Investigation on the Relationship of Insulin Resistance and Ketosis in Dairy Cows

Abstract

Ketosis is an important metabolic disease of dairy cows during the transition period, but it is fully unclear about its endocrine etiology. Our study is to clarify the relationship between oxidative stress, liver function, insulin resistance and ketosis in dairy cows. Sixteen ketotic Holstein cows (T) and twenty-four non-ketotic Holstein cows (C) were used as the experimental animals from an intensive dairy farm in Heilongjiang province, China. Blood samples from all experimental cows were collected at 14 days postpartum during morning fasting. Fifteen parameters for energy balance, liver function, oxidative stress, insulin sensitivity and glucose tolerance test between T and C were measured using commercial kits. Results showed that the concentration of plasma glucose (P<0.01) was lower in T compared with C cows, whereas there were marked increases in the concentration of plasma non-esterified fatty acids and beta-hydroxybutyric acid (P<0.01). The level of plasma AST (P<0.01), TBIL (P<0.05), and DBIL (P<0.01) increased significantly in T cows compared with C cows, but plasma CHE (P<0.01) and TP (P<0.05) decreased significantly, and no significant change in plasma ALT, IBIL, ALB, and GLO. Level of plasma malondialdehyde (MDA) and superoxide dismutase (SOD) was significantly higher in ketotic cows than that of non-ketotic cows (P<0.05), but value of plasma revised quantitative insulin sensitivity index (RQUICKI) was lower significantly in T cows than that of C cows (P<0.05). Concentration of plasma Glc increased significantly in T cows compared with C cows during glucose tolerance test (P<0.05). Therefore, the ketosic cows were in condition of negative energy balance, suffered to certain extent from liver function abnormality, and experienced oxidative stress and low insulin sensitivity. Therefore, a closed relationship between ketosis and insulin resistance should be related to liver function and oxidative stress that can cause insulin resistance.