Comparison of Soy and Fish Oils in Practical Diets for Fingerling Walleyes

Abstract

AbstractA 63‐d feeding trial was conducted to compare growth and other performance variables of feed‐trained juvenile walleyes Sander vitreus fed an open‐formula diet containing 10% soy oil (SO) as a replacement for 11.75% Atlantic menhaden Brevoortia tyrannus oil that is used in the commercially manufactured walleye grower diet (WG). The SO diet was formulated to be identical to the WG formulation except for the oil. The feeds contained 46% crude protein and similar gross energy (SO: 1,121 J/g; WG: 1,192 J/g). Fish were stocked (209 fish; 5.1 g/L) into triplicate 1,000‐L tanks. Fish were fed 7% body weight/d during a 16‐h light period with in‐tank lighting. Juvenile walleyes were 157 d old, 124 ± 1.0 mm in total length (mean ± SE), and 24.4 ± 0.71 g at the start of the trial. Differences between treatment in relative growth, specific growth rate, survival, final mean length, and mean weight between treatments were not statistically significant. Although derived from a short‐term trial, the findings suggest that SO at 10% is a suitable replacement for nearly 12% marine fish oil in a feed for juvenile walleyes. In 2007, the cost of Atlantic menhaden oil in the WG formulation was 1.6‐fold greater (US.39/0.454 kg) than that of the SO (.29/0.454 kg) used in the diets.