Naturally-occurring androgens such as testosterone are important in regulating growth in entire male animals (e.g. Galbraith & Topps, 1981). Synthetic steroids with androgenic properties when given exogenously are also known to alter growth of sheep and cattle. Knowledge on the effects of these androgens on body composition and on their mode of action is Inadequate. The major objective of this study was to compare their effects on growth performance and body composition and to relate the responses obtained to changes in certain characteristics of the endocrine system and glucocorticoid receptors in muscle. The steroids used were testosterone (naturally occurring), trenbolone acetate (TBA) (synthetic compound) and nandrolone (19 nor-testosterone - produced synthetically and considered not to occur naturally in castrate male sheep).

Daily injections of bovine pituitary somatotropin (growth hormone) can markedly increase growth and muscle deposition in fattening lambs, although the optimal dose range for these effects is not known.

This experiment was designed to assess the anabolic and lipolytic activities of biosynthetic somatotropin (produced by genetically-modified bacteria) in fattening lambs, and to determine the effects of dose and method of administration.

Dorset Down x Finn-Dorset lambs were individually penned, fed a barley/soyabean meal diet ad libitum (C.P.=155g/kg DM) and allocated to one of six treatment groups, each containing 5 ewe and 5 wether lambs, such that each group had the same initial mean live weight (18 kg). Between 10 and 21 weeks of age, the lambs of each group received one of the treatments shown in Table 1, comparing 3 doses of somatotropin (0.025, 0.1 or 0.25 mg/kg live weight), dissolved in bicarbonate buffer and injected subcutaneously once each day, with the intermediate dose (0.1 mq/kg/day) given by continuous subcutaneous infusion or by daily subcutaneous injection as a suspension in olive oil.

Recombinant-DNA-derived bovine somatotropin has similar metabolic activities to pituitary-derived hormone in both laboratory animals (growth promotion), and in dairy cows (milk stimulation), but anabolic effects have not been investigated in ruminants. Although there is some controversy as to whether recombinant somatotropin has intrinsic lipolytic activity, the release of non-esterified fatty acids in vivo following a single injection (Hart et al. 1984) and the reduction in carcass fat after long-term treatment periods in sheep (Johnsson et al. 1986) indicate lipolytic and/or antilipogenic activity. This study was initially planned to examine these activities during long-term administration of recombinant bovine somatotropin in lambs. However, four cases of uriolitholiasis caused the proposed study of fat turnover to be abandoned and the following data are from those lambs which showed no symptoms of this problem.

Clenbuterol, a β adrenergic agonist, acts as a repartitioning agent increasing the ratio of protein to fat in the carcass. Recent reports on the action of clenbuterol in the bovine have indentified the repartitioning action but body composition has been estimated from sample joints and regression equations based on untreated cattle. Such data may not be appropriate for use with animals treated with repartitioning agents. A comparative slaughter experiment was designed to study the effects of clenbuterol on body composition and energy content of weight gain in the bovine. Veal calves were chosen as the model since they exhibit rapid weight gain, and in the latter stages of growth, prior to slaughter, a high proportion of the gain is fat; such animals may therefore be sensitive to the effects of a repartitioning agent.

There has been considerable research into individual components of harvesting systems in terms of their effects on nutritive value and animal performance. However few studies have examined total harvesting systems, involving in-field and in-silo losses, nutritive value of the product and the effects on animal output per hectare. The present study was set up to examine these effects.

Four systems of harvesting grass for silage were compared over each of 3 harvests during 1984. The systems were: single chop flail harvester direct cutting (SCD); double chop flail harvester direct cutting (DCD); mown with a rotary mower and picked up with a precision chop harvester either immediately (PCD) or after wilting until the dry matter concentration had increased by approximately 100 g kg-1 (PCW). The field wilting periods for PCW were 48, 48 and 24 hrs for the 1st, 2nd and 3rd harvests respectively.

There is currently increasing interest in the diversity of materials which may be used as energy sources for dairy cow diets. Feeding of concentrates with a high “digestible fibre” content may be of benefit to the lactating dairy cow. In comparison with a concentrate based on a highly fermentable energy source such as cereal starch a concentrate high in digestible fibre content may undergo a slower fermentation within the rumen such that the resultant fermentation pattern may be altered. Diets and feeding regime's that promote low rumen volatile fatty acid ratios of acetic plus butyric:propionic have been associated with the production of milk of low fat content. Feeding of a high “digestible fibre” concentrate may therefore help prevent this problem. The purpose of the trial reported here was to compare the effects of concentrate energy source on the milk performance of dairy cows in early lactation.

Numerous factors such as the digestibility value, fermentation characteristics and chop length of silage have all been shown to increase the intake and performance of dairy cows.

Although the effect of silage preference has been examined with young stock and dry cows there has only been a limited number of studies involving lactating cows.

The aim of the present trial was to determine the effect on intake and performance of lactating dairy cows offered either grass silage alone, a mixture of grass and maize silages blended in a ratio of 1:2 or a free choice of grass and maize silages.

Thirty-three British Friesians in weeks 17-24 of lactation were used in the study. All animals received 6 kg/d of a concentrate supplement containing 190 g/kg DM of crude protein and 12.8 MJ ME/kg CM and allowed ad libitum access to the silages.

There has been much recent debate about the protein requirements of lactatinq dairy cows, and this issue has been heightened by a general reduction in concentrate feeding in response to the imposition of milk quotas. Furthermore, the value of silage as a source of protein has been questioned widely. The objective of the present trial was to determine the effect of increasing supplementary protein on the performance of cows with ad libitum access to high quality grass silage.

The trial, using January/February calving British Frieslan cows in second or subsequent lactations, was performed at Ravenscroft Hall Farm, Middlewich, Cheshire. Four groups of 15 cows were offered either 3 or 6 kg/head/day of cereal/soya/fishmeal based compound feeds containing either 214 (L) or 403 (H) g CP/kg DM, and high quality grass silage ad libitum.

When grass silage is available ad libitum, compound feeds depress the intake of silage by cattle. Castle and Watson (1976) and Gill and England (1984) reported that silage intake was not depressed when protein supplements rather than cereals were given to dairy and beef cattle, respectively. The aim of the present trial was to examine protein supplements as alternatives to cereal based compounds to increase the milk yield of dairy cows without reducing silage intake.

In many regions, ammoniation of straw is hindered by the cost or non-availability of anhydrous or aqueous ammonia and by poor upgrading responses with urea. Ammonium salts constitute a safe, alternative source of ammonia. In vitro studies have shown that ammonia produced by heating ammonium ‘carbonate’ (mixture of the carbamate and bicarbonate) or bicarbonate to 90°C for 15 h with water produced improvements in the digestibility of straw which were similar to those achieved with aqueous ammonia. Under identical conditions ammonium sulphate gave a similar response only when reacted with a stoichiometric excess of quicklime (CaO) or slaked lime (Ca(OH)2 ) and water to produce ammonia. When the straw was treated at 20°C for 35 d, upgrading was achieved only when the volatile or non-volatile ammonium salts were mixed with an excess of CaO or Ca(OH)2 plus water.

Treatment of straw with sodium hydroxide or ammonia to improve its nutritive value to ruminants is now well established. However, these chemicals are corrosive and not ideal for use on farms. Urea has been proposed in recent years as an ammonia precursor for the treatment of straw. Urea is a safe (non-corrosive) chemical to handle in both the solid and aqueous form, and could be applied to straw by the farmer himself without the need for specialized contractors. The aim of the work reported was to determine whether urea is an effective alternative to ammonia for the treatment of straw.

In two preliminary trials treated straws were evaluated by determining digestibility in vitro (Tilley and Terry 1963). The first trial showed that for optimum improvement in digestibility, at least 70g urea/kg straw dry matter (DM), and a moisture content of approximately 500g/kg, were required.

Manual separation of both barley and wheat into distinct botanical fractions, with assessment by laboratory techniques, has shown the fractions to have widely different digestibility coefficients (Manley and Wood, 1978). Whole crop cereal harvesting followed by separation of the chopped whole crop into fractions could thus be of benefit to livestock producers. Claims have been made in the farming press (Power Farming, September 1978) by a Swedish company, that one of the straw fractions produced in their centralised separation plant had a higher energy protein content than unfractionated straw. The purpose of this experiment was to evaluate two barley straw fractions produced by a simple air blast separation system, which would lend itself to on-farm use,thus significantly reducing transport costs.

The effects of supplementing straw based diets with either a protein-rich (fishmeal) or a starch-rich (barley) concentrate or a combination of both were investigated using growing Friesian heifers. Digestion and feeding trials were run in parallel to determine the extent to which the growth rate responses to supplementation could be attributed to changes in nutrient supply.

The fatness (lipid weight at a given liveweight) of a given kind of pig can be varied by feeding. An energy restriction will reduce fatness and a feed of low protein:energy ratio will increase it. Pigs made thin by an energy restriction show “compensatory fattening” when returned to ad libitum feeding. The experiment described here had two purposes: (i) to test if pigs made fat would subsequently show “compensatory thinning” when given a feed of high proteimenergy ratio; it was expected that they would, (ii) To test if pigs would show compensatory protein growth following a period of low protein intake; it was expected that they would not.

To determine the energy requirements for pregnancy it is necessary to know the animal's requirements for both maintenance (MEm) and tissue deposition. MEm represents the intake at which both metabolizable energy (ME) intake and heat loss are equal and therefore in energy equilibrium. The eneroy requirement for tissue deposition comprises energy retained as protein and fat in both the gravid uterus and maternal body, together with the energy associated with their deposition. There is little available information to show whether the requirements for maintenance and for tissue deposition change during pregnancy and the present experiments have been designed to provide this information for the sow.

There is now sufficient evidence to suggest that the ARC (1981) factorial estimates of the energy requirements of the sow during pregnancy are too high, due, possibly, to an over-estimation of the maintenance energy component (MEm). Revised values, based on an MEm value of 439 KJ ME/kg0.75, have therefore been calculated and the present experiment was designed to test these new estimates. An additional feature of the experiment is to determine whether variations in feed intake during lactation have an effect on the utilization of energy in subsequent pregnancies for maternal body weight gain. Since the experiment will be conducted over 4 parities it will be interesting to determine whether variations in feed intake during both pregnancy and lactation influence short- and long-term sow performance.

Fostering piglets at 7 days of aye influences the behaviour of ootn piglets and foster sow in many ways (ilorrell, 1932) and retards growth over the next week (Horrell & Bennett, 1981). The growth retardation is persistent and can occur to lesser degree in piglets fostered at 1 day and in resident piglets in the recipient litter (Horrell, Hodgson & LUNB, 1985). This investigation was designed to determine (a) tne behavioural effects in greater detail, and (b) the behavioural mechanisms retardation underlying the growth

Pairs of sows-(Landrace/Large White derived hyurid) which had farrowed 3-12 piglets within 14 h of each other had equal numbers of piglets exchangeu between them. They were then observed for 3 n immediately afterwards and for 1.5 h on each of 1, 3 and 7 d later.

Observations of the behaviour of confined sows provide information about how difficult it is for each individual to cope with the conditions in which it lives. Behaviour which has been described as occurring more frequently in confined sows than in sows with space to walk around includes stereotypies and apathetic behaviour. A stereotypy is a relatively invariate sequence of movements occurring so frequently in a particular context that it could not be considered to form part of one of the normal functional systems of the animal, feeding, body maintenance, reproduction, etc. (Broom 1983). The term apathetic behaviour has generally implied inactivity and lack of responsiveness. In this study, carried out at the Animal and Grassland Research Institute, the occurrence of stereotypies and the degree of responsiveness of stall-housed sows have been quantified.

Two randomised block experiments, involving 64 British Friesian and Friesian cross steers, have been carried out to compare extracted soyabean, extracted sunflower and fish meals as protein supplements for yearling cattle offered grass silage ad libitum. Two formic acid-treated, precision chopped silages, each made from the primary growth and first regrowth of a perennial ryegrass sward, were used. The control concentrate consisted of (g/kg) 925 barley, 50 molasses, 25 minerals and vitamins. The three high protein concentrates were similar to the control but with 0.30, 0.54 and 0.20 of the barley replaced by soyabean, sunflower and fish meals respectively. The mean chemical compositions of the silages and concentrates used in the two experiments are given in Table 1. All animals received 1.3 kg concentrates per head daily. They were initially 11 months old and 334 kg live weight. The treatments were imposed for 126 days.

A series of five randomised-block experiments, involving 232 finishing beef steers., have been carried out to examine the effects of supplementing grass silage-based diets with extracted soyabean meal (SBM) or fish meal (FM). Eight formic-acid treated, precision chopped, silages which were made from the primary growth and first and second regrowths of perennial ryegrass swards, were used. The chemical compositions of the silages are given in Table 1. They were offered ad libitum and those used in experiments 1 to 3 and the early-cut silages used in experiments 4 and 5 were supplemented with 2.5 to 2.7 kg concentrates per head daily while the late-cut silages used in experiments 4 and 5 were supplemented with 4.5 kg concentrates per head daily. The control concentrates used in each of the experiments were based on barley and had crude protein concentrations of 95 to 108 g/kg dry matter. The high protein concentrates were similar but with a proportion of the barley replaced by SBM or FM.