Influences of dietary n-3 long-chain PUFA on body concentrations of 20:5n-3, 22:5n-3, and 22:6n-3 in the larvae of a marine teleost fish from Australian waters, the striped trumpeter (Latris lineata).

Abstract

We determined the effect of dietary long-chain (> or = C20) PUFA (LC-PUFA), 20:5n-3 and 22:6n-3, on larval striped trumpeter (Latris lineata) biochemistry through early development and during live feeding with rotifers (Brachionus plicatilis). Rotifers were enriched using seven experimental emulsions formulated with increasing concentrations of n-3 LC-PUFA, mainly 20:5n-3 and 22:6n-3. Enriched rotifer n-3 LC-PUFA concentrations ranged from 10-30 mg/g dry matter. Enriched rotifers were fed to striped trumpeter larvae from 5 to 18 d post-hatch (dph) in a short-term experiment to minimize gross deficiency symptoms such as poor survival that could confound results. No relationships were observed between larval growth or survival with dietary n-3 LC-PUFA at 18 dph. The larval FA profiles generally reflected those of the rotifer diet, and significant positive regressions were observed between most dietary and larval FA at 10, 14, and 18 dph. The major exception observed was an inverse relationship between dietary and larval 22:5n-3. The presence of 22:5n-3 in elevated amounts when dietary 22:6n-3 was depressed suggests that elongation of 20:5n-3 may be occurring in an attempt to raise body concentrations of 22:6n-3. We hypothesize that accumulation of 22:5n-3 might be an early indicator of 22:6n-3 deficiency in larval fish that precedes a reduction in growth or survival. A possible role of 22:5n-3 as a biochemical surrogate for 22:6n-3 is discussed.