Polyunsaturated fatty acids (PUFA) especially n-3 PUFA are important components of healthy human diets but these fatty acids are very susceptible to oxidation. Lipid peroxidation has been implicated as contributor to many pathological processes in humans (Byers, 1993). It is well established that tissue vitamin E (α-tocopherol; AT) protects lipid against peroxidation in vivo and in vitro. During lipid oxidation, vitamin E supplies are depleted and there are health benefits from higher intakes of the vitamin. In this study, changes in fatty acid composition and AT content of pig muscle during-oxidation were examined.

Twenty four Large White x Landrace pigs were individually fed, from 50 to 90 kg LW, either a control (CD) diet (containing palm oil) or a diet based on full-fat rapeseed (FFR; 250 g/kg) (diet FRD) with varying levels of α-tocopheryl acetate (ATA) (0, 200 and 500 mg/kg diet for FRD0, FRD200 and FRD500 respectively). Diets were isonitrogenous and isocaloric.

Forsling et al. (1984) have shown that exposure to vibration and noise leads to raised concentrations of plasma lysine vasopressin (LVP) in pigs. Pigs can exhibit symptoms of travel sickness during road transport even when, following commercial practice, they are not fed before transportation. These symptoms appear to be associated with elevated concentrations of plasma LVP (Bradshaw et al. in press). We wished to establish whether concentrations of plasma LVP at exsanguination may reveal which pigs had been travel sick during the journey to slaughter and whether those pigs exhibited subsequent poor meat quality.

Fifty 90 kg slaughter pigs were transported on a lorry (25 each day for two days, food withdrawn the previous evening at 1700) for five hours (0.49 m2 per pig). RHB travelled in the main body of the vehicle scanning the individually marked pigs every 8 min for incidences of standing, lying and symptoms of travel sickness (sniffing, foaming at the mouth, chomping, retching and vomiting).

Despite efforts to standardise breeding, nutrition and husbandry regimes, consumer studies indicate that 17% of all loin chops sold in the UK are unacceptable in terms of toughness and dryness (Warkup et al., 1995). Recent evidence suggests that this unaccountable variability may be at least partly due to changes in the calpain-calpastatin proteolytic system around the time of slaughter, stimulated by changes in the circulating levels of the natural β-agonist adrenaline (Sensky et al., 1996). An increase in calpastatin, the inhibitory component of the system, at slaughter has also been shown to be associated with reduced degrees of tenderisation (Koohmaraie, 1992, Sensky et al., 1996b). Variation in the degree of β-receptor stimulation close to slaughter should therefore correlate with calpastatin levels at slaughter. This study aimed to investigate the validity of this claim.

The diet of 30 female Landrace x Large White pigs (67 ± 1 kg) was supplemented with either 2 or 20 ppm nadolol, a β-antagonist, or clenbuterol, a β-agonist, 16 h before slaughter, giving 5 groups of 6 pigs, including controls (no supplement), with differing degrees of β-receptor stimulation, ranging from low (20 ppm nadolol) to high (20 ppm clenbuterol). Calpain and calpastatin activities were measured in samples of longissimus dorsi (LD) taken immediately after slaughter using chromatographic and fluorimetric techniques (Sensky et al., 1996b).

The solution to the problem of ‘boar taint’, a major limitation to the production of entire male pigs, may lie in the development of an effective sorting (classification) mechanism for quality control purposes. Attempts to relate the concentrations of the major taint - causing compounds (androstenone and skatole) to panel/consumer acceptability have been confused by the complex underlying interrelationships between the compounds and the difficulty in measuring taint reliably using a sensory panel. The main objectives of the study were; 1. To investigate sensory responses to taint compounds. 2. To identify a reliable scale of measurement of response that could lead to the development of a calibration system for the classification of pigs.

Eating quality of fresh pork is important to consumers and processors. To assess the effect of genetic selection and breed substitution it is necessary to examine the relationships between eating quality and performance and carcass traits.

With the advent of the stall and tether ban in the UK it is now a requirement to house dry sows in groups throughout their pregnancy which necessitates their being mixed with other sows at some point after service. It is generally recommended that mixing sows during the embryo implantation period should be avoided as this is thought to effect embryo survival rates. The object of this experiment was to demonstrate the aggression that occurs between sows after mixing and determine the effect on reproductive performance when mixing sows at different times during the 42 days post-service.

294 sows were mixed at six different times during early pregnancy: 0 to 7(T1), 8 to 14,(T2) 15 to 21(T3), 22 to 28(T4), 29 to 35(T5) and 36 to 42(T6) days post service. Six groups of sows from six consecutive weeks weanings were served at the first post-weaning oestrus and kept in stable weekly treatment groups until the sixth group was served.

The mixing of unfamiliar sows usually results in fighting which determines relative social rank. In some situations aggression can be perpetuated and subordinate animals can suffer as a result of competition for resources such as feed and space. Although Moore et al (1993) suggested that newly introduced group members become fully integrated after 21 days there have been few studies which have examined the development of social interactions over the longer term. The aim of the experiment was to determine how social behaviour changed over time and the affects that this may have on the welfare of group-housed sows.

Group housing of sows is becoming a commonly used housing method in modern pig production because of welfare legislation which requires the phasing out of all stall and tether systems by 1999. Since group housing exposes sows to potential social stressors, the objective of this study was to determine whether dominance order has an effect on the behavioural expression of oestrus and mating behaviour of sows.

Disruption in suckling patterns and cross-suckling was observed to a high degree following grouping of litters in a multisuckling system, resulting in a reduction in piglets’ performance before weaning (Wattanakul et al, 1995). Relocation of the sows between crates while litters were grouped in a farrowing house also increased the incidence of cross-suckling, whereas grouping the piglets without relocating the sows did not (Wattanakul et al, 1996). Familiarity with the home location before grouping might therefore reduce the incidence of cross-suckling in a multisuckling system. This experiment was designed to investigate the effects of familiarity with a suckling place prior to grouping on suckling behaviour and performance of piglets.

Neonatal mortality is a major source of economic loss to the pig industry. Polyunsaturated fatty acids (PUFAs), especially DHA, have been implicated in brain development in man and other species and a pre-natal supply of PUFAs may have a role in influencing post-natal survival. The purpose of this study was to investigate the effect of feeding increased amounts of DHA during gestation and early lactation, on piglet viability and tissue composition.

With increasing concern over animal welfare, large straw yard accommodation is being used as a less intensive system for the finishing of pigs. The performance achieved in straw pens can exceed that of fully slatted housing (Lyons et al, 1994). Unfortunately, the main weakness of large groups in straw yards can be the high variation in performance. The objective of this study was to determine the behavioural differences between low and high performing pigs and to investigate pig location preferences in large groups of various sizes.

The constraints upon the sow-piglet relationship differ markedly between husbandry systems. Within the farrowing crate the sow and the piglets are physically unable to remove themselves from one another. In most outdoor farrowing systems the sow must remove herself from her litter in order to feed and drink and, where piglets are successfully restrained within the farrowing hut, may spend a significant proportion of her time seperated from the litter. Frequently piglets are not successfully restrained and from the first week after farrowing will spend time following the sow. The aim of this experiment was to examine whether the constraints upon the access of the piglets to the sow in the neonatal environment effect the post-weaning behaviour of piglets.

On approaching slaughter weight it is common practice to weigh pigs and they are very often slap-marked prior to transport to the abattoir. Weighing involves handling and temporary isolation of the animal. Slap-marking involves hitting the animal, usually on the shoulder, with a series of needles covered in tattooing ink. Both weighing and slap-marking are potentially stressful. This study measured the behavioural and heart rate response of animals to these procedures as they occured on a commercialy run pig unit. These were compared to the responses of animals to weighing and an open-field test in an experimental procedure.

Intensively housed pigs are continuously exposed to aerial pollutants, such as ammonia gas (e.g. Robertson 1994). The objective of this study was to determine if exposure to ammonia, for an extended period, was aversive to a pig. The three chronic choice test experiments catalogued the behavioural responses of Duroc x Landrace pigs to concentrations of ammonia recorded frequently in commercial piggeries. The first experiment established if ammonia was aversive. The remaining experiments indirectly and directly traded off the strength of any aversion against thermal comfort. In the second experiment thermal comfort could be obtained either in the absence or presence of ammonia; in the third experiment thermal comfort could only be gained in the presence of ammonia.

There is increasing interest in the Cornell Net Carbohydrate and Protein System (CNCPS) (Russell et al 1992, Sniffen et al, 1992) for rationing dairy cows, but its use in the UK has been limited because the raw material database was based on North American feedstuffs. The database contained no information on grass silage, and the values for feeds such as maize silage and brewers grains may not be representative of those in the UK. This work was carried out to establish a UK database of forages and raw materials for the CNCPS model.

In classical studies estimates of maintenance energy requirements for cattle have been derived from measurements of fasting heat production (FHP) and urinary energy output following a period of restricted nutrition. Using 8 such sets of data, ARC (1980) developed equations to calculate the metabolisable energy (ME) requirement for maintenance (MEm) for lactating dairy cattle. This approach was further supported by AFRC (1990). However, recent studies using regression techniques at this Institute would suggest that the MEm for lactating dairy cows with access ad libitum to high forage diets is considerably higher than that calculated from AFRC (1990). The objective of the present study was therefore to measure the FHP of dairy cows offered forage diets ad libitum prior to fasting and to establish if this would support the higher MEm for dairy cows obtained using regression techniques .

The maintenance energy requirement of an animal can be defined as the daily metabolisable energy (ME) intake at which it is in zero energy balance. Maintenance energy requirements can be estimated either by measuring fasting metabolism or from a regression relationship between ME intake and energy retention for a number of animals given a range of ME intakes. However maintenance energy requirements may vary according to the composition of the diet, as higher intakes of high-fibre diets have promoted greater rates of gut metabolism than lower intakes of low-fibre diets. In the present study maintenance energy requirements of beef cattle and lambs have been estimated by regressions between ME intake and energy retention using data from a series of studies involving diets based on grass silage or fresh grass and concentrates.

Ordinary least squares (OLS) regression will give negatively biased estimates of slope if the x-variable is subject to measurement errors. In energy balance regression, metabolisable energy intake (MEI) is neither under precise control nor free from measurement errors. In order to improve the accuracy of prediction of energy requirements, it is necessary to recognise the effect of this bias when deriving estimates of maintenance (M) energy requirements and the efficiency of utilisation of energy for growth (kf).

There is a paucity of information on the digestion and utilisation of feeds by horses. Currently, most diets are formulated according to NRC (1989) recommendations which assume digestibility coefficients: for example, a digestibility coefficient for crude protein of 0.46 is used for animals at maintenance compared with 0.55 for lactating mares. However, if the digestibility of diets is uncertain, then use of such assumed values could result in either the under- or over-supply of nutrients. Furthermore, knowledge of the site of digestion is important. For example, only dietary protein digested and absorbed in the proximal small intestine can be efficiently utilised by the horse and the digestion of carbohydrate in the foregut (in terms of ATP yield) is more efficient than its fermentation in the hind gut. Therefore, in order to formulate diets more precisely, it is important to know a) the site at which dietary components are degraded and b) the extent of this degradation. In the present study mobile bags were used to determine the extent of organic matter disappearance (OMD) and crude protein disappearance (CPD) from four botanically diverse feedstuffs in the foregut of caecally - fistulated ponies.

Previous work has shown that equids generally have lower apparent digestibilities in vivo compared to ruminants. This observation may be due to either; (1) higher rates of passage through the digestive tract of equids compared to ruminants; (2) less opportunity for absorption of microbial digestion end products following hindgut fermentation in equids compared to foregut fermentation in ruminants; or (3) to caecal and colonic micro-organisms in equids being less efficient at feed constituent degradation compared to ruminal micro-organisms. To test this latter possibility, this experiment examines the hypothesis that feed constituents will be degraded to a similar extent when exposed to either an equid hindgut or a ruminal foregut microflora for the same time periods.