摘要：The relationship between Sub-Clinical Ketosis (SCK) and liver injuries within the first two months of lactation in three commercial dairy herds with rather constant routines in management and nutrition was studied. A total of 77 cows (38 cows in the first and 39 cows in the second months of lactation) were sampled for blood. The serum concentrations of glucose, beta-hydroxybutyrate (BHB), nonesterified fatty acid (NEFA), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), cholesterol, triglyceride and VLDL-cholesterol were measured at 30 and 60 days after calving. Sub-clinical ketosis was considered in cows with serum concentration of BHB>1000 μmol L-1. The concentration of serum glucose in cows with SCK was significantly (p<0.05) lower than healthy cows after 30 days of calving. However, the concentrations of serum BHB, NEFA, triglyceride and VLDL-Cholesterol in SCK cows were significantly higher (p<0.05) than the healthy cows. In second month of lactation, the concentrations of serum BHB and NEFA in SCK cows were significantly higher than the healthy cows. The concentration of serum BHB, NEFA, triglyceride and VLDL-cholesterol in SCK cows were significantly higher (p<0.05) than the healthy cows at 30 and 60 days postpartum periods. In the first and second months of lactation, a positive significant correlation was observed between serum glucose and GGT (R = 0.409, p<0.05) in the healthy cows. However, significant correlations were observed between serum glucose and cholesterol (R = 0.403, p<0.05) and GGT and cholesterol (R = 0.388, p<0.05) in cows with SCK. Hepatic injuries were not observed in cows with SCK. In spite of negative energy balance in the first and second months of lactation, liver function tests were normal. The results of this study showed that the concentration of serum BHB and NEFA of SCK cows within the first two months of lactation was significantly higher than healthy cows, possibly due to higher energy demands of cows at this stage.
