"JoeBoo" was transplanted from 19A to 13B and was aged at 4 years old.
I'm probably not going to post a complete list of the aging data because it's not exactly "my" data - as in, I didn't pay to have any of the aging analysis done and I think David E. Brown (the biologist who I sent the teeth to) may want to use the info for a book he's currently writing about pronghorn (we should have several of our pictures - or client's pictures - in the book!)
The ideal age for a pronghorn, I would presume, would depend on a lot of variables.
If we assume bucks reach their peak horn growth age at 3 years old we would then have to assume that 3 years old is the ideal age (O'Haco's old World Record was aged at 3 years old.) But, if there's no moisture during the buck's 3rd year of growth, then that buck's 4th year may be a better horn growth year.
If you're managing a ranch you'd want the biggest bucks to live the longest so that they could reproduce the longest and spread their genetics. In that case, you may elect to not take the buck during it's largest year in order to ensure large bucks in the future.
Another thing I've noticed - buck's that are in ideal areas are able to maintain giant status for longer periods of time (this should be fairly obvious, but I thought I'd note it anyway.) For example, on The Plateau years ago, bucks would be giant for only one year and then the effects of age (and possibly lack of feed and water) would cause them to regress substantially the next year. In areas like 19A, when the feed and moisture was consistently good (some of this had to do with the ranchers taking care of the cattle) the bucks would maintain a score of over 90 inches for 2 or 3 years fairly regularly.
So, if you find a giant buck, shoot it if you're in a bleak area and you have no chance at returning next year to hunt. If you're in a great area, you may pass and wait for next year (provided it's your ranch or you at least know that the buck will be there next year for you to hunt.)
Also, if it's an area that you scout hard every year and you spot a giant buck that you've never seen before it may be a good idea to pass and let the buck grow! If you've never seen the buck before it's probably only 2 or 3 years old and if the area is good the buck may continue to grow.
Passing on bucks is usually not something we do or recommend very often because of hunting pressure, predators, the fact that we can't forecast the future, etc...
I'll post more info as questions are asked or as it comes to me. :)