EFFECTS OF DIETARY NATURAL ZEOLITE LEVELS ON AMMONIA EXCRETION RATES IN YOUNG RAINBOW TROUTS (Oncorhychus my kiss)

摘要

The possible effects of dietary zeolite levels on the ammonia excretion rate of young rainbow trouts (Oncorhychus mykiss) were investigated. Triplicate groups of rainbow trout were fed diets incorporated with three different levels of zeolite (0.5%, 1% and 2.5%), and a control diet without zeolite at a constant water temperature of 17 ℃. A decline in ammonia excretion level has been recorded with increasing dietary zeolite level. Cumulative ammonia excretion rates for a period of 6 hours, resulted in 6.09 mg N/100g fish for the control group (0% zeolite), while an excretion rate of 4.64 mg N/100 g fish has been recorded in fish fed the diet with the highest zeolite level of 2.5%. Based on the findings in the present study, the inclusion of 2.5% natural zeolite in the diet reduced the ammonia excretion rate of rainbow trouts by 24%. compared to the control group. This finding could be useful for environmental impact assessment and trout culture management.