Digestibility and energy value of non-starch polysaccharides in young chickens, ducks and geese, fed diets containing high amounts of barley

Abstract

The purpose of the present investigation is to compare the ability of chickens, ducks and geese to digest and utilise a diet containing a relatively large amount of barley (40%) rich in β-glucan (18 g kg −1) and NSP (137 g kg −1) of which 35 g kg −1 were soluble non-starch polysaccharides (NSP). The diets were offered to the birds (50 chickens, 40 ducks and 30 geese) in the period from hatching to 42 days of age. The digestibility of NSP was measured during the last week of the growth period using chromic oxide as an indigestible marker. Emphasis was on total NSP, soluble and insoluble NSP and their constituent sugar residues (rhamnose, fucose, arabinose, xylose, mannose, galactose, glucose and glucuronic acid). The degradation of NSP to short chain fatty acids (SCFA) was determined in the small intestine, caeca and large intestine. Although significant differences were found between species to the extent of degradation of individual soluble, insoluble and total NSP residues in the small intestine and caeca, the overall apparent digestibility of total NSP was similar (39–42%). On the basis of the digestibility of the NSP sugar residues and the formation of SCFA in the gut, the energy value of NSP was estimated on 2.8, 3.2 and 2.7 kJ g −1 NSP ingested ( P>0.05) in chickens, ducks and geese, respectively. On average, NSP contributed approximately 3.5% of metabolisable energy (ME) in the three poultry species.