Fatty acid and tocopherol composition of semen components in the rabbit

The aim of this study was to determine and compare the lipid composition and the tocopherol contents in the different components of rabbit semen: spermatozoa, seminal plasma and granules. Semen was collected via an artificial vagina from 16 rabbits. Semen collection was repeated in two subsequent weeks. Two ejaculates were obtained from each male on the same day. Individual ejaculates were pooled in 3 semen samples from 5-6 bucks each. Sperm concentration, viability and motility were measured. Granule concentration was also estimated. Seminal plasma was separated after centrifugation; spermatozoa and granules were separated by Percoll density gradient centrifugation. Lipid were extracted from semen components and separated by TLC; fatty acid composition of phospholipid was determined by GC on capillary column. The content of tocopherols in semen components was determined by HPLC. Semen quality was good and the mean values recorded were in agreement with standard reproductive performance of bucks. Phospholipid was the most important lipid class found in the different components of rabbit semen. The characteristic fatty acid composition of rabbit spermatozoa has been confirmed: polyunsaturates accounted for the major proportion of fatty acids and were mainly represented by C22:5n-6 (36%); n-3 polyunsaturates were present in very low proportion, and also the proportion of monounsaturates was low. The fatty acid composition of phospholipid in seminal plasma and granules showed a lower level of unsaturation and a greater proportion of oleic acid in comparison with the gamete composition. Of interest was the presence of consistent proportion of different n-6 polyunsaturates, from C18:2 to C22:5, in seminal plasma. Two main forms of tocopherols, alpha and delta, have been found in all components of rabbit semen, and spermatozoa were the preferential site of accumulation.