Changes in lipid composition and quality of boar semen during aging

Sperm lipids contain mainly phospholipids (about 70% of total lipids) and high contents of polyunsaturated fatty acid (more than 50% of total fatty acids in some species). The present study considered the changes of lipid composition and quality parameters in semen during the commercial breeding life of boars. Four classes of age ere established: pubertal, P (under 10 months of age); sexually mature, SM (from 14 to 19 months); adult, A (from 20 to 39 months) amd old boars, O (over 52 months). All quality parameters improved from P to SM, i.e. proportions of motile cells of cells with highest movement quality and of damaged cells. These observation were followed by changes in lipid and antioxidant compositions, i.e. the the content of vitamin E increased from P to SM and remained constant from A and O. The content of docosahexaenoic acido (DHA, n-3) decreased throughout the reproductive stages considered. Neverthless, the level of unsaturation was not dramatically changed as this loss was compensated by an increase of docosapentaenoic acid ( the n-6 analogue of DHA). On seminal plasma, the proportion of saturates in phospholipids decreased during ageing and that of polyunsaturates increased. We suggest that these ubsaturated fatty acids could be made available to spermatozoa as energy metabolites and/or to repair damages of plasma membranes in the ejaculates of older boars.