Abstract
The present study investigated the interactive effect of functional amino acid (AA) supplementation and dietary protein level on growth performance and immune status in Salmonella-challenged pigs. Thirty-two growing pigs (8 pigs/treatment; 13.9 ± 0.82 kg initial body weight) had ad libitum access to 1 of 4 experiment diets in a 2×2 factorial arrangement with factors of dietary protein (LP: Low, 16% protein vs. High: HP, 20% protein) and 2 levels of functional AA supply (AA-: basal vs. AA+: Thr, Met, and Trp provided at 20% above requirement). After 7 d of adaptation, pigs were orally inoculated with saline containing Salmonella typhimurium (ST). Performance parameters [average daily gain (ADG), feed intake, and gain:feed (GF)] were measured in the pre- and post-inoculation periods. Blood samples were collected on d0, 4 and 7 post-inoculation for serum haptoglobin and albumin analysis. Shedding of ST (d1, 2, 4 and 6 post-inoculation) and quantification in digesta (ileum, cecum and colon; d7 post-inoculation) were analyzed. There was no effect of diet on pre-inoculation performance (P > 0.05). Pigs fed AA+ showed increased ADG (0.457 vs. 0.298 ± 0.051 kg/d; P < 0.05) and a trend for improved GF (0.67 vs. 0.40 ± 0.07 kg/kg; P < 0.10) post-inoculation compared to AA- regardless of dietary protein level. Feeding AA+ increased overall albumin levels (35.7 vs. 34.2 ± 0.9 g/L; P < 0.05) and decreased overall haptoglobin levels (1.64 vs. 1.81 ± 0.12 g/L; P < 0.05) and decreased overall shedding score of ST (2.27 vs. 2.51 ± 0.09; P < 0.05) compared to AA-. The ST counts in cecal digesta increased (2.78 vs. 2.23 ± 0.18 Log10 cfu/g; P < 0.05) in pigs fed HP compared to LP-fed pigs and ST counts in colon were reduced (2.08 ± 0.18 vs. 2.61 ± 0.19 Log10 cfu/g; P < 0.05) in AA+ compared to AA- pigs. Supplementation of diets with specific functional AA improved performance and health status of pigs when exposed to an enteric disease challenge.
Effect of dietary protein level and rumen-protected amino acid supplementation on amino acid utilization for milk protein in lactating dairy cows
