The cute-egg project is a study, which aims to quantify and improve the quality of the eggshell cuticle
Commercial poultry production relies on the artificial incubation of eggs. Conditions in the incubators are as ideal for rapid microbial growth as they are for the growth and development of the embryo and keeping micro-organisms out of the egg can be a challenge.
Opportunities for horizontal transmission occur during the collection and transportation of eggs and the vertical transmission from breeder hens to production flocks has been identified by EFSA as the most likely route of transfer of antibiotic resistant E. coli and Salmonella spp. Irrespective of the route or site of transfer, the entry of pathogenic or zoonotic organisms to the egg contents is undesirable for food safety, animal and human health.
The cuticle is a glycosylated protein layer, which covers the surface of the egg. We have previously presented evidence, which confirms that the cuticle forms the first line of defense to the penetration of bacteria and that cuticle deposition can be quantified by staining eggs and measuring the change in % reflectance by spectrophotometry at 640nm. Using this rather cumbersome methodology we were able to establish that cuticle deposition in layer hens is a heritable trait (h2, 0.27) and therefore has the potential for improvement by genetic selection. The cute egg study addresses the physiochemical, physiological and genetic parameters that characterise the cuticle and the development of a new simple one step measurement tool for cuticle assessment. These preliminary results indicate that the repeatability of our new measurement, which makes use of fluorescence is high (0.76) and better than that previously obtained using the staining method (0.56). The correlation between the original dye method and our new fluorescence measurement is moderate; however this may be because our new spectroscopic method is measuring different parameters than the staining method. We are now at the advanced stages of applying our new one step measurement to collect data from pedigreed birds for the estimation of genetic parameters for cuticle coverage in both meat and egg laying strains of poultry and to determine its genetic relationship with measures of production and bacterial translocation into the eggs. The results generated will be useful for accurate genetic selection to improve cuticle coverage and reduce the risk of pathogens entering the egg. This project will also deliver fundamental knowledge about the biological mechanisms which give rise to the cuticle, its role as a physical and chemical barrier to microbial penetration.