Measurements of the live weight and body condition of 105 Scottish Blackface, North Country Cheviot and South Country Cheviot male sheep (rams) per year were made at three locations over a period of 2 years.

A distinct cyclical pattern of change in live weight and body condition throughout the year was apparent in all rams. Maximum values recorded in the autumn were followed by rapid and substantial losses throughout the mating period, with recovery of both weight and condition during the spring and summer months. The amplitude of the annual live-weight curve was of the order of 20 kg (22%) and that of body condition was more than 1 unit.

The patterns of annual change in live weight and of inferred change in body composition of rams are compared with those of ewes, and some of the probable effects on production are considered.

Previous experiments (Osafo, Owen, Said, Gill & McAllan, 1992), investigated the possibility of using low-input technology to improve intake of sorghum stover in sheep and cattle. Physical form of stover influenced intake differently in sheep and cattle; chopping stover increased intake in sheep but decreased intake in cattle.

In an earlier experiment in the same research project, Aboud, Owen, Reed, & McAllan (1990) offered sheep, chopped stovers from bird-resistant (BR) and non bird-resistant (NBR) sorghum. It was hypothesised that intake of BR stover would be lower on account of its higher content of anti-nutritional, polyphenolic compounds. The results were contrary to expectation. The higher leaf:stem in the BR stover was thought to counteract the anti-nutritional factors and account for the higher intake and growth with BR stover. In view of the differences in leaf-plus-sheath:stem ratios between the BR and NBR stovers, the experiment was considered inconclusive. Also the fact that the stovers were supplemented with cottonseed meal may have alleviated any detrimental effect of feeding NBR stover.

Vitamin A is a well-known antioxidant and is essential for embryonic development, growth and differentiation. Oxidative stress is involved in the etiology of defective embryo development. The present study evaluated whether the presence of all-trans retinol (0, 1, 2, 5 and 10 μM) in maturation medium or embryo culture medium would enhance the developmental competence of preimplantation buffalo embryos in vitro. In experiment I, cumulus oocytes complex were matured with varying concentrations of all-trans retinol. Treatment with 5 μM all-trans retinol improved the blastocyst formation (P < 0.001) when compared with control and significant increase (P < 0.01) in total cell number was observed in 5 μM group when compared with control. Supplementation of all-trans retinol in embryo culture medium for the entire culture period under 5% O2 and 20% O2 was tested in experiments II and III, respectively. Supplementation of 10 μM all-trans retinol under 5% O2, significantly reduced blastocyst formation and cell numbers. Presence of 5 μM all-trans retinol under 20% O2 enhanced the frequency of blastocyst formation and total cell number (P < 0.001) when compared with control. DNA damage of individual embryos cultured under 20% oxygen concentration was measured by the comet assay. Supplementation of 5 μM all-trans retinol significantly reduced the comet tail (P < 0.001) when compared with control. Supplementation of all-trans retinol in embryo culture medium for first 72 h of the 8-day culture period under 5% O2 was tested in experiment IV. Addition of 5 μM all-trans retinol resulted in significant increase in blastocyst rate and total cell number (P < 0.001) when compared with control. Our results demonstrate that addition of all-trans retinol to maturation or embryo culture medium may enhance the developmental competence of buffalo embryos in vitro by enhancing blastocyst formation rate and total cell number.

This study determined the correlated responses in reproductive performance after five generations of divergent selection for components of efficient lean growth rate in Large White pigs.

Data were collected from five generations of pigs divergently selected for daily food intake (DFI), lean food conversion (LFC), lean growth rate on ad-libitum feeding (LGA) and lean growth rate on restricted or scale feeding (LGS). In each selection group, there were high, low and control lines, each consisting of 10 boars and 20 gilts. Animals were mated at around 9.5 months of age. Pregnant gilts were fed 2.5 kg daily and farrowed sows up to 3.5 kg twice daily of a 160 g/kg DM crude protein and 132 MJ/kg DM digestible energy ration. Animals were farrowed at 414 (s.d. 19.7) days of age, on average. No cross fostering was practised. Piglets were offered creep feed containing 235 g/kg DM crude protein and 160 MJ/kg DM digestible energy from 14 days and were weaned at an average of 35 (s.d. 3) days. Litter traits were measured on 1220 selected Large White gilts, with 13030 piglet birth weights and 9951 weaning weights.

Groups of five Yorkshire ♂ x Landrace ♀ gilts were either exposed (BE) or not exposed (NE) to a mature boar commencing at 140, 147, 154 or 161 days of age. Each group of BE gilts was slaughtered 10 days after initial boar exposure, for examination of the reproductive tract, with one of the four NE groups killed at a corresponding age.

NE gilts remained prepubertal throughout. Boar exposure induced ovulation in one gilt at 140 days, two gilts at 147 days, two gilts at 154 days and one gilt at 161 days. Boar exposure also increased uterine weight (P < 0·001). There were no effects of age either on the number of gilts ovulating or on uterine weight. There was a significant positive effect of body weight on uterine weight which was greater in BE gilts than in NE gilts. These results suggest that body weight may be a determinant of the response to boar exposure by gilts between 140 and 170 days of age.

Thirteen dairy cows between 7 and 20 days post partum were fitted with catheters in both the jugular vein and caudal vena cava, the latter with the tips anterior to the junction with the ovarian veins. Blood samples were taken from nine control cows from both sites at 15-min intervals for periods of between 8 and 16 h. Four more cows were sampled for 13 h and given 4 × 2·5 ug GnRH intravenously at 3-h intervals starting 1 h after sampling began. Plasma oestradiol-17(3 concentrations were significantly higher in the vena cava than in the jugular vein in the two cows in which they were compared. Twenty-eight LH pulses occurred in the nine control cows during the sampling periods. These were followed within 1 h by increases in caval oestradiol-17β concentrations in 26 cases. LH pulses occurred after 14 of the 16 GnRH injections and with one exception were associated with oestradiol pulses in the vena cava. Oestradiol concentrations generally peaked 15 to 45 min after each LH peak. It is concluded that ovarian follicles are responsive to LH pulses by releasing oestradiol pulses early in the post-partum period.

Ten crossbred (Karan Swiss) cows were induced to calve about 1 month prior to expected term using either 25 mg dexamethasone alone (Group B) or 25 mg dexamethasone in combination with 25 mg vetoestrol (Group C). Another five animals served as controls (Group A). The average time interval from injection to calving was not significantly influenced by the two treatments used, and was 52·2 ± 4·07 h and 49·0 ± 1·55 h for groups B and C respectively. The mean gestation lengths for animals in groups A, B and C were 283·60 ± 2·77, 255·20 ± 1·93 and 255·20 ± 2·3 days respectively. The calves born from cows induced to calve early were significantly lighter at birth compared to controls (P < 0·05). The average live-weight gain over the first 12 weeks among calves was not significantly influenced by treatment averaging 2·58 ± 0·07, 2·81 ± 0·16 and 2·20 ± 0·16 kg/week for groups A, B and C respectively. Foetal membranes had not been voided by 24 h in the animals induced to calve early and hence required manual intervention. The length of the service period, number of services per conception and the milk yield of the cows induced to calve was not significantly different from their previous records (P > 0·05).

Exercise and physical training are known to affect gastrointestinal function and digestibility in horses and can lead to inaccurate estimates of nutrient and energy digestibility when markers are used. The effect of exercise on apparent nutrient digestibility and faecal recoveries of ADL and TiO2 was studied in six Welsh pony geldings subjected to either a low- (LI) or high-intensity (HI) exercise regime according to a cross-over design. Ponies performing LI exercise were walked once per day for 45 min in a horse walker (5 km/h) for 47 consecutive days. Ponies submitted to HI exercise were gradually trained for the same 47 days according a standardized protocol. Throughout the experiment, the ponies received a fixed level of feed and the daily rations consisted of 4.7 kg DM of grass hay and 0.95 kg DM of concentrate. The diet was supplemented with minerals, vitamins and TiO2 (3.0 g Ti/day). Total tract digestibility of DM, organic matter (OM), CP, crude fat, NDF, ADF, starch, sugar and energy was determined with the total faeces collection (TFC) method. In addition, DM and OM digestibility was estimated using internal ADL and the externally supplemented Ti as markers. Urine was collected on the final 2 days of each experimental period. Exercise did not affect apparent digestibility of CP, crude fat, starch and sugar. Digestibility of DM (DMD), OM (OMD), ADF and NDF tended to be lower and DE was decreased when ponies received the HI exercise regime. For all treatments combined, mean faecal recoveries of ADL and Ti were 87.8±1.7% and 99.3±1.7%, respectively. Ti was not detected in the urine, indicating that intestinal integrity was maintained with exercise. Dry matter digestibility estimated with the TFC, ADL and Ti for ponies subjected to LI exercise were 66.3%, 60.3% and 64.8%, respectively, while DMD for HI ponies were 64.2%, 60.3% and 65.2%, respectively. In conclusion, physical exercise has an influence on the GE digestibility of the feed in ponies provided with equivalent levels of feed intake. In addition, the two markers used for estimating apparent DMD and OMD indicate that externally supplemented Ti is a suitable marker to determine digestibility of nutrients in horses performing exercise unlike dietary ADL.

The inclusion of 60 p.p.m. of 2,4-dichlorophenoxy acetic acid (2,4-D) or of M15† in the diet of lambs had no effect on the concentrations of volatile fatty acids and ammonia in rumen liquor, on the contents of haemoglobin, protein and non-protein nitrogen in blood or on the composition of the blood serum proteins. Over weeks 1 to 6 of experiment, there was a significant increase in live-weight gain in lambs receiving a diet containing M1S but the effect had disappeared at the end of 12 weeks. Inclusion of 2,4-D in the diet had no effect on live-weight gain.

Ventilation rates of 0·14, 0·42 and 0·71 m3/min per pig (2·3, 6·9 and 11·5 air changes per hour) were compared at weight ranges from 42 to 65 kg and from 69 to 88 kg and at optimum ambient temperature and at 8°C above optimal. A total of 96 pigs was used, housed so that gases from manure decomposition were present. Growth rate and food conversion were not affected by ventilation rates, but food intake was significantly lower at the lowest ventilation rate compared with the other two rates at the hotter temperature only. The odours and gases at the lowest ventilation rate were such that attendants strongly objected to them.

'Clean’ grazing is accepted as a successful method of overcoming poor performance in lambs and young cattle caused by nematode parasites of the alimentary tract and would virtually eliminate the need for regular anthelmintic treatment. However,it is impracticable on many grass farms and especially where sheep predominate. ‘Safe’ grazing offers a realistic alternative but has not been fully tested under field conditions. Two 2.8 ha paddocks of a predominantly perennial ryegrass sward were managed during the spring and summer of 1985 to produce two different levels of pasture nematode infestation for weaned lamb grazing during the Autumn of that year. Both areas were grazed by non-lactating mature ewes until 5 February 1985. The safe area(S) was then closed for two silage cuts and grazed for 11 days during early August by replacement dairy heifers. The contaminated area(C) was set stocked with 21 cross-bred ewes and their May born Suffolk x lambs per ha between 29 April and 28 August. Dung samples were collected from lambs grazing C at 8,12 and 16 weeks of age. Herbage and dung samples were collected from S and C at weaning (28 August) and 14 day intervals until lambs were removed from trial on 31 October. 138 lambs were divided into two groups by weight and condition at weaning and set stocked at 25/ha on S and C following an anthelmintic treatment. Lambs were selected for slaughter to produce carcasses of MLC fat class 2 or 3.

The use of additives such as ractopamine (Rac) in pregnant sows during early-mid pregnancy is an alternative to increase foetal and progeny growth and development. However, Rac supplementation in finishing pigs can lead to behavioural and physiological changes similar to the typical stress responses. The objective of this study was to evaluate the effects of dietary supplementation with Rac in pregnant sows from day 25 to 50 of gestation (pre-hyperplastic stage) on piglet’s vitality, blood parameters, number, diameter and perimeter of muscle fibres in semitendinosus muscle and developmental characteristics of piglets at birth to weaning. Forty-one hybrid sows were divided into three dietary treatments: (1) control diet without Rac (control), (2) addition of 10 mg/kg of Rac (Rac10) and (3) addition of 20 mg/kg of Rac (Rac20). Higher numbers of low-vitality piglets (P<0.05) were observed in Rac-fed sows, regardless of dose, compared with the control group. Very low-density lipoprotein levels were lower in the Rac10 group when compared with the Rac20 group at day 21. Haematocrit was greater, and the mean corpuscular haemoglobin concentration was lower in piglets from Rac-fed sows. No significant statistical differences were detected regarding piglets body weight, average daily gain, blood gasometry, complete blood count and muscle fibre measurements in semitendinosus muscle. The use of Rac in pregnant sows reduced the vitality parameters of piglets but did not improve the performance from birth until weaning and did not negatively influence the haematological parameter and lipid metabolism.

The performance of predominantly Suffolk-sired lambs from Border Leicester (BL), Bluefaced Leicester (BFL) and ABRO Damline (DL) crossbred ewes was compared on 18 commercial and college farms throughout England and Wales. The comparison took place over the 5-year period 1977 to 1981 and was the second stage in a comparative study on the productivity of the crossbred ewes. A total of 1277 crossbred ewes were involved with data on up to 3 years lambings per ewe, giving a total of 3522 mating records and 4864 lamb records.

The BFL lambs were heaviest and the DL lambs were lightest. The DL lambs had the lowest survival rates, and the BFL lambs the highest. The BFL lambs were slaughtered earlier (12 days) and at heavier weights (1·4 kg) than the DL and BL lambs, and had slightly heavier carcasses. The DL and BFL carcasses had better MLC carcass classifications than the BL, resulting in an advantage of 4 p/kg of carcass.

In productivity per ewe, the BFL litters had the highest slaughter and carcass weights and the highest income per litter, with the DL litters intermediate. An attempt was made to express productivity per unit of sheep weight maintained, taking account of ewe weight, litter size and the lamb slaughter date. On this index, the DL were marginally superior to the BFL, and both were superior to the BL.

Water balance, electrolyte and acid-base status of a group of five South African Mutton Merino wethers given chopped lucerne hay ad libitum was determined before and after ileorectal anastomosis. In general, the sheep recovered rapidly from surgery, resuming, within 10 days, a level of dry matter intake only slightly less than pre-operative levels (1323 (s.e. 147) and 1419 (s.e. 196) g/day respectively, P > 0·05). A new water balance was established at about the same time, when sheep with an ileorectal anastomosis drank about 2500 ml/day more water, while losing about 2400 ml/day more water in the faeces and about 365 ml/day less water in the urine than did the control sheep. Most of the electrolyte and acid-base parameters tested were not significantly affected by the anastomosis but the concentrations of oxygen and potassium in the blood of sheep with an anastomosis were significantly lower (P < 0·001), while those of chloride (P < 0·001) and bicarbonate (P < 0·05) were significantly higher, than before surgery. These observations, together with normal blood pH values, suggest that bypassing the large intestine caused a compensated metabolic alkalosis.

Energy balance was determined on the five sheep with an ileorectal anastomosis as well as five control animals in an indirect, open-circuit calorimeter. Despite a significantly lower (P < 0·05) loss of nitrogen and energy via the urine (due to a lower output of urine) in sheep with an ileorectal anastomosis, total heat loss, whether absolute or relative to energy intake, did not differ from control values and therefore indicated that basal metabolic rate was not significantly affected.

From post-mortem examinations, anastomoses appear to have induced a marked atrophy of the bypassed caecum and colon, whilst the mass of the large intestine was significantly less than in control animals, despite the significant enlargement of the rectum. On the other hand, the small intestine appeared unaffected, either macroscopically or histologically.

The most significant physiological changes that occurred on bypassing the large intestine were related to loss of water reabsorbtion. However, good adaptation to the increased turn-over of water was evident, providing free access to water and a salt lick was allowed.

In a recent study carried out over three years, on a commercial Cheshire dairy herd, 86% of animals were found to be lame at some time. This level of disease is considerably higher than has been reported, (Rowlands, Russell and Williams, 1983; Dohoo, Martin, Meek and Sandals, 1983) and may have important economic implications.

Lameness has been associated with reduced 305 day yields (Rowlands and Lucey, 1986), lower than average lifetime yield (Cobo Abreu, Martin, Wiiloughby and Stone, 1979), lower yields in early lactation (Enevoldson and Grohn, 1991), and a reduction in percentage milk protein (Bigras-Poulin, Meek and Martin, 1990).

The intricate pattern of distribution of the Devon breeds of sheep can be broadly related to variations in natural conditions. Some ebb and flow in the popularity of breeds is to be expected as a result of changing economic circumstances. Pre-war, there was wide scale crossing with the Dorset Down and South Down rams to obtain earlier maturity. Since the war, the ploughing-out and the new marketing arrangements for fat-stock have brought a revival of interest in the pure-breeds, but as in other parts of Britain, the change over to dairying, especially in West and Mid-Devon, has been accompanied by a permanent reduction in sheep flocks.

The growth of male red deer slows during the first winter of life before increasing again during spring. This study aimed to determine if this period of slow growth could be minimized using artificial photoperiods during autumn and winter (10 April (week 1) to 11 September (week 23), southern hemisphere). Four groups of deer (no. = 10) were housed indoors as follows. Two groups were placed on a winter solstice photoperiod (8·5 light (L): 15·5 dark (D)) and given either a natural increase in photoperiod to 11·25L: 12·75D (WSN) or held on 8·5L: 15·5D for 7 weeks followed by an abrupt increase to 11·25L: 12·75D (WSH). One group was exposed to a summer solstice photoperiod of 16L: 8D (SS) and one group exposed to a natural photoperiodic pattern (IC). A fifth group of deer (no. = 10) was maintained outside on a gravelled enclosure under natural changes in photoperiod (OC). All groups were given a diet containing 160 g protein per kg and 11·0 MJ metabolizable energy per kg dry matter (DM) ad libitum. All animals were weighed weekly and group food intake recorded daily. Metatarsal length was measured at weeks 3,17 and 22 from the start of treatments.

The major differences occurred between SS and the other groups. After a period of slower growth (weeks 1 to 5, SS = 88 g/day v. 168 g/day other groups, s.e.d. 31·2, P < 0·05), SS grew more rapidly from week 10 (P < 0·01). As a result, SS was heaviest from week 17 (P < 0·05) until the end of the experiment (P < 0·01). The mean growth rate of SS animals from weeks 10 to 23 was 346 g/day compared with 173 g/day (s.e.d. 15·3; P < 0·001) for the other groups. Over the whole experiment, SS animals gained 42·3 kg live weight, compared with 31·1 kg for WSN, 26·6 kg for WSH, 25·1 kg for OC and 23·7 kg for IC (s.e.d. 2·08 kg P < 0·01). The DM intake of SS from week 9 until the end of the experiment averaged 2·04 kg DM per head per day compared with 1·48 (s.e. 0·041) kg DM per head per day for the mean of the other groups. Metatarsal length increased more in SS than the other groups (P < 0·001) between weeks 3 and 17 and was longest in SS at weeks 17 and 22 (P < 0·01). Exposure to a 16L: 8D photoperiod during winter advanced the rapid growth of red deer calves normally associated with spring and summer. This response may be used to advance slaughter dates for venison production.

In extensive pastoral systems, where mating cannot be controlled, the breeding strategies of intermingling owner flocks interact. We present a method to evaluate a breeding programme in extensive reindeer (Rangifer tarandus) management which can also be applied to other pastoral production systems. Our main objective was to evaluate the method by applying sensitivity analyses. The method included a gene flow model with maternal effects. The potential response Rp was defined as the response that could be achieved in a closed nucleus with a given selection procedure. The value of Rp was derived from the gene flow from dams to daughters, selection differentials, and the realized difference between subpopulations. We studied a population structure having two subpopulations, only one of which had been subjected to selection. Random mating between subpopulations and a common male pool were assumed. A reference case was defined using reindeer data from the literature. After 9 years of continued selection among progeny the estimate of Rp was 7·0 times higher than the realized subpopulation difference. We analysed deviations of Rp from the reference case caused by different female age structures between subpopulations. We also analysed the sensitivity of maternal effects. The method proved insensitive to differences in female age structure between subpopulations but was sensitive to the relative contribution of maternal effects to progeny performance.

1. Observations were made at 2 years of age on 25 freemartins and their castrated brothers. Three of the freemartins belonged to a set of 4-egg quadruplets. For comparison there were 93 normal pregnant twin and single-born heifers and 14 males twin to males.

2. Twelve body measurements on each animal were taken. Averages for each character for 25 single-born Ayrshire heifers and for 10 single-born Friesian heifers were used as standards for comparison with the various groups of twins of like and unlike sex, triplets, and quadruplets.

3. Normal twin heifers were slightly smaller in all respects than the standard. Freemartins were also smaller but more so. The quadruplet freemartins were smaller still, but at 2 years they had the live-weight of normal heifers only 1½ years old. Twin males, whether from like or unlike-sexed pairs, were on average slightly smaller than the standard.

4. Percentage deviations of each group mean from standard varied systematically when characters were listed in a pre-determined order based on earliness of maturing. This relation has been summarised for each group by the regression of the percentage deviation on order of maturity, the order beginning with head width, and ending with the widths of hooks, pins, and chest. Each available group differed significantly from the chosen standard in conformation in such a way that the later a character appeared in the order, the less it exceeded, or the more it fell short of the standard.

5. As judged by the size of these regression coefficients, males twin to males showed the greatest difference in conformation from normal single-born females. Males twin to freemartins showed a slightly smaller difference. Freemartins were intermediate but closer to males. Fertile twin females and single-born females differed very little. These relations held at both 2 years of age and a live-weight of 650 lb. (1½ to 1½ years).

6. The quadruplet freemartins were anomalous in having the linear dimensions of immature normal instead of freemartin females of the same weight as if their early maturing body characters had been permanently retarded during slow growth before and after birth.