Cute-Egg, improvement of eggshell cuticle quality to reduce vertical transmission of zoonotic and pathogenic organisms

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The cuticle is a glycosylated protein layer which covers the external surface of the egg and fills the gas exchange pores through which the embryo 'breathes'. The cuticle is critical to minimising the risk of vertical and horizontal transmission of pathogenic or zoonotic organisms to the egg contents which is un-desirable for food safety, animal and human health. This project will use physiochemical, physiological and genetic methods to provide the information and tools necessary to make precision genetic selection for improved cuticle quality in both meat and egg laying hens.
The objective of the work is;
1) to use excitation-emission-matrix spectroscopy to determine the parameters for discrimination of the cuticle from background fluorescence and to design and build an instrument that can rapidly and accurately measure cuticle coverage,
2) to apply this direct measurement to estimate reliable heritabilities for cuticle coverage in meat and egg laying strains of poultry and to determine genetic correlations with important production parameters to ensure there are no major negative consequences,
3) to test the hypothesis that (i) moderate levels of stress, (ii) events determining the timing of oviposition and (iii) bird age influences the level of cuticle coverage and to estimate the contribution of these environmental factors to cuticle variation,
4) to develop a method to measure the degree of glycosylation of the cuticle using time resolved fluorescence,
5) to test the hypothesis that the cuticle and its degree of glycosylation acts both as a physical and a chemical barrier to bacteria using penetration and recovery experiments with a range of GFP bacteria,
6) Using animals killed during the transition from shell to cuticle formation and oviposition we will profile the expression of genes to increase our understanding of the control of cuticle formation. We will also specifically measure genes we know from proteomic studies that encode cuticle proteins.

The principle benefit from this research will be a reduction in the transmission of potential pathogens from parent to offspring via the egg of poultry. In particular organisms of enteric origin such as E Coli, Enterococcus faecalis, Yersinia enterocolitica, Clostridium Perfringens all of which reduce growth, health and welfare and are known zoonotics.

This is of benefit to the poultry industry where birds that lay eggs with good cuticles will result in savings to farmers all the way down the production chain with reduced losses and better protection from disease. For E. Coli infection alone it is estimated that the cost for a typical farm is in the region of £360,000 per annum (World Poultry Vol. 25 No. 5, 2009). With continual pressure to remove antibiotics any system that improves natural antimicrobial defence is important.

The proposal also addresses the concerns of governmental agencies such as the European Food Safety Authority which has identified vertical transmission of antibiotic resistant strains of bacteria in poultry as a major source of flock infection and an impediment to creating clean flocks.

The development of a simple tool and its application to breeding poultry will therefore ultimately reduce the risk to consumers and improve the safety and sustainability of poultry production by utilizing the natural antimicrobial defenses of the egg.

The development of methods to measure the cuticle will be of interest to a range of academics involved in the poultry industry and in wild birds and may provide commercial opportunities. The novel techniques for measuring glycosylation are likely to have interest across biological disciplines and would have wide application beyond that envisaged in the proposal.