Lower milk Q is the same effect as lower fodder quality for adult animals. Quality of food eaten softcaps the animal's qualities. This isn't an issue for animals you want to become adults (just feed better food until qualities are up), but for ones you're harvesting for cheese and jewelry, you'll want to treat them the best you can in their short life.
To follow up on what redkat said, just milk everything and stick it in barrels much like feeding troughs. As long as you have a couple full barrels around for the calves and such to feed on, you can use the rest for cooking. You won't need to worry if that calf will feed directly from a ewe or sow.

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