In an open float or one with gaps at the sides I dont, because I worry about hay blowing around and getting in their eyes and just generally being not very pleasant for them.
In a standard, closed in float - I do for a long trip (3 hours plus), but I dont bother if its only a short trip (1 to 2 hours).
In the gooseneck, no one gets hay. We travel around a fair bit in the gooseneck and just stop for maybe 20 mins every 3 to 4 hours and let everyone off on the side of the road somewhere to have a bit of a pick of grass. They usually like to have a big piddle at this stage too (they are experienced travellers, they all hold on until we stop, then all 4 stretch out and have a wee together, very funny to see, 2 people on the side of the road holding 4 horses which are all having a piddle, lol)
