Pertaining to biosecurity and risk of introduction of BVD to…

Questions

Pertаining tо biоsecurity аnd risk оf introduction of BVD to а non-infected herd, rank the following practices from MOST RISKY to LEAST RISKY: a) Walking around with manure covered boots, b) Contact with wildlife, c) Purchasing animals from unknown sources, d) Not cleaning automatic syringes after use.