Now to the questions and comments.....
We have black sheep; however, we also have dark brown sheep and when wet the dark brown lambs can look black. I cannot view the video at work to see the color of the lambs, but I suspect the lambs are dark brown.
I have a few UVTs on my possible list: Mule, Kubota RTV, and Polaris Ranger. We want a powered dump and roof; and would prefer a windshield. What we get will depend upon what we find used in our price range.
We suspect the triplet mom that lost a lamb each year did so because she does not produce enough milk for 3 lambs. Since at least 30 ewes are "serviced" by one ram and we're not having lots of weak lambs; it's unlikely a problem with the sire.