Effects of fibre content in pelleted wheat and oats diets on technical pellet quality and nutritional value for broiler chickens

Abstract

Two experiments were conducted to study the effects of either soluble or insoluble fibre naturally occurring in wheat and oats, on technical pellet quality and nutritional value for broiler chickens. In exp. 1, the effects of insoluble fibre were studied by mixing diets based on wheat or naked oats with either coarse or fine oats hulls followed by pelleting. Hull inclusion increased (P < 0.05) starch gelatinisation, especially in the diets based on oats. Addition of finely ground oats hulls improved pellet durability, in particular after storage, while no such effect was observed for coarse oats hulls. Oats hulls inclusion caused a more elastic pellet with higher breaking resistance (P < 0.05). Lower (P < 0.05) energy consumption was observed for diets based on oats compared with wheat, while no effect of fibre inclusion on energy consumption was found. In exp. 2, the influence of pelleting on the viscosity effect of soluble fibres in diets based on wheat or oats was studied. A significant increase (P < 0.05) in intestinal viscosity of broiler chickens was observed for all batches of grain exposed to steam pelleting. Viscosity was doubled (P < 0.05) with wheat diets, while the increase in viscosity was even greater in oat diets. In wheat diets, feed intake and weight gain was reduced (P < 0.05), while feed conversion ratio was not affected. Steam pelleting of oats reduced (P < 0.05) feed intake and weight gain, and increased feed conversion ratio (P < 0.05). The improvements (P < 0.05) in metabolisable energy and dry matter digestibility in wheat diets was not consistent with the observed increases in viscosity or with the results obtained with oats. Key words: Soluble fibres, insoluble fibres, viscosity, starch gelatinisation, steam-pelleting