Yes, I started making tree
hay last year and it was a real success. Easy to do and the animals went nuts for it. I've just started the process for the season, since we are at the point where we need to get nets over the fruit trees and that means trimming off leaders and excess vertical growth. So there's currently a pile of apricot branches with a few hazel ones mixed in, spread out to dry in the sun.
Trees that I've used so far: most deciduous fruit varieties (
apple and pear are ideal because of their tendency to sucker and my tendency to remove, but plum, cherry, fig, quince, grape, kiwifruit, and feijoa are also good), willow, poplar, tagasaste, hazel, oak, and coprosma. Trees with resinous leaves don't get more than a nibble from the stock, so I leave out eucalypts, blackwood, and conifers. I haven't tried maples yet but we have a huge one close to the house that needs a couple of branches removed, so I'll try it.
My method is to cut rods and whips preferentially (not too much branching) and I go for lengths of about 1m. I spread them to dry for a few days, then tie them in bundles with
flax leaves and lay them in the hay shed. Feeding out is just grabbing a bundle or two and watching the critters come running when they see it. The leftovers become
biochar, of
course.