$1:
AFAIK growth hormones are already banned in Canada - ie our milk is better
Last I read, it seems only the SALE of rbst was banned in Canada - actual use, however is not under law (or at least is a grey area). Given the high level of integration in the Canada/US livestock industry I would wonder if its use might be common. Also IIRC, the laws that limit US milk from our shelves don't apply to "milk products" including chocolate milk, butter, cheese, yogurt and ice cream (insert shill: look for the "made from 100% Canadian Milk" label).
Also, fun fact according to Health Canada on cattle:
There are six hormonal growth promoters approved in Canada for use in beef cattle: three natural - progesterone, testosterone and estradiol-17ß; and three synthetic - trenbolone acetate (TBA), zeranol and melengestrol acetate (MGA). Hormonal growth promoters are not approved for use in any species other than beef cattle.