Effects and interaction of dietary electrolyte balance and citric acid on the intestinal function of weaned piglets.

Fifty-six piglets (6.26 +/ assigned to one of eight dietary treatments with seven replicate pens for a 14-day experimental period. The eight experimental diets were prepared via a 2x4 factorial arrangement with citric acid (CA; 0 and 0.3%) and dietary electrolyte balance (dEB, Na + K - Cl mEq/kg of the diet; -50, 100, 250, and 400 mEq/kg). Varying dEB values were obtained by altering the contents of calcium chloride and sodium bicarbonate. An interaction (P <0.05) between dEB and CA in diarrhoea score, the number of goblet cell in jejunum were observed. Ileum pH significantly decreased in weaned piglets fed 250 mEq/kg dEB diet compared with those fed -50 mEq/kg and 400 mEq/kg dEB diets (P <0.05). Supplementation of 0.3% CA decreased the number of goblet cell in ileal crypt (P <0.05) and the relative mRNA expression of CFTR, TNF-alpha, IFN-gamma, IL-1beta, IL-10, ZO-1, Claudin-1 (P <0.05). Increasing dEB values increased the number of goblet cells in the jejunal crypt (P <0.05). A 250 mEq/kg dEB diet decreased the relative mRNA expression of IFN-gamma, IL-1beta, IL-10 (P <0.05) than 100 mEq/kg dEB diet. The interaction between dEB and CA on the relative abundances of Cyanobacteria and Saccharibacteria was observed (P <0.05). Supplementation of 0.3% CA increased relative abundances of Lactobacillus-rennini and Streptococcus-hyointestinalis. Piglets fed 250 mEq/kg diet increased relative abundances of Firmicutes, Lactobacillus-rennini, decreased relative abundance of Proteobacteria, Veillonella, Actinobacillus-minor and Escherichia-Shigella. In conclusion, supplementation of 0.3% CA resulted in differential expression of inflammatory cytokines, ion transporters and tight junction proteins, and changes in the microbial community composition. A 250 mEq/kg dEB diet reduced gastrointestinal pH and promoted the enrichment of beneficial microbes in the gut microbiota, thereby, suppressing inflammation and harmful bacteria. However, the addition of CA to diets with different dEB values did not promote intestinal function in weaned piglets.