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

Autor: Cláudio Alvarenga de Oliveira, Cecilia Constantino Rocha, Ivani Posar Otzuk, Rafael Herrera Alvarez, Alfredo José Ferreira Melo, Guilherme Pugliesi, Patrice Humblot, Gilmar Arantes Ataide Júnior, Fabio Luis Nogueira Natal
Rok vydání: 2018
Předmět:
Ovulation
Time Factors
Pregnancy Rate
medicine.drug_class
Gonadotropins
Equine
medicine.medical_treatment
Chorionic Gonadotropin
Andrology
03 medical and health sciences
chemistry.chemical_compound
0302 clinical medicine
Food Animals
Estrus
Corpus Luteum
Pregnancy
medicine
Animals
Humans
Small Animals
Equine chorionic gonadotropin
Insemination
Artificial
Progesterone
Estrous cycle
030219 obstetrics & reproductive medicine
Dose-Response Relationship
Drug
Estradiol
Equine
business.industry
Artificial insemination
Reproduction
0402 animal and dairy science
04 agricultural and veterinary sciences
medicine.disease
Zebu
040201 dairy & animal science
medicine.anatomical_structure
Fertility
chemistry
Estrogen
Estradiol benzoate
Pregnancy
Twin
Animal Science and Zoology
Cattle
Female
business
Corpus luteum
INSEMINAÇÃO ARTIFICIAL ANIMAL
Zdroj: Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual)
Universidade de São Paulo (USP)
instacron:USP
ISSN: 1879-3231
Popis: 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 μg 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 0.05) in eCG-treated cows. In conclusion, eCG increased the number of double/multiple ovulations in a dose-dependent manner, induced larger and more vascularized corpora lutea, but did not affect the fertility of cyclic or anestrous cows. Although eCG results in twin pregnancies, most of cows underwet embryo/fetus loss and birth a single calf.
Databáze: OpenAIRE
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