Effect of insulin or insulin-like growth factor-I administration at mid-luteal phase of the estrous cycle during superovulation on hormonal profile of Sahiwal cows.

Aim: The present study was designed to study the effect of insulin and insulin-like growth factor-1 (IGF-I) administration during luteal phase of the estrous cycle on the hormonal profile of Sahiwal embryo donor cows during superovulation.

Materials and Methods: Cows (n=18) were selected and divided into three groups; control (n=6, untreated), T-I (n=6, insulin-treated), and T-II (n=6, IGF-I treated). Insulin and IGF-I were given S/C on 5th , 6th , 7th , and 8th days of estrous cycle. Superovulatory treatment was started on day 9th of the estrous cycle. With the sixth dose of follicle-stimulating hormone, prostaglandin was injected to induce superovulatory heat. The superovulated cows were bred, and superovulatory response of each animal was recorded. The embryos were collected non-surgically on the 7th day of superovulatory estrus. About 15 ml blood without anticoagulant was collected on days 5, 7, 9, 11, 13, 15, 17, 19, and 21 or day of embryo recovery where day 0 of estrous cycle was taken as day of estrus. Serum was separated, centrifuged, and transferred into sterilized serum vials. All samples were stored at -20°C till analysis. Progesterone, insulin, and IGF-I were estimated in blood serum by radioimmunoassay using radioimmunoassay kits.

Results and Discussion: The mean concentration of progesterone on days 7 and 11, insulin on days 7 and 9, and IGF-I on days 5, 7, 9, 11, and 15 was significantly higher in insulin-treated T-I groups as compared to untreated control.

Conclusion: It may be concluded that exogenous insulin administration during mid-luteal phase may be helpful in follicular and embryonic development through modulation of progesterone, insulin, and IGF-I in indigenous ( Bos indicus ) Sahiwal embryo donor cows.