Genetic estimation of fat traits in sheep and association of its NR1H4 gene polymorphisms with tail fat deposition

Previously sheep tail fat provided warmth and energy, but now excessive fat harms their health and performance, affecting their economic value. This study analysed the correlation between fat traits and their genetic characteristics. As well, the effect of the NR1H4 g. 182138945 T > A variant on fat deposition in sheep was investigated. Phenotypic correlations showed significant positive correlations between tail fat, perirenal fat and mesenteric fat weights and carcass fat content. The relative weight of tail fat (relative to either carcass weight or live weight before slaughter) negatively correlates with eye muscle area, while those of the relative weights of perirenal fat and mesenteric fat (relative to either carcass weight or live weight before slaughter) show low positive correlations with eye muscle area. Genetically, intramuscular fat had lower heritability compared to most fat traits, while the carcass fat content had higher heritabilities. A significant positive genetic correlation existed between the tail fat weight, carcass fat content, and intramuscular fat. There was also a significant positive correlation between perirenal fat weight and mesenteric fat weight. Eye muscle area is genetically negatively correlated with the relative weight of tail fat (relative to either carcass weight or live weight before slaughter). The NR1H4 g.182138945 T > A association with fat deposition traits showed that the SNP was significantly (P < 0.05) associated with tail fat weight and its relative weight (relative to either carcass weight or live weight before slaughter). The highest levels of NR1H4 were expressed in liver, which may affect the deposition of fat in the tail of sheep by regulating energy expenditure. This SNP could be a potential marker for tail fat improvement in sheep.