Perspectives de l'usage de poudre de jaunes d’oeuf comme additif alimentaire contre Campylobacter jejuni chez le poulet : mode d'immunisation et effet de l’encapsulation
Campylobacteriosis is a zoonosis caused by Campylobacter jejuni, a commensal bacterium of chicken. Chickens are considered the main identified source of human infection. C. jejuni is rarely found in the digestive tract of chickens before two or three weeks of age. Part of this may be caused by the transmission of maternal immunity (IgY antibodies) to the chicks via the egg yolk. At the Research Chair in Meat Safety (RCMS), a characterization of IgY antibody extracted from fresh egg yolks showed different production levels of antibodies, depending on the mode of immunization of the laying hens, and were proven, in vitro, to recognize  the pathogen. These findings suggest that, as a feed additive, a potentiated egg yolk powder could fight against C. jejuni colonization in broilers. In this work, the additive manufacturing process (dehydration by « Spray dry » and then encapsulation) is evaluated and the different methods used to immunize the corresponding laying hens were also compared. Antibodies were extracted from the egg powers or the final encapsulated product, and characterized in vitro (dosage/ELISA, mobility and bactericidal tests, Western blot). Then, an in vivo assessment of the ability of these encapsulated powders, incorporated at 5% in the feed, to reduce or block intestinal colonization by C. jejuni in birds was tested. In vitro results showed antibody concentrations and effectiveness were variable depending on the type of immunization. In this study, it was observed that the “spray drying” concentrated the antibodies in powders and that these antibodies remained functional against C. jejuni. It was also observed that encapsulation does not lead to quantitative and quantitative loss of antibodies contained in the powder. However, despite the encouraging in vitro results, in the in vivo C. jejuni assay, no inhibition or reduction of birds’ colonization could be observed. This lack of effectiveness of the encapsulated egg yolk powders should not be due to a loss of the quantity and/or quality of the antibodies as supported in the in vitro experiments. This shows that more research is needed to determine the optimal conditions for potentialized egg yolk powder to be use in vivo as a food additive to control C. jejuni colonization in chickens.
Campylobacter jejuni Immunoglobuline Campylobacter jejuni Chicken colonization Egg yolk powder Immunoglobulin