The research was conducted on 24 ewes of Awasi sheep. The animal study were divided into 4 groups each includes six ewes. The first three groups were injected via variant proportions of BST hormone ( as serial doses 40 mg, 80 mg, and 120 mg) daily for 2 weeks. The fourth group was considered as control group. It was measured the quantity of morning milk and measurement of fat and protein and lactose one time every week. Tissue specimen was taken from udder to study the changes of secretive vesicles.