Effect of Insemination Time on Pregnancy Rate and Ovulatory Events of Nili Ravi Buffalo Heifers in 7 Day CIDR Co-Synch

Abstract The present study aimed to compare the pregnancy rates at the optimal time of artificial insemination in a 7-day CIDR Co-synch in Nili Ravi buffalo heifers. Forty Nili Ravi buffalo heifers were randomly separated into two treatments based on artificial insemination (A.I.) timing (72 vs 84 hours). All heifers were subjected to controlled internal drug release (CIDR), containing 1.38 grams of progesterone for 7 days. On CIDR removal, both treatments received 150 µg of prostaglandin intramuscularly. In 7-day CIDR Co-synch (n = 20), animals were injected 100 µg of GnRH intramuscularly and inseminated concurrently at 72 hours after CIDRs removal. The remaining half (n=20) were injected and inseminated concurrently at 84 hours of CIDRs removal. Pregnancy diagnosis was performed after 40 days of timed artificial insemination (TAI). The follicular growth rate in 7-day CIDR Co-synch was more significant at 84 than 72 hours. The interval from GnRH/A.I. to ovulation in 7-day CIDR Co-synch was significantly (P < 0.05) differ between 72 and 84 hours. Pregnancy rates were considerably higher in buffalo heifers inseminated at 84 hours (65%) than 72 hours (25%) in 7-day CIDR Co-synch treatment. In conclusion, the buffalo heifers treated with CIDR Co-synch based protocols in relation to TAI at 84 hours improves follicular growth rate, interval from GnRH/A.I. to ovulation, and pregnancy rate.