Quality of eggs and spermatozoa of rainbow trout fed an n-3 essential fatty acid-deficient diet and its effects on the lipid and fatty acid components of eggs, semen and livers

The effect of an n-3 essential fatty acid (EFA)-deficient diet on spawning and on the lipid and fatty acid contents of eggs, semen and livers of rainb ow trout Oncorhynchus mykiss was investigated. Fish were split into two gro ups and fed either of two diets for a period of 4 months prior to the start of the spawning season. The control group was fed a commercial diet, conta ining n-3 EFA, whereas the experimental group was fed an n-3 EFA-deficient diet. Fish were 3 years old at the time of spawning. Eggs and semen were st ripped off five females and five males from each diet group and cross-ferti lized. Two of the five males fed the deficient diet showed a lower sperm mo tility, resulting in slightly lower mean hatching rates when crossed with e ggs of either group. Higher lipid contents in the EFA-deficient diet were r eflected in the egg and semen lipid contents, whereas the lipid contents of male livers of both diet groups were higher than those of female livers. I n livers and eggs, the main polar lipid was phosphatidylcholine accompanied by phosphatidylethanolamine in sperm polar lipids. The non-polar lipids of eggs were mainly triacylglycerols but in livers and semen, free fatty acid s and free sterols were more abundant. Essential fatty acids, namely n-3 hi ghly unsaturated fatty acids and linolenic acid, were generally lower in eg gs, semen and livers sampled from the EFA-deficient diet group. These resul ts indicate that the fertilization, eyed and hatching rates obtained from c rossings with males fed the EFA-deficient diet were slightly lower because of the dietary effect on sperm motility. Moreover, lipids of eggs, semen an d livers of male and female rainbow trout were influenced greatly by their dietary availability.