EFFECT OF CARBOXYMETHYLCELLULOSE, ALPHA-STARCH, AND WHEAT GLUTEN INCORPORATED IN DIETS AS BINDERS ON GROWTH, FEED-EFFICIENCY, AND DIGESTIVE ENZYME-ACTIVITY OF FINGERLING JAPANESE FLOUNDER

A feeding experiment was conducted to examine the effect of several ingredients incorporated in diets as binders on the growth, feed efficiency, and digestive enzymes' activities of fingerling Japanese flounder Paralichthys olivaceus. Carboxymethylcellulose (CMC), gelatinized potato starch (a-starch), and wheat gluten were separately incorporated in flounder diets as binders at the 5% level. These diets were fed to flounder with an initial mean weight of 15 g for 4 weeks at 20 degrees C. Weight gain, feed efficiency, and protein retention of the fish fed a diet containing CMC were significantly inferior to those of the fish fed diets containing alpha-starch or wheat gluten. Apparent digestibility of protein in the diet containing CMC was also significantly lower than the diet containing wheat gluten. After the 4-week feeding trial, proteolitic and lipolitic enzyme activities were measured with the homogenates of stomach or intestine. Proteolitic enzymes' activities such as pepsin-like and trypsin-like were lower in the fish fed the diet containing CMC than those in the fish fed the diets containing alpha-starch or wheat gluten, and especially trypsin-like activities at 4 to 12 hours after feeding were significantly lower. These results suggest that alpha-starch and wheat gluten are suitable as binders for fingerling flounder diets compared with CMC because CMC inhibits the proteolitic enzymes' activities in digestive tracts.