Effect of Dietary Supplementation with Cod Liver Oil on Cold Shock and Freezability of Boar Semen

Contents
The effect of dietary supplementation with cod liver oil (CLO), which is rich in n-3 polyunsaturated fatty acids (PUFAs), on resistance to cold shock and on freezability of boar semen was investigated. Ejaculates from 29 fertile Norwegian Landrace boars, randomly divided into control (n = 15) and CLO-group (n = 14), were frozen before and after a 12 week period of daily oil supplementation. Before each freezing, semen samples were taken to determine the fatty acid composition of the spermatozoa. Docosahexaenoic acid (22 : 6n-3; DHA) was the major fatty acid in total lipids. The n-3 fatty acid DHA increased in the CLO-group from 25.5 to 32.1% at the expense of the n-6 docosapentaenoic acid (22 : 5n-6), which decreased from 11.3 to 4.2% (p < 0.0001). The concentration of these fatty acids were unchanged in the control group. There was also a significant decrease of other PUFAs in the CLO-group (p < 0.05). Eicosapentaenoic acid (20 : 5n-3) was not found in any sample. At four different steps of the preservation process (30, 15, 5°C and after freezing/thawing) both motility and acrosome integrity were assessed. No significant differences were found either within or between the groups at any of the steps. In conclusion, CLO-supplementation alters the lipid composition of the membranes of boar spermatozoa, however, this does not seem to have any beneficial effect on cold shock and freezability of boar semen.