Etiology of sperm DNA damage in Bos taurus and Bos indicus bulls: investigating the impacts of climatic factors

• Grant number: 24/22550-7
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2025
• End date: June 30, 2028
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Marcilio Nichi
• Grantee: Marcilio Nichi
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: André Maciel Crespilho ; Mayra Elena Ortiz D' Avila Assumpcao

Abstract

Brazil's global prominence in bovine production is the result of a combination of factors, including the availability of land, water, and sunlight, a herd predominantly derived from zebu breeds adapted to Brazilian conditions, and advancements in technologies aimed at production in tropical environments. However, due to climate change, the country is experiencing increasingly hot and dry conditions, intensifying heat stress in animals and presenting new challenges to livestock farming, particularly during the breeding season, which occurs in the hottest months of the year. The etiology of sperm DNA damage involves complex mechanisms with direct implications for fertility. These issues can be exacerbated in tropical environments due to heat stress, which directly affects sperm quality. Considering the current climatic scenario and the importance of taurine cattle in enhancing the genetic and productive potential of national herds, there is a critical need to understand the factors contributing to reduced sperm production and quality during the summer in cattle raised in Brazil. We hypothesize that taurine bulls are more susceptible to seasonal climate changes between summer and winter, exhibiting greater DNA damage in the summer, with the etiology of this damage linked to issues in protamination, failures in apoptotic mechanisms, or oxidative damage. Therefore, the objective of this study will be to evaluate sperm function, oxidative status, and sperm DNA integrity in taurine (angus) and zebu (nelore) bulls raised in Brazil, with samples collected during the summer and winter. (AU)