Interaction Between Ingested Feed and the Digestive System in Poultry

Nutritionists rely on the assumption that feed is digested in a manner which is independent of both the ingredient matrix of the diet and the genetics and physiological status of the bird. This fact is evident when observing feed formulation in the poultry industry and in particular the manner in which energy and amino acid specifications are met through ingredient mixing. Such assumptions about digestion may not be entirely valid, however. Additivity of metabolizable energy, for example, is a fundamental tenet of poultry nutrition which is beginning to look less and less secure. The reasons stem from a lack of recognition of the differences in intestinal maintenance energy costs placed on the bird through use of specific ingredients and, more importantly, the role of intestinal microflora in energy and protein utilization. This paper attempts to highlight some recent (and some not so recent) findings which suggest that our reliance on the current formulation systems may overstate their robustness to dietary changes.