Follicullar Development and Embryo Recovery Following 3 versus 8 FSH Injections in Heifers

摘要

Ovarian follicular dynamics and embryo yield were studied during 2 different FSH regimens for superovulation of cattle. Twenty heifers were given intramuscular injections of FSH (total of 35 mg NIH) either once daily for 3 days (Group 3×1) or twice daily for 4 days (Group 4×2). At 72 h after the first FSH injection, each animal was injected with 0.75 mg cloprostenol. Inseminations were performed at 12 h and 24 h after the onset of heat. Transrectal ultrasonography was performed on the day of the first FSH injection, the day of cloprostenol injection, the day of insemination and finally on the day of embryo recovery (day 6 or 7 after heat). The numbers of small (2–4 mm), medium (5–9 mm) and large (>10 mm) size follicles were recorded. The total number of corpora lutea, eggs and transferable embryos were recorded on the day of embryo recovery. No differences were found between the 2 groups in either of the parameters studied (p>0.05). It can be concluded that treatment with this FSH preparation once daily for 3 days gives a folliculogenic and superovulatory response similar to a treatment regimen where it is given twice daily for 4 days.