You know what i just started working there recently. I will find out for you today, and post it later on tonight.
Its most likely spent cows from the Dairy Industry, thats where alot of "ground beef" comes from, after 4 or 5 years on the dairy farm the cows get worn out and their milk production declines so they send them to slaughter to become "low grade" ground beef and fast food hamburgers even pet food, its sad but it makes up over 70% of today's ground beef!!
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