Supplementation of progesterone via controlled internal drug release inserts during ovulation synchronization protocols in lactating dairy cows1

• Published in: Journal of dairy science 2010-03, Vol.93 (3), p.922-931
• Main Authors: Chebel, R.C., Al-Hassan, M.J., Fricke, P.M., Santos, J.E.P., Lima, J.R., Martel, C.A., Stevenson, J.S., Garcia, R., Ax, R.L.
• Format: Article
• Language: English
• Subjects: controlled internal drug release insert; dairy cow; synchronization
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2009-2301

Our objective was to determine the effect of exogenous progesterone (P4) during a timed artificial insemination (TAI) protocol on pregnancies per AI (P/AI) in dairy cows not previously detected in estrus. Lactating cows (n=3,248) from 7 commercial dairy herds were submitted to a presynchronization protocol (2 injections of PGF2α 14 d apart; Presynch), and cows in estrus after the second PGF2α received AI (EDAI; n=1,583). Cows not inseminated by 12 to 14 d after the second PGF2α injection were submitted to a TAI protocol (GnRH on d 0, PGF2α on d 7, and GnRH+TAI 72h after PGF2α). At onset of the TAI protocol, cows were balanced by parity and days in milk and assigned randomly to receive no exogenous P4 (control, n=803) or a controlled internal drug release (CIDR) insert containing 1.38g of P4 from d 0 to 7 (CIDR, n=862). Blood samples were collected at the second PGF2α injection of the Presynch and on the day of the first GnRH injection of the TAI protocol for P4 determination. When P4 in both samples was