Abstract: The aim of this study was to explore the relationship between perinatal subclinical ketosis,reproductive performance and follicular development in early lactation,and to detect changes in blood biochemical of the dairy cows.60 cows from a large intensive dairy farm in Heilongjiang province were assigned to subclinical ketosis group (SCK) and control health group (C) according to ketone bodies levels postpartum.According to the estrus condition within 50 d in milk,16 cows and 14 cows of the SCK group was further divided into the estrus group (SCKE) and the anestrus group (SCKA),respectively.The cows in group C was also divided into estrus group (CE,25 cows) and anestrus group (CA,5 cows).All groups of cows were tracked to record reproductive performance data and follicular development status at 50 d postpartum by rectal examination and B-ultrasound.Results showed that the first estrus days of SCKE cows were 10 d longer than the CE cows (P<0.05),and the difference of diameter of follicles was more than 4 mm (P<0.01).The incidence of uterine incompleteness in SCKA group was significantly higher than that in CE group (P<0.05).The plasma insulin-like growth factor-1 (IGF-1) level was significantly decreased (P<0.05) and the milk yield was extremely significantly increased in SCK group (P<0.01).Compared with estrus cows,the content of triglyceride (TG) in plasma of anestrus cows was increased significantly (P<0.05);The contents of glucose (Glu),insulin (Ins),estradiol (E₂) and progesterone (P₄) decreased significantly or extremely significantly (P<0.05;P<0.01).In conclusion,abnormal energy metabolism and reproductive hormone in cows with subclinical ketosis are the risk factor for reproductive and follicles development disorder postpartum in dairy cows,which will lead to poor fertility in dairy cows.

Key words: subclinical ketosis; dairy cow; anestrus; reproductive performance; follicular development