After doing some more digging, I found portions of an interview done with Diamond Foods. They take the leftover production runs or that which doesn't meet standards for dog food and sell them to the hog farmers, preventing it from simply going to a landfill. They distributed the tainted food before the recall was issued.
Here is a portion of an interview:
Q: Please explain the situation with the pet food that was sold to the hog farmers.A: It is common regulated practice for animal food facilities to provide salvage product to farms with non-ruminant animals. This regulated practice is mindful of the environment as it does not waste energy (food) and saves valuable landfill space. All of the salvage food was sold prior to Diamond Pet Foods being notified of the contamination in rice protein concentrate.
Q: What is salvage pet food?A: Salvage pet food is product that comes off the equipment at the very beginning of a run of food. It is high in moisture and thus can’t be bagged.
Q: If your dry foods are not being recalled, how did the salvage food get contaminated?A: We did manufacture two formulas for Natural Balance that were recalled – Natural Balance Venison & Brown Rice dry dog food and Natural Balance Venison & Green Pea dry cat food – and it was the beginning portions of these runs of food that ended up in the salvage food that was sold.