Influence of body energy reserves on the environment of the uterotubal junction and the anterior uterine horn portion of Nellore cows

• Grant number: 23/02746-1
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2024
• End date: May 31, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Juliano Coelho da Silveira
• Grantee: Schaienni Fontoura Saldanha
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 21/06645-0 - Extracellular vesicles as a platform for diagnostic and manipulation of the in vitro embryo production system: the next generation in animal reproduction, AP.JP2

Abstract

Beef production efficiency and reproductive system are directly influenced by nutritional factors. The factors that regulate ovarian function, embryonic quality, and the establishment of the pregnancy can be affected by energy level and body condition. During the period of pre-implantation, the embryo migrates from the oviduct to the uterus in cattle. At this time, about 40% of embryonic losses occur probably due to the complex biochemical interactions between the conceptus and the endometrium. Extracellular vesicles (EVs) have been linked to the exchange of information between the maternal environment and the conceptus. EVs use extracellular fluids to diffuse and carry bioactive molecules such as miRNAs capable of modulating decisive events for the success of embryonic implantation and consequent pregnancy success. Therefore, we hypothesize that the high body energy reserve modulates: 1) the content of EVs present in the fluid from the uterotubal junction (UTJ) and the anterior portion of the uterine horn (ANT) and; 2) endometrial cells transcripts from UTJ and ANT, reducing the quality of the early embryonic development environment. Thus, the aim is to evaluate the effects of the body's energy reserve in the UTJ and ANT environment. For this, Nellore cows from the same herd were submitted to different nutritional plans to maintain (MBER group) or elevate (HBER group) their body energy reserve. At the end of the feedlot period, animals were submitted to estrous synchronization, artificial insemination and were slaughtered approximately 120 hours after ovulation induction. The reproductive tracts were collected and the ipsilateral horns to the corpus luteum were used to collect samples from the UTJ and ANT. These portions were washed with saline solution and endometrial tissue was collected. EVs were isolated from the collected fluid to evaluate the miRNA content and morphological characteristics. The miRNA and mRNA profiles of the endometrial cells collected will be analyzed. The results of this project will contribute to increasing our knowledge about the impact of the body energy reserve in the environment of early embryonic development in cattle.