Bottle lambs are an excellent, low cost way for homesteaders to get a few sheep. I have sold tons (literally) to homesteaders over the years and look at this as a win-win for everyone.
There are a variety of reasons us commercial sheep farmers have bottle lambs for sale, and it usually is cost and not genetics. Lets say that I get triples; a pretty common occurrence with sheep. With a ewe that has two teats...that math does just not work. What do I do with that third lamb. Even if it could be rotated
enough to suckle off its mother...a doubtful proposition, nutritionally it would drag the ewe down. And since a ewe will not take another lamb that is not hers without a lot of work on the part of the Sheppard, it means you cannot just take a lamb and swap it with a ewe whose lambs have dies. That means bottle feeding, which means getting up every 4 hours and feeding it, and since no one wants to tromp out to the barn at 3AM, they end up in the house. After about 2 days they start baaing for their bottles...at 2 AM in the morning...in your house; so you can see where this is going. There is enough going on with lambing season to not want to put up with that...all for a lamb that will suck up a $60 bag of lamb formula by the time its weaned. There is not a lot of
profit in that for the amount of hours put into it...so we
sell it...cheap!
Now for a homesteader who has the time, wants to nurture this type of lamb, and is spending $60 on a lamb that normally would be $175...it is a great deal. And there is something about getting to give that lamb a bottle at 3 AM; they get to know it, and it grows up with them. There is nothing wrong with that, so that is why I say it is a win-win. A commercial sheep farmer just does not have the time, and since they might have multiple bottle-lambs, it means multiple bags of expensive formula. For us it is best to put a low price on the bottle lambs, sell them quickly, and move on. But the lamb itself? It is just fine.
Another common reason for bottle lambs is the mother just won't take to her own lamb; a very common occurrence with yearlings (ewes having their first lambs). There is nothing wrong with the lamb, they just don't know how to be a mother, so they abandon it. Again it is hard to graft a lamb onto another ewe, so it means bottle feeding, and again a perfectly good lamb. I have one in the house now that is that way, born yesterday to a yearling that won't let the lamb suckle. Very robust, healthy ram-lamb; it will go up for sale soon.
As for head butting: I have watched for patterns of behavior on this and cannot find any. This year I have raised maybe two dozen bottle lambs, and out of that lot, my only head-butter is a ewe-lamb, and the rest of the ram-lambs and ewe-lambs have been fine. I don't perceive her to be a problem, she was just weaned yesterday from the bottle so she
should simmer down with some time. However I have had ram-lambs be head-butters in the past. Most of the time they go for market-lambs so by the time they are of age to do anything aggressive, it is time for them to go into the freezer. Bottle-Fed Ewe Lambs typically get handled enough on smaller farms and 4H farms to get used to human handling and behave, so about the only issue to watch for is a bottle-fed ram-lamb that a homesteader might want to keep for breeding. What is the percentage on that? I have no idea, but VERY low. In 9 years, hundreds of sheep, many different breeds, little handling commercial sheep farm structure; I have put 2 down because they were aggressive.
As for genetics; obviously I can only say what I do, and know not every commercial sheep farmer does this. But I do not like to give away problem sheep, but I have on occasion GIVEN genetically deficient lambs away, telling the people that the lamb has issues. I do this for two reasons; One, there are some amazing people who can devote the time it takes for one lamb to recover. They are just sheep-whisperers. Myself, I just do not have the time. And two, some people cannot have full sized sheep and so they raise these animals to adulthood in a size they can handle. I give them away, I don't charge, and the people know the lamb might not make it because it has problems. But I am giving that lamb the very best chance at life that I can, and that is where it is at...doing the best I can for every sheep here, born here or bought.
So after all that; yeah I think it truly is a win-win situation for homesteaders to buy bottle-fed lambs.