Ileal and total tract digestibility in growing pigs given cassava root meal diets with inclusion of cassava leaves, leucaena leaves and groundnut foliage

Abstract Growing pigs fitted with post-valve T-caecum cannulas were used in a change-over design experiment (5✕5) to determine the ileal and total tract apparent digestibility and hindgut disappearance of dietary components and energy in a cassava root and soya-bean meal-based diet with an inclusion rate at 0·15 of the dry matter (DM) of either cassava leaf meal, ensiled cassava leaves, groundnut foliage, or leucaena leaves. The ileal and total tract apparent digestibilities of organic matter (OM), crude protein, nitrogen-free extractives and energy of the diets were significantly reduced with inclusion of the foliages (P< 0·05). The digestibility of neutral-detergent fibre (NDF) and crude fibre was improved when groundnut foliage was included in the diet (P< 0·05). The dietary content of NDF was a better predictor of the total tract digestibility of OM (R2= 0·87) and energy (R2= 0·90) than the content of crude fibre (R2= 0·68 for OM digestibility and R2= 0·72 for energy digestibility). The disappearance of OM and energy in the hindgut of the foliage diets was 0·36 (s.d. 0·02) and 0·31 (s.d. 0·02), respectively, which was significantly lower (P< 0·05) than on the control diet (0·48 and 0·46, respectively). Ileal as well as total tract digestibilities of OM in groundnut foliage were higher than for the other leaf products (ileal, 0·55 and 0·42; and total tract, 0·64 and 0·55, respectively). For foliage products of cassava and leucaena an average digestible energy value of 11·4 MJ/kg DM was calculated, whereas for groundnut foliage the corresponding value was 10·9 MJ/kg DM. It was concluded that, inclusion of foliages in pig diets will reduce the dietary energy content, due to a high fibre content. However, under tropical conditions foliage at low levels of inclusion may be useful in low fibre diets for growing pigs to improve the dietary protein supply.