Fig. 1

Changes in the total (TM) and progressive (PM) canine sperm motility during cold storage (5 °C) in extenders containing different levels of melatonin versus the controls. A two-way repeated-measures Analysis of Variance (ANOVA) statistical test was used to make a comparison between different levels of melatonin versus the control at different times. Pairwise comparisons with Least Significant Difference (LSD) confidence interval adjustments were carried out to examine the simple effects for the time and study groups. Negative Control (without Melatonin or DMSO), Positive Control (containing DMSO), M1 (containing 0.5 mM Melatonin), M2 (containing 1 mM Melatonin), and M3 (containing 2 mM Melatonin). All numbers are presented as mean’s ± SEM. The asterisks show a statistically significant difference (p ≤ 0.05) between the M2 group compared with the other groups at the specified time points