Previous studies have shown that bovine performance can be improved by manipulating photoperiod. This may be an acceptable alternative to the use of exogenous hormones but responses have been inconsistent. The objective of this trial was to determine the response of finishing cattle to extended photoperiod.

Sixty-four Hereford x Friesian steers and 48 Charolais x Friesian heifers were finished in consecutive years over the winter housing period under either natural daylength (Control) or daylength extended to 16 hours (16 hour). Lights were installed to provide 16 hour animals with 400 lux at animal eye level. A photocell and timeswitch combination ensured that lights were switched on if natural light levels were below this level between 04.00 and 20.00 GMT. Animals were penned in groups of eight and silage was weighed in daily to each pen. Animals were weighed fortnightly and feed conversion ratios calculated. Prolactin assays were carried out on blood samples taken monthly from 10 animals per treatment. Steer and heifer behaviour was monitored over 24 hours on three occasions.

Current consumer demand for leaner beef necessitates a reduction in the fat content of a major proportion of beef carcasses. Recent studies have shown that a greater reduction in carcass fat content can be achieved when plane of nutrition is reduced by reducing the quantity of food given rather than reducing the energy content of a diet given ad litibum. An experiment lias been carried out to examine the effects of restricting food intake during the finishing period on the performance and carcass composition of beef cattle.

Two hundred and ten 12 month old Friesian (F), Limousen x F and Belgian Blue x F bulls, steers and heifers, which had been reared under uniform management and nutrition were used. They were purchased directly from dairy farms between mid October and mid December, at approximately two weeks of age, were artificially reared and were put to pasture from late April until early October.

Recent research has shown that supplemention of beef cattle diets with small quantities (10-20 g/d) of yeast culture can lead to increased liveweight gain and improved feed conversion efficiency (Hughes 1988, Edwards 1991). Supplementation of dairy cow diets has led to reduced weight loss in early lactation, increased milk yield and an improved milk composition (Williams et al 1989). Improved animal performance has usually been associated with increased dry matter intake. The precise mode of action of yeast culture in ruminants is, as yet, unknown. There is evidence that yeast culture increases cellulolytic (Harrison et al 1988) and total rumen bacterial numbers (Edwards 1991). This may lead to increased rates of fibre digestion and increased microbial protein production. A number of in sacco studies have shown increased degradation of substrates at rumen incubation times of 24 hours or less (Williams 1989, Chademana and Offer 1990).

Feeding level is a major factor in maximising feed efficiency and reducing effluent pollution in fish farming. In previous studies on stocking density, feeding levels used in normal commercial practice were employed. The results tended to suggest that these levels were too high for maximum feed efficiency. Consequently a series of trials was undertaken at different times of year to study the effect of feeding level, at a range of water temperatures, on growth and feed efficiency.

Three 21 d trials were conducted in early winter, spring and late summer, to avail of different water temperatures and dissolved oxygen concentrations. Four different feeding levels (22, 19, 16 and 13 g/kg bodyweight) were used in each trial. Trials one and two had three replicates of the four levels and trial three had two replicates. Identical adjacent ponds (18 m3) were used in each trial and were randomised for feeding level. Initial weights were 30, 50 and 20 g in trials one, two and three respectively.

The efficient production of farmed fish depends on a large number of variables such as water temperature, oxygen concentration, feeding level, diet composition and stocking density. These interactions also have important effects on water quality. As part of a series of experiments to establish an effective management system on a fresh water farm producing rainbow trout, two studies were conducted to establish the effects of stocking density on growth and feed efficiency, one under winter and the other under summer conditions of temperature and oxygen tension.

The feeding of turbot during the on-growing phase is done with highly proteinaceous feeds, raw fish and fish meal being the main ingredients. The protein of these feeds is used inefficiently because the amino acids of the protein are metabolised to produce energy instead of contributing to protein growth (Cacho et al. , 1990). Alternative sources of energy, such as carbohydrate, are known to spare protein (Hepher, 1986). The aim of this experiment was to test the idea that fish given free access to feeds with different protein: carbohydrate ratios will (a) eat enough feed to meet their protein requirement and (b) maximise their efficiency of use of protein for growth when a sufficient supply of an alternative source of energy (carbohydrate) is available.

In farmed salmonids the majority of consumed nitrogen is lost in metabolic waste products (mainly ammonia) and the faeces (Table 1). Any improvement in nitrogen retention, brought about by reductions in these components, would decrease environmental load. Inter-individual variation in retained nitrogen has been little investigated as a basis for selection of more efficient fish; this communication points to an experimental approach to measuring individual variation by concentrating on digestive efficiency and protein turnover as possible contributors to nitrogen retention. The utilization of dietary nitrogen was investigated in two species of farmed salmonid, the rainbow trout, Oncorhynchus mykiss and the Atlantic salmon, Salmo salar.

The rainbow trout (Oncorhynchus mykiss) is a seasonally-breeding teleost which typically spawns for a 6-8 week period each year. The consequent seasonality of egg production restricts the profitability of fish farming; year groups of fish all reach marketable size at the same time and farm facilities are either over or under utilised depending on the time of year. Since these problems can be avoided by the production of out-of-season eggs, techniques designed to modify the time of spawning offer considerable commercial advantage. Of the photoperiod regimes available to modify spawning time those utilising continuous light (LL) are particularly attractive because neither time control or blackout are required. However, year-long exposure to LL can produce erratic spawning. This study examines the ability of short (⩽2 months) periods of LL to advance and delay maturation in the rainbow trout.

Feeding different groups of 1 year-old prepubertal female rainbow trout for 0, 4, 8 or 12 months on either high (1.0% body weight day-1) or low (0.4%) rations produced significant changes in fecundity, total egg volume and in the percentages of fish which spawned. Fish fed high ration for the first 4 or 8 months of the year-long cycle had up to 56% higher fecundities even after weight influences had been partitioned by covariance analysis. Groups of fish fed high ration for the first 4 months of the cycle included the highest percentages of spawning fish. By optimising feeding regimes commercial hatcheries could produce up to 3x more eggs from existing stocks.

Birds are normally able to synthesize adequate amounts of ascorbic acid (AA). However, there are many indications that under stress they cannot produce enough AA for their metabolic needs. In particular, heat stress has been implicated in increasing birds’ demand for AA (Scott, 1975; Sykes, 1978; Coates, 1984). These reports suggest that conditions may exist in which endogenous AA synthesis of birds is not adequate to meet the physiological needs for optimum performance and that during such conditions exogenous supplementation with AA could be beneficial. This study was conducted to determine if dietary supplemental AA would alleviate heat-induced deterioration in performance and metabolism of broiler chicks and also to characterize the changes in body temperature, thyroid weight and blood components as affected by supplemental AA and/or heating.

Vicia faba has considerable potential as a protein supplement for farm livestock in many parts of the world. The protein content varies depending on cultivar but has been reported to range from 230 - 390 g/kg (Garrido et al 1991) The extensive use of vicia faba in laying hen diets has been limited by the, presence antinutrients such as tannins, lectins and pyrimidine glucosides which have been reported to decrease protein digestibility (Lacassagne et al. 1988) and adversely affect egg production and quality parameters such as egg number and egg weight (Guillume et al 1977). The production of low tannin cultivars of vicia faba has increased interest in its use in poultry feeds and an experiment was conducted to investigate the effects on egg production and quality of inclusion of whole ground beans; cotyledons or hulls from one such low tannin cultivar ‘Toret’.

The ability of broiler chickens to regulate protein intake when given a choice of high- and low-protein feeds has been demonstrated (Shariatmadari and Forbes, 1990). However, it is not know whether birds take several meals from one feed and then several from the other, or whether both feeds are taken in mixed meals. Therefore, to determine how protein intake regulation operates on a meal-to-meal basis, the meal patterns of broiler chickens were automatically recorded when they were offered two feeds of different protein content.

The objective of this research was to determine the site of dissolution of viscous polysaccharides in the intestinal tract of birds fed a barley-based diets and the site of action of enzymes designed to degrade such polymers. A barley-based diet (60% Condor variety, 4.58% β-glucan) was fed with and without β-glucanase supplementation to broilers from 1-21 days of age (4 replicate pens of 5 birds per pen), at which time weight gain, feed intake and viscosity of digesta supernatant (12,500 x g, 5 min) from the gizzard, first and last half of the small intestine was measured. Two β-glucanase sources were tested, a commercial multienzyme product, blended from several microbial and fungal fermentations containing β-glucanase, xylanase and amylase activities (Avizyme Sx, Finnfeeds International Ltd., BG1) and a single Trichoderma fermentation source of β-glucanase (BG2). Each enzyme was added at 250 β-glucanase U/g (pH 6.8) feed. Addition of BG1 and BG2 improved weight gain by 28 and 28% respectively (p<0.0001) and FCE by 23% and 18% respectively (p<0.0001). Viscosity in the gizzard, first and last half of the small intestine was 10, 88 and 270 cp respectively in control broilers, an unacceptably high set of values, particularly in the hind-gut. Addition of either enzyme source significantly reduced viscosity in all gut sections and prevented the increase in viscosity noted in control fed birds. Foregut intestinal viscosity correlated well with weight gain (R2=0.907, p<0.0001) and FCE (R2=0.871, p<0.0001). The variance associated with weight gain and FCE was substantially reduced with enzyme addition, but particularly so with BG1. BG1 tended to reduce gizzard viscosity to a greater extent than BG2 suggesting that it is either more active at acid pH or that undefined associated activities (eg glucosidase) are necessary for optimum viscosity reduction.

Intensive housing systems are often criticised for preventing certain behaviour, or for constraining appropriate matching of behaviour and environment. However, the effects of such behavioural restriction on animals will depend on the way in which the behaviour is controlled and the way in which it interacts with the environment. This is particularly important where facilities are being provided for animals. Behaviour-environment interactions were investigated in laying hens.

Total collection of faeces from goats fed long straw ad libitum in crates requires much labour. This is particularly so when feeding straw generously to facilitate selection by goats of the more nutritious leaf-plus-sheath component (Wahed, Owen, Naate and Hosking, 1990). Confining goats in crates is also stressful to animals and in future will be discouraged. An experiment was therefore made to compare the digestibility of barley straw supplemented with concentrates, measured by collecting faeces in one of two ways. One involved total collection of faeces from goats confined in metabolism crates. The other involved estimating the output of faeces from the increase in weight of sawdust bedding provided for individually-penned goats.

Commercial cashmere production in the UK is at an embryonic stage. Native feral goats (F) have been crossed with imported stock from Iceland (I), Australasia (A) and Siberia (S) to improve fibre production. At present there is little published data on the amounts and quality of fibre produced from these genotypes and their crosses.

The objective of this study was to establish the extent of the variation in fibre production characteristics, namely fleece weight, yield and down production between the above genotypes and also to estimate the likely improvements made from crossing these pure bred genotypes.

Breeding does at an early age can accelerate genetic progress in a breeding programme. However there is little information on the management and nutrition of bred doe kids. This trial investigated flat rate and stepped rate allocations of energy during the last 9 weeks pre-kidding and the effects of these treatments on the subsequent performance of both does and kids.

In December 1990 42 first and second cross cashmere doe kids were selected for breeding on the basis of liveweight (minimum 18.5 kg) and housed until kidding in early May. Two 3 year old New Zealand bucks were run with them for 4 weeks. A complete diet, consisting of grass nuts and maize gluten was fed during the housing period.

The coat of the cashmere goat is made up of two components: a valuable down (cashmere) and the outer guard hair. Industrial processing is required in order to separate them. Yield is defined as the weight of down as a fraction of total fleece weight. An accurate assessment of yield or down weight is essential in order to determine the relative merit of an animal.

Yield is expensive to determine objectively in the laboratory, and a yield figure is also required if down weight is to be calculated directly from fleece weight. Several Australasian studies have shown good correlations between calculated down weight and down length measured on the animal, and a relationship between yield and cashmere and guard hair lengths has also been demonstrated (Winter at al, 1985). However there is no published information on these relationships derived from Australasian or Siberian cross ferals bred in the UK.

The weight of a sample patch of fibre shorn from a measured area on the animal’s midside has been used as a predictor of fleece weight, either to predict the full fleece weight later in the season or when, for practical reasons, fleece weight cannot be obtained (Russel and Bishop, 1990). This experiment investigated these relationships in a group of cashmere goats.

The primary objective of Angora goat producers is to optimise yields of high quality mohair, characterised by long staples of fine fibres. There is also now an increased interest in the concurrent production of goat meat as an additional source of income. Protein supplementation has been shown to affect mohair yield, quality and liveweight gain in Angora goats both in the USA (Shelton and Huston, 1966) and more recently in the UK (Shahjalal et al., 1991). Throckmorton et al. (1982) detected an improvement in liveweight gain and fibre production when Australian Angoras were fed a supplement high in rumen undegradable protein (UDP) but the effect of protein degradability has not yet been established, particularly under UK conditions. The aim of this trial was to determine the effect of varying protein degradability on yield, staple length and fibre diameter of mohair, and on liveweight gain of British Angora goats.