Effect of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation to lactating sows on growth and indicators of stress in the post-weaned pig

The first experiment was designed to determine the concentration of protected fish oil product (PFO), as Gromega^TM, to be added that would sufficiently decrease the polyunsaturated fatty acid (PUFA) ratio in the sows’ milk and colostrum. Of the 3 diets tested (0.25%, 0.5% and 1%) with a control (0% PFO), only the 1% PFO diet had an effect on the PUFA concentrations. The docosahexaenoic acid (DHA) concentration tended (P = 0.05) to be greater in the 1% PFO diet for both colostrum and milk samples. A second experiment was designed to examine the effects of feeding the 1 versus 0% PFO supplemented diet to sows on growth, markers of acute inflammation and stress in their offspring (16 piglets/treatment group) on d 0 (day of weaning) and d 1 and 3 postweaning. Piglets from sows supplemented the 1% PFO diet had greater gains in weight (P =0.03) postweaning. These pigs also had a lower (P ˂ 0.01) n-6:n-3 PUFA in the plasma when compared to piglets on the control diet. There was an overall treatment effect (P = 0.02) on plasm atotal cortisol, observed by lower concentrations in pigs on the 1% PFO diet. Plasma corticosteroid-binding globulin (CBG) concentrations were not different between treatment groups but were lower (P ˂ 0.001) on d 1 and 3 when compared to d 0. The calculated free cortisol index [FCI (cortisol/CBG)] of pigs on the 1% diet was lower (P = 0.02) on d 1 and 3 when compared to the controls. The cytokines, IL-1β [beta], IL-6, and TNF-α [alpha] were measured following an ex vivo lipopolysaccharide (LPS) stimulation of monocytes and neutrophils in whole blood collected on d 0 and 1. Pigs on the 1% PFO diet tended to have a lower (P = 0.098) mean concentration of TNF-α in response to LPS when compared with that of the controls. These results suggest that providing a PFO supplement as 1% of the diet to sows beginning in late gestation and during lactation can lower the n-6:n-3 PUFA ratio in their offspring, which may reduce the acute physiological stress response in the pigs postweaning.