Feeding tuna oil to the sow at different times during pregnancy has different effects on piglet long-chain polyunsaturated fatty acid composition at birth and subsequent growth

In an attempt to prevent decreases in piglet 20 : 4n-6 status at birth whil e increasing 22 : 6n-3 status, multiparous sows (eight per treatment) were allocated to one of three different treatments: a basal diet fed from day 6 3 of pregnancy to term; basal diet supplemented with tuna oil (17.5 g/kg) f rom day 63 to day 91 and then basal diet alone from day 92 to term; basal d iet alone from day 63 to day 91 and then basal diet supplemented with tuna oil from day 92 to term. Tuna oil supplementation increased mainly 22 : 6n- 3 intake. Supplementation with tuna oil between day 92 and term increased 2 2 : 6n-3 to a greater extent in all piglet tissues (brain, liver, retina an d the remaining carcass) at birth than supplementation with tuna oil betwee n days 63 and 91. However, while piglet 20 : 4n-6 decreased to a greater ex tent in liver and carcass when diets were supplemented with tuna oil betwee n days 92 and term than between days 63 and 91, in the brain and retina, th e reverse was true; 20 : 4n-6 was decreased to a greater extent between day s 63 and 91 than between 92 and term. The effect of pregnancy nutrition on the growth of piglets until 7 d postweaning (35 d of age) was assessed afte r removing any residual effects of pregnancy treatment by cross-fostering s ome piglets at birth. Piglets, the diets of whose dams had been supplemente d with tuna oil during pregnancy, grew faster during the first 35 d of life than the progeny of sows fed only the basal diet. Feeding tuna oil to sows at different times during pregnancy therefore did not prevent decreases in piglet 20 : 4n-6 status at birth, but did suggest that changes in piglet b rain 20 : 4n-6 status between days 63 and 91 of pregnancy were not reversib le by later nutrition. Supplementing the diet of the pregnant sow with tuna oil had beneficial effects on postnatal piglet growth.