What is the fine-grained topic of the following text: The feedstuffs studied that have shown the potential to support virus survival include: conventional soybean meal, DDGS, lysine hydrochloride, choline chloride, vitamin D, pork sausage casings, dry and moist dog food, organic soybean meal, soy oil cake, moist cat food, and porcine-based ingredients. Only return the topic.
Virus survival in various feedstuffs