Modulating the gut flora alters amino acid metabolism in neonatal pigs

Abstract

ObjectiveIntestinal microbes consume and produce amino acids (AA). This may impact intestinal threonine (THR) metabolism necessary for adequate gut function. We hypothesized that modulating the gut flora results in an alteration of intestinal THR utilization and hence whole body AA metabolism.MethodsNeonatal pigs were randomized to one of 3 groups (n=7/group): Control (C), Probiotics (PRO) or antibiotics (AB). After 9 days, piglets received an isotope tracer infusion with intravenous (iv) [15N2] Urea, and 2 days later with iv [1‐15N] THR and intragastric [U‐13C, 1‐15N] THR. Piglets were euthanized and blood, intestinal contents and tissue samples collected.ResultsModulating the gut flora resulted in lower gut weight, protein and DNA concentration, and protein synthesis rate in AB and PRO. PRO increased liver weight, but lowered liver DNA concentration. AB decreased urea flux and increased plasma levels of urea cycle products ornithine and citrulline. In AB, THR flux and plasma levels were increased. THR splanchnic uptake was similar amongst treatment groups.ConclusionsModulating the microbial flora decreases gut protein metabolism and affects the urea cycle. Alterations in total AA metabolism may be due to decreased protein breakdown or decreased urea production from ammonia. This might impact growth and health in neonates that have a high protein requirement and are often treated with antibiotics.