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
R. Vassallo-Agius, T. Watanabe, G. Yoshizaki, S.
Satoh, Y. Takeuchi-2001
Fisheries Science, 67(5): 818-827
(from Current Contents)
Abstract:
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 rainbow trout Oncorhynchus mykiss was
investigated. Fish were split into two groups 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, containing 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 stripped off five females and
five males from each diet group and cross-fertilized. Two of the five males
fed the deficient diet showed a lower sperm motility, resulting in slightly
lower mean hatching rates when crossed with eggs of either group. Higher
lipid contents in the EFA-deficient diet were reflected 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. In 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 acids and free sterols
were more abundant. Essential fatty acids, namely n-3 highly unsaturated
fatty acids and linolenic acid, were generally lower in eggs, semen and
livers sampled from the EFA-deficient diet group. These results indicate
that the fertilization, eyed and hatching rates obtained from crossings with
males fed the EFA-deficient diet were slightly lower because of the dietary
effect on sperm motility. Moreover, lipids of eggs, semen and livers of male
and female rainbow trout were influenced greatly by their dietary
availability.
(Tokyo Univ Fisheries, Dept Aquat Biosci, Tokyo
1088477, Japan, e-mail of T. Watanabe: watana@tokyo-u-fish.ac.jp)