Evaluation of Incubation Yield, Vaccine Response, and Performance of Broilers Submitted to In-Ovo Vaccination at Different Embryonic Ages

ABSTRACT The aim of this study was to evaluate the effects of in-ovo vaccination on different incubation days of broiler embryos derived from young and old breeders on incubation indexes, vaccine response, and broiler performance. A number of 20,160 fertile eggs was distributed according to a completely randomized design in a 4 x 2 factorial arrangement (in-ovo vaccination on 16, 17, 18, or 19 days of incubation, and breeders of 31 or 52 weeks of age), totaling eight treatments with 15 replicates of 168 eggs each. Vaccination procedures and vaccines (strains and doses) were those routinely app...