EFFECT OF VARIOUS LEVELS OF CANOLA MEAL ON MORPHOLOGY OF THYROID GLAND IN BROILER CHICKS

The present study performed to examine canola meal on morphology of thyroid gland in broiler chicks. In this experiment 300 l-day-old unsexed Ross broiler chicks assigned into 5 groups. The chicks were fed by five level of canola meal (0, 5, 10, 15 and 20%). After 42 days feeding four chicks from each pen killed and their thyroid glands removed and immediately were immersed in formaldehyde, before fixation in Bouin's solution and paraffin embedding. Each sample was then sectioned at a thickness of 7 mm, stained with haemetoxylin and eosin, and examined by light microscopy. Measuremcnts of diameter of follicles, epithelial cell number and epithelial cell height in all groups were made at 100 to 400x magnificatin. Diameter of follicles, epilhelial cell number and epithelial cell height in treatment groups (treat,ents 3,4,5) were significantly increased as compared with control group (treatment 1) (p<0.01). These results showed that although glucosinolates in canola or double-zero rapeseed is very low, but canola meal can be affected on morphology of thyroid gland in broiler