Dear Dr. Shanmugam,
For chicks, innate immunity is started from egg yolk utilization. Therefore, we need to recognize the quality of chick, which had absorbed yolk before placed to the house. When you have a good chick quality due to hatchery management, you dont need to care of chicks after placed. They can manage their mortality and production performance ability. I think that you need to focus on the breeder immunity for broiler performance. It can be affected from them. Kind regards.