Effect of One-Day Delaying CIDR Administration in 5-Day Cosynch Protocol in Dairy Heifers.

Effect of one-day delaying progesterone administration at the beginning of 5-day Cosynch protocol was investigated in Holstein heifers for the first artificial insemination (AI). Heifers received a synchronized ovulation and timed AI (TAI) with CIDR inserted on day (d) 0 (CIDR-5; = 206) or d 1 (CIDR-4; = 192). In both group, GnRH was administered on d 0 followed by a single PGF injection and CIDR removal five days later from GnRH.