Analysis of chromatin accessibility in cryopreserved muscle tissue of Bos indicus subjected to early supplementation

• Grant number: 25/16197-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Guilherme Luis Pereira
• Grantee: Laura Silveira
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 23/10842-0 - Effect of concentrate diet on epigenetic marks of Longissimus thoracis muscle tissue of Nellore cattle and their relationships with carcass aspects and meat quality, AP.R

Abstract

Brazil has the largest commercial cattle herd in the world and stands out as the largest beef exporter, with the Nelore breed accounting for approximately 80% of the national herd. Despite advantages such as hardiness and adaptation to the tropical climate, zebu breeds generally mature later physiologically and have a lower capacity for intramuscular fat deposition and firmer meat compared to taurine breeds. However, in addition to this preponderant genetic factor, appropriate nutritional management at different stages of development can contribute to accelerating physiological maturity, as well as fat deposition and cut quality. Among some strategies, creep-feeding has proven effective in improving performance during the breeding period and, in some cases, in promoting physiological adaptations that can impact carcass composition and finishing time, possibly mediated by epigenetic mechanisms. Initially, using the Omni-ATAC-Seq technique optimized for this purpose, this study aims to evaluate the effect of creep-feeding on chromatin accessibility in the Longissimus thoracis muscle of Nellore calves at the end of the breeding period, as an indication of epigenetic adaptation. For this purpose, 40 contemporary cows of the same calving order that raised male calves were initially used. Of these, at 60 days of age, 20 cow-calf pairs were allocated to paddocks with creep-feeding feeders and 20 remained in paddocks without feeders. Using skeletal muscle tissue collected at 234 days (weaning of both groups), the Omni-ATAC-Seq technique for analyzing chromatin architecture modifications will be optimized. Following sequencing, genomic data will be used to identify differentially accessible chromatin regions between animals that received and did not receive supplementation, enabling the identification of chromatin modifications that may be associated with greater or lesser accessibility of genes important for muscle energy metabolism and adipose tissue. The data will also enable the exploration of regulatory motifs and genes associated with the observed epigenetic changes. The results are expected to reveal molecular mechanisms associated with the response to early nutritional management, providing insights for the development of more efficient nutritional strategies aimed at improving beef productivity and quality. The project also aims to generate scientific publications and contribute to the valorization of Nelore beef through practices based on molecular evidence. (AU)