the present study was carried out to estimate responses of Fayoumi chickens to in ovo injection of some nutrients during late stage of incubation and post-hatch. At 18 day of incubation 360 eggs contain live embryos were chosen and distributed randomly into 6 treatment groups each of which contain 60 eggs divided into 3 replicates (20eggs/replicate). Eggs in group 1 confirm control treatment without injection but eggs in group 2 injected with pure Marek's solution and performed sham treatment. Eggs in groups 3, 4, 5 and6 injected with 0.2 mm3Marek's solution contain 5mgglutamine/egg,5mg methionine /egg, 16mg L-carnitine/egg and 5mg betaine/egg respectively. Hatching, growth performance and some hematological parameters were measured, moreover response against Newcastle disease vaccination and liver histopathology were estimated.
The following results were obtained:
1- Most parameters didn't recorded significant differences between control and sham treatment which reflect success of injection procedure and time.
2- In ovo glutamine injection decreased hatchability percent but increased hatch weight compared with control treatment. Glutamine injection improved growth performance compared with other treatments except for betaine injection
3- In ovo methionine injection significantly (P≤0.05) decreased hatchability percent and significantly (P≤0.05) increased hatch weight compared with control. Methionine didn't provide significant improvement in growth performance.
4- In ovo L-carnitine injection decreased hatchability percent and hatching weight than control treatment and recorded the worst growth performance.
5- In ovo betaine injection improved hatching parameters and achieved the best growth performance and physiological state.
6- Histopathological results show that in ovo L-carnitine injection presented liver damage and support hatching and growth results. In general we recommend using in ovo betaine injection to improve hatchability, growth performance and physiological state of Fayoumi chickens.