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

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 (similar to 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.