Water-soluble fractions obtained by enzymatic treatment of wheat grains promote short chain fatty acids production by broiler cecal microbiota

doi:10.1016/j.anifeedsci.2016.05.016

Animal Feed Science and Technology

Volume 218, August 2016, Pages 110-119

https://doi.org/10.1016/j.anifeedsci.2016.05.016 Get rights and content

Highlights

•
Low molecular weight AX increase butyrate production in vitro similarly to FOS.
•
Oligosaccharides (DP < 10) are not essential to enhance SCFAs production in vitro.
•
NSP-enzyme treatment of wheat promotes SCFAs production in vitro.

Abstract

The use of exogenous cell wall degrading enzymes to improve the nutritional values of cereal grains has increased during the last decades. In this study, products from enzymatic hydrolysis of wheat grain were isolated and their ability to induce short-chain fatty acids was investigated using in vitro fermentation with cecal microbiota. Water-soluble fractions were obtained following incubation without and with a multicomponent enzyme preparation (MEP) (2 mL/kg) containing essentially endoxylanase and endoglucanase activities. These were further fractionated by size exclusion chromatography into high molecular weight (HMw) and low molecular weight (LMw) sub-fractions. The MEP treatment increased the content in water-soluble arabinoxylan (AX) and decreased the degree of polymerization (DP) of the xylan-backbone. In vitro fermentation assays using broiler cecal content as inoculum demonstrated that low substituted AX with reduced molecular weight isolated after MEP treatment yielded higher concentrations of acetate and butyrate. This result indicates that cecal fermentation of enzymatic degradation products into short-chain fatty acids, particularly butyrate, is one of the important mechanisms of MEP action on wheat-based diets that can contribute to the improvement of intestinal health and animal performance.

Introduction

Wheat is the most commonly used cereal in poultry diets in Europe. However differences in metabolisable energy are observed amongst wheat based diets, partly due to the presence of non-starch polysaccharides (NSP)(Gutierrez del Alamo et al., 2008). In wheat, the NSP content ranges from 12 to 16% of dry matter. Starchy endosperm NSP consist mainly of arabinoxylans (AX), that represent 70% of the cell walls (Saulnier et al., 2012). Arabinoxylans are composed of a linear backbone of β-(1,4)-linked d-xylose residues that is partially substituted with individual α-l-arabinose residues attached through O-2 and/or O-3 (Izydorczyk and Biliaderis, 1995). The second most important wheat NSP are mixed-linked β-glucans, which are linear homoglucans arranged as blocks of consecutive (1,4)-linked β-d-glucose residues separated by single (1,3)-linkages (Li et al., 2006). It is well demonstrated that these two major components of cereal grain endosperm exert anti-nutritional effects through the viscosity-inducing property of their water-soluble fraction. In the case of wheat, the water-soluble NSP are almost exclusively composed of AX.

Non-starch polysaccharides degrading enzymes (NSP-enzymes) constitute a category of safe additives that improve body weight gain (BWG) and feed conversion ratio (FCR) in broilers (Mathlouthi et al., 2002a, Choct et al., 2004, Wang et al., 2005, Walk et al., 2011). The NSP-enzymes like endo-1,4-β-xylanases and endo-1,3(4)-β-glucanases are widely used separately, in combination or in a more complex mixture to decrease the viscosity of the intestinal content and enhance the nutritional value of cereal diets (Choct et al., 2004, Mathlouthi et al., 2002b). However, the improvement of nutritional performance of wheat-based diets by NSP-enzymes is not only linked to viscosity effect. NSP-enzymes also increase short-chain fatty acids concentration (SCFA) in the ceca (Choct et al., 1999) and alter the microbiota (Van der Wielen et al., 2000).

However, it is not fully explained in the literature what substrates are released by the NSP-enzymes which contribute favorably to the SCFA production in the caeca. The aim of this paper is to contribute to the understanding of the beneficial effects of NSP-enzymes supplementation to wheat-based diets for broilers. Therefore, water-soluble NSP were isolated from wheat grain treated or not with the multicomponent enzyme preparation (MEP) Rovabio^® Excel. Water-soluble NSP were further separated by size exclusion chromatography into high molecular weight (HMw) and low molecular weight (LMw) sub-fractions. Fractions were characterised for their chemical composition and physico-chemical features, and their SCFA production pattern was determined in vitro using broiler cecal microbiota.

Section snippets

Materials

The multicomponent enzyme preparation(MEP) Rovabio^® Excel was provided in liquid form by Adisseo SAS (Commentry, France) (Table 1). The MEP contains glycosyl hydrolases, mainly endo-1,3(4)-β-glucanase (1200 U/g) and endo-1,4-β-xylanase (800 U/g), produced from the fermentation of Talaromyces versatilis sp. nov. (previously named Penicillium funiculosum).

The wheat cultivar Barok, harvested in 2012, was purchased from Euronutrition (St Symphorien, France). Xylo-oligosaccharides (XOS), XOS95P, were

Characterisation of water-soluble NSP fractions

Water-soluble NSP fractions were isolated from Barok wheat with or without MEP treatment and were characterised (Table 2). The enzymatic treatment increased the total amount of water-soluble polysaccharides that were recovered by ethanol precipitation (Ethanol-Insoluble Fraction, EIF). The MEP-untreated EIF represented 2.84 g/100 g of wheat vs. 3.75 g/100 g of wheat after MEP treatment, corresponding to an increase of 32% of water-soluble polysaccharides amount. The EIF isolated after enzymatic

Discussion

The enzymatic treatment allowed, not only solubilising more polysaccharides, but also decreasing their molecular weight. Before MEP treatment, the HMw sub-fraction was essentially composed of arabinose and xylose arising from AX, and also contained a substantial amount of galactose coming from AGp. The average molecular weight and the intrinsic viscosity of the MEP-untreated HMw fraction were in the range typically observed for water-extractable wheat AX (Dervilly et al., 2000, Faurot et al.,

Conclusion

The MEP treatment of wheat increases the proportion of water-soluble AX with reduced molecular weight and did not affect AGp. The MEP-treated HMw and LMw fractions rich in AX stimulate the production of SCFA to same level as recognized prebiotics (FOS an XOS) when incubated in vitro with cecal microbiota. Interestingly, they promoted the production of SCFA, particularly acetate and butyrate. These results suggest that the beneficial action of MEP on broiler performance is notably mediated by

Acknowledgements

The present study was financed by a grant from Adisseo France SAS (Commentry, France). We thank Estelle Devillard for valuable discussion elements. We thank Agnès David, Venessa Eeckhaut, Celine De Maesschalck, Sylviane Daniel, Jacqueline Vigouroux, Michèle Dalgalarrondo and Marie-Jeanne Crépeau for technical assistance.

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Water-soluble fractions obtained by enzymatic treatment of wheat grains promote short chain fatty acids production by broiler cecal microbiota

Highlights

Abstract

Introduction

Section snippets

Materials

Characterisation of water-soluble NSP fractions

Discussion

Conclusion

Acknowledgements

Anim. Feed Sci. Technol.

Life Sci.

J. Chromatogr. A

Enzyme Microb. Technol.

Poult. Sci.

LWT – Food Sci. Technol.

Poult. Sci.

Carbohydr. Polym.

Anim. Feed Sci. Technol.

Pharmacol. Res.

Carbohydr. Polym.

Food Hydrocoll.

J. Appl. Poult. Res.

Carbohydr. Polym.

J. Cereal Sci.

J. Nutr.

Poult. Sci.

Poult. Sci.

Anim. Feed Sci. Technol.

Physiological and anti-inflammatory roles of dietary fiber and butyrate in intestinal functions

J. Parenter. Enter. Nutr.

Prebiotic and other health-related effects of cereal-derived arabinoxylans, arabinoxylan-oligosaccharides, and xylooligosaccharides

Crit. Rev. Food Sci. Nutr.

Effects of a xylanase on individual bird variation, starch digestion throughout the intestine, and ileal and caecal volatile fatty acid production in chickens fed wheat

Br. Poult. Sci.

A comparison of three xylanases on the nutritive value of two wheats for broiler chickens

Br. J. Nutr.