Comparison of the 7-day Cosynch and 8-day Estradiol-Based Protocols for Synchronization of Ovulation and Timed Artificial Insemination in Suckled Bos Taurus Cows

RODRIGUEZ, ALEJANDRO M; MARESCA, SEBASTIAN; LÓPEZ-VALIENTE, SEBASTIAN O; BILBAO, MARIA G; MORAN, KAREN D; BARTOLOME, JULIÁN A; PRATT, SCOTT L; LONG, NATHAN M

JOURNAL OF ANIMAL SCIENCE

AMER SOC ANIMAL SCIENCE

Año: 2022 vol. 100 p. 346 - 346

0021-8812

The objective was to compare pregnancy per TAI on Day 30 and pregnancy loss (PL) between Days 30 and 60 after TAI (Day 0) and plasma progesterone on Day 18 in Angus suckled beef cows receiving a 7-d CoSynch or an 8-d estradiol-based protocol. Cows (n=1148) were submitted at random to either 7-d progesterone CoSynch (7-d P + GnRH) or 8-d progesterone + estradiol (8-d P + ES) protocol for TAI. On Day -10, cows in the 7-d P + GnRH treatment group (n=574) received a progesterone-releasing intravaginal device (PIVD) and GnRH, on Day -3 the PIVD was removed and cows received cloprostenol, then, on Day 0 (64 h after PIVD removal), cows received GnRH and TAI. On Day -10, cows in the 8-d P + ES treatment group (n=574) received a PIVD and estradiol benzoate, on Day -2 the PIVD was removed, and cows received cloprostenol and estradiol cypionate, then, on Day 0 (48 h after PIVD removal), cows received TAI. Pregnancy per TAI was determined on Day 30 and was reconfirmed on Day 60. In a subset of cows (n=81), serum progesterone concentration was evaluated on Day 18. Pregnancy per TAI on Day 30 and PL between Days 30 and 60 did not differ (P>0.15) between treatment groups. In a subset of cows, serum progesterone concentration on Day 18 did not differ (P=0.83) between treatment groups but tended to be lower (P=0.07) in cows that had PL between Days 30 and 60 compared to cows that had no PL. In conclusion, there was no difference in pregnancy per TAI on Day 30 and PL between Days 30 and 60 between cows using 7-d CoSynch or 8-d estradiol-based protocols for synchronization of ovulation and timed artificial insemination.