I imagine it hurts them when they do it, they kinda burn the horn buttons so they stop growing. I don't think it hurts them for a long term period of time though. I don't know how much experiance you've had with goats, but they like to rub there heads on everything. Does a ton of damage.

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Well the buds are underway, and the shrooms have been goin crazy come check it out! Thundercats Grooooooooow!