Replacing fish meal with increasing levels of meat and bone meal, soybean meal and corn gluten meal, in diets of juvenile bluegill, Lepomis macrochirus

A 60-day study was conducted to determine the response of juvenile bluegill Lepomis macrochirus to seven experimental diets, formulated using a blend of alternative protein sources as a replacement for fish meal. Adequate levels (digestible basis) of energy, protein and amino acids were maintained in diets 1-6, whereas slightly lower protein and energy levels were provided in diet 7. Feed cost per tonne ranged from $ 798.9 (diet 1, 550gKg-1 fish meal) to $ 515.8 (diet 6, 0gkg-1 fish meal), or to $ 507.2 (diet 7, 0gKg-1 fish meal). Three commercial diets were included in the study as reference diets: a high-energy and a low-energy trout diet, as well as a catfish diet. Quintuplicate bluegill groups (similar to 22g, n=10 fish group-1) were fed the experimental diets twice daily to apparent satiation. No major differences in feed consumption, feed efficiency and growth rates were detected among the bluegill groups fed the experimental diets. Trout diets generally produced higher fish fat deposition, whereas the catfish diet produced a poorer fish growth rate relative to the experimental diets. Under the reported conditions, results indicate diet 6, comprising predominantly soybean meal and porcine meat and bone meal, to be the most economical diet for juvenile bluegill.