I've just switched my milking Saanen onto a cattle feed instead of the goat/sheep feed she was on before.
I noticed in spring, shortly after we got her, she moulted by shedding a load of hair, looking almost bald before the new growth came through, and put it down to stress of moving, and the previous owner was suspicious she may have been having a false pregnancy.
She moulted a whole heap of hair again the other week, and so I had a wee think, and thought that it may well fit with copper deficiency.
Having switched onto beef nuts, with copper in them, the new hair seems to have grown in much quicker than it did previously, so I think this may well be a copper deficiency.
This bodes well for my sheep, because if they accidentally eat a bit of the cattle feed etc, the low copper in the area should mean they won't get copper poisoning!