Relationship between follicular population and fertility in Holstein cows

• Grant number: 15/21441-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): January 01, 2016
• Effective date (End): December 31, 2016
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Pietro Sampaio Baruselli
• Grantee: Mariana Pallú Viziack
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The fertility with subsequent reproductive efficiency of dairy herds in Brazil is a challenge that leads to the need to select the most fertile animals. Predict the follicular population could be a strategy for the selection of donors and also for use in dairy herds to improve reproductive rates after TAI protocols aimed at using animals with genetically higher reproductive potential. Thus, the overall objective of this project is to evaluate the relationship between follicular population and fertility in Holstein cows submitted to ovulation synchronization protocols for fixed time artificial insemination (TAI). This study will be conducted in the Fazenda São José (Tapiratiba - SP) and Instituto de Zootecnia de Nova Odessa (Nova Odessa - SP) from fertility evaluation of 200 Holstein cows in lactation. All animals will be submitted to the same protocol for TAI and will be evaluated by transrectal ultrasound exams in Day 4 of the protocol to evaluate follicular population and on Days 32 and 56 to do the diagnosis of pregnancy of the animals. The pregnancy rate will be evaluated according to the follicular population of females. The data will be analyzed by the procedure GLIMMIX of SAS®.