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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

A study was conducted to investigate the effect of supplemental fat from flaxseed (FL) on fatty acid (FA) profile, chemical composition, energy value of colostrum and milk, and litter performance. On day 107 of gestation a total of 59 large white sows were selected, blocked by parity and randomly allotted to one of three diets, 15% flaxseed (FL), 10% fullfat soybean (SB) or a control commercial (CO) diet containing corn and soybean meal. Diets were isocaloric and isonitrogenous but differed in fat content and FA composition. Colostrum and milk were collected soon after farrowing and on day 7, respectively, for fatty acid and chemical analysis. Dietary treatments did not affect sow feed consumption, weight loss, number of live pig born and weaned per litter. Similarly, pig birth weights, and day 7, 14, and 21 weights did not differ among treatment groups. FL significantly (p < 0.05) increased linolenic (LNA C18:3co3) and decreased palmitic (C16:0) and oleic (C18:1) acids in colostrum. FL also significantly (p < 0.001) increased LNA and arachidonic acid (C20:4) in milk, while it decreased myristic (C14:0), palmitic and palmitoleic (C16:1) acids. Chemical analysis showed no significant differences in total solids (TS) and energy value of colostrum while a significant (p < 0.05) increase in TS, fat concentration and energy value was observed in milk from FL. A total of 335 piglets were used in the plasma study of lipid metabolites. Triglyceride (TG), cholesterol, HDL cholesterol and glucose were not affected by dietary treatment (p > 0.05). Feeding FL to sows during late gestation and lactation enriches sow milk and piglets with LNA.

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