Abstract
Beef cows were raised in different raising system, and we estimated levels of progesterone, glucose and lipids in blood, the number of days for the occurrence of postpartum estrus, and insemination efficiency. The results obtained were as follows:
1) Body weight after calving decreased slightly until either 6 weeks in grazing cows or 7 weeks in non-grazing cows. After these periods, no significant changes were observed.
2) Levels of total cholesterol, phospholipids and triglyceride in serum decreased on the day of calving, and then showed the tendency to increase. While NEFA level increased on the day of calving, and then slowly decreased. NEFA and triglyceride levels in general were higher in grazing cows than those of non-grazing cows. 3) Plasma progesterone levels were between 2.610.1 ng/ml 1 week before calving in grazing cows and 3.04.3 ng/ml in non-grazing cows and the levels fell sharply below 0.5 ng/ml on the day of calving. A small peak was observed before the first postpartum estrus in grazing cows but no such a peak was observed in non-grazing cows. After artificial insemination, plasma progesterone levels more than 2.0 ng/ml continued for 6 weeks for both grazing and non-grazing cows. 4) The first estrus appeared 42.2 ± 13.3 days after partrition in grazing cows and 72.0 days for non-grazing cows. No significant difference in number of services before conception was observed between grazing and non-grazing cows
