216 - Effect of Dietary L-valine Supplementation on Growth Performance, Immune Response, and Microbial Metabolites in Weaned Pigs Raised in Varying Sanitary Conditions

This study investigated the effects of dietary _L-valine supplementation and sanitary conditions on growth performance, immune response, and microbial metabolites in weaned pigs. Thirty-two weaned pigs (6.98 ± 0.47 kg) were randomly assigned to treatments in a 2 × 2 factorial arrangement based on dietary Val level and sanitary condition (clean or unclean). The pigs were fed either a basal diet containing the standard levels of Val suggested by NRC (2012) or the basal diet with an additional 0.1% of _L-Val. A room designated as the clean room was washed weekly, whereas the designated unclean room was not washed throughout the experiment and 5 kg of manure from the nursery pig barn was spread on the pen floors on day 1. All data were analyzed using a mixed procedure of SAS, with the individual pen as the experimental unit. The pigs raised in unsanitary conditions exhibited a lower average daily gain and average daily feed intake and a higher incidence of diarrhea than those raised in sanitary conditions during the 14-day experimental period (P < 0.05). The pigs in the unclean group also had a lower concentration of butyrate in the jejunum and a higher concentration of ammonia-N in the colon than those in the clean group (P < 0.05). Dietary valine supplementation reduced plasma interleukin (IL)-1α and IL-1 receptor antagonist concentrations as well as isovalerate and ammonia-N concentrations in the colon (P < 0.05). Interactions between dietary Val supplementation and sanitary conditions were observed in the abundance of mRNA-encoding β-defensins 113, 125, and 129 (P < 0.05). In conclusion, dietary Val supplementation beneficially modulates inflammatory response and microbial metabolites regardless of sanitary condition, while transcriptional levels of β-defensins are regulated by dietary Val supplementation in a manner dependent on housing hygiene conditions.