چکیده (انگلیسی):

Objective: To evaluate the ovulation inducing effect of clomiphene citrate along with
human chorionic gonadotropin (hCG) in prepubertal Sahiwal heifers. Clomiphene citrate
(an anti-estrogen) causes gonadotropin secretion from pituitary gland by removing the
negative feedback effect of estrogen. This causes more FSH secretion which ultimately
stimulates follicular growth and upon hCG administration (luteinizing hormone activity)
ovulation occurs.
Methods: Twelve prepubertal Sahiwal heifers were divided into experimental and
control groups, with six animals in each group. The grouping of animals was made on the
basis of plane ovary. The status of ovarian puberty was checked through rectal palpation
and history of previous estrus signs. Experimental heifers were given clomiphene citrate
at 300 mg/heifer for 9 d orally, while heifers in control group were given placebo tablets.
The dose of clomiphene citrate was selected on the basis of previous literature. On day
10, hCG (IVF-C 5000 iu (hCG) LG Life Sciences, Korea) was given to all heifers of both
groups at 2 500 IU/heifer through intravenous route. Two base line blood samples were
collected before start of the treatment at each rectal palpation examination for selection of
animals. Subsequently, during and after treatment three blood samples per week (on
alternate days) for 4 weeks were collected for measuring the progesterone (P4) in serum.
The concentration of progesterone was measured though enzyme linked immunosorbent
assay. For the comparison of variables, student t-test was applied.
Results: The P4 concentrations in five heifers (83.3%) in the experimental group with
(P4 > 1 ng/mL) and one heifer (16.7%) in the control group along with corpus luteum on
ovary showed ovulation. One heifer in control group ovulated that might be due to hCG.
Mean progesterone concentration was significantly higher (P < 0.05) in treated heifers
than in control heifers.
Conclusion: Administration of clomiphene citrate and hCG can induce ovulation induction
in prepubertal Sahiwal heifers.