Dairy does tend to be thin while they are lactating, whether they are raising kids or being milked. They put all those calories into producing milk instead of into maintaining their body weight; goat breeders call this "putting it all in the bucket". A good way to check your goat's body condition is to feel the breastbone, between the front legs. You should be able to feel a layer of fat over the bone. If all you feel is the bone, increase your doe's feed (do so gradually to avoid digestive upset). She needs a higher protein feed and good quality hay while lactating.
Some does will have a lopsided udder, caused by the kids nursing one side and not the other. This happens more often when she is raising a single kid. You can milk the neglected teat to keep her udder "even".
When the doe decides that her kid should be eating more solid food and nursing less, she will discourage the kid from nursing, sometimes by kicking it away, running away, or even lying down on the ground. She hasn't rejected her kid, she's simply encouraging it to grow up.
Some goats like to suck on wire fencing; my daughter and I called this "flossing their teeth". Not all of my goats do it, but a few of them do it regularly after finishing their supper. Standing at the fence, the goat puts her mouth on a strand of wire and moves her head back and forth so that the wire slides through her mouth. I have no idea why some of them do this. Do they need a mineral in the metal, or is it just a habit, like a horse that cribs? Since I've had several do it over the years, I guess it's "normal".
Contrary to what you've seen in cartoons, goats have sensitive digestive systems. They don't eat license plates or tin cans, and when you change their feed, you must do it gradually. They don't graze like horses, they'd rather browse like giraffes, and they prefer weeds, brush, tree leaves and bark over grass.
Do you have any more questions about what's normal? Please leave a comment if you do, and make sure you include your email address so I know you'll see the answer.
Part Two: Goats - What ISN'T Normal?
My hope is to inspire you, and to encourage your homesteading plans and your dreams of a