Follicular function in lactating dairy cows treated with sustained-release bovine somatotropin.

摘要: Abstract The objective of this study was to determine the long-term, short-term, and residual effects bovine somatotropin (bST) onovarian function. Twenty-six Holstein cows were assigned one four groups given either bST (500mg) orsaline for seven injection cycles (14 d between injections). Groups 1) saline (control), 2) bST, 3) three followed by saline, 4) bST. Beginning in middle fourth cycle, an estrous cycle synchronized study. Serum concentrations insulin-like growth factor I lowest during injections increased after injections. Growth first wave dominant follicle similar; however, start second follicular approximately 48h earlier those treated with (groups 2, 3, 4). Cows had a similar pattern growth, but tended have more class 1 (3 5mm) follicles 2 (6 9mm) than did control cows. Peak serum FSH lower occurred There no differences long-term or short-term on ovarian Furthermore, that switched from (group showed effect up 3wk.