I fully understand why Toady doesn't want to allow players to weigh exactly how large a ham hock we get from a pig while they're still in the cages. Giving precise-to-the-Γ measurements makes things a little unrealistic.
Still, there are reasonable features to add that even the stupidest medieval peasant would be capable of doing that would benefit players managing their ranches.
For example, "which of these pigs is the biggest?" is a reasonable thing for a dwarf peasant to be able to do without any tools but their eyes.
Basically, this is another of those "data invisibility in the Interface" things...
Furthermore, there are serious problems players have with animals that are either not sexually active or are gay animals.
I personally believe asexual animals are FAR too common in this game, and are an artifact of assuming human sexuality for animals. Gay animals are fine, but a dog choosing not to hump the pillow because it has commitment issues is crazy. Still, that's more the purview of the bug tracker...
Rather, there should be some sort of interface feature that, when you look at a description of an animal, some of their past history is revealed. A gay dog is distinguishable in real life because they try to hump the other dogs of their gender, while there's zero evidence of that in DF, there's simply an inexplicable dearth of puppies.
Because of this, there should be some sort of "observations" counter, where dwarves with some sort of animal empathy traits or skills add their skill to a counter on each animal whenever they can see those animals. When this counter hits certain points, different aspects of that animal's behaviors become known and reported to the whole fort. For example, "This boar doesn't seem interested in the sows, but has been chasing other boars," or, "This boar seems to chase boar and sow alike."
Additional information might be added, like guesses as to the parentage of each animal, or whether its current pasture is too small (it is getting hungry and/or has been fighting) or too large.
In general, there are many things that the game could do without too much trouble to make ranching easier for the player.