The indigenous sheep breeds of Greece, which are used mainly for milk production, produce lambs which are killed at weaning to provide carcasses (including the head, pluck, liver, spleen and the omental and mesenteric fat) of 5 to 9 Kg. The production of heavier carcases could be of benefit if they are acceptable to consumers and if they could be economically produced. The purpose of this experiment was to characterise the growth and development of the entire males and females of three Greek breeds under conditions presumed to be non-limiting.

Animals. From each of three breeds, Boutsiko (B), Serres (S) and Karagouniko (K), 20 lambs of each sex were used in a serial slaughter experiment. Four animals of each breed/sex combination were killed at live weights which were 25, 35, 50, 70 and 100% of the estimated mature values. All sheep were weaned at 6 weeks of age and the males were entire.

Results of an experiment involving a total of 24 individually-fed pigs, covering the growing period between about 40 and 210 lb. live-weight, indicated that the addition of 20 g./ton griseofulvin to the diet had a slight depressing effect on the rate of growth of the pigs. It had no significant effect on the efficiency of food utilisation, but caused a small reduction in daily food consumption.

The removal of ciliate protozoa, or defaunation, results in the establishment of a new ecosystem in the rumen, consisting only of bacteria and fungi. Although extensive research has been done on ciliate-free ruminants, the role of protozoa in the rumen still provokes considerable debate. The diversity of experimental design, such as animal species, defaunation method, and diet could account for many of the differences observed between defaunation studies. Also it is important to examine the stability of the ciliate-free ecosystem. The aim of this study was to investigate changes in rumen fermentation of ciliate-free sheep over a period of one year.

Eight male castrated sheep, weighing 60-70 kg, received twice daily 700 g of a diet of hay, barley, molasses, fish meal and vitamins/minerals (500, 299.5, 100, 91 and 9.5 g/kg DM respectively). Four sheep were defaunated by the rumen washing technique (Jouany and Senaud, 1979) and kept in isolated pens while the other four were left faunated with a mixed type A ciliate protozoa population. Rumen samples were withdrawn via the rumen cannula and blood samples were taken from the jugular vein -1, 0, 1, 2, 4 and 6 h after feeding. There were three sampling periods: one month, six months and one year after defaunation.

In pigs the quantification of breakdown and synthesis by powers of body protein led to the estimation of turn-over related protein retention efficiency by the equation kP = {1 + [1 − (P/α) (2/9)Q]−1/6}−1, with α the limit value of whole body protein (P) maturity, so that 0 ≤(P/α)≤1. The factor 2/9 is derived from diffusion attributes indicated by cell and nucleus geometries α and Q represents a scaled transformation of intake, 0 ≤ Q ≤ 1, such that a value of Q = 1 may represent ad libitum intake and Q = 0 the intake at the maintenance requirement. Published observations on finishing steers provide estimates of whole body protein synthesis and breakdown at pre-determined levels of intake in confirmation of the theoretical (2/9)Q power associated with (P/α) in kP. Further confirmation of the (2/9)Q power in cattle follows from satisfactory agreement between an estimate of conventional multiple regression retention efficiency and the turn-over related retention efficiency calculated at the given level of intake, for the mid point of the body mass interval covered by the regression estimate. In addition, a simulation experiment on cattle from the literature gives power estimates of protein breakdown and synthesis in general agreement with those accepted for pigs. Examples on both fine and coarse diets are employed to suggest a general rule for prediction on diets causing submaximal efficiency due to suboptimal intakes.

In sheep, evidence derived from estimates of conventional multiple regression efficiencies suggests that the rule (a-b) = (2/9) Q for the calculation of kP should be reserved for the description of compensatory growth. Protein retention efficiency for ordinary growth should be described by an adaptation of the rule derived for suboptimal intakes.

Inaccurate prediction of silage intake is often the greatest source of error in ration formulation but improvements have been hindered by an inadequate description of the silage fermentation in advisory practice. Until recently, only pH and ammonia N have been routinely measured as indicators of silage fermentation characteristics. A new method, based on research in Finland (Moisio and Heikonen, 1989) has been developed and is now in use by SAC. This involves automated titration of juice squeezed from the silage to pH 2 (with HC1) followed by stepwise titration (with NaOH) to pH 12. Concentrations of juice constituents are predicted from the buffering capacities measured over segments of the titration curve (pH 2 to pH 12). Calibrations have been obtained empirically by the addition of known increments of standards to a range of silage juices. Proportions of variance (R2) of measurements made by reference methods accounted for by predictions from titrations for a validation set of 93 silages were 0.90, 0.78, 0.92, 0.82 and 0.82 for lactic acid, acetic+butyric acids (VFA), soluble N, sugar and ammonia N respectively.

Many trials at Reading have shown store lambs to be reluctant to eat straw when first housed after grazing. This is especially so if penned individually, as is often the case in feeding trials. Such isolation may induce stress, including depressed intake (Crampton, 1959; Kidwell, Bohman and Hunter, 1954). Farm animals are generally stimulated to eat more when in a group than when isolated (Curtis, 1983), yet most intake studies, particularly with sheep and cattle, are conducted with individually-penned animals. Concern for the welfare of animals being used for trials calls for systems of housing that minimise stress.

The present experiment tested the hypothesis that straw intake, by store lambs first-housed after grazing, would increase if lambs were penned in pairs rather than individually, or confined in pens allowing pen to pen vision rather than prohibiting pen to pen vision.

Mating is one of the most critical processes influencing the success of any breeding pig enterprise since the efficiency of this process establishes the potential output of pigs. A study was conducted on 100 recently weaned sows during the mating process to determine potential sources of inefficiency.

The study was conducted in a large commercial herd with Large White (LW) x Landrace (LR) first cross sows. 4 genotypes of boar were in use, these being LW, LR, LW x LR and Duroc. The parity of the 100 sows involved in the study ranged from 1 to 9. Sows were housed in small groups of 5 to 6 following weaning at a mean of 18 days post partum and were taken daily to an oestrus detection area to test for standing oestrus (SO). Boars were housed around this area and SO was detected using the back pressure test Within 5 minutes of SO being confirmed, each sow was paired with a boar in a specialist 2.9 v 2.65 m mating pen. This pen had a 15 cm floor covering of sawdust-based deep litter which provided good foothold and comfort Boar-sow behavioural interactions, general behaviour of the mating partners and sow vocalisations were recorded from the first pairing in the pen to the dismounting of the boar following mating.

A latin square design with three periods of 3 weeks was used to measure the dry-matter intake, live-weight gain and water intake of 12 British Friesian calves offered an all-concentrate diet ad libitumin wet form. The diets contained 30% (B), 20% (C) or 15% (D) dry matter. A further six calves were given the same diet in dry form (A) throughout the experimental period. Digestibility and nitrogen balance were measured on four calves on each treatment at the end of the experimental period. In addition, two Ayrshire calves, each fitted with a permanent abomasal cannula, were used to study the site of digestion of the feed when given in dry or wet form.

The mean dry-matter intakes of the calves given the dry and wet feeds were 75·5 and 80·8 g/kg W0·75 per day respectively and mean daily live-weight gains were 849 g for the calves on both types of feed. The mean dry-matter intakes of the calves given the wet diets were 80·9 (B), 81·2 (C) and 75·5 (D) g/kg W0·75 per day, and the live-weight gains (g/day) were 857 (B), 879 (C) and 812 (D). None of these differences were significant. The intake of water by the calves was significantly increased by reducing the dry-matter content of the diet. The form or dry-matter content of the diet offered had no effect on the digestibility of dry matter (76·1%), organic matter (77·9%), energy (75·8%) or crude protein (75·8%) or on nitrogen retention (32·5% of N intake).

The rumen was the main site of digestion for all Tour diets and an average of only 7% of dietary starch passed undigested through the abomasum.

Four groups of 20 Simmental cross heifers were actively immunized against human serum albumin (control, (C), androstenedione (A), a 30 amino acid synthetic fragment of porcine inhibin alpha (I) or A and I in combination (AI). At the time of the third and final antigen injection and again 2 weeks later, all animals were injected with synthetic prostaglandin F2α (PG) to synchronize oestrus. Concentrations of LH, FSH, insulin-like growth factor-1 (IGF-1) and inhibin (C and A heifers only) in serum samples collected twice daily during 3 days before the second PG injection and at 15-min intervals from 24 to 32 h after PG injection were determined. Two weeks later, all heifers were administered PG and ovariectomized 24 h later. Ovarian follicles were dissected from the stroma, measured and cultured in medium 199 for 2h at 37°C. Numbers of small (3·0 to 7·9 mm diameter) and large (>8·0 mm diameter) follicles were not significantly altered by any of the immunization treatments. Intrafollicular concentrations and secretion rates of oestradiol, testosterone, progesterone and inhibin, determined in vitro, were not affected by immunization. Intrafollicular IGF-1 concentrations were not affected; this hormone was not detectable in the culture medium. Intrafollicular concentrations of oestrogen and testosterone and secretion rates of all three steroids were greater (P < 0·05) in animals which had regressing corpora lutea at the time of ovariectomy. Of the animals that had dominant follicles, one of 17, one of 13, four of 19 and six of 15 in the C, A, I and AI groups, respectively, had two or more. Only the difference between AI and C cows in the incidence of dominant follicles was statistically significant (P < 0·05). Mean circulating concentrations of LH, and inhibin (C and A groups only) and mean LH pulse frequency and pulse amplitude were unaffected by treatment but FSH concentrations were higher in A (P < 0·001) and lower in AI and I heifers (P < 0·001) compared with C animals while IGF-1 concentrations were lower in A heifers (P < 0·001) and higher in AI heifers (P < 0·05) compared with C heifers. It is concluded that immunization against inhibin, either alone or in combination with immunization against androstenedione increased the incidence of multiple dominant follicles in heifers but did not increase their ovulation rate.

On hill farms where breeding cattle are kept there are advantages in retaining until the following spring at least a proportion of the surplus calves. The ability to winter them presents wider scope in choice of markets, while the sale of calves in spring, in addition to the dung produced, can provide a greater profit margin if wintering costs are minimised. Grass used efficiently in autumn offers an opportunity to reduce the requirement of the relatively expensive hay, silage, other crops and purchased feed. The value of extended grazing throughout autumn and winter months has been demonstrated by Smith (1953-4) for Blackface ewe hoggs, and for store stock and in-calf heifers by Hughes (1954) and Corbett (1954). In the case of calves, however, the period when late grass can be utilised depends on the continuance of moderate temperatures and availability of shelter from wind and rain, and therefore in most seasons will be relatively short. With these considerations in mind it was decided to compare the performance of two groups of weaned calves, one of which was housed and fed in courts immediately after weaning, while the other remained on grass for several weeks prior to court feeding.

Calculating optimal truncation values for independent culling selection procedures has been difficult. Previously published charts took much of the tedium out of the calculations but the charts are difficult to read with accuracy and are not available for all possible parameter values. Therefore a computer program was written to calculate optimal truncation values for two-trait independent culling, with the option of restricting the genetic change of one or both traits. The program is described and an example of its use is given.

The technology to measure individual feed consumption of pigs in groups using electronic feeders is a recent development. As well as providing information on total feed consumption and consequently feed efficiency it is also possible to examine feeding behaviour under normal social conditions (ad libitum feeding in groups). Changes in feeding behaviour over a performance test are of particular interest to determine if growing pigs increase consumption by larger meals, more frequent feeding or a combination of both.

Selection for high lean growth rate may lead to changes in both feeding behaviour and duration of feeding which could have undesirable side effects in a genetic selection programme. Increased feeding activity may lead to aggression and lost efficiency of feed conversion due to greater activity.

Previous experiments have shown important differences in milk production when mixed starch sources were replaced by mixed high quality by-products in high concentrate diets with hay as the forage (Sutton et al. 1987). The purpose of the present experiment was to compare rolled barley with sugar beet feed (SBF) in both molassed and unmolassed forms when given alone with grass silage in a high-concentrate diet. Additionally the effect of altering protein concentration of the concentrates was examined.

A breed improvement programme has been initiated at both ADAS Redesdale (Scottish Blackface) and ADAS Pwllpeiran (Welsh Mountain) to improve carcass conformation of hill ewes. From a base population of 1100 Welsh Mountain and 1600 Scottish Blackface ewes, nucleus flocks of 60 ewes have been established. Selection of ewes into the nucleus flock at each site has been based on their ability to consistently produce wether lambs crops with good conformation and above average carcass weights when selected for slaughter at a fat class 2/3L. The next objective is to replicate these ewes through multiple ovulation and embryo transfer (MOET) since theoretical studies (Smith, 1986) indicate that this can substantially increase the rates of genetic improvement through the female line. However, to date little work has been conducted to determine whether this technology can be successfully applied to hill sheep maintained in harsh hill environments in the UK, and this formed the basis of the current study.

One hundred and eight high genetic merit Holstein-Friesian heifers were used to determine the effects of rearing regime on the development of the mammary gland and claw abnormalities. Heifers were allocated to one of four rearing regimes at 7 weeks of age and slaughtered at 18 (s.d.0.7) months of age; mating commenced at 14 months of age. Treatment 1 heifers were reared to calve at 540 kg and treatments 2, 3 and 4 heifers reared to calve at 620 kg. Treatment 1 and 2 heifers were offered grass silage-based diets during the winter and grass-based diets during the summer; treatment 2 heifers received additional concentrates. Treatment 3 heifers were offered a straw/concentrate diet during the winter and a grass-based diet during the summer. Treatment 4 heifers received the same winter diets as treatment 3 but were housed and offered a straw/concentrate diet in summer. Increasing plane of nutrition increased the weight of dissected udder fat (P < 0.01), but had no effect on the weight or chemical composition of dissected udder parenchyma. Offering straw- compared with silage-based diets reduced fat deposition in the udder (P < 0.01) and increased the proportion of parenchyma in the udder (P < 0.01). Keeping heifers housed during the first summer and offering straw-based diets relative to those turned out to grass had no effect on weight of fat although there was a tendency towards a reduction in the proportion of parenchyma in the udder (P < 0.06). Heifers reared on a low plane of nutrition had lower values for heel height (P < 0.001), lateral claw length (P < 0.001) and heel erosion scores (P < 0.01). A higher plane of nutrition also increased live weight/sole area although this was only significantly higher for treatment 3 (P < 0.05) compared with treatment 1 heifers. Housing heifers in the first summer increased the incidence of feet lesions in the white line area and solear area relative to turning heifers out to grass in the first summer (P < 0.05).

Thirty-six entire male pigs were used to investigate the effects of two levels of dietary crude protein (150 and 220 g/kg) each in combination with four levels of feeding (1·0, 1·32, 1·64 MJ digestible energy/kg M0·73 per day and ad libitum) on growth, body composition and energy utilization over the live-weight range 7 to 19 kg.

Growth rate responded linearly (P < 0·001) to increasing energy intake but was depressed (P < 0·05) when dietary crude protein was reduced from 220 to 150 g/kg.

Raising digestible energy intake increased and decreased respectively the proportions of fat and protein in the empty body at 19 kg live weight. However, the magnitude of the response of both components to change in digestible energy intake was reduced in the case of pigs fed the lower protein diet.

Total energy retained and that retained as fat and as protein responded linearly (P < 0·001) to change in digestible energy intake of either diet. Extrapolation of the regression of total energy retained on digestible energy intake yielded a digestible energy requirement for maintenance of 510 kJ/kg M0·75 per day, which was unaffected by level of dietary protein.

The partial efficiencies of protein utilization, estimated from the regressions of protein deposition (g/day) on protein intake (g/day), were 0·616 and 0·411 for pigs given the diets containing 150 and 220 g crude protein per kg respectively.

A stochastic bio-economic model has been used to determine the effects of new reproductive technologies over a 15-year period. A strategy of using conventional artificial insemination (AI) or embryo transfer (ET) using two sex-controlled embryos at different conception rates (CRs) and herd sizes resulted in a 24 state model. The genetic means of AI population increased over the years, and the genetic means of milk production for all of the embryo strategies were greater than those of AI. In addition, the genetic means of milk yield using different embryo-based scenarios in the expanding herds were greater than those for the fixed herds. The net profit of using sexed ET in the expanding herds was greater (P < 0.05) than that of fixed size herds. In general, there was a roughly consistent trend in net profit per cow for sexed ET strategies in the expanding herds over the years, but there was an increasing trend in net profit per cow for sexed ET strategies in the fixed herds over the years. Medium to high CRs for ET and the use of sex-controlled embryo systems, especially for induction of twin births to produce dairy replacements, will be critical elements of a system that produces significant numbers of female calves. The greater number of female calves produced in the sex-controlled scenarios allows the farmer to select animals with the best genetic potential as dairy replacement heifers; therefore, the rate of genetic gain increased in the dairy herd. Results of sensitivity analyses showed that a significant decrease in the production costs and increase in the ET performance are essential for embryo-based technologies to be profitable.

Although there are numerous reports on the influence of dietary fats on milk yield and milk composition in the dairy cow (see review by Palmquist, 1984) little is known about the value of fat supplements in the diet of lactating ewes, a species which produces milk of a much higher fat content than the dairy cow. We now report the results of three experiments in which lactating ewes received diets supplemented with a lipid source that was protected from hydrolysis in the rumen.

Individually-penned Finnish Landrace x Dorset Horn ewes, each suckling two lambs by Suffolk rams were used in all three experiments. They were given a diet containing (per kg): 500 g hay (milled through a 4 cm screen), 300 g barley, 90 g white fish meal, 5 g dicalcium phosphate, 3 g salt and 2 g of a trace mineral/vitamin supplement. The crude protein and metabolizable energy contents per kg dry matter were 145 g and 10 MJ respectively. The source of the protected lipid was calcium palmitate (Megalac, Volac Ltd) with lipid and calcium contents (g/kg) of 850 and 90 g respectively.

Work in New Zealand has suggested that treatment of dairy cows with buserelin an analogue of GnRH between days 11 and 13 after insemination can increase pregnancy rate by reducing embryo loss (MacMillan, Taufa and Day, 1986). This effect is probably mediated via a luteoprotective mechanism (MacMillan, Thatcher & Drost 1989; Thatcher, MacMillan, Hansen & Drost, 1989). The present study was carried out to attempt to confirm this effect of buserelin under UK conditions.

A total of 660 Holstein/Friesian cows on 10 commercial dairy farms were used. The cows were paired according to date, of previous calving and allocated at random to control or treated group on the day of service. Only cows in the parity range 1-5 with no obvious reproductive disorders were used. Bulls and inseminators were used on the same number of cows in each group. Milk samples were taken on the day of service for progesterone assay. Cows not in oestrus were removed from the study. Cows in treated groups were given an intramuscular injection of 10 ug buserelin [2.5 ml Receptal, Hoechst] 12 days after first insemination. Cows not observed to return to oestrus before Day 24 were re-sampled for progesterone assay. Pregnancy was confirned by palpation or ultrasonic scanning at six weeks.

The primary aim of the calf rearer is to ensure a successful transition from non ruminant to ruminant status while achieving rapid growth and an early intake of solid food. Newbold, Blake and Hagges (1991), found that increasing the concentration of ME in either the starter or milk replacer will not promote more rapid growth, but will simply reduce the rate of starter consumption. This present study investigated the extent to which the energy density of a calf starter ration affected starter intake and liveweight gain in calves receiving a fixed allowance of a high energy milk replacer with ad libitum access to solid calf starter rations.