Apparent protein and energy digestibility of selected carbohydrate-rich feed ingredients for african catfish Heterobranchus longifilis (Valenciennes, 1840)

Apparent digestibility coefficients (ADCs) of dry matter, protein, and energy of 4 raw materials (corn, millet, sorghum and rice meals) were determined for juvenile African catfish Heterobranchus longifilis. A reference diet and 4 test diets (Maize, Millet, Sorghum, Rice), each including 70 % of reference diet and 30 % of the raw material to be tested were formulated. The reference diet contained 1 % of chromic oxide (Cr2 O3 ) used as inert marker. Groups of 40 fishes (average weight, 125 g) stocked in 90-L cylindro-conical tanks were fed with each diet fed in two replicates. Faeces were collected from duplicate groups of fish using a fecal collection column attached to the fish rearing tank. The ADCs of dry matter, protein and energy of raw materials varied between 66.43 - 77.78 %, 88.85 - 91.77 % and 78.35 - 88.43 %, respectively. The ADCs of dry matter (75.24 %), protein (90.20 %) and energy (77.24 %) of millet were higher. Protein ADC of rice was low (50.48 %), but its energy digestible remained higher, as compared to other raw materials. Fish fed with Maize, Millet and Sorghum diets had comparable growth performances. In fish fed with Corn and Millet, feed intake, specific growth rates and protein efficiency ratios were relatively higher. The results suggest the possibility of using of millet, maize and sorghum in the diet of Heterobranchus longifilis. These raw materials available locally, at low cost, could reduce the costs of fish production.