On-Farm Feed Resources for Catfish (Clarias gariepinus) Production in Laos Evaluation of Some Local Feed Resources

The aim of the thesis was to collected information African catfish (Clarias gariepinus) production systems, and the chemical composition and nutritive value of potentially available feedstuffs. Moreover, the apparent digestibility (AD) of nutrient and amino acids (AA) in raw, sun-dried and ensiled Golden Apple snails (GAS) was evaluated, as well as the potential of GAS to replace fish meal in the diet for growing African catfish fingerlings. The farmers used traditional feedstuffs such as maize, broken rice, cassava root meal, rice bran, soybean, soy waste, dried fish and fish meal. In addition, some more unconventional feedstuffs such as leucaena meal, earthworms, termites and GAS were used. The fish diets were low (150-220 g kg dry matter (DM)) in crude protein and had to low protein to energy (P/E) ratio. Catfish pond areas per farm ranged from 100 to 5,000 m with a fish yield that ranged from 1.7 to 3.0 tons ha 6 months. The average AD of crude protein (CP), crude fat, total carbohydrates and energy in potentially available feedstuffs was 90.6 % (SD 2.4), 87.0 %, (SD 3.4), 77.7 % (SD 3.7) and 84.5 % (SD 2.3), respectively. Only a few of the currently available and used feedstuffs have the potential to provide optimum P/E ratios in the diet for growing African catfish (25-30 g CP/MJ digestible energy (DE)). The content of DE ranged from 13.2 MJ kg DM for rice bran to 18.1 MJ kg DM for frogs. The AD of CP, AA and energy was highest in sun-dried, followed by raw and ensiled GAS. The CP to DE ratio that ranged from 17.8 g MJ in raw GAS to 24.8 MJ in ensiled GAS. It was concluded that sun-drying, rather than ensiling should be the preferred preservation method of GAS. High addition of sugar cane molasses (>15 % in DM) was needed to maintain an acceptable quality of GAS ensiled for 28 days. Finally, it was shown that protein from GAS can completely replace fish meal in diets for growing African catfish fingerlings without negative effects on growth performance and feed utilization.