Enhancing broiler embryo immunity and tibia ossification via In ovo L-glutamine injection

In ovo, injection of nutrients into the chicken embryo can modulate the embryo’s immune response. This hypothesis was tested with an in ovo L-glutamine (L-glu) solution injection. On the 10th day of incubation, 225 embryonated eggs were injected and/or not injected with 300 µL of L-glu solution. Residual yolk sac weight, relative embryo weight, tibia weight and length, and mortality were recorded during the incubation. On the day of hatching, blood samples were collected to assess immune responses, and the histology of lymphoid organs was examined. Additionally, the gene expression of interleukins, including IL-2, IL-6, IL-10, and IL-17, as well as IFN-γ, IFN-β, IFN-α, TNF-α, and TLR-4, was assessed in the spleen and bursa of Fabricius. On the day of hatching, the in ovo L-glu injection showed zero mortality, compared to the control groups, which recorded a mortality rate of 1.66%. Tibia bone weight and length were enhanced (p ≤ 0.01) in the L-glu-treated group compared with those in the control group. Regarding the immune response, the in ovo L-glu injection generally induced an increase in the embryo’s immunoglobulin level at 21 days of incubation. Therefore, the in ovo iinjection of L-glutamine could potentially boost broiler chickens’ immune responses, enhance tibia bone development, and improve overall health.