Effect of heat stress on organ histology of broilers and ameliorative effect of herbal antioxidants

A study of 42 days duration was conducted in broiler chicks during summer months to know the effect of herbal antioxidant supplementation on organ histology of heat stressed (HS) broilers. Forty two chicks were divided into 7 groups with six birds in each group. G-I was given basal diet (BD), while for G-II and III, BD was supplemented with Tulsi at 0.25 and 0.5% levels, respectively. For G-IV and V, Turmeric was added to BD at 0.2 and 0.4% levels, respectively. And for G-VI and VII, combination of herbals Tulsi (0.25%) + Turmeric (0.2%) and Tulsi (0.5%) + Turmeric (0.4%), respectively, was added to BD. A control group of six birds was raised separately in stress free environment. At the end of 6^th week, birds were sacrificed and tissues of liver, brain, bursa and spleen were collected for histopathological study. The control group revealed no lesions of pathological importance, while the tissue sections of HS group revealed degenerative changes. The birds supplemented with herbs at lower inclusion levels (G-II and IV) shown less degenerative changes compared with HS group, while the sections of birds supplemented with Tulsi and Turmeric at higher inclusion rates (G-III and V) evidenced mild lesions. However, combination of herbals at either doses (G-VI andVII) could not ameliorate the heat stress induced changes in organs of HS birds. The study indicated that Tulsi and Turmeric at 0.5% and 0.4% level of inclusion, respectively, could protect the oxidative damage to tissues in broilers, thus revealed mild lesions.