...most studies recommend adequate KE to "kill" certain animals and they would be a minimum of 45 ft lbs for deer sized animals and 55 ft lbs for elk sized animals.
I've seen those figures too, Rob, and have to say it's total BS. Ifit were true, then nobody shooting a recurve or longbow of less than 55 pounds would ever kill a deer because they don't get that much KE. Back in the 60's, the most common draw weight for deer hunting was 45 pounds. A great many elk have been taken with 50 pound recurves.
I don't know what those guys doing the studies have been smoking when doing their work, but they were definitely in Neverneverland when they came up with those numbers.
How much energy you need depends on a whole mess of different factors.
What weight are the arrows you're shooting? Lighter arrows have to have more KE to get the job done than heavier ones.
What kind of broadhead is on them? Mechanicals have to have more KE to do the job than replaceable blade fixed heads. Replaceable blade fixed heads have to have more KE than 3-blade cut on contact heads. 3-blade cut on contact heads have to have more KE than 2-blade cut on contact heads. In all cases, heads with a larger cutting diameter have to have more KE than heads with a smaller diameter. You could even get into the length to width ratio too!
Are you shooting from the ground or from a treestand? An angled shot needs more KE to penetrate to the vitals than a straight on shot.
Anybody that tells you that you need X amount of KE to kill animal Y, without giving specific information on all the above is blowing smoke.