Effects ofinjection of 25(OH)Din combination with Marek's disease vaccine on hatchability, performance and bone health of broilers.

Abstract

1. This study assessed the effects ofinjection of Marek's disease vaccine (MDV), alone (control) or combined with 1.25 μg of 25-hydroxycholecalciferol (25(OH)D), on hatchability, chick quality, performance and bone quality in Cobb 500 broilers. At d 19 of embryo development, eggs were injected with 0.05 ml of MDV or MDV plus 1.25 μg of 25(OH)Dinto the amniotic fluid following hatchery protocol. Post-hatch, 840, one-day-old male chicks were reared until d 35 of age.2. Hatchability and general chick quality were not affected by the treatments. However, the male chicks that received MDV + 1.25 μg of 25(OH)Dpresented longer length at flock thinning compared to those that received only MDV. At 35 d of age, broiler performance, gait score and leg deformities (valgus and varus) were not affected.3. Although chicks receiving the MDV + 1.25 μg of 25(OH)Dhad lower macroscopic tibial dyschondroplasia (TD) scores at 7 d of age compared to those given MDV, this difference was not sustained as they matured. Tibia weight, thickness and length were similar across treatments at all time points. However, the tibiae from chicks in the MDV + 1.25 μg 25(OH)Dgroup demonstrated greater strength on d 1 and 7 but not at later times.4. In conclusion, this study showed that combining 25(OH)Dwith MDV does not impact hatchability or overall performance but does enhance early bone strength and growth in broiler chicks.