Progesterone -based hormonal protocols are effective to treat anestrus in buffaloes. However, most of those protocols are costly, thus, requiring a cost-effective protocol that minimizes handling frequencies. This study, therefore, evaluated the effectiveness of the 'once -used CIDR co -synch protocol' with or without initial GnRH for treating anestrus in buffaloes during low breeding season. Anestrous buffaloes (n=29) were divided into two Treatment groups. As a part of the 'once -used CIDR co -synch protocol,' the first group (T1, n=18) received an initial GnRH on a random day (day 0) while the second group (T2, n=11) did not receive it. On day 0, the once -used CIDR device was inserted intravaginally in both groups, with GnRH administered in T1 but omitted in T2. On day 7, during CIDR removal, each buffalo received PGF 2 alpha , and on day 10, GnRH was given, and fixedtimed artificial insemination (FTAI) was done. Ovarian status was assessed on d0 and on 8 to 9 -day post-FTAI using transrectal ultrasonography. Plasma progesterone concentrations on 8 to 9 -day post-FTAI were determined using ELISA. No significant differences in estrus expression, ovulation and pregnancy rates were observed between two Treatment groups, with overall rates of 93%, 69%, and 34.5%, respectively. However, the overall pregnancy outcome (from FTAI plus natural breeding of buffaloes that returned to estrus) up to 2 months post-FTAI was 48.3%. Parity affected the ovulation among treated buffaloes, with higher (P=0.04) ovulation rate in buffaloes <= 4 th parity (79.2%) compared to >4 th parity (20%). There were no differences in CL size and plasma progesterone concentrations during 8 to 9 -day post-FTAI between two treatment groups. In conclusion, omitting the initial GnRH in 'onceused CIDR Co -synch protocol' proved equally effective as the protocol with initial GnRH for the treatment of anestrus in buffaloes during the low breeding season.
