Spermatozoa undergo a significant transformation during the cryopreservation process, including oxidative stressors during dilution, cooling, equilibration, or freezing and thawing stages that postpone their motility and viability. When duck egg yolk is added to low-density lipoproteins (LDL), which has a considerable cryoprotective effect, the sperm is successfully protected from cold shock and the lipid-phase transition during the freeze-thaw process. The amino acid cysteine, on the other hand, functions as a precursor of intracellular glutathione (GSH). The purpose of the current study was to examine the effects of employing 10 percent LDL duck egg yolk, with or without cysteine, for Holstein bull spermatozoa and to use cryopreserved straws in fertility trials to verify the findings. According to experimental findings, 10mM cysteine applied to 10% LDL duck.