Fishmeal hydrolysation and non-protein energy sources affect the kinetics of nutrient digestion in the gastrointestinal tract of African catfish (Clarias gariepinus)

The kinetics of nutrients digestion and development chyme characteristics in African catfish (Clarias gariepinus) were assessed response to fishmeal hydrolysation non-protein energy (NPE) sources. Four diets formulated contain starch or fat as NPE source, hydrolysed protein source a 2 × factorial design. Juvenile (average weight, 63 g) stocked glass experimental tanks connected common recirculation aquaculture system fed restrictively for 3 weeks. hours after the consumption single meal, fish dissected collect from gastrointestinal tract (GIT). Chyme was collected stomach, proximal- distal intestine analysed dry matter (DM) content, crude (CP) marker concentration. Postprandial water fluxes GIT stomach evacuation calculated using yttrium oxide (Y2O3) an inert marker. Faecal DM CP apparent digestibility coefficient (ADC) determined by method. Results showed that had no effect (P > 0.1) on content all compartments. However, replacing dietary resulted higher < 0.01). In proximal intestine, did not influence but at “fat diets” “Starch-diets” larger influx into compared 0.001), also re-absorption 0.05). rate affected 0.05) slower starch-fed fish. Hydrolysation increased this dependent indicated interaction increase containing diets”. other compartments, similar between 0.1). faecal ADC CP. Our results suggest can alter process along GIT. addition, macronutrient composition postprandial without being reflected digestibility.