Effects Of Phytase On Apparent Digestibility Of Nutrient And Digestive Enzyme Activities Of Rainbow Trout (Oncorhynchus Mykiss Walbaum)

A feeding experiment was conducted to investigate the effects of microbioal phytase pretreatment of soybean meal and phytase coating in diets on apparent digestibility coefficients (ADC) of nutrient material and digestive enzyme in digestive tract of rainbow trout. Microbioal phytase was added in soybean diets with two methods and different levels. The results can provide the data and theory reference for phytase widely used in diets of cold-water fishes.Rainbow trout was fed the diets containing phytase-sprayed and phytase-pretreated soybean meal with different phytase levels, and investigate the effects of microbioal phytase on apparent digestibility coefficients of nutrient material. The spraying experiment results showed: the ADC of dry matter and crude protein was significantly influenced by sparying phytase (P<0.05). In 3000U/kg group, the ADC of dry matter was the highest and the ADC of crude protein was the highest in 1500U/kg group. However, there was negative effect of phytase on the ADC of crude fat, but no significant differences were found (P>0.05). The ADC of Ca and P also was significantly improved with dietary phytase supplementation (P<0.05), and the ADC of Ca and P had the highest value in 2500U/kg group. Also the ADC of microelement was significantly improved with dietary phytase supplementation (P<0.05). In summary, about 2500U/kg diet phytase should be an optimal level by spraying method. The preteatment experiment results showed: the ADC of crude fat, dry matter, P, Mg, Mn, Zn and Cu were significantly improved for the diet supplementation with phytase (P<0.05). But no significant difference was seen among 500～1500U/kg groups (P>0.05). The ADC of Ca and Fe was higher than the control group, but there was no significant difference found (P>0.05). There was negative effect of phytase on the ADC of crude fat with no significant differences found (P>0.05). In summary, about 500U/kg diet phytase should be an optimal level by pretreatment method. Comparing with two methods, phytase-pretreated method was better than sprayed method.Rainbow trout was fed the diets containing phytase-sprayed and phytase-pretreated soybean meal with different phytase levels, to investigate the effects of microbioal phytase on digestive enzyme in fish digestive tract fed soybean meal-based diets. The spraying experiment results showed: protease activity in stomach and hepatopancreas was slightly improved by phytase spraying in diets, but there was no significant difference found (P>0.05). Protease activity in intestine was improved significantly in 2000U/kg group (P<0.05). The amylase activity in stomach and intestine was improved significantly by phytase spraying (P<0.05), but there was no significant effect in hepatopancreas (P>0.05). The lipase activity in stomach and hepatopancreas was significantly reduced by phytase spraying (P<0.05), but there was no significant effect in intestine (P>0.05). The pretreatment experiment results showed: The protease activity in stomach was improved by phytase pretreatment in diets, but no significant differences were found (P>0.05). The amylase activity in stomach, intestine and hepatopancreas was slightly improved by phytase pretreatment in diets (P>0.05). The lipase activity in stomach was significantly reduced by phytase pretreatment (P<0.05), but there was no significant effect in intestine and hepatopancreas (P>0.05).