Fiber and nonstarch polysaccharide content and variation in common crops used in broiler diets

Abstract

The current paper reviews content and variation in fiber and nonstarch polysaccharides (NSP) of common crops used in broiler diets. The cereal grain is a complex structure, and its cell walls (CW) differ in their composition and hence properties. Arabinoxylan (AX), mixed linkage (1→3; 1→4)-β-glucan (β-glucan), cellulose, and the noncarbohydrate component lignin are the predominant polymers in cereals. They occur in different proportions depending on the species and tissue type. Rye, triticale, wheat, corn, and sorghum are all rich in AX, whereas barley and oats contain a high level of β-glucan. The AX from rye, wheat, and triticale and β-glucan from barley and oats are to a large extent soluble, whereas the solubility of AX found in corn and sorghum is lower than the other cereals. The ratio of arabinose to xylose gives a crude indication of the AX structure, which varies between the endosperm, the aleurone and the outer grain layers as well as between the same tissues from different grains. Varietal differences in AX structure of the endosperm are also identified. From the analysis of the released oligomers after hydrolysis with a specific (1→3,1→4)-β-d-glucan hydrolase, it is found that the ratio of trisaccharides (degree of polymerization 3) and tetrasaccharides (degree of polymerization 4) varies depending on the source, being higher in barley than in oats but lower than in wheat. The molecular weight of β-glucan is higher than that of AX, and both polymers contribute to the viscosity of the extract. However, because AX molecules are more resistant to degradation than β-glucan, the use of AX rich grains in broiler diets is usually more problematic than those containing high concentrations of β-glucan. The cereal coproducts (brans and hulls) are concentrated sources of cellulose, lignin, and insoluble AX, but β-glucan can also be present mainly in rye and wheat brans. The CW composition of seeds and grains of protein crops and feedstuffs are different from that of cereals. The main CW polymers are pectic substances (homogalacturonan, rhamnogalacturonan type I and II, xylogalacturonan, and arabinogalactans type I and II), xyloglucans, and cellulose, but there are significant differences in the composition of the parenchymatous (cotyledon) tissues and that of the hulls. In the hulls, cellulose is the predominant polysaccharide, followed by acidic xylans and pectic substances. The implications of the heterogeneous CW for the action of exogenous enzymes are discussed.

Improving the nutritional value of rapeseed cake and wheat dried distillers grains with solubles by addition of enzymes during liquid fermentation

“…However, the composition of the constituent sugars reflects the presence of the polysaccharides arabinoxylans, cellulose and ␤-glucans present in the parent grain (Bach Knudsen, 1997;Souffrant, 2001;Knudsen, 2014). The fermentation process itself did not increase the solubility of NSP in wDDGS, although this has previously been shown when fermenting wheat (Sholly et al, 2011).…”

The effect of addition of yellow lupin seeds (<i>Lupinus luteus</i> L.) to laying hen diets on performance and egg quality parameters

“…other protein-rich plants (Gdala and Buraczewska, 1996;Knudsen, 1997Knudsen, , 2014 and is still a nutritional problem. These authors claimed that the soluble NSP content in some old Polish cultivars of yellow lupin seeds ranged from 2.0 to over 12.0%.…”

Influence of non-starch polysaccharide-degrading enzymes on growth performance, blood parameters, and carcass quality of broilers fed corn or wheat/barley-based diets

“…Wheat and corn are rich in arabinoxylan, whereas barley has high levels of β-glucan (Knudsen, 2014). The anti-nutritional properties -expressed by watersoluble NSPs, such as pentosans (arabinoxylans) and β-glucans-can be reduced by including NSP degrading enzymes (xylanase-glucanase and cellulase) in broiler diets.…”