Abstract: A method for monitoring the presence or absence of a megavirus in animal feed, an animal feed ingredient, or an animal product uses a surrogate virus assay. The surrogate virus assay generally includes, inoculating the animal feed, animal feed ingredient, or animal product with a surrogate virus as a proxy for the megavirus, subjecting the animal feed, animal feed ingredient, or animal product to a treatment that inactivates the megavirus and the surrogate virus, waiting a predetermined period of time, and determining the presence or absence of the surrogate virus in the animal feed, animal feed ingredient, or animal product, thereby monitoring the presence or absence of the megavirus in the animal feed, animal feed ingredient, or animal product.