Fig. 2

Changes in the canine sperm viability and abnormal morphology during cold storage (5 °C) in the extenders containing different levels of melatonin versus the controls. A two-way repeated-measures ANOVA statistical test was used to make a comparison between treatment groups at different times. Pairwise comparisons with LSD confidence interval adjustments were carried out to examine the simple effects for the time and study groups. The different numbers and letters in the bar superscripts indicate a statistically significant difference (P ≤ 0.05) between the time points in each study group and between the study groups at each time point, respectively. The asterisk shows a statistically significant difference (P ≤ 0.05) between time points. 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), ns, non-significant. All numbers are presented as means±SEM