The effect of different concentrations of N-acetyl cysteine on liquefaction, quality and fertility of chilled semen in dromedary camel

Abstract

The objectives of the current study were to evaluate the effects of N-acetyl cysteine (NAC) on semen liquefaction and sperm quality during short-term preservation in dromedary camel. In experiment 1, 9 ejaculates from 3 bulls were diluted in the base extender with different concentrations of NAC (0, 6, 12, and 24 mM). The viscosity reduction was investigated at 5, 15, 30, and 120 min and 24 h post-dilution. In the second experiment, 15 ejaculates from 5 dromedary bulls were diluted with an extender containing 0, 6, and 12 mM of NAC, and viability, motility, and kinematics, as well as functional and DNA integrity of spermatozoa, were evaluated at 2, 12, 24, and 48 h of chilled storage at 5 °C. Experiment 3 evaluated the effect of adding NAC in the semen extender by carrying out 60 inseminations with 26- and 48-hour chilled semen. The pregnancy rates were compared between NAC and the control extender. Adding NAC to the extender resulted in a significant drop in viscosity compared to the raw and extended samples at all evaluation time points with a dose-dependent effect (P 0.05). At the same time, concentrations greater than 6 mM lowered viability, motility, and functionality of sperm from 12 h post-dilution (P < 0.05). Chilled sperm in the EXT+NAC 6 mM showed a marked improvement in DNA integrity status from 2 h post dilution onwards, with better motility and functional integrity at 48 h compared to the control (P < 0.05). Pregnancy rates with 26 h of chilled semen were similar between NAC-treated sperm and the control (33.33% vs. 38.09%, respectively; P > 0.05), corroborating the safety of NAC regarding its effect on sperm fertilizing capacity. In conclusion, adding NAC to the semen extender at concentrations of 6 mM assists with the liquefaction of dromedary semen without compromising sperm quality during subsequent storage in chilled status.