Digestibility and digestive organ development in indigenous and improved chickens and ducks fed diets with increasing inclusion levels of cassava leaf meal

Growing indigenous Cambodian chickens and ducks, and broiler chickens and White Pekin ducks were fed diets containing 0%, 7%, 14% and 20% of cassava leaf meal (CLM) to study the effects of CLM level on diet digestibility and gastrointestinal tract (GIT) and organ development. The coefficient of total tract apparent digestibility (CTTAD) of dry matter (DM) and intake of digestible DM decreased with increased dietary CLM. DM and digestible DM intake was higher for local breeds than for the corresponding exotic breeds, and higher for ducks than for chickens (p < 0.001), although there were no species or breed effects on CTTAD of DM (p > 0.05). Weight of small intestine, caeca, gizzard and pancreas, expressed as per kg body weight, increased with increased CLM in the diet (p < 0.001). There was no consistent diet effect on liver weight. Length of small intestine and caeca, expressed on a mass-specific basis, increased with dietary CLM content (p < 0.001). When expressed as per kg body weight small intestine, proventriculus, gizzard, pancreas and liver weights, and small intestine length, were higher in ducks than in chickens (p < 0.001), and were higher in the indigenous than in the improved breeds (p < 0.01), except for small intestine weights, which were similar. However chickens had higher weight of caeca (p < 0.001) and colon (p < 0.01) in absolute units and per kg body weight.