Influence of Organic Fertilizer Source on Fatty Acid Composition of Zooplankton and Sunshine Bass Fingerlings

Abstract

We evaluated the influence of three organic fertilizers—cottonseed meal, ground rice bran, and ground flaxseed—on the fatty acid composition of zooplankton and fingerling sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis ). Flaxseed contains about 10‐fold greater lipid and percent α‐linolenic acid (18:3[n‐3]); values relative to the other two organic fertilizers. Five 0.04‐ha nursery ponds were randomly selected per treatment; 5 d before fish stocking (4 d posthatch; 150,000 fish/ha) and again at day 20 poststocking, ponds were individually fertilized at a rate of 350 kg/ha. After 27 d of culture, zooplankton in the flaxseed treatment contained significantly more 18:3(n‐3) than those in the other fertilizer treatments (10.5% versus ∼7.0%). Likewise, after 40 d of culture, sunshine bass fingerlings reared in ponds fertilized with flaxseed possessed almost twofold higher 18:3(n‐3) (10.7%) than those reared in rice bran (4.7%) and cottonseed (5.8%) treatment ponds. Fish reared in cottonseed meal ponds, however, possessed the highest mean weight (8.2 g versus 6.0 g for flaxseed ponds and 4.8 g for rice bran ponds). We provide evidence that fatty acid composition of organic fertilizers, specifically 18:3(n‐3), significantly influences fatty acid composition of resident zooplankton and sunshine bass fingerlings in nursery ponds.