Keeping sows in large groups necessitates ‘dynamic’ grouping, that is, the removal and addition of sows at regular intervals to a group of more or less constant size. However, the lack of stability of dynamic groups raises questions about the nature of the dominance hierarchy and the pattern of feeder use within them. Behaviour and feeder use was observed in a dynamic group of 35-40 sows by both direct observation and video-recording over 13 feed cycles. An initial 4-day recording was made of a stable group of 40 sows to evaluate each sow's feeder use before removal/addition began. On three occasions at weekly intervals five sows were removed and five trained sows added to the group after feeding. Recording covered each day before addition, the day of addition and the following day. Direct observation was carried out for 8 hours on the days before each addition and for 6.5 hours on the following days, starting within 20 minutes of sows being added to the group. The 25 sows remaining in the group throughout removal/addition (‘resident’ sows) were individually marked and observed. Each batch of five sows added was marked as a group and each groups’ feeder use and social activity was recorded.

The study of motivational states underlying behaviour is seen as critical to understanding the implications of restricted husbandry conditions on animal welfare. Yet the measurement of the strength of motivation remains a perennial problem in welfare studies. Previous work at Edinburgh using operant conditioning identified an apparently high level of feeding motivation throughout the day in pigs fed [ARC, 1981] recommended levels for sows and boars [Lawrence et al. 1988]. Pigs trained to press a panel consistently 10 times for a food reward (fixed ratio or FR responding) maintained high levels of panel pressing across the day when offered 0.6 of their ad libitum intake approximating to ARC (1981) recommended feeding levels. However, as the level of operant responding required was not great, it is arguable to what extend these results demonstrate a strong need for food by pigs on restricted feeding. The present paper reports on an experiment to test more accutely the strength of feeding motivation in relation to food restriction by comparing responding on FR with that on a progressive ratio (PR) where the animal has to work progressively harder for successive rewards. It was hoped that PR. reputedly a sensitive measure of motivation, would indicate with greater certainty restrict fed pigs need for food.

Animals show considerable individual variation in many behaviour patterns such as feeding and mating behaviour. Often, this individual variability is ignored in favour of a more general description of the population. However, this may mask important information regarding the causes and functions of this individual variability. Behavioural work on other species has suggested that individuals tend to respond actively or passively to environmental challenge. It is of interest to know if a similar dimension of responsiveness exists in pigs as it may serve, amongst other things, to explain the considerable individual variability in pigs responses to putitive stresses such as tethered housing. This paper describes a series of tests made of behavioural responsiveness in pigs to assess the extent of consistent variability in individuals responses to a wide variety of environmental challenges.

The subjects were two groups [Group A and B: n = 26 and 36 respectively) of modern hybrid non-pregnant gilts [Cotswold Pig Development Company Ltd, UK). Initially, the gilts were subjected to a number of tests of behavioural responsiveness at the Cotswold unit.

The number of pigs weaned per sow per year has increased substantially in recent years due mainly to changes in husbandry with probably some contribution from breed substitution and crossbreeding (Haley et al 1986). Because of emerging difficulties in relation to responses to continued selection for leaness and reassessment of the economic importance of prolificacy in pigs there is considerable interest in selection for increased litter size. It is generally agreed that the heritability of litter size is about 0.1 and attempts to increase litter size by within population selection have not been particularly successful. On the other hand selection for increased ovulation rate in pigs has been effective but the correlated change in litter size has been small. This apparent failure to achieve significant correlated response in litter size has been attributed to a negative genetic association between ovulation rate and embryo survival. However, there is very little information on the magnitude of genetic variation in embryo survival or its relationship with ovulation rate.

The partition of nutrients during lactation, In particular the extent to which body reserves are utilised to support milk production, is important in determining the reproductive performance of sows. For example, if the mobilisation of body reserves by young sows during lactation is excessive then the Interval between weaning and re-mating may be extended. The aim of this present experiment was to manipulate the use of body reserves by sows during their first lactation by altering both feed Intake and suckling intensity (litter size) in an attempt to investigate how the dynamics of nutrient metabolism during lactation may influence reproductive function.

In a 2 X 2 factorial experiment, 28 Landrace x Large White gilts were fed a diet containing 12.5 MJ DE and 156 g CP per kg either to appetite (H) or 3.0 kg/day (L) with litter size adjusted to either 6 (6) or 12 (12) piglets at each feeding level for a 21-day lactation..

In the past, the use of silage-based diets for finishing lambs indoors has met with limited success. Good quality silage is required to maximize voluntary intake but liveweight gains on silage alone are still generally low (Reed, 1979). While cereal supplements have been shown to improve lamb performance at the expense of silage intake, additional protein may have a stimulatory effect on both (Yilala and Bryant, 1985). This trial was therefore designed to investigate the performance responses of silage-fed hill lambs to increasing levels of whole barley and fishmeal supplementation and to examine the effect of a store period on these responses.

Two hundred and forty Scottish Blackface wether lambs, 5 months of age with a liveweight of 26.5 ± 0.18 kg (mean ± s.e.), which had all been reared as singles, were selected for the trial. On housing in September all lambs were kept under artificial lighting conditions of 14th light : 10h dark to remove the confounding effect of daylength.

The use of overwinter food restriction of lambs produced on hill and upland farms followed by a period of rapid spring growth may be used to achieve a more even spread of lambs onto the market. However, pattern of feeding and growth may affect performance and body composition of the lambs.

Sewage sludge contains a range of essential and non-essential elements for livestock nutrition, many of which are toxic at elevated levels. Where sludge is applied to the surface of pasture regularly, contaminants principally heavy metals will accumulate in the surface layer (Davis et al 1988), and may represent a potential health hazard for grazing animals through the direct ingestion of contaminated soil much greater than that from plant uptake. Whilst it is known that soil ingestion can supplement mineral intake with benefits to grazing animals in some situations, the potentially toxic effects of ingesting soil from heavily sludged pastures are of principal concern (Stark 1988). Bearing in mind the strategic importance of grassland for sludge disposal, it must be demonstrated whether existing soil metals limits (DoE 1988) will adequately protect grazing animals. The principal objective of the trial was to study animal growth performance as well as mineral balance from a diet with elevated copper levels derived from a sludge treated soil. Lambs were used for their greater sensitivity to copper than cattle, and the length of the trial simulated the normal finishing period of five months for lambs on pasture.

Although the nutritive value of forage brassicas for lambs has been found to be high, as described by digestibility values of approximately 0.8 or higher, performance of lambs finished on these crops has been low and unpredictable. One of the possible reasons for such low and variable performance is low voluntary food intake which has been attributed to the presence of anti-nutritive factors such as SMCO and glucosinolates in the vegetative material. Glucosinolates undergo enzymic hydrolysis following chewing and the addition of saliva to produce a number of toxic metabolites including isothiocyanates, vinyloxazolidine-thiones and nitriles. (Fenwick et al, 1983). Historically, isothiocyanates were considered to be the major glucosinolate hydrolysis products (Kjaer, 1960); however more recent studies have shown nitriles to predominate under natural conditions such as those occuring during plant autolysis (Cole, 1976). The aim of the present study was to determine whether glucosinolates, following their hydrolysis to nitrile compounds in vivo might be responsible for low intake among lambs offered forage brassicas.

Oats constitute a small and decreasing share of the cereals grown and utilized in the United Kingdom. Compared with the major cereals wheat and barley, oats are perceived to have a low nutritive value in terms of metabolisable energy (ME). Unlike other cereals, the husk remains attached to the oat kernel at harvesting, hence increasing the fibre or cell wall content of the grain.

The proportion of kernel to husk which largely determines the nutritive value of the oat grain is dependent on variety, environment and season.

Previous values for oats (MAFF 1986) were based on a study of 16 samples at the Rowett Research Institute (RRI 1976) in which most were spring sown varieties with low oil contents. The aim of this present work was to examine currently recommended winter varieties and also to study naked oats. These differ from traditional husked oats by having a thin, non-lignified husk from which the grain threshes free.

New cultivars of forage maize have recently been introduced into this country which make maize silage an attractive alternative crop to grass silage. Little advice is available on feeding maize silage to pregnant ewes in the United Kingdom. This experiment compares in physical and financial terms, the feeding of maize silage with grass silage, when offered to pregnant housed ewes.

Straw mixed with grass before ensiling absorbs excess water and reduces effluent, but dilutes nutrients like crude protein and water soluble carbohydrates, and increases cell wall constituents of the mixture. Earlier studies by the authers showed that treating straw with urea before ensiling with grass increased the digestibility of grass+straw silages. A cellulase enzyme preparation had small but positive effects on fermentation and digestibility. The present paper describes the effect of treating straw with urea and a cellulase enzyme preparation on chemical composition and nutritive value of Silages.

Shredded barley straw was treated with urea (60 kg/t of straw dry matter) and a cellulase enzyme preparation (FS01, Forum Feeds Finland; 2 1/t of straw), just before mixing with the precision chopped perennial ryegrass in the ratio of 40:60 on a DM basis, in a 2 X 2 factorial experiment. All the four premixes were ensiled in polythene silos ( 1 t capacity). Eight male sheep were fed four silages in a 4 X 4 latin square design. Each feeding period consisted of a 4-day adjustment period, a 10-day preliminary feeding period and a 7-day period for measurement of digestibility.

There has been a great deal of work carried out on the control of voluntary intake by sheep but little on the selection of foods. In view of the fact that grazing ruminants usually have a choice of plant materials there is a need to understand what controls their selection. Introduction of salts of short chain fatty acids into the rumen depresses intake of a single feed (Balle and Forbes, 1974; Forbes, 1986); sodium chloride has also been shown to depress food intake (Ternouth and Beattle, 1971; Carter and Grovum, 1988; Grovum and Blgnell, 1989) and it is now clear that the osmolality of rumen contents has a marked effect on intake. There have been several observations on food selection by sheep (e.g. Cropper et al. 1985; Gllmp, 1971; Gordon and Tribe, 1951) but none of these have Involved manipulations of short chain fatty acids or osmolality in the rumen.

It has long been recognised that there is a strong positive relationship between the level of absorbed (microbial) purines and purine derivative excretion in the urine. We have used estimates based on urinary allantoin N excretion (AN) to investigate some of the factors influencing the energetic efficiency of microbial yield from the rumen (E). Figures 1 and 2 illustrate the model that has been adopted.

It has been tentatively assumed that, at reasonable levels of intake, exogenous purine supply exceeds “a” moles (Figure 2) so that purine salvage is saturated (Condon & Hatfield, 1970), de novo synthesis inoperant (Condon, Hall & Hatfield, 1970) and the net endogenous contribution to AN negligible. In these circumstances AN will be linearly related to microbial (purine) yield from the rumen.

Twenty-eight lamb ewes (44 + 0.45 kg live weight) were used to study the effect of type and level of supplementation on voluntary intake of barley straw, treated with 30 g/kg of anhydrous ammonia (TS) or untreated (US) but given with urea to ensure the same nitrogen content as TS (18 g/kg DM). Each type of straw was offered ad libitum, supplemented with grass hay, rolled barley and sugar beet pulp at rates of 150, 300, 4 50 and 600 g/d, in 6 Latin Squares (4 x 4). In addition, another 2 sheep received each straw alone during the same periods. Supplements were totally consumed, except hay, which was refused in 10 - 13 and 28 - 34 per cent for US and TS, respectively.

Daily dry matter intake (DMI) of US (OMD = 0.423) and TS (OMD = 0.515) offer as sole feed were 511 ± 29.1 and 858 ± 45.2 g. As show TABLE 1, US was consumed at rates of 527, 576 and 568 g DM when supplemented with 150 g of hay, barley and sugar beet pulp, and no significant differences were found with further levels of supplementation. DMI of TS decreased linearly from 850 to 618 g/d (r = 0.75) and from 717 to 518 g/d (r = 0.63) when the level of barley and sugar beet pulp increased from 150 to 600 g/d. Substitution rates were estimated to be 0.31 and 0.27 for barley and sugar beet pulp, respectively. Decrease in TS intake when supplemented since 150 to 600 g/d of hay (720 to 605 g, respectively) were found not significative.

Lamb performance at grass falls in July/August on upland farms. Allowing sward height to rise has been recognised as having an amoreilating effect. The objective of this trial was to determine the influence of both sward quantity (sward height) and sward quality (sward type) on ewe and lamb performance from mid April to September. An associated objective was the evaluation of the use of clover to replace nitrogen fertiliser.

Previous work at the Edinburgh School of Agriculture has suggested that sheep, like pigs, can select amongst foods which differ in protein:energy content according to their protein needs. The proportion of high protein feed which was selected by young sheep gradually diminished as the animals grew towards maturity over a period of measurement of 10 weeks (Cropper, 1988). The experiment reported here was designed to test this idea further by allowing sheep, initially differing in age and weight, to select between a high and low protein food (both available ad libitum) throughout their growth to a stable mature weight and body composition.

Two pelletted feeds were formulated and prepared which differed in protein concentration but with similar calculated energy (metabolisable energy, ME) (Table 1) concentration and abundant in minerals and vitamins. Seven sheep (Suffolk x Greyface wethers) aged 3 months (n = 3), 18 months (n = 2), and 30 months (n = 2) at the start of the experiment were individually penned and given experience of each of the two feeds individually before having ad libitum access to both. Tap water was freely available from a bucket. Voluntary consumption of each feed was recorded daily by weighing and drying refusals. The sheep were weighed weekly and scanned using a Vetscan ultrasonic scanner to estimate fat and muscle depths at the 13th rib on days 126, 225, 336, 436 and 539.

The benefits of mixed grazing sheep and cattle have been reviewed by Nolan and Connolly (1977). Sheep performance was improved in practically all comparisons and cattle perfomance in the majority of reports. As dairy producers manage their milk quota through various efficiency options, surplus land may become available for alternative use. Based on results from other sheep/dry stock studies the introduction of sheep onto the dairy farm, to utilise surplus/waste grass throughout the year, should lead to increased pasture utilisation and improved overall farm efficiency. The sheep enterprise may be established as a distinct unit and strategically used to exploit feed surpluses on the dairy unit throughtout the year. Alternatively, the full integration of a sheep enterprise with the dairy cows to exploit the benefits of mixed species grazing, may be considered. This latter approach is being evaluated and this report covers the first year of an on-going study.

There is considerable interest at present in reducing the amount of stress imposed upon farm animals. However, before this objective can be achieved it is first necessary to obtain some measurement of the stress response of the animal. Changes in plasma hormone and metabolite concentrations have been used in the past as Indicators of stress. Plasma cortisol concentrations increase after stress in all species studied. For example, after transport in calves (Kent and Ewbank, 1986), after tethering in pigs (Barnett, Winfield, Cronin, Hemsworth and Dewar, 1985) and after electrical stunning in sheep (Pearson, Kilgour, de Langen and Payne, 1977). In a recent study in the sheep B-endorphin and cortisol were released together in response to shearing and electroimmobilisation (Jephcott, McMillen, Rushen and Thorburn, 1987).

The aim of the present study was to examine the release of B-endorphin and cortisol in lambs after routine stressful stimuli such as handling, transport and slaughter at a commercial abattoir.

The stimuli which are most potent in eliciting a stress response to handling are often part of the management procedure itself (eg wool removal during shearing). If sheep handling is to be made less stressful, then alternative methods may have to be found which do not interfere with the procedure. Such alternatives may involve altering either the context in which sheep undergo handling procedures, or their experience of handling. This study tested whether repetition could modify the physiological response of sheep to handling.

Twenty three-year-old Merino wethers were sham shorn four times at intervals of two weeks. Sham shearing involves the noise and physical manipulations of shearing, but no wool is removed, allowing the procedure to be repeated. Two blood samples were collected via jugular catheters before sham shearing and eight were taken over the following eighty minutes. There were significant increases in haematocrit and plasma Cortisol after each exposure (p < 0.05). The Cortisol response to sham shearing was reduced by the previous experiences of the procedure (p < 0.05). This was manifested more in a diminution of the basal concentrations (23.34 ± 5.26 ng/ ml to 9.84 ± 5.50 ng/ml; n = 19) rather than a decline of the peak response (63.29 ± 5.50 ng/ml to 56.54 ± 7.25 ng/ml). There was no difference between the first and fourth exposures in the overall haematocrit response or in maximum haematocrit (33.3 ± 0.7% and 31.34 ± 0.9%; n = 17), however basal haematocrit was lower (p < 0.05) after the fourth exposure than it was after the first (23.6 ± 0.6% and 26.22 ± 0.8%) respectively.