PSIII-18 - Low feed intake reduces intestinal glutathione content in weaned pigs

Abstract: At weaning, pigs face nutritional, immunological, and environmental challenges that collectively reduce feed intake and may heighten demand for dietary sulfur amino acids. Cysteine is a sulfur amino acid and a constituent of glutathione (GSH), a key regulator of intestinal redox status. The objective of this study was to evaluate the relationship among increasing levels of feed intake and cysteine utilization for glutathione production, growth performance, and gut structure and function in weaned pigs. Pigs (initial body weight = 6.42 kg ± 0.25) were weaned at 21 ± 1 day age. Catheters were placed in the left and right external jugular veins. The pigs were fed a corn starch- and soy protein isolate-based diet (ME = 3,700 kcal/kg, CP = 24%) at one of four levels of feed intake according to metabolizable energy requirements for maintenance (MEm): F25, 0.4 × MEm (n = 7); F50, 0.8 × MEm (n = 6); F75, 1.2 × MEm (n = 6); and F100, 1.6 × MEm (n = 8). Blood samples were taken daily. After 4 d, pigs were euthanized and bile, jejunum, and ileum samples were collected. Average daily gain increased linearly as feed intake increased linearly from the F25 group (15 ± 10 g/d) to the F100 group (209 ± 13 g/d; P < 0.01). Serum dispensable amino acids (DAA) decreased from day 1 to day 2 (P < 0.001) for all treatments; however, serum indispensable amino acids (IAA) were not different from day 1 to day 2 among treatments (P > 0.10). Serum DAA and IAA increased linearly with increasing feed intake on day 4 (P < 0.001). Serum methionine concentrations increased linearly with increasing feed intake on day 4 (P < 0.001). Serum cysteine tended to decrease linearly on day 4 as feed intake increased (P = 0.07). Jejunum villus height (VH) tended to increase as feed intake increased from F25 group (331 ± 13 µm) to the F100 group (406 ± 197 µm; P = 0.07); however, crypt depth (CD) and VH: CD was not affected (P > 0.10). Cysteinylglycine, a product of GSH degradation increased linearly in the jejunum mucosa with increasing feed intake (P < 0.05). Total GSH increased in the jejunum mucosa as feed intake increased from F25 group (17.7 ± 1.3 nmol/mg protein) to F100 group (24.2 ± 2.0 nmol/mg protein; P < 0.05). Despite low feed intake after weaning pigs can maintain serum IAA. Low feed intake depletes total GSH content, potentially impairing jejunum structure and function.