Comparison of Traditional and Fermented Soybean Meals as Alternatives to Fish Meal in Hybrid Striped Bass Feeds

Soybean meal is one of the most common fish meal alternatives used in aquafeeds because of its high protein density, favorable amino acid profile, comparatively low price, and widespread availability. However, palatability issues and antinutritional factors limit soybean meal inclusion, particularly in feeds for carnivorous fishes. Various processing strategies, including fermentation, may offer some advantage in terms of reducing or eliminating antinutritional factors while enhancing protein content, improving protein absorption rate, and feed intake. Accordingly, we assessed production performance of juvenile hybrid Striped Bass (White Bass Morone chrysops x Striped Bass M. saxatilis) fed diets containing 30% menhaden fish meal, or reduced or fish-meal-free feeds (0, 5, or 10% fish meal) containing traditional soybean meal (47.5% crude protein) or PepSoyGen fermented soybean meal (52.0% crude protein) as the principal sources of dietary protein. Each dietary treatment was fed to quadruplicate tanks of fish (10 fish/tank; average individual weight = 18.1 +/- 0.2g [mean +/- SE], n = 4) in a recirculation system for 8 weeks. Production performance tended to decline among fish fed diets containing less than 10% fish meal; however, this effect was less overt among those fed the fermented soybean meal-based feeds. At each level of fish meal replacement, fish fed the fermented soybean meal treatment outgrew those fed the corresponding traditional soybean meal feed, though differences at the 5% fish meal level were not statistically significant. Fermentation appears to increase the acceptability and biological value of soybean meal in hybrid Striped Bass feeds, and PepSoyGen shows promise as a fish meal alternative for aquafeeds for carnivorous fishes. Received October 19, 2012; accepted December 1, 2012