The effect of Marek's disease vaccination and day-old debeaking on the performance of growing pullets and laying hens.

In a 2 X 2 completely randomized factorial design, four hundred day-old Single Comb White Leghorn pullets were randomly assigned to four treatment combinations of vaccinated, non-vaccinated, debeaked and non-debeaked groups. Vaccination and debeaking were performed at day-old by administering 2,000 P.F.U. of HVT vaccine/chick and by removing approximately 2/3 of the upper beak, respectively. All the data were analyzed at 5% level of probability. Vaccination reduced feed consumption significantly only during the early growing period of the first 12 weeks, whereas debeaking caused a significant reduction in feed consumption throughout the experimental period of 80 weeks. Mortality during the 20-week growing period was not affected by either vaccination or debeaking. During the laying period (20-80 weeks of age), vaccination reduced the mortality numerically, while debeaking reduced the mortality significantly. Final body weight, hen-day egg production, egg weight, albumen height and egg shell thickness were not influenced by either vaccination, debeaking or a combination of the two. Debeaking had no effect on the incidence of blood-spotting in the eggs. Vaccination, however, significantly reduced percent blood spots in the eggs. Day-old debeaking effectively prevented the occurrence of cannibalism.