OVARIAN FOLLICULAR DYNAMICS AFTER SYNCHRONISATION OF OVULATION IN BUNAJI CROSS-BRED COWS IN NORTHERN NIGERIA

Abstract

Gonadotrophin- releasing hormone (GnRH) and its synthetic analogues (Buserelin, Guserelin, Leprorelin etc) are widely used in veterinary practice to treat cystic ovarian disease and to synchronise oestrus and ovulation in cattle. The aim of this study was to evaluate the follicular dynamics in response to administration of GnRH in combination with prostaglandin F2 alpha (PGF2 ) in treated and untreated apparently healthy Bunaji Cross-bred cows. Animals were arranged into control (n=5) and treated (n=5) groups. The treated group was given first dose of GnRH on day 0 followed by PGF2 on day 7 and second dose of GnRH on day 9. In the control group, animals received 2 ml normal saline at time of hormonal treatments. All animals were allowed a daily ultrasound examination from day-1 to day 12. The animals were examined 12 hourly from day 9 until detection of ovulation. All animals had follicles > 8mm at time of first GnRH administration. Ovulation rates obtained in the untreated group were 0 and 20% as at the time of first and second GnRH administration respectively. This differed significantly from what obtained in the treated group where ovulation rates were 60% and 80% as at the time of first and second GnRH treatment respectively. There was no significant difference in the size of dominant follicle at time of first GnRH analogue injection and peak size of pre-ovulatory follicle after second GnRH administration. In conclusion, the ovsynch protocol has a beneficial effect on the ovulation rate when applied at any stage of the oestrus cycle in Bunaji cross-bred cows.