Does Low-Level Mycotoxin Exposure Compromise Bovine Reproductive Cell Biology?

Background: Mycotoxins are toxic secondary metabolites produced by fungi which can be detrimental to the health of livestock. Although cattle are quite tolerant to mycotoxins, potential effects of exposure on reproductive cell function at low levels are unknown. This in vitro study aimed to determine the impact of combined, low-level mycotoxin exposure on bovine spermatozoa using the most frequently isolated mycotoxins worldwide; Deoxynivalenol (DON), Deepoxy-Deoxynivalenol (DOM-1) and Zearalenone (ZEA). Methods: Semen straws from two bulls were processed and spermatozoa (10x106 sperm/ml) were exposed to T1 (DON 10ng/ml, DOM-1 60ng/ml and ZEA 0.1ng/ml), or T2 (DON 20ng/ml, DOM-1 120ng/ml and ZEA 0.5ng/ml) for 8h, mimicking the time spent by the spermatozoa in the reproductive tract before fertilisation (i.e., following artificial insemination or natural mating in cattle). Mycotoxin concentrations reflect levels detected in clinically healthy cows in either follicular fluid or blood. A control solvent (0.5% methanol) was also included. A fluorescence assay was performed to simultaneously assess membrane damage (Hoechst 33342 and DRAQ-7), acrosome integrity (FITC-PSA) and mitochondrial membrane potential (JC-1) via fluorescence microscopy and Zeiss ZEN software. Data was analysed by ANOVA. Results: Following 3 replicates, membrane damage (Control 65.28 ± 6.27, T1 66.72 ± 9.87, T2 66.70 ± 10.18) acrosome damage (Control 40.01 ± 5.82, T1 36.34 ± 9.57, T2 35.97 ± 4.46) and low mitochondrial membrane potential (Control 46.70 ± 20.64, T1 40.49 ± 4.02, T2 46.88 ± 22.28) were not significantly affected by the treatment groups after 8 h exposure (p > 0.05). Conclusion: Overall, this study suggests low-level mycotoxin exposure does not significantly compromise sperm quality during a time period that reflects transport in the female reproductive tract.