Abstract: Measuring the index of bursa of fabricius to research the law of growth.10 health broilers from ten different days age were selected randomly from broilers. And 10 health layers from twelve different days age were selected randomly from layers. Bursa of fabricius were weighted after aliveness weight and dissection. Then measured the length, width and thickness of bursa of fabricius. Meanwhile made paraffins section for HE staining, and measured the length, width, thickness of cortex and medulla of folliculus. The results showed that the weight increase of bursa of fabriciu were positive correlation along with days and weight increasing for broilers, and grew to the top on the 49 day-age, and the law of growth for folliculus was same to the bursa of fabriciu. The weight increase of bursa of fabriciu was growing from 1 to 68 days old, and reduced from 68 to 96 days old for layers, and the law of growth of folliculus was same to the bursa. However, the ratio of bursa of fabriciuto weight had certain correlation along with days and weight increasing for broilers and layers.

Key words: broiler chicken; layer chicken; bursa of fabricius; folliculus