Evaluation of Methods for Determining In Vivo Digestion Coefficients for Adult Red Swamp Crayfish Procambarus clarkii

Abstract

AbstractAdult red swamp crayfish (Procambarus clarkii) were held in fecal collection chambers and fed common feedstuffs isosubstituted in experimental diets. Apparent dry matter digestibility (ADMD) and apparent crude protein digestibility (ACPD) coefficients were determined by the total collection and indicator (chromic oxide) methods. Feedstuffs tested were menhaden fish meal, soybean meal, alpha‐soy protein, casein, gelatin, wheat bran, rice bran, wheat gluten, shrimp meal, crab chitin, cellulose, squid meal, corn starch and diatomaceous sand. Rate of consumption of plant feedstuffs was generally higher than feedstuffs of animal origin. Consumption of fish meal and shrimp meal was low (0.59 and 0.44% body weightlday, respectively). Fecal chromium concentrations were lower than chromium concentrations of experimental diets and precluded calculation of realistic coefficients by the indicator method. Analysis of refused feed samples indicated that crayfish did not consume the indicator in the same proportion as the remainder of the diet; therefore, the total collection method was judged the better approach to determining digestion coefficients. ADMD and ACPD coefficients of plant feedstuffs were generally higher than coefficients determined for animal feedstuffs. ADMD coefficients indicated substantial carbohydrate digestion by crayfish.