Dietary glycerides of valerate ameliorate diarrhea and impact intestinal physiology and serum biomarkers in weaned piglets infected with enterotoxigenic Escherichia coli F18

Abstract In the commercial swine farm setting, the post-weaning period is a critical window during which piglets are highly susceptible to infection and enterotoxigenic E. coli (ETEC)-associated diarrhea. Short chain fatty acids and their glycerides are compounds which may influence intestinal health; however, valerate is one that has not been well-characterized for its role as a dietary supplement. Therefore, the major objective of this experiment was to investigate two forms of valerate glycerides on diarrhea, intestinal physiology, and systemic immunity of weaned pigs experimentally infected with ETEC F18. Dietary treatments included a control diet and three additional diets supplemented with 0.075% monovalerin, 0.1% monovalerin, or 0.1% trivalerin, respectively. Piglets were weaned (21-24 d of age), individually housed, and experimental diets were fed throught the 28-day trial period. After a seven-day period, all piglets were inoculated on three consecutive days with 1010 CFU ETEC F18/3 mL. Growth performance was monitored throughout the trial and daily diarrhea scores were recorded. Rectal swabs were collected for bacterial culture to confirm the presence or absence of β-hemolytic coliforms throughout the trial. Serum samples were collected and analyzed for inflammatory biomarkers on d 0, 3, 6, and 21 post-inoculation (PI) and untargeted metabolomics on d 6 PI. Intestinal mucosa and tissue sections were harvested from pigs sacrificed on d 7 PI for gene expression and histology analysis. All data, except for frequency of diarrhea and metabolomics, were analyzed by ANOVA using the PROC MIXED of SAS. Dietary trivalerin reduced (P < 0.05) the frequency of severe diarrhea over the entire trial period and the frequency of β-hemolytic coliforms on d 7 PI compared with control. The intestinal villus height on d 7 PI in jejunum tissue was increased (P < 0.05) in pigs fed trivalerin. The mRNA expression of TNF-α was decreased (P < 0.05) in the trivalerin group, while that of ZO1 was increased (P < 0.05) compared with control. Throughout the trial, serum TNF-α was reduced in pigs fed trivalerin compared with control. Serum metabolites, adenosine, inosine, and shikimic acid were reduced (P < 0.05) on d 6 PI in all treatment groups compared with control. In conclusion, the present results indicate supplementing dietary valerate glycerides exhibited beneficial impacts on diarrhea, inflammation, and intestinal gene expression of piglets during the post-weaning period.