nutrition. The sceptical view on the inclusion of different fibre sources has gradually been replaced by interest in fibre supply and now gets into the focus of poultry nutritionists. Even though this learning process is not yet completed, it is now generally accepted that a balanced inclusion of fibre contributes directly and indirectly to proper intestinal functions and promotes gut health as a basis for high resorption capacity of nutrients. In this context, the most important criterion is the quality of supplemented fibre. A highly insoluble, slowly fermentable and mycotoxin-free fibre source will stimulate the gut motility, contribute to gizzard development and can even, to a certain extent, provide additional energy. Different fibre sources meet some of these criteria, but there is one specific lignocellulose product combining them all. Although this so-called “eubiotic” lignocellulose (OptiCell®


, agromed Austria GmbH) derived


from fresh wood is purely insoluble and acts physically on the gut wall optimizing its peristaltic activity within physiologic limits, it contains a share of fermentable portion, which will be degraded microbially after passing through the small intestine and entering the caecum. Within this fermentation process the formation of volatile fatty acids cause a drop of intestinal pH-value providing an unfavourable milieu for pathogenic bacteria, and, more importantly, butyric acid will be directly utilized by the hens’ colonocytes as a source of energy, allowing for an improved gut development. Intestinal villi significantly increase in their length, which improves the intestinal absorptive surface and, hence, facilitates the uptake of nutrients and minerals. This effect was measured in a feeding trial at the University of Sao Paulo in 2018, where 312 laying hens were randomly allocated to three treatments. Birds either were fed a standard diet or a diet supplemented with above mentioned eubiotic lignocellulose (LC) in two different inclusion rates. The effects on the gut development are summarized in table 1. This holistic approach of having impact on the entire gastrointestinal tract contributes to high laying performance and can help to strengthen eggshell quality. In both LC-treatments the force needed for breaking the eggs was significantly higher (50.9 N and 51.1 N for an LC inclusion of 1% and 2%, respectively) compared to the control group (49.2 N). In another, relatively novel, approach wood-based feed


supplements are added to layer feed due to the bio-active substances contained in selected wood species and special parts of those trees. One of these wood-derived products (agromed®


ROI, agromed Austria


GmbH) contains a lignan rich bark. These wood lignans are potent at reducing or scavenging free radicals, inhibiting lipid peroxidation and to preventing the formation of hydroxyl radicals. A combination of antioxidative and anti-inflammatory effects enables small dosages of these wood-derived supplementary feeds to efficiently counteract oxidative stress and contributes to a well-functioning liver tissue, which is of fundamental importance for a highly elastic eggshell especially in old laying hens.


PAGE 44 JANUARY/FEBRUARY 2021 FEED COMPOUNDER


Conclusion Different strategies to improve performance in laying hens aim for benefits in both economic and environmental aspects. A prolongation of the hens’ laying cycle with a stabilization of laying persistency is a major aim. One crucial challenge is the negative correlation of egg size and bird’s age. A thinner eggshell in bigger eggs increases the risk of breakage and thus, represents a limiting factor of the duration of a laying cycle. Asides from genetic selection, nutritional strategies can counteract these problems and contribute to an improved laying performance. Feed additives derived from wood represent a promising solution to address various challenges in egg production. This is on the one hand due to their physical and physiological effects on the entire digestive tract, which are realised through a sophisticated composition of different fibre qualities to improve intestinal development and on the other hand due to the bioactive substances of certain parts of selected wood species that counteract physiological stress.


References: M.M. Bain, Y. Nys & I. C. Dunn (2016) Increasing persistency in lay and stabilizing egg quality in longer laying cycles. What are the challenges? British Poultry Science, 57:3, 330-338 I. Bouvarel & Y. Nys (2013) Optimizing egg mass and quality traits in modern laying hens through nutrition. Proceedings of the 19th


European


Symposium on Poultry Nutrition, Potsdam M.S. Fernandez, C. Escobar, I. Lavelin, M. Pines & J.L. Arias (2003) Localization of osteopontin in oviduct tissue and eggshell during different stages of the avian egg laying cycle. Journal of structural biology, 143:3, 171-180 A. Molnar, L. Maertens, B. Ampe, J. Buyse, I. Kempen, J. Zoons & E. Delezie (2016) Changes in egg quality traits during the last phase of production: is there potential for extended laying cycle? British Poultry Science, 57:6, 842-847 R. Pottgüter (2016) Feeding laying hens to 100 weeks of age. Lohmann Information, 501, 18-21 R. Pottgüter (2019) Der Weg zu stabilen Eischalen und Knochen. Conference Presentation, Germany M. Reynard & C. J. Savory (1999) Stress-induced oviposition delays in laying hens: duration and consequences for eggshell quality, British Poultry Science, 40, 585-591 J. R. Roberts (2004) Factors affecting egg internal quality and eggshell quality in laying hens. Journal of Poultry Science, 41, 161-177 E. Sengor, M. Yardimci, S. Cetingul, I. Bayram, H. Sahin & I. Dogan (2007) Effects of short chain fatty acid (SCFA) supplementation on performance and egg characteristics of old breeder hens. South African Journal of Animal Science, 37, 158-163 S. Swiatkiewicz, J. Koreleski & A. Arczewska (2010) Laying performance and eggshell quality in laying hens fed diets supplemented with prebiotics and organic acids. Czech Journal of Animal Science, 55, 294-306


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