Hi
My baby nipped me a couple of times, for two reasons.
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<LI>naughtiness, ie attention or stroppiness
<LI>accidently when hand fed, due to greediness
For naughtiness a firm whack on the shoulder made him remorseful, but a month or two later he did it again. I checked the weh and came up with a strategy called the 3 second kill. Its based on the notion that the mother will reprimand her reprobate very quickly, very aggressively and then back off, and go back to grazing. Well I tried it. Waved my arms and shouted loudly (poor neighbours) and it worked like a charm. The recommendation is that this is reserved for extreme behaviors, ie biting and rearing. It is not for every day use.
The second, greediness, I used clicker training to amend. I created the problem by feeding the herd over the paddock fence as I passed, and they became very competative. In the box, the older horses were fine, knowing they'd get their turn, but the baby was quite ungentlemanly. I'd feed a treat to the neighbour, then to baby. But baby couldn't reach and grab for it, he had to stand back an inch or two from the door, with his head back. Then (with a small child's toy clicker) I'd click&treat. Now at the fence I can feed the herd, and he stands slightly back, ears perky looking so proper. Click treat.
Click&treat works very well for all manner of training.