Ileal and total tract digestibility in pigs of naked and hulled barley with different starch composition

Abstract

Ileal and total tract digestibility of dietary components and energy in naked and hulled barley containing starch varying in amylose: amylopectin ratio was studied in a 5 × 5 Latin square design with ileal cannulated growing pigs. There were significant differences in ileal and total tract dietary components digestibilities between naked and hulled cultivars as a result of differences in the content of fibrous components between barley types. Apart from the ileal digestibility of starch, total, insoluble and soluble β-glucans of diets with naked and hulled regular barley, the diet based on naked amylopectin-rich barley showed a significantly ( P < 0.05) higher ileal and total tract digestibility of dietary components and energy than diets of the other barley types. Except for crude fat the diet with naked regular barley showed significantly ( P < 0.05) higher total tract digestibilities than diets with hulled regular and hulled amylopectin-rich barley. At the ileal level, the diet with hulled amylose-rich barley showed significantly ( P < 0.05) lower digestibilities of organic matter, nitrogen free extracts and energy than diets with hulled regular and hulled amylopectin-rich barley. Despite a similar fibre content in diets with naked amylopectin-rich and naked regular barley, ileal nutrient digestibilities were significantly ( P < 0.05) lower in the latter. Apart from organic matter, nitrogen free extracts and energy the diet with naked regular barley showed similar ileal digestibilities as the diet with hulled regular barley. Naked barleys showed a marked advantage compared to hulled barleys with respect to the hindgut digestion expressed as a proportion of the ileal flow of dietary components and energy. The present results indicate that other factors in addition to hull, fibre and β-glucan content are of importance for ileal and hindgut dietary components digestion in barley.