Poultry production faces several challenges related to the use of natural resources, with feed efficiency being the factor that can be influenced through the use of different nutritional strategies. Proper use of exogenous enzymes, such as xylanase, could improve growth performance, feed conversion, gut health, and improve environmental problems as fewer undigested nutrients are excreted. In this way, the present work seeks to increase the knowledge about the suggested action mechanisms of this enzyme as well as to investigate the relevance of some dietary factors that may be affecting the efficiency of xylanase in the production of broiler chickens. Four studies were designed with the aim of testing the following hypotheses. The carbohydrases, specially xylanase, could be a part of a multidisciplinary antibiotic's displacement strategy. Therefore, the Article I is a literature review performed in order to compare the xylanase suggested mechanisms (nutrient digestibility, microbiota modulation and improvement of intestinal health) and the described antibiotic effects when are used as growth promotors in animal diets. The available literature showed that it is difficult to consider that enzymes per se can replace antibiotics in efficient animal production, but it is plausible to think that they can be part of a holistic program that reduces the negative impact of antinutritional components as challenging compounds for intestinal health and efficiency. The variability in the physicochemical composition of corn could affects the xylanase response. Therefore, Article II is an "in vitro" test that was carried out using the genetic background of corn and the position of the ear as a source of nutrient variability and where the xylanase response was evaluated. The results showed that the xylanase supplementation increase the soluble components of the corn independently of the physicochemical variation, however, the xylotriose production interact for both the position of the kernels in the cob and genotype, showing that the corn physicochemical composition can affect the response of the enzyme at least in the production of XOS. The nutrient variation associated to the genotype affects the broiler performance and nutrient utilization. Therefore, in Article III an in vivo trial was development in order to study how the variability of physicochemical composition of corn, due to genetic background, could produce negative interactions among the different physicochemical components, and consequently changes in broiler chicken's growth performance and nutrient digestibility. The results showed that the variation in the content and nature of the non-starch polysaccharides in corn can reduce the performance and digestibility in broilers mainly due to the capture of nutrients. The corn particle size distribution affects the xylanase response influencing the performance and intestinal health of broiler chickens fed with corn-based pelleted diets. Therefore, in the Article IV the xylanase response was evaluated in different particle size distributions of corn-based pelleted diets. The results showed that the xylanase prebiotic mechanism was affected by particle size in corn-based pelleted diets. The effectiveness of the enzyme and gizzard development could be improved by considering using coarse particle size distribution in pelleted diets.
Feed-associated factors to xylanase response in corn-based poultry diets
Melo Duran, D. A. (Author). 28 Sept 2021
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis