Plant-Based Lipid Blends Can Completely Replace Menhaden Fish Oil in Female White Bass Broodstock Diets without Impacting Embryonic or Larval Survival

The n-3 long chain polyunsaturated fatty acids (LC-PUFA) found in marine oils are essential for maximizing ova quality and embryonic survival of many finfish.  However, larval survival is often independent of ova n-3 LC-PUFA content, and may depend on the presence of other nutrients (i.e., saturated fatty acids, SFA; or C₁₈ PUFA) during the endogenous feeding period.  Accordingly, we monitored white bass larval survival throughout the endogenous feeding period after feeding female white bass broodstock diets with LC-PUFA (as 22:6n-3; DHA) concentrations equivalent to fish oil but varying levels of SFA and C₁₈ PUFA.

Female white bass (376 ± 3.5 g; mean ± standard error) were stocked into a recirculation system and fed diets, 43% protein and 16% crude lipid, containing flax (source of C₁₈ PUFA) & DHA, coconut (source of SFA) & DHA, or fish oils as the primary dietary lipid source for 5 months.  Ova were collected by manual stripping and fertilized using white bass semen.  Egg viability, fertilization and hatch were assessed, and larval survival and fatty acid profile were monitored through 5 days post hatch (DPH).

Ova fatty acid composition largely mirrored maternal dietary intake with the exception of broodstock fed the coconut & DHA diet whose ova did not reflect elevated dietary intake of SFA.  Embryonic (55.3 ± 6.7%) and 5 DPH larval (13.4 ± 2.5%) survival estimates were similar among all dietary treatments despite 5 DPH larvae produced by the flax oil-fed broodstock having elevated whole body C₁₈ PUFA concentrations.

These data support the use of SFA and/or PUFA-rich plant oils supplemented with algal DHA as alternatives to fish oil for use in maternal white bass broodstock diets.  The plant-based lipid blends enable broodstock to produce ova with the n-3 LC-PUFA needed for embryonic survival while reducing dependence on marine-derived feedstuffs.  Additional research is needed to identify nutrients necessary to further improve larval survival during early development.