MJ) daily intakes of digestible energy, and high (550 to 745 g) and low (302 to 318 g) daily intakes of crude protein during lactation, was conducted with 68 first-litter sows. Average lactation length was 32 days, and average backfat changes during lactation were +0·3, −1·4, −7·2 and −5·4 mm for the high energy/high protein, high energy/low protein, low energy/high protein and low energy/low protein combinations, respectively. The corresponding mean live-weight losses during lactation were 3·9, 32·5, 29·8 and 35·8 kg. Within 8 days of weaning, more sows receiving high intakes of both energy and protein during lactation exhibited oestrus (0·88 v. 0·53, x2 = 6·7, P < 0·01) than sows whose energy and/or protein intake throughout lactation had been restricted. Nitrogen balances of sows were determined between 18 and 22 days after farrowing. Sows receiving high intakes of both energy and protein during lactation were in positive nitrogen balance, whereas the nitrogen balances of sows on the other three dietary treatments during lactation were similar to each other but negative. Ovulation rate, subsequent litter size and embryo mortality were not significantly affected by energy or protein intake during lactation.

Livestock food was contaminated with starling excrement by placing caged starlings (Sturnus vulgaris) over livestock food troughs and feeders, and allowing starling excreta to fall on food for periods ranging from 30 to 56 consecutive days. Several levels of contamination were tested by varying the number of caged starlings over troughs, from 1 to 18 birds per m2 of trough area. During the winters of 1979 and 1980, four trials were conducted involving 78 pigs of both sexes, 24 steers and 18 male calves. No significant differences were observed in daily rate of weight gain or efficiency of food conversion (food offered per unit gain), suggesting that neither cattle nor pigs appeared to be adversely affected by exposure to starling excreta in their food. Food rejection observed during these trials appeared to be a negligible problem overall. Although limited disease incidence did occur, it did not appear to be associated with food contamination.

Thirty-two female growing pigs (25 to 55 kg live weight) were subjected to four dietary treatments combining two levels of isoleucine and two levels of leucine to investigate the effects of leucine supply on the requirement for isoleucine.

Results for daily live-weight gain, food conversion efficiency and carcass quality judged by ham dissection indicated that 3·8 g isoleucine per kg diet was marginally adequate for the growing pig in diets containing 13·4 g leucine per kg. An interaction between dietary leucine and isoleucine was demonstrated. Increasing the dietary leucine concentration to 20·4 g/kg clearly resulted in a deficiency of isoleucine in the basal diet, as daily gain, food conversion efficiency and carcass quality were significantly improved by increasing the isoleucine concentration from 3·8 g to 4·5 g/kg diet. Dietary leucine concentration did not influence performance at the higher level of isoleucine supply. Changes in plasma urea and amino acid concentrations confirmed the findings from the growth experiment of the interaction between isoleucine, leucine and valine.

Data on 1474 lactation records obtained from 1972 to 1978 were used to study environmental and genetic influences on production characters in the Damascus goat. Year and month of kidding had a significant effect on 90- and 150-day milk production after weaning, lactation length and litter weight at weaning (P < 0·01), but no influence on litter weight at birth. Milk production after weaning was not related to litter weight at birth or at weaning. Age of goat at kidding had a significant quadratic effect on milk production, and litter weight at birth and at weaning. No such effects were found for lactation length.

Estimates of heritability, from paternal half-sib correlations, for 90- and 150-day milk production were similar (0·29 (s.e. 0·14)). The genetic correlation between 90- and 150-day milk yield (0·92 (s.e. 0·03)) was high, indicating that part and whole lactation yields are influenced by the same genes. The phenotypic correlations among milk yield traits and lactation length were also high and positive.

Blood samples were taken from Scottish Blackface ewes of five lines (selected for long and short cannon bones, for hairy and fine fleeces, and an unselected control line) at ages ranging from 9 to 69 months. The samples were analysed for the concentrations of copper, glucose, calcium, magnesium, phosphorus, total protein, albumin and globulin in plasma.

The components of variance and covariance between sires and within sires were estimated and heritabilities were calculated for the eight blood constituents and live weight. The heritabilities ranged from 0·20 (s.e. 0·08) for the concentration of copper to 0·43 (s.e. 0·10) for total protein. Only one of the 34 genetic correlations was significantly different from zero, this being between the concentrations of calcium and phosphorus.

Ewes that had had a single lamb 9 months earlier had lower concentrations of copper, calcium, albumin (P < 0·001) and glucose (P < 0·01) than ewes that had not lambed. Concentrations of glucose (P < 0·05) and total protein (P < 0·001) were also decreased according to the number of lambs born to the ewe 3 months later.

Ewes with low red cell potassium concentrations had higher concentration of glucose in plasma than ewes with high red cell potassium concentrations (P < 0·05). Haemoglobin type affected the concentrations of copper (P < 0·01) and total protein (P < 0·05), with ewes of type B having higher and lower concentrations respectively. The constituents measured were not significantly affected by transferrin type.