My opionion - as we all know auditors come from different backgrounds and will ask different questions. And yes, some of their questions, or even their conclusions, may not be relevant to our operation. I believe the better question to ask, rather than "how do I satisfy the auditor," is "can I adequately justify what I'm doing in light of both regulatory and food safety requirements?"
I believe that in this case, with regard to food safety programs, since the waste product does not go directly to human consumption the responsibility for determining its suitability lies with the purchaser, or the cattle operation. It is not the seller's responsibility to develop a risk analysis about what happens to the feed once it's sold to the cattleman, and whether that's a risk to humans.
it's very important to note, though, that there are some specific regulations in place regarding animal feed for animals in the human supply chain. I'm not intimately familiar with them, but the seller should ask the buyer for some guidance on any related requirements that they need to know about, and do a little research. Also keep in mind that the FSMA will make some changes to these requirements, so you'll want to stay abreast of any new legislation or drafts that come out in that regard.