Effects Of Antinutritional Factors In Soybean On The Growth Performance And Digestive Physiology Of Japanese Flounder, Paralichthys Olivaceus

Feeding experiments were conducted to evaluate the effects of antinutritional factors in soybean–phytic acid, stachyose, raffinose and genistein on feed intake, digestive enzyme activities, apparent digestibility, intestinal histology and the growth performance of Japanese flounder, Paralichthys olivaceus. Results of the present study are presented as follows:1. Feed intake significantly increased with increasing dietary phytic acid (P<0.05). There were no significant differences in both amylase activities and protease activities of liver, intestine and stomach among dietary treatments except pepsin (P>0.05). The pepsin activities in fish fed the diets with phytic acid (59.47, 61.27 and 64.82 U/mg protein) were significantly lower than that of the control group (79.34 U/mg protein) (P<0.05). With increasing dietary phytic acid, the apparent digestibility coefficient of dry matter and protein significantly decreased (P<0.05). The fish fed the diets with phytic acid induced histopathological changes in the intestine. Hyperplasia of intestine epithelia was observed and lamina propria was separated from intestine epithelia in fish fed the diets with phytic acid. The lamina propria became thin, and the amount of blood vessels, nerves and lymphatic vessels in the intestine villi was obviousely decreased compared with the control group. No significant differences in survival were found among dietary treatments (P>0.05). Specific growth rate decreased with increasing dietary phytic acid, but no significant differences were observed among dietary treatments (P>0.05). Dietary phytic acid significantly reduced feed conversion efficiency, protein efficiency ratio and net protein utilization (P<0.05). The feed conversion efficiency (74.0, 73.7 and 69.2%) in fish fed the...