Impact of incubation temperature profile on chick quality, bone, and immune system during the late period of incubation of Cobb 500 broiler strain

The present study was conducted to examine the impact of incubation temperature profile on embryonic growth and chick quality post-hatch. Hatching eggs (n = 405) were incubated in a Jamesway PS-5000 single-stage incubator at 37.5°C and 56% RH until embryonic day 14 (ED14). At ED14, 135 eggs each were transferred into 3 identical G.Q.F. MFG. CO incubators, and each set to one of the following incubation temperatures: 36.5°C, 37.0°C, and 37.5°C. Data on eggshell temperature (EST) and embryo quality were collected from ED15 to ED20. At hatch, chick quality and leg bone qualities were assessed. Blood collected from chicks was used to assess hematological and immunological parameters. The remainder of the chicks was reared on standard broiler feed for 8 wk to measure growth performance. Data were analyzed using the SAS Proc. GLM at P ≤ 0.05. The daily EST was higher at 37.5°C incubation temperature compared to 36.5°C and 37.0°C during ED15 to ED21. Chicks of 37.5°C had early external pipping and hatching times compared to 36.5°C. There were no significant differences in external chick quality parameters. The chick leg bone Ca and P levels increased with increasing incubation temperature at day old, 4 wk, and 8 wk. Besides mean corpuscular hemoglobin and concentration, which were higher at 37.5°C compared to 36.5°C and 37.0°C, all blood parameters measured were not different. Bone mineral levels may not be the same as bone development. Therefore, appropriate incubation and nutritional strategies are needed to increase bone development, and broiler growth to reduce leg problems.