Effect of replacement of fish meal with soybean meal plus supplementary enzymes on growth performance, survival rate and apparent digestibility of rainbow trout (Oncorhynchus mykiss)

This study was carried out to measure the effects of a supplementary multi enzyme on growth performance , survival rate and apparent protein digestibility of rainbow trout fed some diets containing different amounts of soy bean meal. Five exprimental diets with replacement of 25, 50, 75 and 100 percent of fish meal protein by soy bean meal protein were made and 0, 500 and 1000 ppm dosages of supplementary multi enzyme had used in each of them. By the means a diet with fish meal as the only source of protein has used as the control. So this study had 13 treatments. The trouts in 89.40±4.01 gr mean weight were stocked in 39 experimental fiberglass tanks in abundance of 30 fish per any tank. These specimens fed experimental diets for 8 weeks and ten of them in each tank fed same diets which added Cr2O3 to them for one more week to measure the apparent protein digestibility in them. The results shown that supplementary multi enzyme (Avizyme) which contains Protease , Amylase and Xylanase , caused increases in growth performance , survival rate and apparent protein digestibility in trouts which fed soybean meal. Also this study shown that using 1000 ppm of Avizyme in diets which containing soybean meal had the best results and the diet which contained 39 % soybean meal with this amount of enzymes, had no significant differences by the control in any of the studied factors.