The aim of the present study was to evaluate the cryoprotective effect of Laminaria japonic polysaccharide (LJP) on boar sperm. Semen samples were collected from seven mature Yorkshire boars once a week by the gloved hand technique and frozen-thawed in the extender with LJP added. Extender with LJP added at concentrations of 0.25, 0.5, 1.0, 1.5 and 2.0mg/mL to the extender and its effects on the quality of frozen-thawed boar sperm were assessed. Results showed: (i) sperm motility and plasma membrane integrity were greater in the extender containing 0.5 and 1.0mg/mL LJP, as compared to other groups (P<0.05); (ii) extender added 1.0mg/mL LJP showed the greatest plasma membrane and acrosomal integrity percentages in comparison with other groups (P<0.05); (iii) mitochondrial activity was significantly higher at the concentration of 0.5 and 1.0mg/mL LJP than those of other groups (P<0.05); (iv) in terms of biochemical assessments, 0.5 and 1.0mg/mL LJP improved SOD (superoxide dismutase) and CAT (catalase) concentrations, compared to other groups (P<0.05). However, no significant difference was found in GSH-Px (glutathione peroxidase) concentration when supplemented with LJP. Interestingly, LJP exhibited a dose-related response and the lesser concentration represented greater protective effects. It is also important to note that 1.0mg/mL LJP provides for an enhanced cryoprotective effect in boar semen.
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