HGG Community Forums

Here's a good article on PT and breeding ability from the old forum, in case you haven't seen it yet:
http://www.kinetocoredesign.com/showthread.php?38512-PT-Scores-Showing-vs-Breeding

However, I know that's not exactly what you're asking here. To the best of my knowledge, the quality of a horse's foals is some combination of factors including showing ability, breeding ability, (probably) consistency, and (maybe) something else, but I'm not positive about this, that only Ammit knows the exact formula for. She keeps such knowledge a secret because if we knew exactly what a breeding would result in, the game would be so predictable as to be boring. There are differences between the formula for a mare and a stallion, but, once again, only Ammit knows what they are.

All we know is that a stallion's breeding ability falls within a given range that can be identified at birth and his paper level doesn't change, whereas a mare's breeding ability, while also a fixed number at birth, her paper level is affected to some extent by the quality of the stallions she is bred to. This is why you may at some time find that a mare that had papered one color may, when an automatic mare repapering takes place, or when you decide to test her again, paper something different.