"Replacement of fish meal with soybean meal in formulated diets for early juveniles of Cherax quadricarinatus"

GUTIÉRREZ, M. L.; RODRIGUEZ E. M.

Kuopio, Finland.

Simposio; 17th Symposium of International Association of Astacology; 2008

International Association of Astacology

Five isoproteic (35%) and isocaloric (10% lipids and 20% carbohydrates) diets were assayed on early juveniles (initial weight: 22.49 ± 0.083 mg, N=225) of the crayfish C. quadricarinatus. A first diet comprised only fish meal as protein source (D100), while the others incorporated soy meal as replacement of fish meal in a percentage (w/w) of 25, 50, 75 or 100% (diets D75, D50, D25 and D0, respectively). Survival, weight gain (WG) measured as ((Wax)/Wig) x 100, and specific growth rate (SGR) were determined. After 90 days, the content of protein and lipids was also determined in both the hepatopancreas and abdominal muscle of all surviving animals. Concerning mortality, no statistical differences were observed among experimental diets, although best survival was observed with D25. WG was higher in those diets with partial replacement with soy meal, in comparison to the diets having a single protein source (D100 and D0), yielding D0 the lowest values of both WG and SGR. Concerning organic reserves, no differences were observed among diets containing fish meal in any percentage, neither in hepatopancreas or muscle. However, D50 and D75 produced higher lipid levels in hepatopancreas than the remaining diets, while D25 and D50 showed the highest lipid levels in muscle. For culture purposes, the election of a diet with replacement of fish meal by soybean meal in a percentage ranging from 50 to 75 % would yield the best growing at the lowest cost, taking into account the high cost of fish meal.