Evaluation of mitochondrial distribution and meiosis progression on the in vitro maturation of ovarian cattle with low and high count of antral follicles

• Grant number: 19/02017-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2019
• End date: July 31, 2020
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Sheila Merlo Garcia Firetti
• Grantee: Wellington Ribeiro Martins
• Host Institution: Faculdade de Ciências Agrárias. Universidade do Oeste Paulista (UNOESTE). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil

Abstract

The development of alternatives to optimize herd productivity has been one of the researchers' current challenges. Many studies have shown a positive relationship between antral follicle count (AFC) and bovine herd fertility parameters, and point to this characteristic as an important and reliable tool that could make the selection of donors with high embryo production potential in vitro (PIVE). In vitro maturation (IVM) is one of the most important phases of PIVE, and several factors may affect maturation rates. Thus, the objective of the present project will be to evaluate the influence of ovarian antral follicle count on oocyte quality and acquisition of competence for in vitro maturation. For this, five replicates will be performed, using ovaries from females coming from a slaughterhouse. At each repetition, the ovaries will be separated into two experimental groups: group 1 - high CFA and group 2 - low CFA. The follicles will be aspirated and the oocytes recovered and classified according to their morphological characteristics. Only grade I and II oocytes will be selected and evaluated (separately) before and after in vitro maturation (IVM). The group that presented better maturation was evaluated according to three indicators of oocyte competence: meiotic progression, through Hoechst staining; membrane potential and mitochondrial distribution by staining with JC-1. The data will be submitted to the Shapiro-Wilk normality test and analyzed using the ANOVA or Chi-square test (X²) at a significance level of 5% according to the normality results. All analyses will be performed using the Statistical Analysis System for Windows (SAS Inst., Inc., Cary, NC) software. With this research, it is hoped to obtain important results that will add the knowledge of the present area of study and optimization of the PIVE technique.