Effects of dietary supplementation with different forms of flax in late-gestation and lactation on fatty acid profiles in sows and their piglets.

The impact of feeding flax as seed, meal, or oil to late-pregnant and lactating sows on fatty acid profiles in sows and their piglets was studied. Sixty second- and third-parity sows (Yorkshire x Landrace) were fed 1 of 4 diets from 68 d of gestation until 21 d of lactation. Diets were: control without flax (CTL, n = 15); 10% flaxseed supplementation (FS, n = 16); 6.5% flaxseed meal supplementation (FSM, n = 14); and 3.5% flaxseed oil supplementation (FSO, n = 15). All diets were isonitrogenous and isocaloric. Jugular blood samples were obtained from sows on d 62 and 110 of gestation and on d 2 and 21 of lactation. Milk samples were obtained on d 3 and 20 of lactation. Fatty acid profiles were established in plasma and milk. One piglet per litter was slaughtered on d 1 for determination of fatty acid profiles in carcass and brain tissue. On d 110 of gestation, sows fed FS and FSO had less SFA (P < 0.05), more PUFA (P < 0.001), more n-3 fatty acids (P < 0.001), and a decreased n-6/n-3 ratio (P < 0.001) in their serum than sows fed FSM. These same differences were present on d 21 of lactation with a decrease in MUFA also being observed (P < 0.05). Milk from sows fed FS and FSO showed increased n-3 fatty acids (P < 0.01) and decreased n-6/n-3 ratio (P < 0.001) on d 3 and 20 of lactation, as well as less SFA (P < 0.01) and MUFA (P < 0.05) and greater PUFA (P < 0.001) concentrations on d 20. Carcass and brain tissues from their newborn piglets also exhibited increased n-3 fatty acids (P < 0.001) and decreased n-6/n-3 ratio (P < 0.01) compared with piglets farrowed by sows fed FSM. Results demonstrated that feeding flax as seed or oil has significant effects on the fatty acid profile in sows and their offspring and that these changes are due to the oil content of flax because they were not observed when sows were fed FSM.