268 - Effect of Functional Amino Acid Supplementation in Low and Normal Birth Weight Pigs on Performance and Immune Status During Subsequent Salmonella Challenge

Abstract: Functional amino acid (FAA) supplementation improves growth performance and immune status of weaned pigs. The objective was to determine the effects of birth weight and FAA supplementation in the post-weaning period on the response of pigs to a subsequent Salmonella (ST) challenge. Thirty-two low (1.09±0.11 kg; LBW) and normal birth weight (1.58±0.11 kg; NBW) pigs were assigned to a nursery feeding program for 4 wk in a 2 × 2 factorial with factors of birth weight category (LBW vs. NBW) and basal (FAA–) or supplemented FAA profile (FAA+; Thr, Met, and Trp at 120% of requirements). Pigs were then placed onto a grower diet and, after a 7-d adaptation period, were inoculated with ST (2.2 × 10⁹ CFU/mL) and monitored for 7 d post-inoculation. Growth performance, rectal temperature, gut health, ST fecal shedding and translocation, and blood parameters were measured pre- and post-inoculation. Inoculation with ST increased rectal temperature (39.7 vs. 38.9±0.5 ^oC) and overall rectal temperature was higher in LBW compared with NBW pigs (39.6 vs. 39.0±0.5 ^oC; P< 0.05). Salmonella shedding (1.8 vs. 2.3±0.1 score) and translocation to spleen (1.3 vs. 2.5±0.1 score) were less in NBW-FAA+ than NBW-FAA- pigs (P< 0.05). Post-inoculation weight gain was greater in NBW-FAA+ compared with the other groups (0.57 vs. 0.45±0.03 kg/d; P< 0.05). Post-inoculation haptoglobin (d 4; 1.0 vs. 0.7±0.1 g/L) and colonic myeloperoxidase (d 7; 4.3 vs. 2.5±0.6 µU/mL) were greater in LBW-FAA- pigs compared with the other groups (P< 0.05). On d 4 post-inoculation, plasma superoxide dismutase was less in LBW- FAA+ than in LBW-FAA- (60.5 vs. 93.3±7.7 mU/mL; P< 0.05). Reduced:oxidized glutathione at d 7 post-inoculation was greater in NBW compared with LBW pigs (2.5 vs. 1.7±0.3; P< 0.05). In conclusion, negative effects of Salmonella infection are ameliorated with supplementation of FAA to a greater extent in NBW than in LBW pigs.