A Comparative Study of Growth Performance, Small Intestinal Function, and Metabolite Composition of Duroc × Landrace × Yorkshire and Ningxiang Piglets During the Post-Weaning Period

The Ningxiang (NX) pig, recognized for its strong resistance as one of China’s esteemed indigenous breeds, has been the subject of limited investigation concerning its intestinal mucosal immune function. This study aimed to conduct a comparative analysis of the intestinal mucosal immune function and metabolites between Duroc × Landrace × Yorkshire (DLY) piglets and NX piglets. The findings revealed that NX piglets exhibited a significantly higher average daily feed intake, liver index and kidney index compared to their DLY counterparts. Notably, the serum concentration of interleukin-17 was markedly elevated in NX piglets. In terms of the mechanical barrier function, NX piglets demonstrated increased relative mRNA expression of Claudin2 and Occludin in the jejunal mucosa, along with higher Claudin3 and Occludin expression in the ileal mucosa. Furthermore, the relative mRNA expression of porcine β-defensin-1 was significantly higher in the jejunal mucosa of NX piglets. Conversely, expression levels of porcine β-defensin-2 and regenerating islet-derived 3 gamma were reduced in NX piglets compared to DLY piglets. Spearman’s correlation analysis in DLY and NX piglets revealed that the gene expression of proline-arginine-39 (PR-39) was significantly positively correlated with histamine and cholic acid, and significantly negatively correlated with the gene expression of interleukin-6. In summary, the results suggest that NX piglets possess superior intestinal mucosal immune functionality, offering new perspectives for comparative studies on the immune traits of different pig breeds. Moreover, this study identifies the antimicrobial peptide PR-39 as a key biomarker strongly correlated with specific metabolites and inflammatory responses, highlighting its potential as a co-dependent marker of genetic differences between DLY and NX piglets.