Growth Performance and Tissue Fatty Acid Composition of Largemouth Bass Fed Diets Containing Fish Oil or Blends of Fish Oil and Soy-Derived Lipids

Abstract

Dietary fatty acid (FA) composition influences the composition of fish tissues to a greater or lesser extent depending on the proportion of saturated FAs (SFAs) and medium-chain (MC) polyunsaturated FAs (PUFAs) that the feed contains. Our purpose was to evaluate the growth performance and tissue composition of largemouth bass Micropterus salmoides that were fed diets containing soy-derived lipids modified to contain more SFAs and less MC-PUFAs. Triplicate tanks of largemouth bass (∼1.6 g) were fed diets containing fish oil (FO diet) or 50:50 blends of fish oil and low-18:3(n-3) soybean oil, hydrogenated soybean oil (HYD-SBO diet), or SFA-enriched soybean oil (SFA-SBO diet). After 10 weeks, production performance was unaffected by diet, and weight gain (mean ± SE = 518 ± 19%), feed conversion ratio (1.29 ± 0.03), specific growth rate (2.59 ± 0.04% of body weight/d), and feed intake (1.42 ± 0.03% of body weight/d) indicated that all diets were accepted and well utilized. Carcass FA composition changed to reflect the diet, but composition of largemouth bass that were fed the HYD-SBO and SFA-SBO feeds was not markedly different from that of fish given the FO feed. Fish oil can be spared without affecting production performance of juvenile largemouth bass; however, to minimize changes to tissue FA profile, soy lipids containing more SFAs and less MC-PUFAs may be most appropriate.

Received December 8, 2010; accepted February 7, 2011

ACKNOWLEDGMENTS

Our sincere thanks are extended to the Illinois Soybean Association for supporting this research project under Grant Number 09-ISA-35-409-3. We also thank Stephanie Block for providing technical and pricing information for the various soy oils tested. Finally, we are grateful to Archer Daniels Midland for providing the soy oils we evaluated, and we thank Omega Protein, Tate and Lyle, and Darling International for the donation of fish oil and other feedstuffs used in the experimental feeds.

Notes

^aOmega Protein, Inc., Houston, Texas.

^bArcher Daniels Midland, Decatur, Illinois.

^cTate and Lyle, Decatur, Illinois.

^dDarling International, Inc., Cleveland, Ohio.

^eFormulated to contain 25.000% L-ascorbyl-2-polyphosphate, 13.160% vitamin K, 12.500% inositol, 12.500% nicotinic acid, 7.500% riboflavin, 6.250% calcium pantothenate, 2.500% pyridoxine hydrochloride, 1.250% thiamine mononitrate, 1.000% vitamin A palmitate, 0.500% cyanocobalamin, 0.450% folic acid, 0.125% biotin, and 0.010% cholecalciferol in a cellulose base.

^fFormulated to contain 24.897% zinc oxide, 14.933% ferrous sulfate, 3.470% manganese oxide, 0.967% cupric carbonate, 0.262% potassium iodide, 0.060% sodium selenate, and 0.030% cobalt carbonate in a cellulose base.

^gValues represent least-squares means (±SE) of triplicate samples.

^aSaturated FAs (SFAs): sum of all FAs without double bonds.

^bMonounsaturated FAs (MUFAs): sum of all FAs with a single double bond.

^cPolyunsaturated FAs (PUFAs): sum of all FAs with two or more double bonds.

^dLong-chain PUFAs (LC-PUFAs): sum of all FAs with a chain length of 20 or more carbon atoms and with three or more double bonds.

^eMedium-chain PUFAs (MC-PUFAs): sum of all PUFAs with a chain length of 18 carbon atoms.

^aSaturated FAs (SFAs): sum of all FAs without double bonds; includes 13:0, 15:0, 17:0, 20:0, 21:0, 22:0, 23:0, and 24:0 in addition to individual reported SFAs.

^bMonounsaturated FAs (MUFAs): sum of all FAs with a single double bond; includes 14:1, 15:1, 17:1, 22:1(n-11), 22:1(n-9), and 24:1(n-9) in addition to individually reported MUFAs.

^cPolyunsaturated FAs (PUFAs): sum of all FAs with two or more double bonds; includes 16:2(n-4), 16:3(n-4), 18:3(n-6), 20:2(n-6), 20:3(n-6), 20:3(n-3), and 22:2 in addition to individually reported PUFAs.

^dLong-chain PUFAs (LC-PUFAs): sum of all FAs with a chain length of 20 or more carbon atoms and with three or more double bonds; includes 20:3(n-3) in addition to individually reported LC-PUFAs.

^eMedium-chain PUFAs (MC-PUFAs): sum of all PUFAs with a chain length of 18 carbon atoms; includes 18:3(n-6) and 18:3(n-4) in addition to individually reported MC-PUFAs.