Effects of feeding tuna oil on the lipid composition of pig spermatozoa and in vitro characteristics of semen

The aim of the present study was to characterize the effects of feeding tuna oil on the lipid and fatty acid composition of boar spermatozoa and to relate changes in composition to boar semen characteristics. Ten boars were paired by age and allocated to one of two diets (five boars per diet). The diets, which were offered for 6 weeks, consisted of a basal diet that was either unsupplemented or supplemented with 30 g tuna oil kg(-1) diet. Adding tuna oil to the diet increased the ether extract concentration of the diets fed from 65 to 92 g kg(-1) dry matter and supplied 10.5 g long chain polyunsaturated (n-3) fatty acids per 100 g total fatty acids. There were no changes in semen fatty acid composition after 3 weeks of feeding tuna oil. However, after 5 and 6 weeks, the proportions (g per 100 g total fatty acids) of 22:6(n-3) in sperm phospholipid fatty acids were increased from 34.5 to 42.9 g by feeding tuna oil and 22:5(n-6) decreased from 29.8 to 17.9 g. No changes were observed in other sperm lipids or seminal plasma phospholipids as a result of the diets fed. Feeding tuna oil increased the proportion of spermatozoa with progressive motility and with a normal acrosome score and reduced the proportion of spermatozoa with abnormal morphologies.