Abstract
Sixty Holstein heifers, aged between 25 and 28 months, were used. Blood collection was conducted weekly from 8 weeks before calving to 10 weeks after calving. The serum chemical components studies include total cholesterol, GOT, total protein, albumin, globulin, A/G, glucose, Ca, inorganic P, Ca/P, γ-GTP, NEFA, phospholipid and triglyceride. Days open in cows which suffered diseases, especially those related to reproductive organs, was significantly longer than that in normal cows (P<0.01). Correlation between fertility status and serum chemical conponents was observed to be more significant within 3 weeks after calving in the periods of 8 weeks before calving to 10 weeks after calving. A negative correlation between total cholesterol level and the number of services per conception was observed within 3 weeks after calving. Similar correlation was observed between the level of albumin, Ca/P and days open. As for γ-GTP, a positive correlation was observed with days open within 3 weeks after calving. Cows which showed the initiation of ovarian activities within 4 weeks after calving as detected by changes in progesterone levels had significantly less disease occur-rence (P < 0.05).
