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Abstract

This study compared the effectiveness of once used versus new Controlled Internal Drug Release (CIDR) device in CIDR co-synch protocol for resuming reproductive function in anestrous buffaloes during low breeding season. Either a new (T1, n=19) or once used CIDR (T2, n=31) was inserted into the vagina of buffalo on a random day (d0) and removed on d7. Buffaloes in both treatment groups received GnRH at the time of CIDR insertion and PGF2? during its removal. At 60-66 hrs after CIDR removal, fixed time artificial insemination (FTAI) was done and GnRH was injected. Ovarian status during CIDR insertion, corpus luteum (CL) size on 8-9 d after FTAI and pregnancy diagnosis were determined using transrectal ultrasonography. There was no significant difference between the two treatment groups in terms of estrus expression, ovulation, pregnancy rates and local inflammatory response into the vagina of treated buffaloes. Although FTAI pregnancy rate was 16%, the overall pregnancy from FTAI and natural breeding within 50 d after FTAI was 42%. Estrus expression was affected by the ovarian cyclicity status at the start of the protocol. The size of the CL during 8-9 d after FTAI was larger in pregnant buffaloes as compared to non-pregnant buffaloes. In conclusion, the once used CIDR was as effective as the new CIDR for resuming reproductive function in anestrous buffaloes during low breeding season, however, the efficacy of protocol depended on the ovarian cyclicity status at the start of the protocol and the size of CL during 8-9 d after FTAI.