Ruminants can digest high carbohydrate foods, i.e. corn, but under some fairly common conditions a meal of corn will kill them. I suggest a web search for “grain overload,” the common term, or “carbohydrate engorgement,” the technical term I learned in vet school. Also any veterinary text on large animal medicine will cover it. (Side note is this condition can also affect horses.)
In short, ruminants that are on a roughage or forage diet like grass, hay or other low energy food that take a large high energy meal or are placed on a high energy diet like corn, without time for their rumen flora to adjust to the new food, will have that meal/diet ferment in their rumen. The rumen becomes acidic and all sorts of bad things follow. The signs described in the original article are consistent with grain overload cases in cattle I saw while in practice and grain overload cases were some of the most awful animal deaths I witnessed.
While it is very tempting to put out bait to lure wildlife into viewing range, one should consider that such actions are not natural for the wildlife. This type of abnormal congregation of wildlife has lead to the establishment, or “wildlife reservoir,” of Brucellosis in the elk and bison in the greater Yellowstone area and bovine TB (yes, tuberculosis) in the free ranging whitetail deer of northeastern lower Michigan. Both of these diseases are zoonotic, meaning people can (and do) get them from the wildlife.
So the next time you put out bait to lure wildlife in close, and this includes bird feeders, ask yourself if the pleasure you derive from seeing these critters up close is worth the real and potential damage you are causing by the abnormal congregation of the wildlife that already surrounds you without being baited.
Bill Hench, D.V.M.