!
Do you suppose (not having had anything to do with this sort of preparation, I wouldn't know) that when the horses are schooled over fences at home they use much higher fences?
http://www.horsedeals.co.uk/bigjump2.aspx?horseid=6715
Talking of horses jumping big.
Forget that these are foals jumping OK. Look at these babies, and look at the fence, it can't be more than 18" high!
No more than any old log in the field that we have all seen babies loose jump for fun.