Endocrine and metabolic basis of fertility impairment in aged embryo donor mares

• Grant number: 25/10941-4
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: November 05, 2025
• End date: November 04, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Cezinande de Meira
• Grantee: Giovana Siqueira Camargo
• Supervisor: Yatta Linhares Boakari
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: Texas A&M University, United States
• Associated to the scholarship: 22/14517-4 - Effect of sexing, conditioning and vitrification biotechniques of pre-implantation equine embryos produced in vivo on embryo viability, BP.DR

Abstract

Aged mares face multifactorial declines in fertility, ranging from reduced oocyte quality to changes in the uterine environment, negatively impacting fertilization rates and embryo recovery. Metabolic disorders compromise not only circulatory homeostasis but also endocrine balance, disrupting hormonal profiles and reproductive functions. The objective of this project will be investigate the relationship between the presence of metabolic disorders and their effects on hormonal and molecular activities, proteins, and metabolites, to identify the impacts on the fertility of aged embryo donor mares and enable reproductive strategies for these females. Fourteen mares between 15-20 years old were monitored across five reproductive cycles through follicular dynamics, with daily blood and plasma sampling collection, as well as reproductive history. The mares were divided into two groups: control and metabolic (Equine Metabolic Syndrome and/or Pituitary Pars Intermedia Dysfunction). Follicular fluid was collected at two time points: aspiration for ablation to reset the follicular wave (M0), and a second aspiration when the largest growing follicle reached between 23 and 25 mm (M1). Within moment M1, follicular fluid samples were categorized into two groups: large follicles (>23-25 mm) and a pool of smaller follicles. Plasma (N=14) metabolomic analyses will be processed at the Comparative Reproductive Laboratory at Texas A&M University. To complement the research data, hormonal assays of the follicular fluids (N=42) will be conducted at the Bet Laboratories in Lexington-KY-USA The project is a collaboration between UNESP (Brazil) and Texas A&M University (United States), funded by FAPESP, with the aim of fostering future research partnerships.