Abstract
Aims: This study aimed at elucidating the effects of recombinant human follicle stimulating hormone (r-hFSH) on the ovarian follicular dynamics, progesterone, estradiol-17 beta profiles, and pregnancy of dairy cows.
Materials and Methods: Three groups (G, n=5 cows) of multiparous dairy cows were used. G1 (C) control cows were given controlled internal drug release (CIDR) and prostaglandin F2a; G2 (L) cows were given low dose (525 IU and G3 (H) cows were given high dose (1800 IU) of r-hFSH on twice daily basis at the last 3 days before CIDR removal. All cows were ultrasonically scanned for follicular growth and dynamics, and blood samples were collected every other day for two consecutive estrus cycles for the determination of estradiol-17 beta and progesterone.
Results: Estrus was observed in all C and L but not in H cows. Dominant follicle was bigger in L compared to C and H cows. Dominant follicle in C (16.00 +/- 2.5 mm) and L cows (17.40 +/- 2.3 mm) disappeared at 72 h after CIDR removal. However, in H cows, no ovulation has occurred during 7 days post-CIDR removal. Progesterone was not different (p>0.10) among groups, whereas estradiol-17 beta revealed significant (p<0.01) reduction in H (15.96 +/- 2.5 pg/ ml) cows compared to C (112.26 +/- 26.1 pg/ ml) and L (97.49 +/- 15.9 pg/ ml) cows. Pregnancy rate was higher in L cows (60%) compared with C cows (20%). However, H cows were not artificially inseminated due to non-ovulation. Only a cow of C group has calved one calf, however, 2 of the L cows gave birth of twins and a cow gave single calf.
Conclusion: Administration of a low dose (525 IU) of r-hFSH resulted in an optimal size of dominant follicle, normal values of progesterone and estradiol-17 beta, and 40% twinning rate, howeverusing 1800 IU of r-hFSH, have adverse effects on ovarian follicular dynamics and hormonal profiles with non-pregnancy of dairy cows raised under hot climate.