Physiological and reproductive parameters of 14- to 16-month old Bos indicus heifers subjected to different circulating concentrations of progesterone and different ovulation induction protocols

• Grant number: 21/09904-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): August 01, 2022
• Effective date (End): August 31, 2024
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Roberto Sartori Filho
• Grantee: Rodrigo Lemos Olivieri Rodrigues Alves
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 18/03798-7 - Studies on ovarian and uterine physiology and improvement of Assisted Reproduction Technologies to increase reproductive efficiency in cattle, AP.TEM

Abstract

The animal category of heifers presents the greatest genetic potential within bovine herds. Recently, interest in reducing the age to puberty and first calving has been awakened, in order to increase the productive life of females on farms and increase the economic benefits to production systems. The Nelore breed makes up most of the national beef cattle herd, and the use of younger heifers, between 14 and 16 months of age, is constantly increasing. Therefore, it is very important to understand the physiological events that underlie the reproduction of this animal category and, based on that, develop strategies aiming to reduce age to puberty, through the use of optimized hormonal protocols. Thus, the present proposal aims to evaluate, in this category, the effects of different circulating concentrations of progesterone (P4) and different ovulation induction protocols on physiological and reproductive parameters. Thus, four experiments will be performed, the first two being related to the effects of different concentrations of P4 on ovarian dynamics and hormonal profile; and the last two refer to the effects of using hormonal protocols to induce ovulation at the uterine and embryonic levels, in addition to the results on fertility and pregnancy loss. As an experiment that encompasses from basic physiological principles to hormonal protocols applied to the reality of the field, this proposal has great value, both scientific and practical, bringing new information to science and, for producers, useful tools to make decisions. (AU)