Effects of herbicide mixtures on the fertilizing capacity of bovine sperm

Herbicides are the most commonly used pesticide type worldwide. In Brazil, glyphosate-, dichlorophenoxyacetic acid (2,4-D)-, and atrazine-based pesticide formulations are intensively applied to crops, and mixtures of these compounds occur frequently in the environment. Owing to their proximity to these areas and management practices, bovines are exposed to these pesticide mixtures, and their impact on their health is unknown. In this study, we evaluated the in vitro effects of herbicide mixtures on bovine sperm. Semen from four bulls was prepared as a pool and divided into groups: control, dimethyl sulfoxide (DMSO), glyphosate (Gly; 50 µg/mL), 2,4-D (0.11 µg/mL), atrazine (Atz; 0.0107 µg/mL), Gly + 2,4-D (GD), Gly + Atz (GA), Atz+ 2,4-D (AD) and Gly + 2,4-D + Atz (GDA). Sperm cells were evaluated after 3 h of incubation with the different treatments at 37℃. Results showed that the Gly, 2,4-D, and AD groups decreased progressive motility, mean path velocity, and beat cross frequency compared to the control group. Similarly, Gly and 2,4-D reduced curvilinear and straight-line velocities, and 2,4-D affected the amplitude of lateral head displacement. Although no differences in reactive species levels were detected, an overall reduction in antioxidant capacity was observed. Membrane integrity, acrosome damage, and mitochondrial membrane potential results did not differ significantly among the groups. However, the mixture diminished sperm fertilization capacity in groups GD, AD, and GDA, when compared to the control. No effects appeared in the DMSO group. Herbicides showed distinct impacts on bovine sperm, emphasizing the importance of evaluating pesticide mixtures thoroughly.