Are these Hebrideans? There's no reason you can't show a lamb with a broken horn but you are extremely unlikely to have him placed as it's an animal's appearance on the day that counts, not what he might look like in a year or so.. I can't think of any Heb shows where lambs are forward in fact. There is of course no reason not to use him for breeding if he still looks good in a year. Usually a broken horn on a lamb will grow back, not as big as the unbroken one but by maturity it doesn't really show
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