title: Application of one injection of prostaglandin F(2alpha) in the five-day Co-Synch+CIDR protocol for estrous synchronization and resynchronization of dairy heifers.
abstract: The objective was to determine if the 5-d Co-Synch+CIDR (controlled internal drug releasing insert) protocol can be used in dairy heifers for a synchronized timed artificial insemination (TAI) with one injection of PGF(2alpha) for first and second services. In experiment 1, heifers were assigned randomly to receive 1 (n=295) or 2 (n=298) injections of PGF(2alpha) in the 5-d Co-Synch+CIDR protocol. Corpus luteum (CL) regression was measured in one replicate (n=218). No difference in pregnancy per TAI (P/TAI; 46.1 and 48.6%) or CL regression (86.9 and 92.8%) was detected for 1 versus 2 injections of PGF(2alpha), respectively. In experiment 2, nonpregnant heifers (n=86) were assigned to a resynchronized 5-d Co-Synch+CIDR with 1 PGF(2alpha)/TAI or insemination at detected estrus. There was no difference in P/TAI (52.2 and 55%) between groups. In experiment 3, nonpregnant heifers (n=110) were assigned randomly to receive a CIDR (n=54) or no CIDR insert (n=56) in the 5-d Co-Synch protocol for resynchronization of TAI. Pregnancy per TAI was lower without the CIDR device (39.3 vs. 51.8%). In a commercial field evaluation, 416 heifers were synchronized for the first and resynchronized TAI with the 5-d Co-Synch+CIDR protocol with 1 injection of PGF(2alpha). Pregnancy per TAI on d 60 was 58.2 and 47.5% for first and second TAI, respectively; there was a sire effect to the second TAI. In conclusion, the 5-d Co-Synch+CIDR protocol with 1 injection of PGF(2alpha) is an effective reproductive management program for first and second TAI in dairy heifers.
authors.affiliation: College of Veterinary Medicine, University of Florida, Gainesville 32610-0136, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Rabaglino
authors.forename: C A
authors.initials: CA
authors.lastname: Risco
authors.forename: M-J
authors.initials: MJ
authors.lastname: Thatcher
authors.forename: I H
authors.initials: IH
authors.lastname: Kim
authors.forename: J E P
authors.initials: JE
authors.lastname: Santos
authors.forename: W W
authors.initials: WW
authors.lastname: Thatcher
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying / Q000379:methods*; D015237:Dinoprost / Q000008:administration & dosage*; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D011247:Pregnancy; D011897:Random Allocation
chemical_list: D015237:Dinoprost