Author(s): Bonato, Denis Vinicius ; Filho, Luigi Carrer ; Santos, Eriko Silva ; Figueira, Murilo Rezende ; Cerezetti, Marcela Bortoletto [UNESP] ; Morotti, Fábio ; Seneda, Marcelo Marcondes
Date: 2022
Persistent ID: http://hdl.handle.net/11449/222664
Origin: Oasisbr
Subject(s): Breeding biotechnology; Category; Cattle; Conception; Ovulation
Made available in DSpace on 2022-04-28T19:46:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01
We evaluated the effects of nulliparous, primiparous, and multiparous conditions on the estrus and pregnancy rates in females that did not show estrus but were treated with gonadotropin-releasing hormone (GnRH) at the time of timed artificial insemination (TAI). Nelore females (n = 531) were allocated according to the following categories: nulliparous (n = 144), primiparous (n = 132), and multiparous (n = 255). The animals received a conventional TAI protocol, and estrus expression was identified by the absence of paint in the sacrococcygeal region on the day of TAI. Females that did not show estrus were treated with 10 µg of GnRH together with insemination. The rates of estrus and pregnancy were analyzed using a logistic regression model (P < 0.05). The estrus expression was lower (P = 0.006) in the primiparous (61.36%) group than in the nulliparous (76.39%) and multiparous (75.69%) groups. Similar pregnancy rates were observed in females that showed estrus (nulliparous 84.54%, primiparous 86.42%, and multiparous 80.31%; P = 0.39) and in females that did not show estrus and received GnRH (nulliparous 41.18%, primiparous 56.86%, and multiparous 58.06%; P = 0.24). The total pregnancy rates were also similar (P = 0.98) among the categories (nulliparous 74.3%, primiparous 75.0%, and multiparous 74.9%). The primiparous females had a lower rate of estrus, and the pregnancy rates were similar among the categories that received GnRH.
Universidade Paranaense UNIPAR, PR
Neopecuária Genetics na Bovine Reproduction Company NEOPECUARIA, PR
Universidade Estadual de São Paulo USP, SP
Laboratory of Animal Reproduction and Professional Master in Veterinary Clinics Universidade Estadual de Londrina UEL, PR
Laboratory of Animal Reproduction and Animal Science Program UEL, PR
Universidade Estadual de São Paulo USP, SP
