Progeny benefits by the use of Salmonella Enteritidis oily vaccine in broiler breeders.

Background: Bacteria of the genus Salmonella spp. are recognized as being one of the most common bacterial causes of foodborne disease. Its presence in chickens and hatching eggs is an important barrier to exports, besides posing a potential risk to human health. Companies producing broiler breeders aim at having excellent quality progeny for good hatching results and for providing healthy chicks. The use of inactivated, oily vaccines is one of the strategies to control Salmonella Enteritidis, by providing protection for broiler breeders. This protection can also benefit the progeny, so giving it some protection on the early period post-hatch. Thus, this study aimed at evaluating the benefits on the progeny of the use of inactivated, oily vaccine for Salmonella Enteritidis in broiler breeders. Materials, Methods & Results: Inactivated, oily Salmonella Enteritidis vaccine was injected in eight, and 19 weeks old breeder birds. Monitoring for Salmonella was performed by the use of drag swabs, two per each house, and 10 cloacal swabs by each poultry house, where each swab represented a pool of three birds sampled. In the hatchery, monitoring for Salmonella was performed on each lot, where each sample consisted of 10 pipped eggs per lot (850 samples) and 10 stillbirth chicks (850 samples), totaling 1.700 samples altogether. From the 850 pipped eggs samples, 1.18% were positive in vaccinated batches while 33.88% were positive in non-vaccinated batches. Regarding the 850 samples of stillbirth chicks, 1.88% were positive in vaccinated batches and 24.70% were positive in non-vaccinated batches. The percentage of Salmonella positive flocks in drag swabs collected from houses with broilers descending from non-vaccinated mothers was 4.38% (502 swabs), while those originated from vaccinated mothers showed a positivity of 1.26% (475 swabs). Nonparametric test (Chi-square) was used the to assess the frequency of Salmonella at a significance level of 5% and the results were analyzed by Epi Info software version 7. Discussion: The administration of inactivated, oily vaccines was able to confer protection to the progeny, reducing its sensitivity to early bacterial infections, through the protection given by maternal antibodies, and as a consequence reducing the Salmonella Enteritidis isolation rates in pipped eggs, stillbirth chicks in the hatchery and in drag swabs performed on chicken farms. Salmonella was recovered from progenies of unvaccinated lots, either from pipped eggs or stillborn chicks. The stillborn chicks originated from vaccinated breeders showed a lower frequency of Salmonella isolation when compared to stillborn coming from non-vaccinated batches. The progenies of breeder birds vaccinated against Salmonella Enteritidis (inactivated vaccine) were more resistant to infection by the presence of maternal antibodies. The controlling of the agent through immunization with inactivated vaccines is a measure of utmost importance, since protecting birds against clinical disease reduces contamination of products intended for human consumption. On the other hand, despite vaccination is an important tool for the control of Salmonella in poultry, its sole use is deemed insufficient for the complete control of the bacteria, since Salmonellosis have been detected even in a mother vaccinated progeny. Biosecurity practices, adequate management and training of involved personnel are also necessary for the effective control of the bacterial agent.