Effect of addition of nicotinamide and cholesterol before cryopreservation on the quality of sheep semen and its fertilizing potential.

This study evaluated the effects of nicotinamide and cholesterol, alone or in combination, added to a Tris-egg yolk extender on the post-thaw quality and fertilizing potential of ram sperm. Ejaculates from six rams were cryopreserved under different treatments (control, cholesterol, NAM 30 µM, NAM 60 µM, NAM 30 µM + 2 mg cholesterol, and NAM 60 µM + 2 mg cholesterol) and analyzed after thawing. Sperm traits, including kinematics, morphology, plasma membrane and acrosome integrity, mitochondrial activity, DNA fragmentation, and oxidative stress, were not significantly affected by the treatments. However, NAM at 30 µM, NAM at 60 µM, and the combination of NAM 30 µM with 2 mg cholesterol showed higher embryo cleavage rates compared with the control. In conclusion, supplementation with NAM, either alone or in combination with cholesterol, does not affect most post-thaw sperm quality traits, although some treatments were associated with higher cleavage rates.