Egg Quality is Improved by Feeding Hens Fermentable Fibre, Xylo-oligosaccharides and Xylanase

The aim of this study was to evaluate the impact of feeding xylo-oligosaccharides (XOS), xylanase (XYL) and fermentable fibre, in the form of wheat bran (WB), on egg quality. It is theorised that WB stimulates and trains the microbiota in the hindgut to hydrolyse and ferment dietary xylan, and XOS and XYL may further upregulate xylan fermentation pathways, resulting in improved nutrient utilisation and thus egg quality. Isa Brown hens (n = 96 hens) were obtained at peak lay (39 weeks of age) and fed one of 12 dietary treatments, Egg quality and feed conversion ratio (FCR) were determined after 14 days. A commercial laying hen ration was fed (wheat, corn, sorghum, canola meal and soybean-meal based). For half of the treatments, 10% of the diet was replaced with wheat bran. Analysed protein, energy and ash level was similar across all treatments. The diets were then supplemented with either (1) no supplements; (2) XOS 50 g/t; (3) XOS 2 kg/t; (4) XYL; (5) XYL + XOS 50 g/t, or (6) XYL + XOS 2 kg/t.

In the absence of XYL, XOS increased egg weight when in the presence of WB, but had no impact when WB was not fed. It is suggested this performance benefit was brought about by stimulating the growth of xylan-degrading bacteria in the gastrointestinal tract by provision of fermentable XOS. These probiotic bacteria utilize the XOS, but also accelerate insoluble xylan fermentation, inducing positive effects on nutrient absorption. In the presence of XYL, supplementing XOS increased egg weight in the absence of WB. XYL supplementation in diets with low fermentable fibre content may induce production of soluble xylan, which possibly provides sufficient fuel for probiotic bacteria, causing them to respond positively to XOS. Feeding 2000 g/t XOS caused decreased egg weight when both XYL and WB was present, suggesting providing excessive XOS has detrimental effects of the gastrointestinal environment and microbiota balance. Feeding XYL and 2000 g/t XOS in the absence of WB resulted in a lower FCR value compared to feeding WB with no XOS or XYL. This highlights both the benefits of supplementing XYL and XOS to laying hen diets poor in fermentable fibre, and the need to supply XYL and XOS when feeding diets rich in fermentable fibre.

ACKNOWLEDGEMENTS: The authors are grateful for financial support from Australian Eggs and Australian Government Department of Agriculture, Water and Environment.