148 Use of an Alpha-Linolenic Acid Source to Reduce Omega-6:3 Ratio in Prrs-Virus Challenged Nursery Pigs

A total of 1,056 pigs [PIC TR4 × (Fast LW × PIC L02)], originating from an active PRRSV-positive sow farm, were used in a 46-d study to evaluate growth performance and mortality and removals of nursery pigs. Pigs were fed diets containing increasing levels of O3 Trial Feed (NBO3, Manhattan KS), a source of omega-3 fatty acids (alpha-linolenic acid). At placement in the nursery, pens of pigs were randomly assigned 1 of 4 dietary treatments in a completely randomized design with 22 pigs per pen and 12 replications per treatment. The dietary treatments included increasing percentages of O3 Trial Feed (0, 0.75, 1.5, and 3%). Omega-6:3 ratios for the 4 treatments within each phase were: Phase 1 (15.1:1, 8.4:1, 5.9:1, 3.7:1); Phase 2 (16.5:1, 9.2:1, 6.4:1, 4.0:1); Phase 3 (20.8:1, 10.4:1, 7.0:1, 4.2:1); and Phase 4 (25.3:1, 12.5:1, 8.3:1, 5.0:1), respectively. Pigs remained on treatments throughout the 4 dietary phases over the 46-d study. Overall, pigs fed increased O3 Trial Feed had increased (linear, P < 0.001) ADG, ADFI and G:F. The greatest impact on growth due to dietary treatment began when pigs tested positive for PRRSV during week 3 of the study. This was confirmed by testing oral fluids, collected on a weekly basis, for PRRSV using a PCR test. Pigs fed increasing O3 Trial Feed also had decreased (linear, P = 0.027) total removals and mortalities. In summary, adding O3 Trial Feed to reduce the Omega 6-3 ratio improved growth performance and reduced mortality in nursery pigs with an active PRRSV challenge.