title: Field safety and efficacy of in ovo administration of HVT + SB-1 bivalent Marek's disease vaccine in commercial broilers.
abstract: The field safety and efficacy of a bivalent Marek's disease (MD) vaccine (herpesvirus of turkeys + strain SB-1) administered in ovo were evaluated. The vaccine was administered to commercial broiler chicken eggs using Embrex's INOVOJECT automated egg-injection system. Comparisons were made with a conventional method of vaccination, in which the vaccine was administered subcutaneously to chicks at hatching. In ovo administration of the vaccine at day 17.5-18.5 of incubation significantly reduced the number of culled chicks, early mortality, and overall mortality during the grow-out period compared with conventional vaccination. However, hatchability was significantly lower in in ovo-treated chicks. Overall livability and feed efficiency were higher in the in ovo-treated chicks than in conventionally vaccinated chicks. Total field-caused condemnations and condemnations due to airsacculitis and septicemia/toxemia were also lower in the in ovo-vaccinated chicks. No difference in the leukosis (MD) condemnation rate was observed between the two treatment groups. In ovo vaccination provided 93.25% protection against challenge with a very virulent strain of MD virus (strain RB1/B); by comparison, the conventional vaccination method provided 89.58% protection.
authors.affiliation: Tri Bio Laboratories, Inc., State College, Pennsylvania 16803, USA.
authors.forename: G
authors.initials: G
authors.lastname: Sarma
authors.forename: W
authors.initials: W
authors.lastname: Greer
authors.forename: R P
authors.initials: RP
authors.lastname: Gildersleeve
authors.forename: D L
authors.initials: DL
authors.lastname: Murray
authors.forename: A M
authors.initials: AM
authors.lastname: Miles
mesh_terms: D000818:Animals; D001835:Body Weight; D002642:Chick Embryo; D002645:Chickens / Q000254:growth & development; D004334:Drug Administration Schedule; D004734:Energy Metabolism; D008380:Marek Disease / Q000517:prevention & control*; D012449:Safety; D014611:Vaccination / Q000379:methods / Q000662:veterinary*; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D014765:Viral Vaccines