Manipulation of the bacterial population of the intestine has been shown to result in changes in the structure and function of mucosal tissues. The objective of the present experiment was to investigate the effect of inclusion of a non-therapeutic antibiotic, virginiamycin, in the diet of sheep on the activity of the Na* -dependant transport of glucose and alanine by enterocyte cells. These transport mechanisms can be studied by isolation of brush border membrane vesicles following sub-cellular fractionation of the mucosal tissues.

Tissue was obtained from two separate growth trials in which the effect of inclusion of virginiamycin on lamb growth was being studied. In Trial 1 (glucose studies) the animals had been fed a concentrate diet plus hay ad libitum and virginiamycin was included at 100 ppm in the treatment group. In Trial 2 (alanine studies) the sheep were fed a concentrate diet with virginiamycin included at 50 ppm in the treatment group.

In ruminants duodenal purines,mainly derived from microbial nucleic acids, are catabolised and excreted in the urine as xanthine, hypoxanthine, uric acid and allantoin. The use of purine derivatives as an index of net microbial syntesis in the rumen requires a better understanding of the contribution of endogenus losses to total urinary excretion.

Similar levels of basal excretion of purine derivatives has been determined in ruminants maintained by intragastric nutrition (Giesecke et al. 1984, Fujihara et al. 1987) and preruminants fed on liquid diets (Linberg, 1989). However, lower excretion of allantoin and uric acid were recorded when exogenous supply was reduced by fasting (Rys et al. 1975).

Two experiments have compared the effects of forages or concentrates offered to dairy cows, continuously stocked in late Summer at a low stocking rate in Experiment 1 or a higher stocking rate in Experiment 2.

In Experiment 1 (July - October 1984) 20 Spring calving British Friesian cows were allocated to a Latin square design with four, three week periods and four treatments, a control group, grazing only (TO), grazing with 5 kg dry matter fresh lucerne per day (TL), grazing with 5 kg dry matter hay per day (TH) and grazing with 4 kg DM concentrate per day (TC). In Experiment 2 (August -October 1985) 24 cows of similar calving dates were used in an incomplete Latin square design lasting eight weeks to compare treatments TO, TL, TS and TC where silage (TS) replaced hay. All supplements were offered for 1 hour after each of two milkings per day.

Intake of herbage by grazing animals is determined by the weight of herbage harvested per bite and the number of bites taken. A knowledge of ingestive behaviour can, therefore, play a valuable role in understanding animal responses to changes in sward conditions and management practices and thus aid the interpretation of results from grazing experiments. This paper will firstly consider briefly some methods of recording behaviour and, secondly, present some results illustrating the use of behaviour recording within a grazing experiment.

Direct observation is the most frequently used method of recording behaviour. It is, however, laborious and often carried out under unpleasant conditions; it is difficult to record activities continuously and in some cases it is not possible to directly observe a particular behaviour. These limitations have led to numerous attempts to record grazing behaviour automatically.

An experiment was carried out to determine which feeding method maximised feed intake of growing pigs and to record growth rates, feed conversion efficiency and backfat measurements. There is an increasing tendency for dry fed pigs to be fed ad libitum or to appetite in order to increase growth rates and throughput of building.

Limited information is available on how the modern genetically improved pig will respond to high levels of feeding and whether ad libitum feeding will encourage higher feed intake than feeding to appetite either wet or dry.

Oilseed rape meal is high in protein and available in the UK relatively cheaply. Toxic constituents limit its inclusion in feeds for pigs and poultry but this is not a problem with ruminant animals where microbial action in the rumen removes them. However, the bitter taste of rape meal has been thought to reduce its palatability for ruminant animals (Stedman and Hill, 1987) and it is recommended that its inclusion in compound feeds for cows should not exceed about 150kg/tonne; masking agents are incorporated to reduce this limitation.

The question to be addressed can be summarized as “can higher rates of inclusion of rape meal in dairy compound feeds be concealed by more mask?”. Twelve dry cows in late pregnancy were offered feeds with various levels of rape meal in combination with several levels of mask and rate of consumption was monitored.

Growing pigs spend considerable time orally manipulating their environment, which can include their pen-mates. In certain situations this leads to problems such as tail-biting. It is unclear if this active behaviour represents foraging or exploratory motivation, a problem exacerbated by the possibility that both share certain behavioural elements. The aim of this experiment was to distinguish appetitive foraging (extrinsic exploration) from intrinsic exploration by manipulating both feeding motivation and the content of the external environment. The objective was to discover which behavioural elements are common to either behavioural category. This would allow hypotheses to be proposed concerning the causation of oral-manipulation of the environment and inappropriate stimuli such as pen-mates, and furthermore to control for the effects of intrinsic exploration in continuing experiments concerning foraging behaviour.

Grass silage provides an alternative feed for extensively kept sows, but previous experiments have indicated very variable intake and utilisation, dependant on silage quality. ‘Maxgrass’ silage additive (BP Nutrition) is a blend of compounds including ammonium hexamethanoate, ammonium hexapropanoate and octanoic acid. It is designed to modify fermentation, so that the resulting silage retains a higher proportion of water soluble carbohydrates. This should improve the nutritive value for pigs.

The experiment comprised two parts: an intake/growth study and a separate digestibility study. The same two experimental silages, either treated with Maxgrass or an untreated control, were offered to groups of pregnant sows in a randomised block experimental design in each experiment. Second cut, mainly perennial ryegrass herbage was cut by mower conditioner and direct ensiled. Alternate loads were left untreated or treated with Maxgrass at a mean rate of 6.04 litres/tonne.

Best Linear Unbiased Prediction (BLUP) is now the method of choice for the estimation of breeding values in dairy and beef populations. The advantages of this mixed model methodology over traditional methods are well documented and include the simultaneous estimation of fixed effects and prediction of random effects and the utilization of records from all relatives to predict an individuals breeding value. In addition, account is taken of genetic trend and of reduction in genetic variance due to selection. In Canada, BLUP is now used for breeding value estimation of pigs but the structure of the Canadian pig industry is one of many herds practising selection with the herds linked by a widespread use of artificial insemination. The advantages of BLUP have not been investigated for the situation of the UK pig industry where most selection is performed within closed nucleus herds.

The objectives of this study were to use computer simulation to determine rates of response, accuracy of prediction and accummulation of inbreeding for pigs in closed nucleus herds when selection decisions were based on estimated breeding values (EBVs) derived from BLUP compared to more traditional methods of phenotypic selection and index selection.

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.

Leg disorders in male turkey breeding stock are associated with pain during locomotion (Duncan et al 1990). Musculo-skeletal diseases are prevalent in broiler breeder males and the experiment was designed to evaluate birds of two ages for evidence of pain during movement. Two experiments were conducted, the first examined differences in sexual motivation and the second the rate of walking towards a food reward. At the end of the experiment the birds were killed and the legs dissected to establish the presence of musculoskeletal disease.

Commercial broiler breeder males were housed singly with 15 females in 4 rooms each containing 12 floor pens measuring 1.5 x 2.4 m. There were 24 males in each of two age groups (40 and 60 weeks at the start of the experiments). To determine sexual motivation, males were removed to an empty pen in a spare room. They were returned after 3-5 h and observed for 15 min. The time to make a sexual approach (AP) and to mount a female (MT), and the number of copulations were recorded on three different days. Subsequently, males were trained to walk through a 20 m long alley constructed of hardboard to receive their daily food allocation. During testing, the time taken to reach the food was recorded 3 times before the male was returned to its pen. The males in two rooms were used in a 2-period crossover experiment to evaluate the effects of naloxone (an opiate receptor antagonist) and three analgesics on walking speed (Table 1). All measurements of time were transformed to natural logarithms for analysis. A censored analysis was used for AP and MT. The total number of copulations observed (COP) was modelled using Poisson errors. The models included effects for age and day (where appropriate). The data were reanalysed with the lesion score as a fixed effect. The initial model for walking speed included period and carry over effects. Mixed model methods (REML) were used to assess the final model with birds as blocks and treatment and lesion as main effects.

In some grazing experiments stocking rates are adjusted during the experiment. For these and other experiments in which the initial number of animals per treatment is subsequently reduced a more powerful statistical analysis than the normal analysis of variance may be possible. The methodology of the analysis is presented in this paper and applied to an example.

In countries with developed agricultural systems the proportion of dairy cattle inseminated artificially increased substantially following the Second World War, but a similar expansion in the use of artificial insemination (AI) has not been experienced for beef herds. The availability of deep frozen semen provided a further incentive to increase the percentage of dairy cattle artificially inseminated, for the more progressive herd owners soon realized that the technique offered the advantage of a long-term breeding programme with semen from progeny-tested sires available at a relatively modest cost. More recently, however, various developments in herd management have tended to militate against the use of AI in dairy herds, and during the past year there has been a substantial decrease in the total number of dairy cows inseminated which can only be partially explained by the smaller decrease in the size of the national herd. Amongst reasons advanced is the increase in average size of individual herds, resulting in more cows per man and therefore less time available for the observations of oestrus. Since accurate detection of the onset of oestrus is so important in obtaining high fertility following AI, some herd owners have returned to using natural mating. Evidence supporting this view can be derived from the fact that during 1973/74 there was an increase of over one thousand in the number of bull licences issued in England and Wales above the seventeen thousand issued in 1972/73. Of the 18.2 thousand bulls licensed, there were 3.2 thousand crossbred bulls, some obviously for use in dairy herds. The availability of synchronized and controlled ovulation would largely remove the difficulties which have been encountered, and would permit planned management techniques to be more widely applied within such herds.

In animal housing ammonia is an aerial pollutant resulting from the microbial conversion of nitrogenous materials excreted in faeces and urine. Ammonia is an irritant to cells lining the respiratory tract and an increased incidence of pneumonia in pigs and humans and atrophic rhinitis in pigs have been correlated with elevated ammonia levels. In a survey of 12 farms and 49 pig buildings concentration of ammonia was identified specifically as a causative agent in the aetiology of atrophic rhinitis (Robertson, Wilson and Smith 1990). Furthermore, high levels of ammonia can delay the onset of puberty in gilts perhaps as a result of the masking of boar odour (Malayer, Brandt, Green, Kelly, Sutton and Diekman 1988).

Regulations have been introduced (Control of Substances Hazardous to Health (COSHH)) limiting the exposure of humans to atmospheric ammonia to a mean level of 25 ppm over an 8h work shift and 35 ppm for 10 minute exposure. As part of a study on the effectiveness of a feed additive formulated to control atmospheric ammonia, levels of ammonia in pig housing were monitored.

Use of a farrowing crate can benefit newborn piglets but imposes severe restriction on sow movement throughout lactation. It is necessary to find a compromise between the commercial requirements for control in the immediate neonatal period, to maximise piglet survival, and enhanced welfare for the animals, by reducing environmental restriction. This might be achieved by combining individual farrowing in controlled systems with later multisuckling of a group of contemporary litters in a larger and more diverse environment. Application of modern understanding on nutrition and environment could allow such systems to function more successfully than in the past and provide a commercially attractive option.

A total of 33 purebred Landrace or Large White sows and their litters were used in the study. All sows farrowed in commercial accommodation based on farrowing crates in partly slatted pens. These pens had a covered creep area for the piglets which was bedded with shavings. Control litters remained in this accommodation until weaning. Experimental litters were moved to specially constructed multisuckling pens.

Premature loss of wool from fleece casting prior to shearing is a problem in some sheep genotypes, in particular in the North Country Cheviot. The reasons for this ocurrence are not fully understood, but it is believed that it is due to a complex of factors including heredity, nutritional and managerial (stress) practices, the wool growth cycle, and physiological parameters such as pregnancy. Prolonged stress is reported to be particularly important in the case of wool slip in ewes which are housed and shorn (Morgan et al, 1986).

The present study aimed to investigate the incidence of visible fleece casting in the North Country Cheviot (NCC), Scotch Halfbred (HB) (Border Leicester x NCC), and Border Leicester (BL), which has no history of premature wool loss. The study was implemented on 8 commercial farms in Scotland, and links between key productive parameters and wool loss were studied, and an attempt to identify fleece types most liable to cast was also made.

The production of colostrum by prolific ewes is of particular importance because of the increased demand of larger litters. Robinson (1985) has shown that there is a sharp increase in the ewe's net protein requirement for udder growth and colostrum production in the last 2 weeks pre-partum.

The trial was designed to investigate the effect of level of protein in the diet during the last weeks of pregnancy on the quantity and quality of colostrum produced by prolific ewes.

Forty-four Cambridge ewes aged 2 to 7 years and scanned as carrying two to four lambs were used. Ewes were housed and sheared approximately 2 months pre-partum and fed a complete diet at a restricted level and hay ad libitum until the commencement of the feeding trial at 2 weeks pre-partum. The ewes were then individually penned until 5 days post partum. During this period the ewes were fed ad libitum one of the two complete diets detailed in Table 1 together with hay ad libitum.

It is hypothesized that the fat colour of steers raised at pasture can be manipulated by altering animal growth patterns using the effects of post-pubertal surgical castration and oestradiol treatment. The fat colour of 151 steers of three genotypes of beef cattle, castrated at approximately 9 months or 18 months of age and treated, or not treated, with oestradiol after castration, was studied.

Surgical castration of beef cattle at both 9 months of age or 18 months of age caused no readily apparent animal welfare problems. The combined effects of early or late castration and oestradiol treatment produced varying growth patterns with early castrates exposed to two post-castration episodes of growth associated with carotene-rich forage and late castrates only one such episode of growth.

Late castrates and early castrates treated with oestradiol had a less yellow fat than early castrates not treated with oestradiol. The proportion of carcasses with commercially significant yellowness in the fat was decreased by either late castration or by oestradiol treatment. There was no effect of genotype on fat colour.

Lamb output in terms of both reproductive performance and lamb growth during lactationof hill gimmers (18 months old at first mating) is typically well below that of their multiparous contemporaries. This paper reports an attempt to evaluate the effects of supplementary feeding during the mating period and mid-pregnancy on gimmer performance.

Three hundred and ninety three Scottish Blackface gimmers from two hirsels (flocks of sheep from contiguous areas of land) of Auchtertyre Farm in west Perthshire were split according to the following design.

It is not clear when the optimum time of harvesting the winter barley as whole crop for silage should be in terms of feeding value for dairy cows and yield of the crop. Little information is available using whole crop barley as a buffer feed. The aim of these experiments was to evaluate the feeding value of whole crop barley (WCB) silage harvested at three stages of growth as a supplementary feed for grazing dairy cows during the late season.

Winter barley (var. Pipkin) was harvested at 4 stages of growth : T1:250, T2:350, T3:450 and T4:550 gDM/kg, at the following dates : 25/5, 19/6, 3/7 and 11/7/1991, respectively. The chopped material from T1-T4 was stored in minisilos and from T1-T3 in larger silos for animal studies.