Influence of different doses of equine chorionic gonadotropin on follicular population and plasma estradiol concentration in Chinese Holstein Dairy cows
2015
Shu-Bin, F. (Huazhong Agricultural Univ. (China). Ministry of Education) | Riaz, H. (Huazhong Agricultural Univ. (China). Ministry of Education) | Khan, M.K. (Huazhong Agricultural Univ., Wuhan (China). State Key Laboratory of Agricultural Microbiology) | Hua-Lin, Z. (Huazhong Agricultural Univ. (China). Ministry of Education) | Jian-Guo, C. (Huazhong Agricultural Univ., Wuhan (China). Coll. of Veterinary Medicine) | Li-Guo, Y.
The present study was designed to compare the effect of different doses of equine chorionic gonadotropin (eCG) on follicular population and plasma estradiol concentration in Chinese Holstein cows synchronized with prostaglandin F2 alpha (PGF2 alpha). One hundred cows were divided into five treatment groups. Each group (n=20) was administered with an injection of eCG at dose rate of 2, 2.5, 3, 3.5, or 4 IU/kg b.w., respectively, followed by administration of PGF2 alpha 48h later. Ovarian scanning was performed by transrectal ultrasonography around estrus, while plasma estradiol concentration at administration of eCG, PGF2 alpha, estrus and 12h after estrus was measured by Radioimmunoassay (RIA). The results showed that medium follicles (5-10 mm) varied (P less than 0.05) among all treatment groups with an increasing trend. However, there was no significant difference (P greater than 0.05) in the number of large follicles (greater than 10 mm). Plasma estradiol concentration differed non-significantly (P greater than 0.05) in all groups before estrus. At estrus, the concentration was at peak in high dose treatment group (4 IU/kg, P less than 0.05) than those of low dose treatment groups (2 and 2.5 IU/kg). The study concluded that eCG increases the recruitment and development of medium follicles in dose dependent manners however it has no subsequent effect on large follicles population.
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