Dietary lipid enhancement of
broodstock reproductive performance and egg and larval quality in Atlantic
halibut (Hippoglossus hippoglossus)
C. Mazorra, M. Bruce, J. G. Bell, A. Davie, E.
Alorend, N. Jordan, J. Rees, N. Papanikos, M. Porter, N. Bromage
Aquaculture, 227(1-4): 21-33
Abstract:
Two series of experiments were conducted to assess
whether the trash fish-based diet traditionally used by the industry for
broodstock halibut could be replaced by a formulated pelleted feed and to
investigate the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid
(EPA), and arachidonic acid (AA) on halibut fecundity, blastomere morphology
and fertilisation and hatching rates.
In the first experiment, two formulated broodstock
feeds (one containing Krill meal and one supplemented with tuna orbital oil,
which provided higher dietary levels of DHA and AA), gave similar
performances (Relative fecundity 9557±3462 and 10,551±2166, fertilisation
rate 40.0±6.4% and 40.0±9.1%, respectively) to that of a fish fed a trash
fish-based diet (Relative fecundity 11,782±1873, fertilisation rate 41.0±4.0%).
In a second experiment, the spawning performance and egg quality of two
groups of broodstock maintained on two formulated diets, each containing
different levels of AA (1.8% and 0.4%) was compared over two successive
spawning seasons. The diet with the higher (1.8%) level of AA resulted in
significantly higher (p<0.05) fertilisation rates (59.0±5.8%),
blastomere morphology scores (14.2±0.4) and hatching rates (51.0±3.6%)
compared to those on the 0.4% AA diet (31.0±4.9%, 12.5±0.3 and 28.0±5.7%,
respectively). The eggs selectively accumulated DHA up to 30% of the total
fatty acids. DHA/EPA and EPA/AA ratios of 2 and 4 in the eggs respectively
were associated with improved egg and larval quality, similar to that
achieved by fish maintained on the trash fish-based diets.