I would say that a 55 pound bow would be the perfect weight bow for the average shooter on larger big game animals but....
I shoot a 50 pound black widow that is 22 years old. I have taken 20 species with it and many were very large critters such as wildebeest, gemsbok etc. I do shoot heavy arrows with two blade lower profile heads like stingers on the really big stuff. I have taken several eland with this setup with the largest one over 2,000 pounds. I got a pass through on my last eland and none of them has traveled over 50 yards.
I am not an advocate of low poundage bows but 50 pounds is what I can handle accurately an it is just enough bow on larger animals.