AbstractIn this study, sows were fed 200 (LD), 800 (ND) and 3200 (HD) IU of vitamin D3/kg basal diet during pregnancy (from 41 d to birth), respectively. All their offspring pigs were fed the same vitamin D3 replete die. At 150 days of age, a total of 18 offspring pigs (six offspring pigs per maternal diet group, sex balance) were weighed and slaughtered to investigate effects of maternal vitamin D3 during pregnancy on fatty acids synthase (FASN) and hormone-sensitive lipase (LIPE) expression in offspring pigs. The results showed that LD offspring pigs had higher FASN mRNA expression and the ratio of FASN/LIPE mRNA expression in subcutaneous adipose tissue, as well as higher LIPE mRNA expression of longissimus dorsal muscle, whereas, had lower the ratio of FASN/LIPE mRNA expression in longissimus dorsal muscle compared with ND or HD offspring pigs, respectively. Meanwhile, LD offspring pigs had higher carcass fat, average backfat thickness (ABFT), serum insulin and leptin levels, lower intramuscular fat (IMF), serum free fatty acid and triglycerol levels compared with ND or HD offspring pigs. In addition, the ratio of FASN/LIPE mRNA expression was negatively correlated with IMF content, and positively correlated to carcass fat content and ABFT in offspring pigs. Meanwhile, FASN mRNA expression was positively correlated with carcass fat content, while negatively correlated with ABFT in offspring pigs. These results suggested that maternal vitamin D3 affected fat accumulation and meat quality by regulating FASN and LIPE mRNA expression in offspring pigs.