Are any livestock species used for food, susceptible to coronavirus COVID-19 infection to the extent that they might die or need to be slaughtered and discarded to prevent human exposure through the food chain?

This will not become a problem. It might arouse too much suspicion. There can be carriers among the animal kingdom and this, as you know, is not uncommon as the leading scientific theory for viruses that pop up causing an epidemic or pandemic is a migration from lower species and eventually adapting to become a human pathogen. So to find animal carriers is not at all unusual for multiple classes of viruses, the question is whether they will cause symptoms to be noticed. But this is not necessary for the work of the Extraterrestrial Alliance to cause mass infections of livestock in order to impair human. It is a trivial exercise to spray an area where humans are passing through and create multiple infected individuals to spread the scourge. In effect, livestock are practicing social distancing from their human handlers, so this would create quite an intense scientific scrutiny should there be mass infections among livestock, so this is unlikely to be pursued.