In vitro carbohydrate digestibility of fermented rice straw in hybrid catfish (Clarias macrocephalus X C. gariepinus)

Abstract

The study of In vitro carbohydrate digestibility of fermented rice straw in hybrid catfish (Clarias macrocephalus X C. gariepinus) was designed in 4x5 factorial in Completely randomized design. Rice straw was fermented under anaerobic conditions with two determining factors: the incubation time at 0, 24, 48 and 62 hours and addition of molasses at 0, 2, 4, 6 and 8% with 20 treatment groups and 6 repetitions per treatment groups. Hybrid catfish (161.54±0.96 g) were extracted for digestive enzymes. The amylase specific activity was 0.344±0.043 Unit/mg protein and cellulase specific activity was 0.020±0.003 Unit/mg protein. ln-vitro digestibility of carbohydrate was determined. It was found that molasses level and fermentation time had a significant influence on the carbohydrate digestibility (p≤0.05). The interaction between the molasses level and the fermentation time was also studied (p≤0.05). The addition of molasses at different levels without rice straw fermentation did not affect the carbohydrate digestibility. The hybrid catfish could digest carbohydrate 58.57-59.21 mg maltose/ g rice straw. The optimal level for fermentation of rice straw in improving the digestion efficiency of carbohydrate from hybrid catfish was considered to be the addition of 2% molasses with 24-hour fermentation by natural microorganisms. The value was 77.28±1.68 mg maltose/g rice straw; this could be used as a practical guideline to increase the value and utilization of rice straw in hybrid catfish feed.