Subcutaneous implantation of the synthetic oestrogens, hexoestrol and stilboestrol is known to increase the daily rate of live-weight gain and to improve the efficiency of food utilisation in lambs (see review by Averill, 1955; Wilkinson et al., 1955; Gill et al.,1956; Jordan & Croom, 1956).

A critical review of these reports shows that despite the numerous experiments testifying to increased and more efficient weight gains as a result of implantation it is not known how much of this extra gain is represented by products saleable for human consumption. Further there is only limited information relating to the chemical composition of the increased live-weight and none concerning the precise nature of the increased efficiency of food conversion in units other than live-weight.

The aim of this study was to determine the effects of restricted feeding before puberty on reproduction, lactation and offspring growth performance in replacement ewe lambs over two breeding seasons. At weaning, 41 Dorset ewe lambs were assigned to one of three diets: an ad libitum control diet with medium-quality forage (MQF; 13.3% crude protein (CP), 1.81 Mcal metabolizable energy per kg, 42.8% ADF; diet A-MQF); a restricted diet with the same forage as A but less feed concentrate (diet R-MQF); or a high-quality forage (HQF) diet (14.8% CP, 2.15 Mcal ME/kg, 34.7% ADF; diet F-HQF). The quantity of concentrate offered to the group R-MQF and F-HQF ewe lambs was adjusted to obtain 70% of the control ewe lambs’ growth rate. The diets were offered for 75 days following weaning to cover the allometric phase of mammary gland development. Prepubertal restriction did not affect (P > 0.10) the gestation rate, number of lambs born or the body weight and body condition score of ewes at lambing or at the end of lactation. Ewes from groups R-MQF and F-HQF tended to produce more milk during their first lactation compared to those from group A-MQF (P = 0.07). During the second lactation, groups R-MQF and F-HQF had better standardized milk production than group A-MQF (P < 0.05), and group R-MQF produced more milk than group F-HQF (P < 0.05). Milk fat and protein content were not affected by treatments (P > 0.10) Fat and protein yield were affected by treatments only at the second lactation (P < 0.10 and P < 0.05, respectively). Lamb birth and weaning weights were not affected by prepubertal restriction of feeding in their mother (P > 0.10). However, the average daily gain of second breeding season lambs was higher for the R-MQF group than the F-HQF group (P < 0.05), and a similar trend was observed for total gain (P < 0.10). Restricted feeding before puberty does not impair future reproductive performance; however, it has a positive impact on lactation and on lambs’ growth performance.

The response of 376 weaned bull calves to two different housing types was studied in a 2-year feedlot trial. Overall, animals with shelter had a higher rate of gain than animals with no shelter. The difference in the rate of gain between the housing types was, however, restricted to the coldest periods. No significant interaction between housing type and age of calf was observed. Regression analyses showed that whilst average daily temperature appeared to have a negligible effect on growth, temperature fluctuations between weighing days appeared to affect growth of calves in both housing types. Overall, climatic variables contributed more to the variance in gain of calves with shelter than of calves with no shelter.

Sixty gilts were allotted to one of the following feeding regimes: CR, a conventional diet offered at a restricted level according to Swedish feeding standards; SA, a simplified gestation diet (mainly oats and barley) offered at a restricted level and a conventional diet offered ad libitum during lactation; CA, a conventional gestation diet offered at a restricted level and the same diet offered ad libitum during lactation. The sows were followed for four parities. Piglet birth weight was unaffected by sow feeding, but differences in piglet live weight were found from 3 weeks of age to the end of the experiment when the piglets were 9 weeks old. CA piglets were heavier than SA piglets at 3 and 9 weeks of age and heavier than both CR and SA piglets at weaning (35 ± 3 days). Litter size was unaffected by treatment as was piglet mortality, whereas the cause of death varied with treatment. Mortality due to trauma was higher among CA piglets than among others, while mortality due to weakness was higher among SA piglets than others and there was also a tendency for higher mortality due to diarrhoea among CR piglets. It was concluded that the CA feeding regime was superior with regards to piglet performance.

1. Total concentrations of volatile fatty acids and molar proportions of acetic, nrooionic and butyric acids were determined in the rumen of Blackhead Persian sheep given sixteen low-protein diets.

2. Total concentrations of acids ranged from 2·89 to 9·33 millimoles/ 100 ml. of rumen liquor. Both digestibility and protein content of the ration had a significant effect on the concentration of volatile fatty acids in the rumen liquor. Protein content of the diet probably influenced the latter through controlling the rate of ruminal fermentation.

3. Molar proportions of acetic acid varied from 59·7% to 69·3%, of propionic acid from 21·2% to 29·6%, and of butyric plus higher acids from 7·6% to 16·3%. Protein content of the diet had no significant effect on the composition of the acid mixture, but organic matter digestibility was inversely related to the proportion of acetic acid.

4. The fermentation in the rumen of Blackhead Persian sheep, as judged by the volatile fatty acids produced, appears to be similar to that found in European breeds of sheep.

The aim of this study was to examine the metabolic response to feed deprivation up to 48 h in low and high yielding lamb genotypes. It was hypothesised that Terminal sired lambs would have decreased plasma glucose and increased plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB) concentrations in response to feed deprivation compared to Merino sired lambs. In addition, it was hypothesised that the metabolic changes due to feed deprivation would also be greater in progeny of sires with breeding values for greater growth, muscling and leanness. Eighty nine lambs (45 ewes, 44 wethers) from Merino dams with Merino or Terminal sires with a range in Australian Sheep Breeding Values (ASBVs) for post-weaning weight (PWT), post-weaning eye muscle depth and post-weaning fat depth (PFAT) were used in this experiment. Blood samples were collected via jugular cannulas every 6 h from time 0 to 48 h of feed deprivation for the determination of plasma glucose, NEFA, BHOB and lactate concentration. From 12 to 48 h of feed deprivation plasma glucose concentration decreased (P < 0.05) by 25% from 4.04 ± 0.032 mmol/l to 3.04 ± 0.032 mmol/l. From 6 h NEFA concentration increased (P < 0.05) from 0.15 ± 0.021 mmol/l by almost 10-fold to 1.34 ± 0.021 mmol/l at 48 h of feed deprivation. Feed deprivation also influenced BHOB concentrations and from 12 to 48 h it increased (P < 0.05) from 0.15 ± 0.010 mmol/l to 0.52 ± 0.010 mmol/l. Merino sired lambs had a 8% greater reduction in glucose and 29% and 10% higher NEFA and BHOB response, respectively, compared to Terminal sired lambs (P < 0.05). In Merino sired lambs, increasing PWT was also associated with an increase in glucose and decline in NEFA and BHOB concentration (P < 0.05). In Terminal sired lambs, increasing PFAT was associated with an increase in glucose and decline in NEFA concentration (P < 0.05). Contrary to the hypothesis, Merino sired lambs showed the greatest metabolic response to fasting especially in regards to fat metabolism.

In ruminants a dynamic state of protein turn-over has been poorly understood although the methodology of measuring the rate of protein turn-over has recently been advanced to a great extent (Waterlow, Garlick and Millward, 1978). Available evidence suggests that ruminants such as sheep and cows are no exception among various mammalian species when whole-body protein synthesis of adult animals is compared on a metabolic body-weight basis (Waterlow et al., 1978; Reeds and Lobley, 1980).

Seventy-two crossbred barrows (28.7 ± 0.3 kg live weight (LW)) were used to examine whether there is a relation between eating traits, and performance and carcass traits in ad libitum and restrictedly fed group-housed pigs. The experiment included two replicates, each consisting of 36 pigs. From day 1 to 42, all pigs were maintained with free access to a starter diet containing 12.7 MJ metabolizable energy (ME) and 8.2 g ileal apparent digestible lysine per kg. The experimental period was from day 42 (55.9 kg LW) to the end of the experiment (110.2 kg LW). The pigs in treatment 1 were maintained with free access to a high (H) energy diet (13.1 MJ ME and 7.1 g ileal apparent digestible lysine per kg). For pigs in treatments 2 and 3 the daily energy allowance per pig was restricted to 18 MJ ME above the daily energy requirement for maintenance using diet H, and a low (L) energy diet (12.5 MJ ME and 6.7 g ileal apparent digestible lysine per kg), respectively. The weekly measured LW was used to compute the energy requirements for maintenance (M = 0·719 MJ ME × LW (kg)0.63). Daily food intake and eating traits per pig were determined using transponders and an electronic feeding station equipped with an antenna.

Daily energy intake of the ad libitum and restrictedly fed pigs was correlated with growth and lean meat tissue content of the carcass. In the pigs given food ad libitum, daily energy intake was correlated with daily feeder visiting time, time per meal and food intake per meal, but not with number of meals per day and rate of food intake. In the restricted treatments, number of meals per day was correlated with energy intake, but not with lean tissue content of the carcass. In conclusion, number of meals per day explained part of the variation of lean tissue content of the carcass in ad libitum, but not in restrictedly fed group-housed pigs.

Records on birth weight and pre-weaning growth of 3959 Boran calves, which were progeny of 51 sires and 979 dams, were analysed by least-squares analysis of variance. The variance components for sires, dams and maternal grandsires were estimated from the data. On the basis of assumed genetic correlations −0·44 and −0·55 between direct and maternal effects on birth weight and weaning weight, respectively, the maternal genetic component and the genetic covariance between direct and maternal effects were estimated. The heritabilities for direct effects on birth weight and weaning weight were 0·11 and 0·22, respectively, while the heritabilities of maternal effects were estimated as 0·02 and 0·11, respectively for the same traits. Selection indices for direct and maternal genetic components of weaning weight were constructed for practical use. These selection indices combined information on the individual, the parents and sibs.

In a study involving over 300 pelves from lambs of known age at slaughter it was shown that time of ossification was poorly related to age of lamb. The youngest lamb with an ossified pelvis was a female aged 22·4 weeks and at the other end of the scale a third of a group of 45-week-old castrated male lamb pelves were not ossified. Female lamb pelves ossified earlier than castrated male lamb pelves. Carcasses with ossified pelves at a given age tended to be heavier than those with pelves not ossified and pelves of well-fed lambs probably ossified before those of poorly fed lambs. The results indicate that the suggested Codex method for a carcass classification or grading system for dividing lamb carcasses into those under and those over 6 mo of age at slaughter was not accurate. The reason for wanting such a classification is also questioned.

The aim of the present research was to evaluate bovine muscles to be subjected to freeze-drying for an instant meal. Physicochemical and senescence parameters were evaluated. The experimental part was divided into two steps. In the first step, the Semitendinosus muscle was chosen to establish methodology and experimental conditions. Physicochemical, microstructure and senescence parameters were analysed. In the second step, economic bovine muscles such as Semimembranous and Spinalis dorsi were subjected to the same methodology and conditions as in the first step in order to compare them by analysing the same parameters. L* and a* values were statistically significant (P<0.05) for Semimembranous and Spinalis dorsi muscles, showing differences among condition effects and in muscles. Humidity and water activity showed among the muscles analysed that cooked and rehydrated samples did not exhibit differences. Microstructure of Semitendinosus and Semimembranous were not separated and fragmented as occurred with Spinalis dorsi after freeze-drying. Results allowed us to select among the muscles studied that Semimembranous was suitable and economic to be used in an instant meal.

An experiment was designed to examine the interaction between birth status and plane of nutrition of calves in relation to postnatal and lifetime performance. The experiment was a 2 × 2 × 2 factorial arrangement of birth status (single and twin), plane of nutrition from birth to 16 weeks (period 1) and plane of nutrition from 16 weeks to slaughter at a mean live weight of 530·4 (s.e. 0·13) kg (period 2). The planes of nutrition were control and low with metabolizable energy (ME) intakes of 32·1 and 21·4 (s.e. 0·46) MJ/day from birth to 16 weeks, and 73·9 and 64·1 (s.e. 0·95) from 16 weeks until slaughter. The birth weights of the single and twin-born calves were 47·2 and 39·7 (s.e. 0·90) kg respectively. There was no interaction between birth status and plane of nutrition in either main period and by 40 weeks of age the live weights of the twin calves were similar to those of the single-born calves. For period 1 plus period 2 the live-weight gains per unit of ME intake were 12·4 and 13·1 (s.e. 0·28) g/Mf for single and twin-born calves respectively. Although twins had slightly poorer carcass conformation and higher proportion of bone in the carcass, the concentrations of saleable meat and high-priced joints in the carcass were similar. Birth status had no effect on the ultimate pH of muscle. It is concluded that viable twins have similar beef producing potential to single-born calves.

The control and low planes of nutrition imposed during the periods from birth to 16 weeks and 16 weeks to slaughter produced live-weight gains of 822 and 573 (s.e. 31·0) g/day, and 857 and 690 (s.e. 12·6) g/day respectively. Calves which had been on the low plane during the initial period had a compensation index of 0·30 by 64 weeks of age. Carcass measurements were not affected by the plane of nutrition during either period. Steers grew faster than heifers, had lower area o/m. longissimus dorsi but less separable fat and more bone in the forerib joint than heifers at equal carcass weight.

Thirty-six Corriedale rams were weaned at 3 months of age and subjected to four treatments until 2½ years of age. The treatments consisted of two levels of nutrition, with rams on the high level of nutrition being maintained approximately 15% heavier than those on the low level, and two levels of sexual experience. Sexually experienced rams were kept throughout with ewes that were infertile but showed regular oestrus and inexperienced rams were reared in monosexual groups isolated from females except during periodic mating tests. These 2-h tests were carried out at intervals of 3 to 4 months commencing when the rams were 6 months old. Up to 17 months of age there were no significant differences between treatment groups in the development of ability to serve ewes, except that low nutrition reduced the number of rams which had served ewes at 10 months of age. Between 17 and 28 months of age, rams kept with ewes tended to achieve more serves per test during the breeding season than rams kept without ewes.

To avoid winter scarcity of fresh goat milk, simple methods of advancing the season of kidding would be commercially valuable. A combination of long-day light treatment followed by melatonin is successful but other aspects of seasonality including coat growth are also reset. To investigate whether effects on breeding season and coat growth can be dissociated, British Saanen dairy goats (no. = 30) were randomly allocated to one of six groups. Control goats were untreated. Goats in the other five groups received 2 months of treatment with 20 h light: 4 h darkness (20L: 4D) and were then given 3 mg melatonin orally at 16.00 hfor 2 months. The treatments started on 11 January (group 1), 29 March (group 2), 14 June (group 3), 30 August (group 4) and 8 November (group 5). Weekly blood samples were taken for the measurement of progesterone to monitor ovarian activity and prolactin. Side patches (10 cm ×10 cm) were clipped monthly from alternate sides and weighed to measure coat growth. The onset of ovarian activity was advanced from a median date of 15 November in controls to 24 May in group 1 (P < 0·01), 16 August in group 2 (P < 0·05) and 18 October in group 3 (? < 0·05). Groups 4 and 5 showed no significant change in the onset of oestrus (median onset dates 8 November and 1 November, respectively). Group 1 goats came into season again with controls in November. In all except group 5, treatment interacted with time to affect significantly the growth of the coat. The pattern of coat growth was most altered (P < 0·001) in groups 1 and 2. This was associated with effects on plasma prolactin concentrations of light stimulation and melatonin suppression. Group 1 goats resynchronized with control goats to show a coat of normal weight in the winter following treatment. Division of milking goat herds into spring and autumn kidding groups is, therefore, a practical possibility, but effects on overall milk yield require study.

The objective was to investigate the effect of intake before fasting on concentrations of metabolites and hormones, respiratory quotient (RQ) and fasting heat production (HP) using the washed rumen technique and to compare these values with those from the fed state. Six Holstein steers (360±22 kg) were maintained at 21°C and fed three different energy intakes within a replicated 3×3 Latin square design with 21-day periods. Steers were fed alfalfa cubes to provide 1.0, 1.5 and 2.0×NEm during 19 days of each experimental period. Steers were placed in individual metabolism stalls fitted with indirect calorimetry head-boxes on day 20 of each experimental period (FED steers) and fed their normal meal. On day 21 of each period the reticulorumen was emptied, washed and refilled with ruminal buffer (NaCl=96; NaHCO3=24; KHCO3=30; K2HPO4=2; CaCl2=1.5; MgCl2=1.5 mmol/kg of buffer) aerated with 75% N2 and 25% CO2 before introduction to the rumen (steers were not fed; WASHED steers). Each gas exchange was measured over 24 h. HP for 1.0, 1.5 and 2.0×NEm were 479, 597 and 714 kJ/daykg0.75 (s.e.m. =16), respectively. The plateau RQ was 0.756, 0.824 and 0.860 for the 1.0, 1.5 and 2.0×NEm intakes for the FED steers, respectively. After rumen washing, fasting HP was 331, 359 and 400 kJ/daykg0.75 (s.e.m.=13) for 1.0, 1.5, and 2.0×NEm intakes before fasting, respectively. The RQ for WASHED rumen steers was 0.717, 0.710 and 0.719, respectively. Cortisol and β-hydroxybutyrate concentrations in WASHED rumen steers did not exceed threshold levels for severe energy deficit and stress as can be induced from prolonged fasting. This study demonstrates that a fasting state can be emulated using the washed rumen technique, minimizing the time required as opposed to traditional fasting methodologies, without causing a severe energy deficit and stress.

The results of a nitrogen balance experiment with growing pigs have shown that 5 % feather meal was inferior to 7 % white-fish meal, when both supplements supplied the same amount of total crude protein in a barleyweatings- minerals-vitamins ration.

A comparative feeding trial in which white-fish meal was partially replaced by feather meal in the diets given to growing pigs gave inconclusive results.

Charolais cows were individually given hay ad libitum around calving for two successive winters (no. = 40 and no. = 43). Profiles of hay intake are defined for each cow as the evolution of individual daily intake level around calving.

The aim of this work was to build a typology of these profiles, using multivariate analysis. Four and three groups of cows were distinguished respectively for a 2-month and a 4-month period around calving (PI and PI). These groups corresponded to different kinetics of intake level around calving which were defined as follows: group 1 — plane profiles, with a low difference of intake level between pregnancy and lactation; group 2 — profiles characterized by a marked decrease in intake level just before calving followed by a long and regular increase after calving; group 3 — profiles with no decrease before calving but an early break in the increase in intake after calving; group 4 — intake profiles with a large difference in intake level between pregnancy and lactation. Groups 2 and 3 were pooled for P2.

Cows from groups 2 and 4 increased intake after calving fast enough to prevent the use of their body reserves even with a high milk-production level. Their calculated energy balance became positive very quickly, only 1 week after calving. At the other extreme, a decrease in body reserves was observed for cows which needed at least 1 month after calving to reach their maximum intake capacity and then recover a positive energy balance.

Two groups of crossbred ewes, produced by crossing the Scottish Blackface with two prolific sheep breeds, the East Friesian and the Animal Breeding Research Organisation Dam Line, were compared in good lowland conditions over three ages (2 to 4 years) from 1976 to 1978. The East Friesian crossbred ewes were heavier, had larger, heavier litters and had heavier lambs at weaning. More of their lambs were slaughtered directly off their dams, at heavier weights and at earlier ages. The total weight of lamb sold per ewe was about 15% higher than for the Dam Line crossbred ewes.

From among 27 rams of haemoglobin type A the two rams with the highest plasma copper concentration and the two rams with the lowest were selected on the basis of a single determination. In the same way four rams were selected from among the 29 rams of haemoglobin type B. The average difference between the ‘high’ and the ‘low’ rams was 103 μg copper per 100 ml plasma. The rams were mated to 105 unselected females. Lambs born as a result of these matings were blood-sampled on eight occasions from 3 weeks to 29 weeks of age.

The plasma copper levels of the lambs sired by the ‘high’ copper rams were higher on average than those sired by ‘low’ copper rams. The two groups diverged from 12 weeks of age onward to a maximum difference, at 29 weeks, of 18 μg copper per 100 ml plasma. There was also an initial difference of 13 μg at 3 weeks but a much smaller one at 6 and 9 weeks.

There was no corresponding difference in plasma copper concentration between the offspring of haemoglobin A and haemoglobin B rams. The results are therefore consistent with the hypothesis that the association previously observed in the same flock between haemo-globin type and plasma copper level is unlikely to be due to an effect of the gene controlling haemoglobin type, but could be due effectively to a linked ‘copper gene’.

Correlations between maternal plasma copper concentration 3 weeks after parturition and lamb's plasma copper level showed a marked decline as the lambs grew older, starting from around 0·6 at 3 or 6 weeks old. This suggests a maternal ‘environmental’ influence on lamb's plasma copper in addition to any genetic effects.

Male crossbred lambs weighing 10 kg were given, by continuous abomasal infusion, one of a series of diets, equal in energy and nitrogen contents, which provided from 0·887 to 14·863 g lysine per 16 g nitrogen. Gross energy intake was l·38MJ/kg0·75 per day. Oxygen consumption and carbon dioxide production were measured using an open-circuit respirometer when the lambs weighed 12·5 kg. Neither heat production, as calculated from respiratory gas exchange and urinary nitrogen excretion, nor the gross efficiency of utilization of metabolizable energy were affected by the lysine content of the diets.