Physiological, endocrine and molecular responses to protocols for artificial insemination stimulated with chorionic gonadotropins

• Grant number: 13/26956-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): July 01, 2014
• Effective date (End): February 28, 2018
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Acordo de Cooperação: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Roberto Sartori Filho
• Grantee: Alexandre Barbieri Prata
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated scholarship(s): 16/05628-6 - Does equine chorionic gonadotropin (ECG) bind to FSH and LH receptors in follicles of cows?, BE.EP.DR

Abstract

In recent years, several changes have been observed in reproductive physiology of dairy cows, affecting conception rates. These changes are apparently related to high milk production, the result of intense feed intake, genetic selection and management techniques for milk production. Given the direct relationship between the increase in milk production and decreased fertility, management alternatives are needed to increase fertility indexes. One alternative is the development of fixed-time artificial insemination (FTAI) protocols using exogenous hormones, since endogenous steroid hormones in high producing dairy cows are metabolized in a high proportion because of the high liver blood flow. This study will involve several experiments that, at the end, may develop a FTAI protocol that ensures high rates of synchronization of ovulation, as well as appropriate oocyte and embryo quality in high-producing dairy cows. In Experiments 1, 2 and 3 we will evaluate whether supplementation with hCG or hCG in FTAI protocols can increase circulating proestrus estradiol, the size of the dominant follicle and thereby increase the volume of the CL and progesterone at diestrus. In Experiment 4, we will evaluate whether stimulation with gonadotropins is able to change the amount and size of CL cells and mitochondria. Moreover, it will be assessed whether these hormones can alter the expression of genes related to steroidogenesis, angiogenesis, and luteolysis. The perspective of this study is to promote substantial increase in knowledge of the factors involved in the success or failure of FTAI protocols, and increase the knowledge about the reproductive physiology of dairy cows managed under intensive and semi-intensive systems. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

PRATA, ALEXANDRE B.; PONTES, GUILHERME C. S.; MONTEIRO, JR., PEDRO LEOPOLDO J.; DRUM, JESSICA N.; WILTBANK, MILO C.; SARTORI, ROBERTO. Equine chorionic gonadotropin increases fertility of grazing dairy cows that receive fixed-time artificial insemination in the early but not later postpartum period. Theriogenology, v. 98, p. 36-40, AUG 2017. (13/26956-3)

PRATA, ALEXANDRE B.; DRUM, JESSICA N.; MELO, LEONARDO F.; ARAUJO, ESTELA R.; SARTORI, ROBERTO. Effect of different chorionic gonadotropins on final growth of the dominant follicle in Bos indicus cows. Theriogenology, v. 111, p. 52-55, APR 15 2018. (13/26956-3)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

PRATA, Alexandre Barbieri. Ovarian function, steroides hormones and fertility in cows stimulated with gonadotropins. 2018. Doctoral Thesis - Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) Piracicaba.