Effects of early weaning on fetal programming of gonadal development traits in Nelore females

• Grant number: 22/13791-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2022
• End date: November 30, 2023
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Guilherme Pugliesi
• Grantee: Leonardo Soares Locoselli
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 17/18937-0 - Earlier weaning of calves from Nellore cows and its effects on the fetal programming and on the produtive and reprodutive performance of the next progeny, AP.TEM

Abstract

The objective of this project is to evaluate the effects of early weaning (5 months) compared to conventional weaning (8 months) on fetal programming of characteristics associated with gonadal development of Nellore females. The main hypothesis to be tested is that heifers from cows that were weaned earlier have more antral follicle counts (AFC), serum concentrations of anti-Mullerian hormone (AMH) and greater efficiency in in vitro embryo production. For this, 57 heifers from primiparous and pluriparous Nellore cows submitted to early (n = 28; 150 days) or conventional (n = 29; 240 days) weaning will be used, which occurred around 2-3 months of gestation of these heifers. After completing 14-15 months of age, heifers will be evaluated by ultrasound to measure ovarian size and AFC determination and a blood sample will be collected to determine serum AMH concentrations. In addition, a subgroup of 24 heifers (n=6 in calving order of the mother and experimental group) will undergo follicular aspiration for later fertilization and in vitro embryo production. The amount and rate of viable oocytes, cleaved structures and blastocysts will be determined. Data will be analyzed by ANOVA and frequency test.