INFLUENCE OF SUPPLEMENTAL PHYTASE ON FISH MEAL REPLACEMENT BY SOYBEAN AND ITS EFFECTS ON GROWTH AND BODY COMPOSITION OF RAINBOW TROUT (ONCORHYNCHUS MYKISS)

Document Type : Research Paper

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Abstract

Influence of phytase enzyme and replacement of fishmeal protein by soybean meal protein on growth and body composition of rainbow trout (Oncorhynchus mykiss) specimens each with a mean weight of 121.75±5.95 gwere studied. Experimental diets by factorial method 3 * 3, containingthree levels of replacement (0.0, 35 and 70%) and three levels of microbialphytase (0.0, 1000, 2000 units/kg diet) were formulated and prepared. Nine treatments and three replicates of random groups of 20 fish per each 2 cubic meter (2´2´0.5m) tank were used in the study. All diets contained 36-38% protein and about 4000 cal/g energy. During the 9 weeks period of the study, fish were fed to satiation level, three times daily. Statistical results indicated that the increase of replacement level to 35%had no significant effect on growth index (P2£0.05). Effect of replacement on body composition was not significant, except for crude energy which decreased in 70% level (p£0.05). Effect of phytase enzyme on growth index was positive and 2000 units/kg diet of phytase showed the best result (p£0.05), but phytase levels had no significant effect on body composition. Result also showed that there was a significant interactionbetween phytase enzyme and meal replacement (p£0.05). We suggest using 2000 units/kg diets of phytase with at least 35% replacement of fish meal protein by soybean meal protein as a suitable formula for growing rainbow trout.




 

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Iranian Scientific Fisheries Journal
Volume 16, Issue 2
January and February 2008
Pages 75-84

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