Influence of priming dose of GnRH analogue [cystorelin] on the ovarian activity in postpartum Egyptian buffalo-cows

ABSTRACT

This work aimed to study the effect of GnRH injection at 44 days postpartum when preceded by a priming dose, on the ovarian activity and consequently, the initiation of the postpartum ovarian cyclicity in Egyptian buffalos. Routine rectal examination was carried out to diagnose the postpartum [pp] conditions of the ovaries in 18 normal parturient buffalo-cows at day 30 pp. These animals did not show any signs of etrus till day 44 pp. The animals were assigned randomly at day 44 pp into 2 groups. Group 1 [n=12], was treated with 100 mul GnRH [Cystorelin]. Each animal received 2 injections of GnRH 50 mul i.m./one hour apart. Group 2 [n=6] defined as controls and received saline [1 ml i.m.]. Visual examination was done following GnRH injection to detect the sings of estrus. Rectal examinations were conducted in the 1st week [51 days postpartum] and 2nd week [58 days pp] to detect any ovarian changes after treatment on both groups. Serum samples were collected parallel to rectal palpation to detect the progesterone and estradiol 17 beta levels before and after treatment. The animals were allowed freely for natural service by a fertile buffalo-bull and examined for pregnancy at day 45 post service. The results revealed that, the injection of GnRH analogue preceded by 1 hour apart priming dose resulted in a significant increase in the treatment and consequently induced cyclicity and shortened of the period from calving to first postpartum estrus in Egyptian buffalos