Pathological Changes and the Effects of Ascorbic Acid on Lesion Scores of Bursa of Fabricius in Broilers Under Chronic Heat Stress

摘要

The present study was undertaken to understand the effect of chronic heat stress on the pathological changes and the effects of ascorbic acid on lesion scores of bursa of Fabricius in broilers. Broilers were maintained at an environmental temperature of 33±1°C for 21 days. Broilers were divided into 4 groups, i.e., broilers received ascorbic acid in their diets at 0 (group 1), 200 (group 2), 400 (group 3) and 800 (group 4) mg kg-1, respectively. The pathological changes and effects of ascorbic acid on lesion scores of bursa of Fabricius in heat stress ed broilers were investigated. The results revealed the following information: After broilers were under heat stress for 21 days, bursa of Fabricius shrunk. The cortex area of the bursa increased while the medulla area decreased. Moreover, the number of lymphocytes in both the cortex and medulla of the bursa in broilers under heat stress decreased. The lesion scores of the bursa of the broilers in groups 2 and 3 were lower than those of group 1 (p heat stress had an effect on the bursa of Fabricius and ascorbic acid at 200 mg kg-1 in a diet was a suitable level to improve the abnormality in the bursa of Fabricius in broilers under chronic heat stress ed.