Effect of Embryonic Development on the Chicken Egg Yolk Plasma Proteome after 12 Days of Incubation

To better appreciate the dynamics of yolk proteins during embryonic development, we analyzed the protein quantitative changes occurring in the yolk plasma at the day of lay and after 12 days of incubation, by comparing unfertilized and fertilized chicken eggs. Of the 127 identified proteins, 69 showed relative abundance differences among conditions. Alpha-fetoprotein and two uncharacterized proteins (F1NHB8 and F1NMM2) were identified for the first time in the egg. After 12 days of incubation, five proteins (vitronectin, alpha-fetoprotein, similar to thrombin, apolipoprotein B, and apovitellenin-I) showed a major increase in relative abundance, whereas 15 proteins showed a significant decrease in the yolks of fertilized eggs. In unfertilized/table eggs, we observed an accumulation of proteins likely to originate from other egg compartments during incubation. This study provides basic knowledge on the utilization of egg yolk proteins by the embryo and gives some insight into how storage can affect egg quality

Antimicrobial potential of egg Yolk ovoinhibitor, a multidomain Kazal-like inhibitor of chicken egg

Chicken egg ovoinhibitor is a multidomain Kazal-type serine protease inhibitor with unknown function. Comparison of expression between different tissues indicated that ovoinhibitor is highly expressed in the magnum and liver followed by the uterus, which secrete egg white, egg yolk, and eggshell precursors, respectively. The results also revealed that ovoinhibitor expression is increased in the liver during sexual maturation followed by a subsequent decrease in mature hens. Ovoinhibitor was purified from the egg yolk plasma from nonfertilized eggs using two consecutive affinity chromatographies and gel filtration. Purified egg yolk ovoinhibitor was shown to inhibit trypsin and subtilisin. It was shown that purified egg yolk ovoinhibitor exhibited antimicrobial activities against Bacillus thuringiensis. The results suggest that this anti-protease plays a significant role in antibacterial egg defense against Bacillus spp., preventing contamination of table eggs (nonfertilized eggs) and protecting the chick embryo (fertilized eggs)

Strategies for reinforcing hygienic quality of table eggs.

This review describes different strategies which have been explored to reduce food safety risks associated with egg contamination. The first one aims to reinforce the physical (eggshell) and chemical (antimicrobial proteins) protective mechanisms of eggs by identifying genes that code for proteins involved in egg protection. The following step is to explore phenotypic variability in egg protection against Salmonella related to environmental factors during egg production and storage and the feasibility to select hens with superior eggshell strength or anti-microbial alleles using marker assisted selection. A complementary approach is to eliminate eggs at risk by improving the technology for egg grading using non-invasive methods to enhance the detection of eggs with the greatest risk to the consumer. Finally, the risk can be controlled by reducing the degree of egg contamination by developing innovative egg decontamination treatments as alternatives to egg washing. We explored the decontamination efficiency of hot air, gas plasma sterilization, modified atmosphere packaging or chitosan treatment of eggs. These approaches were developed under two European programmes, Eggdefence and Rescape