Trenbolone acetate is an anabolic steroid. It has been used to improve body weight, feed conversion and nitrogen retention. It is normally administered as a subcutaneous implant and is rapidly hydrolysed to its free active form, trenbolone. In bovine species, 17 alpha -trenbolone is the major metabolite detected in excreta, bile and liver, whereas 17 beta -trenbolone is the major metabolite detected in muscle. (9)