ABSTRACT
This chapter discusses the effect of diet composition on the digestibility at the end of the ileum and over the whole digestive tract. Protein digestibility in the small intestine occurs under the influence of enzymes secreted by the pigs, while the digestion in the large intestine depends on the action of microorganisms and their enzymes. The digestive breakdown of protein, the absorption of free amino acids and peptides, and the secretion of endogenous amino acids all depend on the composition of the diet and, thus, also on protein intake. The influence of diet composition on the digestibility of each individual amino acid may be different from the effect on protein digestibility. The carbohydrate fraction of a diet includes different components such as sugar, starch, pectin, hemicellulose, cellulose, and lignin. Each fraction has a specific effect on the ileal and fecal digestibility of amino acids. Protein digestibility in the large intestine depends on the action of microorganisms and their enzymes.
