An investigation into the gut health promoting mechanisms of a xylooligosaccharide based prebiotic in broilers

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Amir, S.E., 2021. An investigation into the gut health promoting mechanisms of a xylooligosaccharide based prebiotic in broilers. PhD, Nottingham Trent University.

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Abstract

Poultry meat and eggs are highly significant sources of (nutrient dense) animal proteins in human nutrition. Fast growth, affordability, global acceptability and low environmental impact makes poultry a leading contender in the race for securing food for the future. The EU-wide ban in 2006 on the use of in-feed antibiotics as growth promoters obligated the poultry industry to use plant or microbial derived additives to promote bird health and performance which would ensure sustainable growth of the poultry industry without adding to the threat of antibiotic resistance. Prebiotics are a category of in-feed antibiotic alternatives produced from human inedible agricultural residues and have been shown to improve gut health and thus the overall health of the animals. Amongst prebiotics, xylooligosaccharides (XOS) are gaining significant attention due the vast abundance of its parent molecule, xylan, in the plant kingdom. A limited understanding of the mechanisms of action of XOS has hampered improvements to their efficacy. The aim of this research project was therefore to examine the underlying effects of XOS that may lead to gut health promotion and performance improvement of broiler chickens. Two broiler trials, one under controlled research conditions and another under suboptimal conditions mimicking commercial broiler production units were conducted and an in vitro study was undertaken to achieve this aim.

The results demonstrated that in birds raised under controlled research conditions, neither 0.1 g/kg XOS nor xylanase nor their combination had any significant effect on performance or the assessed gut health parameters which included composition and diversity of caecal microbiota, gene expression of biomarkers of gut integrity and caecal short chain fatty acid (SCFA) concentrations. On the other hand, under sub-optimal conditions the same dose of XOS significantly improved performance up to 28- days of age. Although, there was no significant difference in the diversity or overall composition of microbiota in birds raised under sub-optimal conditions, XOS specifically enhanced the numbers of certain members of Lachnospiraceae family (phylum Firmicutes) known to produce SCFAs. In addition, in the same trial, expression of mucin glycoprotein (MUC2) and tight junction protein occludin (OCLN) in the ileum and caecal acetate and propionate were significantly increased at day 35. In the in vitro study, shot-gun proteomics analysis on proteins extracted from the caecal microbiota was used to provide the earliest evidence support the stimbiotic mechanism of XOS which essentially implies that they stimulate the growth of the fibre fibre-degrading microbiota members eventually increasing the nutritive value of feed. The caecal bacteria from chickens fed a XOS supplemented diet, had upregulated the proteins involved in degradation of xylan compared to bacteria from the control group.

Overall, this study supports the use of XOS to improve gut health and performance of broilers raised under challenging environmental conditions or as a "stimbiotic" to improve nutritive value of feed by facilitating the breakdown of its fibre fraction.

Item Type:	Thesis
Creators:	Amir, S.E.
Date:	June 2021
Rights:	This work is the intellectual property of the author, Saba Erum Amir. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the owner(s) of the Intellectual Property Rights.
Divisions:	Schools > School of Animal, Rural and Environmental Sciences
Record created by:	Linda Sullivan
Date Added:	28 Mar 2023 10:05
Last Modified:	28 Mar 2023 10:05
URI:	https://irep.ntu.ac.uk/id/eprint/48641