Reproductive performance of Bos indicus beef cows treated with different doses of equine chorionic gonadotropin at the end of a progesterone-estrogen based protocol for fixed-time artificial insemination

Alvarez, Rafael Herrera; Pugliesi, Guilherme; Nogueira Natal, Fabio Luis; Rocha, Cecilia Constantino; Ataide Junior, Gilmar Arantes; Ferreira Melo, Alfredo Jose; Otzuk, Ivani Posar; de Oliveira, Claudio Alvarenga; Humblot, Patrice

doi:10.1016/j.theriogenology.2018.06.003

Research article2018Peer reviewed

Reproductive performance of Bos indicus beef cows treated with different doses of equine chorionic gonadotropin at the end of a progesterone-estrogen based protocol for fixed-time artificial insemination

Alvarez, Rafael Herrera; Pugliesi, Guilherme; Nogueira Natal, Fabio Luis; Rocha, Cecilia Constantino; Ataide Junior, Gilmar Arantes; Ferreira Melo, Alfredo Jose; Otzuk, Ivani Posar; de Oliveira, Claudio Alvarenga; Humblot, Patrice

Abstract

Two experiments were performed to evaluate the reproductive performance of zebu beef cows treated with different doses of eCG at the end of a progesterone (P4)/estrogen based protocol for timed artificial insemination (TAI). In Experiment 1, suckling Bos indicus Nelore cows (n = 261) received, on day 0, a progesterone (P4) intravaginal device (PD) and an injection of 1 mg estradiol benzoate (EB). On day 8, the PD was removed, 500 pig of cloprostenol was injected, and cows were assigned to one of the following groups: Control (no treatment), 300 (300 IU of eCG), 600 (600 IU of eCG), and 900 (900 IU of eCG). On day 9, all cows received 1 mg EB and TAI performed 54-56 h after cloprostenol injection. A pregnancy diagnosis was done by ultrasound scanning 40 days after TAI, and the number of fetuses and calves was recorded at pregnancy diagnosis and at birth. More cows treated with eCG displayed estrus within 48 h after removal of the PD (42.3% vs. 11.6%, P < 0.01), and ovulated more than one follicle (42%, 58/138 vs. 1.8%, 1/54; P < 0.01). This effect on ovulation rate was dose dependent (P < 0.05). The pregnancy rate was affected only by cow parity (primiparous, 25.3% vs. multiparous, 48.9%; P < 0.01). Twin pregnancy was higher (P < 0.01) in cows treated with eCG (42%, 58/138) than controls (0%, 0/54). However, few cows (33.3%) were able to keep both fetuses intact until birth. For evaluation of ovarian characteristics by B mode and Doppler ultrasonography, 43 Nelore cows were submitted In Experiment 2 to the same four groups described in Experiment 1. Although no difference (P > 0.1) was observed for size and blood perfusion in the pre-ovulatory follicles, corpus luteum was larger and with greater blood perfusion (P

Keywords

eCG; TAI; Twin; Fertility; Nelore cows

Published in

Theriogenology
2018, volume: 118, pages: 150-156
Publisher: ELSEVIER SCIENCE INC

SLU Authors

Humblot, Patrice
- Department of Clinical Sciences, Swedish University of Agricultural Sciences

UKÄ Subject classification

Clinical Science

Publication identifier

DOI: https://doi.org/10.1016/j.theriogenology.2018.06.003

Permanent link to this page (URI)

https://res.slu.se/id/publ/96476