Effects of fecal collection methods on estimation of digestibility of protein feedstuffs by winter flounder

An accurate method for estimating digestibility of nutrients is essential w hen developing diets suitable for aquaculture species. Two methods of fecal collection (stripping and sedimentation) were evaluated for estimating cru de protein and gross energy digestibility of three protein sources by juven ile (159 +/- 8.48 g) winter flounder Pleuronectes americanus in a 3 x 2 fac torial design experiment (protein x method) with three replicates of each d iet. Fish meal (FM), canola protein concentrate (CPC), and soybean meal (SB M) were the three protein sources and were each included as 15% of a marine fish diet. Chromic oxide (0.5% of dry matter) was added as an inert marker . Crude protein digestibilities determined for stripped feces were signific antly higher (P < 0.05) than for feces collected by sedimentation. Gross en ergy digestibilities based upon stripped fish were also higher (P < 0.05) t han those from the sedimentation method. No significant differences in dige stibility occurred among the diets containing the different protein sources (P < 0.05). Crude protein and gross energy digestibility in FM, CPC, and S BM were similar. The difference in digestibility using different fecal coll ection methods might be the result of uneven movement of chromic oxide thro ugh the digestive tract.