Effects of feed particle size on the digestive processes in domestic birds

Abstract

A bibliographic study has investigated the effects of feed particle size on the digestive processes in domestic birds. This paper is divided into two parts: the effects on digestive transit times and thoses on the availability of intracellular plant components.

Coarse particles compared to fine ones generally result in an increase in total transit time due to a longer retention time in the gizzard. According to the literature, it seems that coarse grinding should be positive for reducing water losses, and also, in some cases, for protein digestibility. The latter effects would be explained by a better control of the intestine transit time by the gizzard emptying when using coarse ground feeds.

Coarse grinding may result in low availabilities for some of the intracellular components of dicotyledon whole seeds as observed for soyabeans, rapeseeds, faba beans and peas. In contrast, cereals seem to be much less sensitive to particle size variations. In dicotyledon seeds, the intracellular components do not show the same sensitivity : the highest sensitivities to particle size variations are generally observed for lipids and starch. However, if a pelleting process is applied after grinding, the effects of the grinding intensity are considerably reduced with, in this case, similar digestibility values close to a maximum.