Administration of a single dose of 300 IU of human chorionic gonadotropin seven days after the onset of estrus improves pregnancy rate in dairy goats by an unknown mechanism

L R Côrtes; J M G Souza-Fabjan; D S Dias; B B Martins; A L R S Maia; M O Veiga; E K N Arashiro; F Z Brandão; M E F Oliveira; P M Bartlewski; J F Fonseca

doi:10.1016/j.domaniend.2020.106579

Administration of a single dose of 300 IU of human chorionic gonadotropin seven days after the onset of estrus improves pregnancy rate in dairy goats by an unknown mechanism

Domest Anim Endocrinol. 2021 Jan:74:106579. doi: 10.1016/j.domaniend.2020.106579. Epub 2020 Oct 9.

Authors

Affiliations

¹ Faculdade de Veterinária, Universidade Federal Fluminense, Rua Vital Brasil Filho, 64, Niterói, Rio de Janeiro, Brazil.
² Faculdade de Medicina Veterinária, Universidade do Grande Rio, Rua Professor José de Souza Herdy, 1160 Duque de Caxias, Rio de Janeiro, Brazil.
³ Universidade Presidente Antônio Carlos, Av. Juiz de Fora, 1100 Juiz de Fora, Minas Gerais, Brazil.
⁴ Embrapa Caprinos e Ovinos, Rodovia MG 133, km 42, Coronel Pacheco, Minas Gerais, Brazil.
⁵ Department of Preventive Veterinary Medicine and Animal Reproduction, São Paulo State University, Via de Acesso Prof. Paulo Donato Castelane, s/n, Zona Rural, Jaboticabal, São Paulo, Brazil.
⁶ Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
⁷ Embrapa Caprinos e Ovinos, Rodovia MG 133, km 42, Coronel Pacheco, Minas Gerais, Brazil. Electronic address: jeferson.fonseca@embrapa.br.

PMID: 33161234
DOI: 10.1016/j.domaniend.2020.106579

Abstract

This study examined the effects of exogenous hCG administration on ovarian function and pregnancy rates in estrous-induced dairy goats during the transition into the breeding season. Eighty-six Toggenburg does received 60 mg of medroxyprogesterone acetate intravaginal sponge for 6 d plus 200 IU of equine chorionic gonadotropin and 30 μg of d-cloprostenol i.m. 24 h before sponge removal, and were then bred for 96 h. Seven days (D7) after first mating the does received either 1 mL of saline (the control group, n = 43) or 300 IU of hCG (the hCG-treated group, n = 43) i.m. Transrectal ovarian ultrasonography (B-mode and color Doppler) was performed on D7, D13, D17, and D21 and ultrasonographic pregnancy detection on D30. Pregnancy rate was higher (P < 0.05) in hCG-treated goats (90.7%; 39/43) than that in control animals (74.4%; 32/43). Accessory luteal structures (ALSs) were detected in 46.5% (20/43) of hCG-treated does. All hCG-treated does that had ALSs and 82.6% of goats without ALS post-treatment remained pregnant. The total luteal area increased (P < 0.05) from D7 to D13 in pregnant animals of both groups, whereas mean vascular area declined (P < 0.05) by D21 in all nonpregnant does. Serum progesterone concentrations increased (P < 0.05) on D21 in pregnant goats of both groups, but they were related to changes in luteal tissue content only in control does throughout the present study. Mean daily numbers of small- and medium-sized antral follicles decreased (P < 0.05) only in pregnant animals of both groups with a decline in medium follicle numbers occurring earlier in hCG-treated (D13) compared with control does (D17). To summarize, a single dose of hCG given on D7 after estrus was followed by a decrease in the number of medium-sized antral follicles in gestating hCG-treated does, induced the formation of ALSs in ~47% of all hCG-treated does, and significantly increased the pregnancy rate in estrous-induced Toggenburg goats in the transition to the breeding season.

Keywords: Conception rate; Goat; Ovary; Progesterone; Ultrasonography; hCG.

Publication types

Randomized Controlled Trial, Veterinary
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Chorionic Gonadotropin* / administration & dosage
Drug Administration Schedule
Female
Goats* / physiology
Ovulation Induction* / methods
Ovulation Induction* / veterinary
Pregnancy
Pregnancy Rate*
Reproductive Control Agents* / administration & dosage

Substances

Chorionic Gonadotropin
Reproductive Control Agents