Effect of in ovo Injection of Royal Jelly on Post‐Hatch Growth Performance and Immune Response in Broiler Chickens Challenged with Newcastle Disease Virus

The aim of this experiment was to study the effect of in ovo injection of royal jelly (RJ) on growth perform-ance and immune response in broiler chickens challenged with Newcastle disease virus. A total of 200 hatching eggs were divided into four groups of 50 eggs each one using a completely randomized design. The eggs were injected with sterilized sodium bicarbonate buffer (pH=10.4) or RJ (88%) in a 0.3 mL vol-ume into the albumen at d 7 of incubation. A non-injected control and a dry punch control (shell pricked without injecting solution; needle) were included. Chicks hatched from the respective treatment group were reared in floor pens until d 28. The chickens were challenged against Newcastle disease virus on days 7 and 21. On d 21, the chickens emanated from the RJ injected egg had the highest body weight. In ovo injection of RJ had a significant effect on feed intake in broiler chickens during starter period (d 1 to 21) and throughout the trial (d 1 to 28; P<0.05). On d 14, serum antibody titer against Newcastle disease virus (NDV) was not significantly different among treatments. On d 14 and 28, heterophil and lymphocyte num-ber and their ratio were affected by in ovo injection. In conclusion, the results of the present study suggested that in ovo injection of RJ on d 7 of incubation exerted a beneficial effect on growth in starter phase and could stimulate feed intake in broiler chickens challenged with Newcastle disease virus, although the antibody titer against NDV was not influenced.