Metabolomics Profiling of Serum and Urine from Chuanzang Black Pigs with Different Residual Feed Intake.

Simple Summary: Heretofore, a series of research has targeted enhancing feed efficiency and identifying dependable feed efficiency biomarkers, yet less research has focused on improving RFI in Chuanzang black pigs. Therefore, our study facilitates a deeper understanding of the differences in serum and urine metabolites of Chuanzang black pigs with different residual feed intakes in seeking to identify differential metabolites with residual feed intake. Our study used a nontargeted metabolomics approach to analyze pig metabolite markers by differences in Chuanzang black pigs' serum and urine metabolites, providing new insights into the biological differences in residual feed intake selection in Chuanzang black pigs. We believe this paper would be of great interest to breeders of animals. This study was conducted to evaluate associations of blood variables and urine variables with different residual feed intakes (RFIs) in growing Chuanzang black (CB) pigs. A total of 228 growing CB boars from 99 days were used. The same basal diet was offered ad libitum and individual feed intake and body weight were measured over a period of 181 d. The CB pigs were categorized based on their residual feed intake values, with six individuals each from the high and low ends selected and divided into two groups: the low residual feed intake group (LS) and the high residual feed intake group (HS). Serum and urine samples were collected at the end of the experiment for determination of metabolomics profiling. Results showed that there were significantly different metabolites in serum and urine of different RFI groups (fold-change, FC > 2.0 or FC < 0.5, and p < 0.05), and 21 metabolites were identified in serum and 61 in urine. Cluster analysis showed that 20 metabolites were up-regulated and one metabolite was down-regulated in serum; 44 metabolites were up-regulated and 17 metabolites were down-regulated in urine. Kyoto Encyclopedia of Genes and Genomes analysis showed that the differential metabolites of serum were enriched in linoleic acid metabolism, and the differential metabolites of urine were enriched in steroid hormone biosynthesis, taurine and hypotaurine metabolism, and primary bile acid biosynthesis. The correlations between serum metabolites and urine metabolites indicated a significant positive correlation between all fatty acyls in serum metabolites and L-glutamate in urine. However, no compelling genetic or blood biomarkers have been found to explain the differences in RFI, suggesting multiple approaches to effective feed use in pigs. This study provides new insights into the subsequent assessment of RFI by metabolomics profiling, as well as the development of novel feed additives for the factors that will facilitate future research directions in CB pigs. [ABSTRACT FROM AUTHOR]