Effect of day of GnRH administration on conception rate in buffaloes

Abstract

The effect of GnRH administration at different stages of estrous cycle on conception rate was studied. Buffaloes
(n=40) in estrus having normal gynaecological condition were randomly divided into 5 groups of 8 animals in each group.
Each buffalo in groups l,2 and 3 was administered 2.5 ml(10 micro gram) of receptal on day 0 (day of estrus), days 5 and 12 of estrous cycle respectively. Buffaloes in group 4 were given 2.5 ml (10 micro gram) receptal 3 times i.e. on day 0.5 and 12 of estrous cycle, while buffaloes in group 5 were given injection of normal saline to serve as control. All buffaloes were inseminated in the same cycle of treatment and pregnancy was confirmed per rectally 60 days later.

First service conception rate (CR) was 50.0%, 37.5%, 70.0%, 75.0% and 37.5% in groups l,2,3,4 and 5, respectively,
and to the second service 50.0,60.0, 100.0 and 40.0% in groups 1,2,3,4 and 5 respectively. CR in third service was 50.0, 50.0 and 33.33% in groups 1,2 and 5 respectively. The overall conception rate (OCR) was 87.5% in groups 1 and 2, 100% in groups 3 and 4 and 75.0% in group 5. Thus GnRH may improve conception in buffaloes when administered on day 0,5 or day 12 but more effectively on day 12 of estrous cycle.