Extraction, structural characterization and SNP identification of related genes of collagen from local pigs in Guizhou

BACKGROUND: Collagen, as one of the important components of living organisms, plays a crucial role in supporting and maintaining tissue structure and biological functions. The local pig breed in Guizhou is renowned for its elastic skin, tender meat, and excellent taste. The collagen content in pig skin accounts for approximately 87.7% of the protein content. However, as a by-product after slaughter, the utilization rate of pig skin is not high. Additionally, the content and structural characteristics of collagen have a certain impact on the quality of meat. METHOD: In this study, the skin and longissimus dorsi muscle of local pig breeds in Guizhou (Qiannan pig, Baixi pig, Qianbei pig, Zongdi pig, Kele pig, Congjiang pig) were used as raw materials to optimize the extraction method of collagen, and to explore the differences in the content, type and structure of collagen in the skin and longissimus dorsi muscle tissues of different pig breeds. Based on whole-gene resequencing technology, the screening and identification of differential genes and variant sites in three pig breeds, namely the two pig breeds with the greatest differences in collagen content (Baixi pig and Kele pig) and the pig breed with differences in collagen structure in skin tissue (Zongdi pig), were completed. RESULTS AND CONCLUSIONS: This study determined that the optimal conditions for extracting collagen from local pig tissues in Guizhou are: pH 2.0, enzyme dosage 2%, feed-to-liquid ratio 1:20 (w/v), temperature 37℃, enzymatic hydrolysis time 8 h. Based on the experimental results, it is speculated that the difference in collagen content in the tissues of white-washed pigs and Kela pigs may be related to the COL1A1 and COL4A4 genes and their SNP loci. The structural differences in collagen in the skin of Zongdi pigs may be related to the COL4A3 and COL4A4 genes and their SNP loci, which is helpful to reveal the molecular mechanism of the skin characteristics of local pig breeds in Guizhou, open up new ways for the breeding of characteristic pig breeds in Guizhou.