Functional amino acid (FAA) supplementation improves growth performance and immune status of Salmonella Typhimurium (ST)-challenged pigs, which was further improved by a longer adaptation period. It is expected that the effects are associated with increased activity of intestinal alkaline phosphatase (IAP). The objective of this study was to evaluate the effects of FAA supplementation and adaptation period on the ileal, cecal, and colonic activity of IAP in weaned pigs challenged with ST. In experiment 1, a 2 × 2 factorial arrangement with low (LP) or high protein (HP) content and basal (FAA–) or FAA profile (FAA+; Thr, Met, and Trp at 120% of requirements) as factors was used. In experiment 2, four dietary treatments were looked at, being FAA− fed throughout the experimental period (FAA−) or an FAA profile fed only in the post-inoculation (FAA+0), for 1 wk pre- and post-inoculation (FAA+1), or throughout the experimental period (FAA+2). In experiments 1 and 2, after a 7- and 14-d adaptation period, respectively, pigs were inoculated with saline solution containing ST (3.3 and 2.2 × 109 CFU/mL, respectively).
In experiment 1, plasma alkaline phosphatase was decreased with ST inoculation and the overall content was increased in LP-FAA+ compared with LP-FAA− (P < 0.05). Moreover, ileal IAP was increased in FAA+ compared with FAA− pigs in both studies (P < 0.05) regardless of adaptation time (P > 0.05). Ileal IAP activity correlated with systemic markers of antioxidant defense, which highlights the enzyme’s role in attenuating systemic infection. These results demonstrate a positive effect of FAA supplementation, but not adaptation period, on ileal alkaline phosphatase activity in Salmonella-challenged pigs, which may be associated with improvements in antioxidant balance.
Ileal alkaline phosphatase is upregulated in Salmonella-challenged pigs fed functional amino acids (full article)
