EFFECT OF FEEDING TUNA OIL OR SOYBEAN OIL AS SUPPLEMENTS TO SOWS IN LATE PREGNANCY ON PIGLET TISSUE COMPOSITION AND VIABILITY

To investigate whether long-chain n-3 polyunsaturated fatty acids coul d cross the porcine placenta in late pregnancy and alter neonatal pigl et tissue composition, multiparous sows (seven per diet) were fed on d iets containing a supplement (30 g/kg) of either soyabean oil or tuna oil for the last 21 d of pregnancy and the first 7 d of lactation. The proportions of all fatty acids, except 18:1n-7, differed between diet s: in particular, the tuna-oil-containing diet supplied more 22:6n-3 a nd less 18:2n-6 fatty acids than the soyabean-oil-containing diet. The proportions of n-3 fatty acids, particularly 22:6n-3 (g/100 g total f atty acids) in sow plasma, colostrum and milk were increased and the p roportion of 18:2n-6 was decreased by feeding tuna oil. Piglet tissue n-3 fatty acid proportions (particularly 22:6n-3), obtained shortly af ter birth, were increased in piglets born to tuna-oil-fed sows compare d with progeny of soyabean-oil-fed sows. The increase in the proportio n of n-3 fatty acids (g/100 g total fatty acids) in piglet tissues as a result of tuna-oil feeding, compared with soyabean-oil-feeding, was in the order plasma>liver>erythrocytes > spleen>brain>retina. Piglets born to tuna-oil-fed sows had a lower viability score at birth than th e progeny of soyabean-oil-fed saws. The proportions of long-chain n-3 fatty acid in tissues of new-born piglets were increased by feeding tu na oil to the sow in late pregnancy; however no improvements in piglet viability were observed.