Session: Production, Management, and Environment II

279 - ReBreed21, a Rapid Reinsemination Program: Fertility in Bos Indicus Cattle of Different Parities

Friday, July 16, 2021

3:15 PM – 3:30 PM EST

Location: Kentucky International Convention Center (KICC), L007/008

Presenting Author(s)

JA

João Paulo N. Andrade, M.S.

Ph.D. candidate
University of Wisconsin-Madison, Department of Animal and Dairy Science
Madison, Wisconsin

Author(s)

Pedro L. Monteiro, Jr., n/a

Researcher
monteirojr@wisc.edu
Madison, Wisconsin
AP

Alexandre B. Prata, n/a

GlobalGen Vet Science
Jaboticabal, Sao Paulo
AR

Adelino Robl, n/a

Agropecuária Roncador
Querência, Mato Grosso
JL

José Leite

Agropecuária Roncador
Querência, Mato Grosso
CP

Cesar Pimenta

Agropecuária Roncador
Querência, Mato Grosso
JD

José Dias

Agropecuária Roncador
Querência, Mato Grosso
AG

Afonso Guimarães

University of São Paulo Department of Animal Science, Luiz de Queiroz College of Agriculture (ESALQ)
Piracicaba, Sao Paulo
BL

Beatriz Lippe

University of São Paulo Department of Animal Science, Luiz de Queiroz College of Agriculture (ESALQ)
Piracicaba, Sao Paulo
HR

Heuller Ribeiro

Agropecuária Roncador
Querência, Mato Grosso
SM

Same Merhi

Agropecuária Roncador
Querência, Mato Grosso
DH

Diego Hartmann

Agropecuária Roncador
Querência, Mato Grosso
RS

Roberto Sartori, n/a

University of São Paulo Department of Animal Science, Luiz de Queiroz College of Agriculture (ESALQ)
Piracicaba, Sao Paulo
MW

Milo C. Wiltbank

University of Wisconsin-Madison, Department of Animal and Dairy Science
Madison, Wisconsin

This study evaluated efficiency of a reinsemination program allowing timed AI (TAI) every 21 days (ReBreed21; RB21) vs. a traditional Resynch program in Nellore females (n = 2,085) of different parities. First TAI followed estradiol (E2)/progesterone (P4)-based synchronization, and was considered d0. For RB21 (n= 1,357), cows received P4 insert on D12. On D19, P4 was removed, followed by treatment with equine chorionic gonadotropin (eCG) and 0.6 mg E2 Cypionate (RB21+EC, n = 60) or nothing (RB21, n=687). On D21, Doppler ultrasound was used to determine CL blood flow [ < 25%=nonpregnant (NP)] and NP cows received TAI immediately together with 25µg licerelin acetate (GnRH). A second RB21 program using the same groups was done in cows that received TAI on D21 to allow a third potential TAI on D42. Pregnancy diagnosis was performed on D33 after each TAI. Cows designated pregnant on D21 but NP on D33, were termed False-Positive (FP). On D33, all control (n = 728) designated NP and FP cows were resynchronized with P4+E2 protocol for the second TAI at D42. Data were analyzed with SAS and shown in Table 1. For all cows, there were no differences in the three groups (Control, RB21, RB21+EC) for pregnancy/AI (P/AI). In nulliparous heifers, cumulative pregnancies were greater for both RB21 groups compared to Controls at D21 or D42 of the breeding season. Primiparous cows had greater cumulative pregnancies at D21 but not D42. Primiparous cows at second TAI had lower P/AI in RB21 (34.2%) vs. Control (51.7%); however, RB21-EC (55.8%) was similar to Control. No other parities had differences between RB21 and RB21+EC. Multiparous cows had high fertility at first TAI [69.3% (418/603)] and no differences between groups in cumulative pregnancies (P = 0.23). Thus, ReBreed21 program increases the reproductive efficiency in Nulliparous and Primiparous but not Multiparous Bos Indicus cattle. Adding EC to RB21 program only improves P/AI in Primiparous cows.