EFFECT OF GONADOTROPHIN RELEASING HORMONE ON LUTEINIZING HORMONE SURGE, OVULATION AND PROGESTERONE LEVELS IN BUNAJI COWS.

Abstract

This study evaluated the ovarian and hormonal responses of Bunaji cows to ovsynch protocol initiated at a random stage of oestrus cycle. Animals were arranged into three groups; control (n=5), groups A (n=5) and B (n=5). The control group received 2mL normal saline at time of hormonal treatments. Group A received 50g GnRH on day 0 and day 9followed by 500g of PGF2 on day 7. Group B received 100g of GnRH on day 0 and day 9 followed by 500g PGF2 on day 7. Ultrasound examination was done from day 1 to 9 and after every 12h until detection of ovulation. Blood was sampled at 15 to 30 minutes intervals for 6 h after the GnRH administration to determine serum concentration of LH and once daily for 12 days after the injection of the first GnRH to determine concentration of plasma progesterone. The ovarian response of the treated groups showed no significant difference between the two dosages of ovsynch protocol but differed significantly between the treated and the control groups. Peak values of serum LH obtained on day 0 and day 9 of GnRH administration differs significantly (P<0.05). Plasma progesterone increased among treated groups following injection of GnRH reaching a peak on day 7 than in control, but did not differ among treated groups. In conclusion, GnRH analogue at the doses indicated were able to elicit sufficient LH and progesterone responses to cause disappearance of dominant follicles and subsequent ovulation thereby increasing the reproductive efficiency of Bunaji cows.