RETN and obesity due to melanocortin 4 receptor deficiency: In the present study, the serum LEP concentration in type II ketosis cows was higher than that in type I ketosis cows; however, the difference was not significant, which may be due to the high body fat and obesity of dairy cows, and resistin being associated with obesity and IR, which is produced by islets and regulates the secretion of INS and glucagon in vitro [19].