The meaning of "Indian buck" came up earlier on the thread. A contributor suggested that maize was meant.

But the OED shows that "buck" was formerly a synonym for "buckwheat." It notes helpfully that while buckwheat cakes are eaten for breakfast in America, "The seed is in Europe used as food for horses, cattle, and poultry."

Perhaps the sense of the words is "I'd think myself lucky to be fed on animal fodder like buckwheat, as long as it was happening in Ireland (and not here)."

Just a guess, but I'm not at all sure of the relevance of "Indian." Did Ireland import buckwheat from India for use as fodder? (Reference to American Indians seems equally difficult to explain.)