GROWTH PERFORMANCE, NUTRIENT UTILIZATION, METABOLIC AND DIGESTIVE ENZYMES STUDIES IN MRIGAL (Cirrhinus mrigala) JUVENILES FED GRADED LEVELS OF CARBOHYDRATE

A 45-days experiment was carried out to evaluate the growth performance, digestive enzymes activities along with their gene expression in mrigal fish (Cirrhinus mrigala) fed with graded levels of carbohydrate. Three isonitrogenous and isolipidic diets containing either 30, 40 or 50% carbohydrate were formulated using purified ingredients. One hundred and eight fingerlings of Cirrhinus mrigala (av. wt. 5.83- 6.08g) were equally distributed in three in three groups in 9 plastic tanks of 100L capacity each. Each of the three experimental diets was fed triplicate groups of fish held under natural light cycle of 12h daylight and 12h darkness. Weight Gain (%), specific growth rate (SGR), feed conversion ratio (FCR) and hepato-somatic index (HSI) were evaluated and found to vary significantly (P 0.05) was found in % weight gain, SGR, and FCR between the 30 and 50% carbohydrate fed groups but the HSI increased significantly across the inclusion levels. Amylase enzyme activity was highest in 40% fed group relative to the 30 and 50% counterpart. Chymotrypsin and trypsin activities were not significantly different between the 40 and 50 % carbohydrate fed groups .Various metabolic enzyme activities in the muscle (aspartate amino transfarase (AST), alkaline amino transaminase (ALT) and malate dehydrogenase (DH) varied significantly (P<0.05) in response to increased levels of carbohydrate. Gene expression among the digestive enzymes reflected both transitional and translation effect; amylase and trypsin exhibited higher expression with the increasing level of carbohydrate of the experimental diets but the reverse was the result for chymotrypsin expression. Gene expression over study period had an initial higher significant The IJA appears exclusively as a peer-reviewed on-line open-access journal at http://www.siamb.org.il. To read papers free of charge, please register online at registration form. Sale of IJA papers is strictly forbidden.