Maintenance of Pregnancy in Dairy Cattle After Treatment with Human Chorionic Gonadotropin or Gonadotropin-Releasing Hormone

Abstract

The objectives were to determine whether a single injection of either human chorionic gonadotropin (hCG) or GnRH would: 1) increase ancillary formation of new luteal structures, 2) increase serum concentrations of progesterone, and 3) increase pregnancy survival in dairy females treated once between 26 and 71 d of pregnancy. A total of 421 cows were enrolled between January and November 2001, with 92, 106, and 223 females (included 68 nulliparous heifers at 1 location) treated at the 3 locations. Upon diagnosis of pregnancy, females were allocated randomly to receive 100 microg of GnRH, 1,000 IU of hCG, or 2 mL of saline. Blood samples were collected at 0, 1, 2, and 4 wk after treatment, and pregnancy status was reassessed at 1, 2, and 4 wk. New luteal structures were formed in 23.8% of cattle, with hCG (50%) and GnRH (26%) being more effective than saline (7%). Treatment had no effect on the proportion of females forming 2 new luteal structures (7.6%), and 36.2% of all induced structures regressed during the 4-wk study period. Pregnancy losses were unaffected by treatment, stage of pregnancy, or number of induced luteal structures but were nearly 9-fold greater in females in which induced luteal structures regressed. No loss occurred in females having 2 new luteal structures. Pregnancy losses decreased quadratically from 30 to 42 d. Serum progesterone did not differ among treatments, but among females forming new luteal structures, progesterone was greater at 1 (7.2 +/- 0.3 vs. 6.3 +/- 0.2 ng/ mL) and 2 wk (7.0 +/- 0.3 vs. 6.1 +/- 0.2 ng/mL) after treatment. Progesterone at the first pregnancy diagnosis was predictive of imminent pregnancy loss; the lower the initial progesterone, the sooner subsequent loss was observed. The right ovary was dominant in the location of new luteal structures. Regression of new luteal structures occurred more often on the left ovary and contra-lateral to the corpus luteum of pregnancy (53.2 vs. 22%). In conclusion, treatment of dairy cattle with either GnRH or hCG failed to prevent pregnancy loss, but concentrations of progesterone were predictive of subsequent pregnancy loss.

Administration of human chorionic gonadotropin to suckled beef cows before ovulation synchronization and fixed-time insemination: Replacement of gonadotropin-releasing hormone with human chorionic gonadotropin1

“…The capacity of hCG to induce ovulation of small follicles has been reported (Burns et al, 2008;Stevenson et al, 2008b). Ovulation of small follicles may result in poorer fertility possibly because of a resulting smaller CL with a decreased capacity to produce P4 (Vasconcelos et al, 2001).…”

Factors Affecting Pregnancy Rates After Ovum Pick Up-Derived Embryo Transfer in Lactating Holstein Recipients Under Tropical Conditions

“…This proportion was approximately twice that reported in this trial for Buserelin (51.06%). Even lower results (25.7%) were reported by Stevenson et al (2008). These differences may be related to dosage, agonist type, or other conditions not controlled among the trials studied.…”

Predictive Value of Free β-hCG Multiple of the Median for Women with Preeclampsia

“…Human chorionic gonadotropin (hCG) signals the corpus luteum to sustain progesterone secretion during the beginning of pregnancy [39]. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries to allow fetal development [40].…”