Développement d’une stratégie d’immunisation passive du poulet de chair vis-à-vis de Salmonella Enteritidis et Typhimurium à l’aide d’anticorps du jaune d’œuf

The present study investigates the potential of oral immunotherapy using hen egg yolk immunoglobulins (IgY) as a strategy to reduce the impact of Salmonella contamination on broilers. In a first step, hyperimmune eggs were obtained from laying hens immunized using Salmonella Enteritidis (SE) and Typhimurium (ST) outer membrane proteins in emulsion with Freund adjuvants. This led to the production of high levels of IgY antibodies directed against the two Salmonella serovars in egg yolks. Furthermore, no adverse affects were detected on mortality or laying rate in hens injected with this vaccine. Powders were obtained from these eggs by spray- or freeze-drying the whole yolk. In order to study the effect of these powders on broiler’s growth performances, a challenge trial was conducted. 384 Salmonella spp.-free day-of-hatch chickens received supplemented feed (5 % freeze-dried egg yolk powder) since arrival, and were infected at day four with 106 cfu of SE and ST per animal. We found a significant improvement in growth performances for the groups receiving the yolk-enriched diets. Nevertheless, none of the supplement concentrations allowed to raise the same body weight after 28 days of complementation than in uninfected broilers (p < 0,05). Interestingly, nonimmune egg yolk powder also exhibited a positive effect on performances of broilers experimentally infected with SE and ST. Our results suggest that passive immunization through egg yolk powders could be useful to reduce negative effects of Salmonella infection on broilers growth performances.