The resource requirements and social behaviour of pigs housed in large groups were examined in a series of experiments. (i) The nipple drinker requirement was addressed by using four treatments (60 pigs, 3 drinkers; 20 pigs, 1 drinker; 60 pigs, 6 drinkers and 20 pigs, 2 drinkers). Drinker provision had no effect on water use, but in a larger group more water was used in less time (p<0.001). The diurnal pattern of drinking, overt aggression and lesion score indicated no difference between treatments. (ii) Pigs, housed on deep straw in groups of 20 or 80, were provided with a low (50<I> </I>kg/m²) or high (32 kg/m²) floor space allowance. Large groups had a lower growth rate. Skin lesions were elevated and immune response was lowered by a low space allowance. (iii) Two feeder space allowances (32.5<I> </I>and 42.5<I> </I>mm/pig) for pigs housed in groups of 20 or 80 were investigated. Food intake was lower in the low feeder allowance treatments and pigs in large groups tended to have a reduced growth rate. (iv) Pigs from the same pen in an unfamiliar arena maintained a similar degree of proximity regardless of origin group size. (v) Pigs from groups of 80 demonstrated reduced aggressiveness (increased latency to fight, decreased rate of aggression) towards unacquainted pigs in an arena, but showed even less aggression towards pen mates. (vi) No evidence of spatial sub-division of the large group into smaller units capable of maintaining a dominance hierarchy was found. Resource provision and group size largely did not interact, but may independently compromise productivity and behaviour. A large group was associated with a reduction in performance. The dominance hierarchy was of less importance in large groups, despite recognition being intact, and sub-grouping behaviour did not provide an alternative strategy for group social organisation.

No description available.

No description available.

This thesis compares growth and behaviour of domestic sows and piglets in confined pens versus get-away pens (where sows could leave their fitters at will), to ask whether parent-offspring conflict occurs, whether it increases with offspring age, whether it involves offspring access to the udder, and whether it affects animal production or welfare. Parent-offspring conflict occurs in domestic pigs: piglets of Confined sows suckled more and ate less solid food but grew at the same rate as piglets from Get-away sows, indicating they obtained more milk. Confined sows lost more weight than Get-away sows and returned to oestrus later, indicating a fitness cost of providing the additional milk. Parent-offspring conflict increased with piglet age: as the fitter aged, Get-away sows spent more time away from their young and the differences between Get-away sows and Confined sows in weight loss and nursing frequency increased. In Get-away sows, the reduction in contact with their young occurred rapidly, but its timing varied greatly among individual sows. Behavioural conflict over access to the udder is a plausible mechanism by which conflict is expressed in swine: piglets from Confined pens spent more time nuzzling the udder than piglets of Get-away sows. Piglets from Get-away sows nuzzled the udder a higher proportion of the time when the sow was present than piglets from Confined sows. Get-away sows terminated more nursings than Confined sows thus limiting the amount of contact piglets had with the udder after nursing. Mowing sows to control maternal provisioning improved productivity: there was a slight benefit of reduced time to the next oestrus for Get-away sows. Piglets from Get-away sows gained more weight and consumed more food after weaning than piglets from Confined sows. There was only slight evidence that get-away pens reduced behavioural indicators of post-weaning stress (e.g., movements, vocalizations, response to playback of vocalizations) for either the pi