Hypophyseal and gonadal response to PGF2α and GnRH at onset of puberty in Murrah buffalo heifers (Bubalus bubalis)

The objective of the present investigation was to study the releasing pattern of FSH, LH, prolactin, estradiol and progesterone at onset of puberty in Murrah buffalo heifers. Twelve Murrah buffalo heifers included in experiment had not exhibited behavioural estrus but had follicles or luteal tissue, or inactive ovaries at 32 months of age. The heifers with follicular phase had significantly (P < 0.01) higher concentration of plasma FSH (31.43 +/- 3.25 ng/ml), prolactin (127.93 +/- 7.36 ng/ml) and estradiol (57.04 +/- 12.53 pg/ml) than the concentration of FSH (14.63 +/- 1.39 ng/ml and 9.93 +/- 1.54 ng/ml), prolactin (74.08 +/- 1.46 ng/ml and 89.70 +/- 8.36 ng/ml) and estradiol (23.67 +/- 0.81 pg/ml and 23.70 +/- 1.67 pg/ml) in heifers having, respectively, luteal phase and inactive ovaries. The progesterone concentration was higher in heifers having luteal phase (2.37 +/- 0.23 ng/ml) than the heifers of follicular phase (0.49 +/- 0.10 ng/ml) and having inactive ovaries (0.33 +/- 0.07 ng/ml). However, plasma LH concentration in heifers having follicles (0.56 +/- 0.04 ng/ml), corpus luteum (0.72 +/- 0.05 ng/ml) and inactive ovary (0.67 +/- 0.19 ng/ml) were similar. PGF(2)alpha caused luteolysis with subsequent follicular growth, elevation of estradiol, FSH and prolactin release. Administration of GnRH in heifers having inactive ovaries induced follicular growth, increased estradiol, FSH and prolactin concentrations with subsequent ovulation and corpus luteum formation.