Roles of hCG in Advancing Follicular Growth to Ovulation after Concurrent Injections of and GnRH in Postpubertal Holstein Heifers Bearing a CL | Zendy

Ricky Johnson | Zendy; William A. Bennett | Zendy; E. J. Cuadra | Zendy; V. N. Njiti | Zendy; Yoonsung Jung | Zendy; M. C. Mason | Zendy

Open Access

Roles of hCG in Advancing Follicular Growth to Ovulation after Concurrent Injections of and GnRH in Postpubertal Holstein Heifers Bearing a CL

Author(s) -

Ricky Johnson,

William A. Bennett,

E. J. Cuadra,

V. N. Njiti,

Yoonsung Jung,

M. C. Mason

Publication year - 2010

Publication title -

veterinary medicine international

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.62

H-Index - 30

eISSN - 2090-8113

pISSN - 2042-0048

DOI - 10.4061/2010/394236

Subject(s) - ovulation , follicular phase , corpus luteum , medicine , human chorionic gonadotropin , prostaglandin , equine chorionic gonadotropin , gonadotropin releasing hormone , endocrinology , hormone , andrology , luteinizing hormone

A study was conducted to test the hypothesis that injecting Gonadotropin-releasing hormone (GnRH) concurrently with Prostaglandin F2 alpha (PGF 2 α ) followed by an injection of human Chorionic Gonadotropin (hCG), would advance follicular growth to ovulation in Holstein heifers bearing a corpus luteum (CL). After manual examination of the CL, group 1 (PGF; n = 12) received an injection of PGF 2 α (25 mg, im). Group 2 (PGF + GnRH; n = 13) received an injection of GnRH (100 μ g, im) immediately after an injection of PGF 2 α . Group 3 (PGF + GnRH + hCG; n = 12) received concurrent injections of PGF 2 α and GnRH followed with hCG (1500 IU, im) two days later. Follicular size and day of ovulation were monitored by daily ultrasonographic examination from days 1 to 10. Blood was collected on days-7, 0 (PGF 2 α administration), 2, and 7. Progesterone was not different ( P > .05) on days-7, 0, and 2 between the experimental groups. However, it was higher ( P < .005) in the PGF + GnRH + hCG group on day 7 compared to PGF + GnRH heifers, but not significantly higher than the PGF. Additionally, heifers in the PGF + GnRH + hCG group ovulated earlier ( P < .05) than heifers in the PGF + GnRH and the PGF group. This data indicates that hCG advances follicular growth to ovulation in spite of high levels of progesterone when injected 48 h after concurrent treatments of GnRH and PGF 2 α on heifers bearing a CL.

The content you want is available to Zendy users.

Already have an account? Click here to sign in.

Having issues? You can contact us here

Accelerating Research