Animals should have variations in size, strength, and/or other visual indicators based on their respective qualities.
Deer and moose could have larger antlers, or just antlers with more or less points. More points, higher quality.
Boars come in various sizes, 90kg on the high end of average weight. But once in a blue moon be found in the wild weighing over 200 kg, being slower, but much more powerful.
The same goes for bears along with other animals, including some fish.
Along with variations in size should come variations in quantity of meat. A large catfish, for example, should give meat proportionally to how much space it takes in your inventory.
And instead of variations to physically indicators for each point in quality, it would probably be easy to have, say, 3 "levels" per animal.
Base Quality to 50% better than BQ could be your normal sizes. (ie Boars q 30 - 45)
51% higher than BQ to 150% could have a noticeable increase or indicator (46-75)
151% and up will be their largest size (76+)
Of course the numbers are up for debate, but the concept could make hunting more interactive. A hunter can see game and can typically tell if its of better quality by sight alone, and we should be able to as well!
It's an alternative to inspecting that makes sense.
Add more details if you wish community!