The dry sow is well suited to utilise high fibre diets and there are some suggestions that feeding such diets in pregnancy may enhance litter size and subsequent piglet performance. This experiment was designed to investigate the effects on performance of inclusion of a high level of fermentable fibre in the form of unmolassed sugar beet pulp (SBP) in the diet of dry sows.

24 gilts and 20 multiparous Landrace x Large White sows were allocated to one of two diets according to weaning or entry date, parity and liveweight. The diets comprised a barley/soya basal diet with either 450 g/kg wheat (diet W) or SBP substituting for this wheat to provide the same quantity of corrected digestible energy (diet B). The two diets were fed at differential levels, to supply the same daily total of corrected digestible energy, from weaning or gilt entry until farrowing. The allocated amount of diet was given in a single daily feeding period to animals confined in individual feeding stalls, and a period of one hour was allowed for the ration to be consumed. After farrowing all animals were fed twice daily on a standard diet, according to a scale related to litter size.

Although the amount of food given to dry sows in commercial situations is nutritionally adequate for maintenance and reproductive performance, it may not be adequate in other aspects. There is evidence that low levels of food intake increase the incidence of abnormal behaviours. It might be desirable to feed greater amounts, but without causing excessive nutrient intake and obesity of the sow which occur when feeding commercially used diets at high levels. One solution might be to provide bulky, low density diets. The objectives of this experiment were to obtain information on level and variation in voluntary food intake in dry sows on fibrous diets and on the relationship between chemical aspects of the diet, intake, and apparent digestibility.

The level of glucosinolates in the seed of many double low varieties of rapeseed is still very close to 20 μM/g, which will be the limit for EEC subsidy from 1992. Besides the effects on the price, the high level of glucosinolates in rapeseed meal, and their possible products of decomposition, may limit their usefulness in feeding strategies and programmes for pigs.

The possibility that the agronomical conditions under which the rapeseed it grown and harvested may influence the glucosinolate content of the seed, and hence alter its nutritional value to pigs, was investigated in the present experiment. Substantial variation in glucosinolate levels between batches of seeds of the same variety has been found in different years, depending upon the site and conditions under which the crop is grown.

Evidence from trials elsewhere has indicated that the porcine gammaglobulin preparation of porcine blood origin (IMMUSURETM Porcine: a trademark of Cambridge Bionutritionals Ltd) was effective in providing passive protection for piglets deprived of colostrum. Passive protection is conferred soon after birth and a piglet which has not sucked would be “at risk”. The light-weight piglet is considered “at risk” as it may not compete effectively for a teat and suckle. Consequently it may have less energy reserves and lower passive protection against disease. The object of the experiment reported here was to assess the effect of porcine gammaglobulin supplement on the performance and survival of light-weight piglets from birth to ten weeks of age on a commercial farm.

The Codes, of Recommendations for the Welfare of Livestock : Pigs (1990) suggest that sufficient clean water should be made available to pigs but makes no specific reference to sucking piglets. Similarly ARC (1901) provide no recommendations on the water requirements for this class of pig. The RC 1989 proposal, for a Regulation concerning minimum standards for the protection of intensively farmed pigs, is more specific. It states that all pigs after the age of two weeks shall have access to adequate fresh, potable water at all times. The aim of this study was to establish the supplementary water requirements of sucking piglets weaned at three weeks of age and whether this reguirement was modified by the provision of creep feed.

The inclusion of fibrous ingredients in diets for weaned piglets has been reported to enhance health but also to reduce voluntary intake and performance. This experiment was designed to investigate the effects of inclusion of a highly digestible fibre source by including different levels of molassed or unmolassed sugar beet pulp (SBP) in the diet of piglets weaned at 25 days of age.

Flaking is widely used by the feed industry since it is considered to improve the digestibility and palatability of cereals for young pigs. Pelleting is believed to give similar benefits plus a reduction in feed wastage and improved voluntary intake. However, the scientific literature lacks consenssus on this subject and provides no clear indication whether the response to feed processing is influenced by the type of cereal used. This experiment examined the effects of flaking, cereal type and diet pelleting on the voluntary intake and performance of early weaned piglets.

The Meishan breed has evolved in China on high fibre diets. This experiment was designed to investigate whether, in consequence, they are better able to utilise high fibre diets than modern UK hybrid pigs. This might be achieved by a higher voluntary intake to compensate for low nutrient density of diets and/or by a more efficient gut fermentation of non-starch polysaccharides.

The utilization of diets high in fibre (defined here as non-starch polysaccharide - NSP) is dependent on the extent to which the NSP is fermented by the gut microflora, and the subsequent utilization by the animal of the end-products of fermentation - the VFAs. It has frequently been assumed that fermentation of NSP in the pig occurs almost exclusively in the hind-gut. However, a number of studies using pigs fitted with ileal-cannulas have suggested that some fermentation of NSP may occur prior to the hind-gut (e.g. Graham et al., 1985). The aim of this study was to determine the relative roles of the small and large intestine in a) the digestion of feeds containing non-starch polysaccharides, and b) the subsequent utilization of energy by growing pigs. This was achieved by comparing the abilities of intact or ileo-rectomised pigs to digest and grow on cereal-based diets containing 0 or 300 g/kg sugar beet pulp.

The continued genetic improvement for lean tissue growth rate and efficiency of pig production has allowed the liberal feeding of modern pigs without adverse effects on carcass quality or food conversion efficiency, even at heavy slaughter weights (Cole and Chadd, 1989; Webb, 1989). This genetic improvement has, however, been associated with a reduction in appetite so that the food intake of modern genotypes of pigs cannot be precisely assessed from the prediction equations established for the older and fatter genotype of pigs. The present experiment was designed to measure voluntary feed intake in order to facilitate the establishment of nutrient requirements and feeding strategies for modern pig genotypes.

With the increase in the use of wet feeding systems, there has been a controversy over the optimum water to feed ratio to be used in these systems. Braude et al., (1967) showed that the feed conversion ratio was 20% higher for wet fed pigs compared to dry fed pigs. However, Forbes et al., (1968) found no significant difference in daily gain between wet and dry fed pigs.

Gill et al., (1987) conducted an experiment to investigate the effects of different water to feed ratios on the performance of growing pigs provided with an additional water supply. They showed that liveweight gain and feed conversion significantly improved (p < 0.05) as the water to feed ratio of the liquid feed was increased from 2:1 to 3.5:1.

The objective of this experiment was to investigate whether water to feed ratio effects digestibility, digestible energy and nitrogen retention.

Much of the early studies investigating the water consumption of pigs have measured water use rather than actual water intake. Water use includes an unknown component of waste from the drinking utensil used.

WATER USE = WATER INTAKE + WATER WASTAGE

One of the objectives of this study was to measure actual total water Intake of growing pigs and to calculate actual total water to feed ratio.

Recommendations of water feed ratio for liquid feed systems have been commonly made from experimentation with non wet fed pigs. The Code of Recommendations for the Welfare of Livestock : Pigs (1985) state that where water is not freely available, for example by means of bowls or drinkers, at least 2 litres of water should be added to each kg of meal. Water to feed ratios calculated in this way may be over estimated as they include an element of waste from drinking utensils which does not occur with wet fed pigs. Also recommendations of this nature make no allowance for the amount of water a pig may choose to consume with its feed. The second objective of this study was to investigate how much water pigs choose to drunk with their feed and how much is drink interprandially.

Previous experiments at Shinfield (Taylor, Salter and Lister, 1990) have shown an association between serum cholesterol and carcass fatness. This was particularly marked when cholesterol levels had been altered through feeding a hypercholesterolemic diet. In the present experiment, serum cholesterol and fat deposition have been studied in entire and castrated pigs at different planes of nutrition and stages of growth.

In a 2 x 2 factorial experiment (Taylor, Salter, Close, Laswai and Hudson, 1990) 18 castrated and 18 entire male pigs, of initial weight 20 kg, were fed either 2.25 (Low) or 3.4 (High) x maintenance energy requirements, to a scale based on liveweight. Nitrogen and energy balances (including calorimetry) were measured over 7-day periods when the pigs reached approximately 30, 60 and 90 kg. Fasting blood samples were taken on the morning after each balance period and serum was analysed for total- and HDL-cholesterol and triacylglycerol. LDL-cholesterol was calculated as: Total cholesterol - HDL-cholesterol - (triacylglycerol/6). Fat deposition was calculated as the difference between total energy retention and energy retained as protein.

Catecholamines are the major lipolytic agents in fat cells and are mediated primarily by beta-adrenergic receptors. The present experiment was designed to study p-receptor numbers in growing pigs of various genotypes in relation to their body compositions.

Fat samples from 5 representative pigs of each genotype were removed immediately after slaughter, at about 60 kg body weight, and stored at -80°C prior to analysis. Adipocytes were extracted by incubation with 1 mg/g (w/v) collagenase in a tris/MgCl2/ EDTA/Bovine serum albumin buffer (pH 7.4) for 1 hour at 37°C. Cells were mechanically ruptured and membranes were removed by ultracentrifugatlon (37,000 rpm for 20 minutes). Recovery was estimated by protein assay using the method of Lowry (1951). Approximately 20 μg of adipocyte membrane protein in 300 μl tris/MgCl2/EDTA assay buffer was added to graded concentrations of the 125I-labelled β-antagonist Iodocyanopindolol (100 μl) together with 100 μl of either assay buffer or the non-specific β-antagonist propanolol (to determine non-specific binding). Samples were then incubated for 1 hour at 37°C. Total β-receptor numbers (maximum binding - Bmax) expressed as pmol/g protein, were estimated by Scatchard analysis using the computer programme ‘EBDA’ by Elsevier - BIOSOFT, Cambridge.

It is well established that high environmental temperature can have adverse effects on sperm concentration and the normality of sperm in the boar. Induced abnormalities include reduced motility, abnormal heads, proximal droplets, coiled and bent tails and abnormal acrosomes (Malmgren and Larsson, 1989). While all stages of spermatogenesis can be adversely affected, the primary spermatocytes are most vulnerable to these influences. Since spermatogenesis occurs over 45 days, any adverse effects of elevated ambient temperature can affect sperm quality for around 6 weeks. The maximum period of infertility appears around weeks 3 and 4 after heat stress. Reduced levels of testosterone and sometimes of LH following heat stress are implicated in these adverse effects. There is evidence that boars subjected to high constant temperature (30°C), which have become acclimatised to such, are affected less in terms of sperm output and quality (Cameron and Blackshaw, 1980) than when boars are subject to sudden major increases in temperature from fairly low levels (15 to 30 C) e.g. during the summer months (Antonyuk et al, 1983). There also appears to be large differences between boars in their ability to adapt to exposure to high environmental temperature by minimising temperature rise and avoiding adverse effects on semen quality (Cameron and Blackshaw, 1980). These workers found that boars prone to heat stress show an acute rise in body temperature in response to elevated environmental temperature and this sudden rise has a more adverse effect on semen quality than the length of exposure to the elevated temperature. There appears to be little information available on the reasons for such important between boar differences. This study was carried out to determine rectal temperature responses of boars to varying summer temperature in an intensive pig enterprise in Scotland and to attempt to determine some of the factors associated with ‘high’ and ‘low’ responding boars.

The breeding boar is the single most important animal in the pig herd because he can sire very many piglets in a year, even moreso when used for AI. When a very superior boar is isolated following performance or progeny testing, good management and AI technology can be combined to exploit his potential. One possible way of making even more effective use of such a sire is through treatment of both the boar and his semen with analogues of prostaglandin F2α (PGF2α ). There have been reports from commercial practice of treatment of boars with PGF2a having desirable influences on libido, an increase in ejaculate volume and subsequent litter size in sows they serve. There have also been claims that when human semen is treated directly with an analogue of PGF2α sperm velocity increases. The purpose of this study was to further investigate the effects of PGF2 on semen production and semen quality of boars.

Performance testing at central test stations and on farm testing are primarily used to select superior breeding stock. Since there may be environmental differences between batches, contemporary comparisons are often used in which each pig's performance is compared with its group's mean.When batch sizes are small, the accuracy of selection can be improved by using an exponentially smoothed average for the contemporary mean of the form where xt is the exponentially smoothed average, the mean of the present batch and po the smoothing parameter.

When batch sizes are variable, too much emphasis is placed on the current mean when the batch is smaller than average, and conversely for batches larger than average, there is too little emphasis on the current mean. Two alternative smoothing parameters are proposed which take into account variation in batch sizes. The accuracy with which pigs of superior genetic merit could be identified using the conventional and the alternative smoothing parameters was investigated by simulating batches of pigs and calculating the proportion of pigs correctly identified as being of superior genetic merit.

Mixed model methods allow genetic merit to be compared directly for pigs measured in different environments or generations. They take into account genetic relationships among all individuals in the population, and allow continuous selection throughout the animal's life. The advantage is more accurate selection in larger populations. The risk is that selection decisions are decentralised to many different sites, requiring a high degree of supervision.

In 1986 a “group nucleus” using BLUP and AI was established for a pig dam line in order to improve both litter size and lean growth. Selection occurs at several different stages in the life cycle, and this study examines selection differentials during performance testing together with the loss of differential resulting from visual appraisal.

Preliminary studies at the Bernard Weitz Centre have shown that maize silage has the potential to increase forage intake and milk production. The trend towards earlier calving, encouraged by the Milk Marketing Board pricing policy, means that maize silage may not be available for early lactation; as most farmers rely on the current seasons crop, and few carry stocks over from the previous year. The objective of the current trial was to determine the eflect on forage intake and milk production of incorporating maize silage into grass silage based rations either from early or mid-lactation.

Following the introduction of milk quota many farmers attempted to place greater reliance on home grown forage as a means of decreasing concentrate inputs and thus reducing input costs. As a high energy forage, maize silage should have the potential to increase forage intake and influence milk yield and quality. The objective of the current trial was to examine the effect on forage intake and milk production of incorporating maize silage into rations based on grass silage with average or high energy concentration.

Sixty-three multiparous and 28 primiparous Friesian cows were used in a trial lasting 20 weeks. Following a two week covariate period cows were allocated to treatment. Treatments were based on forage mixtures of maize silage and grass silage of either average (A) or high (H) energy value in which maize formed 0, 25, SO or 75% of the forage mixture DM.