Dose-related Effects of Follicle Stimulating Hormone on Superovulation in Indigenous Cows of Bangladesh

The present study aimed at determining the effective dose of Folltropin, a follicle timulating hormone (FSH), on superovulation in indigenous cows of Bangladesh. Fifteen regularly cycling 5～7 years old dry cows, weighing 200～250 kg with 2.5～3.0 body condition scores (BCS) were divided into three groups (n＝5). Individual groups were superovulated with 100, 200 or 300 mg of Folltropin per animal. The superovulation treatment was initiated at Day 10 or Day 11 of the estrous cycle (Day 0＝day of estrus). Alfaprostol (6 mg) was injected to each cow 72 h after the initiation of superovulation treatment to induce eestrus. After confirming standing estrus, the cows were inseminated 2～3 times, 12 h apart, depending on the duration of estrus. At Day 6 or Day 7, individual horns of the uterus were flushed with 150～200 $m\ell$ of phosphate buffered saline supplemented with BSA (0.2％), penicillin (100 IU／$m\ell$) and streptomycin (100 $\mu\textrm{g}$／$m\ell$) using a two-way foley catheter. The embryos were concentrated, removing the excess medium through an embryo filter, and identified under a stereomicroscope. The identified embryos were collected, washed four times, evaluated and graded as excellent, good, fair or poor. The excellent, good and fair embryos were considered as transferable quality embryos. The mean (range). numbers of embryos collected vs. transferable quality embryos far 100, 200 and 300 mg of Folltropin were 4.5 (1～10) vs. 3.5 (1～8); 2.5 (1～4) vs. 1 (0～2) and 0.0 (0～0) vs. 0.0 (0～0), respectively, Folltropin at a dose of 100 or 200 mg produced suitable ovarian stimulation for superovulation in indigenous zebu cows of Bangladesh. A dose of 300 mg or more Folltropin consistently caused preovulatory corpora lutea formation in the ovaries and resulted in zero embryo recovery.