In various organisms, α-ketoglutarate (AKG) is a central molecule in the citric acid cycle (Krebs cycle). It can be rapidly transaminated to glutamic acid and then further aminated, to glutamine (Gln). Acting as both an energy donor and a scavenger of ammonium ions, a source of Gln that stimulates protein synthesis in intestinal epithelial cells. AKG can improve daily weight gain and feed-efficiency in pigs and plays a key role in systemic, intestinal, and gut bacterial metabolism. The purpose of this study was to investigate the effects of dietary supplementation with AKG on the intestinal microbiota and metabolites using the growing pig model. Sixteen healthy animals (Large White × Landrace; 84 ± 1 d of age) of similar initial weight (40.08 ± 0.78 kg) were randomly assigned to two dietary groups (n = 8). Pigs were fed a basic diet containing either 0 (control) or 10 g AKG/kg (supplemental diet). After a 28-d trial period, the luminal digesta of the cecum and ileum were collected to analyse the amounts of short-chain fatty acids and ammonia, as well as populations of gut microbiota.
Supplementation with AKG decreased the pH value of ileum digesta. Moreover, the AKG concentration in the ileal digesta was significantly higher in pigs fed the supplemented diet than in control pigs. The addition of AKG also significantly increased the amounts of Lactobacillus and Bifidobacterium in the cecum, and Lactobacillus and Firmicutes in the ileum. But decreased the amounts of Escherichia coli in the ileum and in the cecum when compared with the control group. The dietary AKG also increased the concentrations of valerate in the caecal digesta and butyrate in both the caecal digesta and the ileal digesta. Concentrations of ammonia also dropped in the caecal and ileal digesta in response to AKG.
Therefore, our results indicate that supplementing the diet of young pigs with AKG increases the populations of some presumably beneficial bacterial species as well as SCFA concentrations in the intestinal luminal contents. Simultaneously, it decreases the amounts of several potential pathogens and concentrations of ammonia. These novel results provide some evidence to support the use of AKG as an acidifier that has potentially beneficial effects on animal development.
Chen, J., Yang, H., Long, L., Zhao, Y., Jiang, Q., Wu, F., Kang, B., Liu, S., Adebowale, O. T., Fu, C., and Yao, K. (2017). The effects of dietary supplementation with α-ketoglutarate on the intestinal microbiota, metabolic profiles, and ammonia levels in growing pigs. Animal Feed Science and Technology. https://doi.org/10.1016/j.anifeedsci.2017.03.017