Different doses of equine chorionic gonadotropin on ovarian follicular growth and pregnancy rate of suckled Bos taurus beef cows subjected to timed artificial insemination protocol

Autor: Gilson Antonio Pessoa, F. G. Leivas, I. Claro Junior, M. C. C. Rodrigues, M. F. Sá Filho, Ana Paula Machado Martini, Pietro Sampaio Baruselli, G. W. Carloto, Mara Iolanda Batistella Rubin, Cássio Cassal Brauner, Marcio Nunes Corrêa
Rok vydání: 2016
Předmět:
Male
medicine.medical_specialty
Pregnancy Rate
Gonadotropins
Equine
medicine.medical_treatment
Chorionic Gonadotropin
Andrology
03 medical and health sciences
chemistry.chemical_compound
Oogenesis
0302 clinical medicine
Ovarian Follicle
Ovulation Induction
Food Animals
Pregnancy
Follicular phase
Animals
Medicine
Small Animals
Equine chorionic gonadotropin
Insemination
Artificial
Gynecology
Estrous cycle
030219 obstetrics & reproductive medicine
Dose-Response Relationship
Drug
Equine
business.industry
Artificial insemination
0402 animal and dairy science
04 agricultural and veterinary sciences
Estradiol cypionate
medicine.disease
040201 dairy & animal science
humanities
Animals
Suckling
Pregnancy rate
chemistry
Estradiol benzoate
Cattle
Female
Animal Science and Zoology
GONADOTROFINA CORIÔNICA
Estrus Synchronization
business
medicine.drug
Zdroj: Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual)
Universidade de São Paulo (USP)
instacron:USP
ISSN: 0093-691X
DOI: 10.1016/j.theriogenology.2015.09.057
Popis: This study evaluated the effect of different doses of eCG (control, 300 or 400 IU) administered at progesterone (P4) device removal in suckled Bos taurus beef cows undergoing a timed artificial insemination (TAI) protocol. A total of 966 cows received a P4 insert and 2.0 mg intramuscular estradiol benzoate at the onset of the synchronization. After 9 days, P4 insert was removed, and 12.5 mg of dinoprost tromethamine and 1 mg of estradiol cypionate were administered, followed by TAI 48 hours later. Then, the cows received one of three treatments as follows: control (n = 323), 300 (n = 326), or 400 IU of eCG (n = 317). A subset (n = 435) of cows in anestrus had their ovaries evaluated using ultrasound at the time of P4 removal and at TAI. Data were analyzed by orthogonal contrasts (C): C1 (eCG effect) and C2 (eCG dose effect). Estrous occurrence (control = 53.7%, 300 IU = 70.6%, and 400 IU = 77.0%) and pregnancy per artificial insemination (control = 29.7%, 300 IU = 44.8%, and 400 IU = 47.6%) were improved by eCG treatment (C1; P = 0.0004 and P0.0001, respectively). Furthermore, the cows receiving eCG presented larger follicles at TAI (control = 13.5 ± 0.3 mm, 300 IU = 14.0 ± 0.2 mm, and 400 IU = 15.1 ± 0.3 mm; P0.0001; C1). However, there was no effect of eCG dose on any response variables studied (C2; P0.15). In conclusion, the eCG treatment administered at the time of P4 removal increased the occurrence of estrus, the larger follicles at TAI, and pregnancy per artificial insemination of suckled B taurus beef cows. Despite the greater occurrence of estrus in noncyclic cows receiving 400 IU of eCG, both eCG doses (300 and 400 IU) were equally efficient to improve pregnancy to artificial insemination.
Databáze: OpenAIRE
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