Effect of Thermal Manipulation During Embryogenesis on Hatched Broiler Immunity
This study was conducted to investigate the effect epigenetic adaptation by thermal manipulation (TM) during
different stages of embryogenesis broiler breeder eggs by using an intermittent temperature treatments with amplitude of 1
°C higher than the standard incubation temperature for 4 hours daily at embryonic days (ED): T1 (1-5), T2 (8-12), T3 (14-
18), T4 (19-21) and T5 was control (no TM), also through early age thermal conditioning chicks by exposing them to 38.0 ±
2 °C for 12 hours/day at 5th and 7th days of age then from the beginning of 4th week and onward the birds acclimated to
elevated heat of 26±2 °C, on post-hatch broiler weekly and accumulative mortality percentage (%) and immunity. Six
hundred (600) day-old chicks were randomly assigned according to treatment groups during hatching process. Chicks were
distributed into five treatments with four replicates/group, with thirty chicks per each replicate (15 for each sex), all
treatment groups were subjected to 38 ±2 °C for 12 hrs/day at 5th and 7th days (d) post-hatching as thermal conditioning
(TC). At 30 days of age blood samples were taken to determine the serum antibodies titer against NDV, IBD and IBV. The
overall data showed that T2 and T3 showed significantly (p≤0.05) lower mortality percentage than other thermally
manipulated groups also than control group along the rearing period of (1-35d & 1-42d). While, T4 had significantly
(p≤0.05) higher immunity than other groups.
It can be concluded that: Using of epigenetic adaptation lead to T2 and T3 groups had less accumulative mortality
percentage along the period of (1-35d) and (1-42d). T4 group owned highest immunity against NDV, IBD and IBV.
Keywords— Epigenetic adaption, Thermal manipulation, Early age heat conditioning, Immunity.