Nutritive value of potential feed resources used in Laos for African catfish (Clarias gariepinus) production

Abstract

The present experiment was performed to determine the digestibility of nutrients and energy in carbohydrate-rich (rice bran, broken rice, maize, cassava root meal) and in protein-rich (dried fish, snails, earthworms, frogs, termites) feed resources that are commonly used to formulate diets for the African catfish (Clarias gariepinus) in Laos. The apparent digestibility (AD) of organic matter ranged from 78.1 to 87.5 %, and was on average 83.2 % (SD 2.7). The AD of crude protein (CP) in the test diets ranged from 86.6 to 93.2 % (average 90.6 %, SD 2.4) and the AD of crude fat (EE) ranged from 79.9 to 91.2 % (average 87.0, SD 3.4). The AD of the carbohydrate components was lower than the AD for CP and EE. However, despite a larger variation in the AD between diets and ingredients, on average 72.2 % (SD 6.7) of the nitrogen-fee extracts and 77.7 % of the total carbohydrate fraction (SD 3.7) were digested. The AD of energy in the test diets was high and ranged from 80.3 to 88.2 % (average 84.5 %, SD 2.3). The estimated content of digestible energy (DE) ranged from 13.2 MJ/kg DM for rice bran to 18.1 MJ/kg DM for frogs. On average, the DE content of the carbohydrate-rich feed ingredients was lower than that of the protein-rich feed ingredients. The protein: energy ratio (P/E ratios) ranged from 2.2 to 6.4 g CP/MJ DE for the carbohydrate-rich feed ingredients, and from 17.4 to 26.1 g CP/MJ DE for the protein-rich feed ingredients. To reach optimum P/E ratios in the diet for growing African catfish (25-30 g CP/MJ DE) only the protein-rich feed ingredients has the potential to meet required levels. Thus, there is a need to search for other potentially useful feed ingredients for catfish production.