Apparent digestibility coefficients of carbohydrates and enzymes activity in major carps in response to Chromium Chloride Hexahydrate

This study investigated the effect of carbohydrate-based corn diets with chromium chloride hexahydrate supplementation on nutrient digestibility and enzyme activity in major carps (Cirrhinus mrigala, Catla catla, and Labeo rohita) for a period of 90 days. One control (T1) and five experimental diets (T2, T3, T4, T5, T6) were prepared by using gelatinized and non-gelatinized corn with the combination of various levels (0.0, 0.6, and 0.8 mg/kg) of CrCl3H12O6. After acclimatization with a control diet (T1) (32% CP), twenty fingerlings of these species were randomly stocked in eighteen digestibility tanks, each with one replicate. At the end of the trial, results showed that gelatinized corn with chromium supplementation significantly enhanced (P<0.05) digestibility of nutrients and enzyme activities (amylase and protease) in liver and gut in all treated groups. Crude protein (76.05±0.54), crude lipid (84.53±0.46), carbohydrate (69.15±2.19), and gross energy (76.92±0.74) showed the highest apparent digestibility in Labeo rohita as compared to Catla catla and Cirrhinus mrigala. While highest amylase (liver:3.27±0.126 U/ml and gut: 1.29±0.045 U/ml) and protease activity (liver:1.22±0.116 U/ml and gut 3.42±0.087 U/ml) was recorded in Catla catla subsequently followed by Labeo rohita and Cirrhinus mrigala. Among the treatments, highest amylase activity was observed in the corn gelatinized group at 0.6 mg/kg chromium level, while maximum protease activity was observed at 0.8 mg/kg of chromium level (gelatinized group). Comparison among gelatinized and non-gelatinized corn diets suggested that gelatinization in fish feed performed best as a carbohydrate energy source with chromium supplementation at an appropriate level (0.6 mg/kg) for three major carps as compared to non-gelatinized corn.