초록
The objective of the investigation was to study the effect of intramuscular $PGF_2\;{\alpha}$ and GnRH on estrus behavior and ovarian response in Murrah buffalo heifers. Twelve Murrah buffalo heifers at 32 months of age that had not exhibited behavioral estrus symptom were included in the experiment. Out of 12,4 heifers were in follicular phase (plasma estradiol $57.05{\pm}12.52pg/ml$), another 4 heifers were in luteal phase (Plasma progesterone $2.24{\pm}0.25ng/ml$) while the ovaries of remaining four heifers were inactive (estradiol $23.70{\pm}1.66pg/ml$and progesterone $0.32{\pm}0.06ng/ml$). $PGF_2\;{\alpha}$ (25 mg, Lutalyse, im) and GnRH (200 ug, Fertagyl, iv) was administered to each heifer at interval of 10 days. The plasma progesterone concentration decreased within 48 hrs after $PGF_2\;{\alpha}$ injection and followed thereafter with follicular growth, estrus and ovulation. GnRH administration induced follicular growth, elevation of plasma estradiol concentration with subsequent exhibition of behavioral estrus in 2 out of 4 heifers having inactive ovary. The observation reveals that Murrah buffalo heifers at 32 months of age have developed receptors for $PGF_2\;{\alpha}$ and GnRH on ovarian and pituitary tissue respectively and response the single injection of $PGF_2\;{\alpha}$ and GnRH similar to the mature cycling animals.