Goats are very wasteful of hay. If it drops on the ground, they won't eat it. This seems horrible to us, but for goats it means survival. Since goats are browsers, they aren't meant to eat things low to the ground the reason for this is that the parasite larvae that infest goats usually climb up to about 3 to 6 inches above the ground on grass and other vegetation. If goats are grazing/browsing that low then they are ingesting massive amounts of parasites which can and will kill them.
A two inch by four inch mesh usually is fine. However, adding tray under it to catch the hay usually leads to goats putting their feet on the tray so they can reach higher up and reach the choices tidbits. After all the harder it is to reach the better it tastes for goats. Often young goats will get all four feet up there and end up pooping and peeing in the tray and things just get nasty. I really can't understand why anyone who has ever own goats wants a tray to catch hay under the feeder and they usually put a tray under there that doesn't have drainage so you get a horrible moldy nasty mess in that tray.
If you have other animals like pigs or cows, or horses, you can pick up the hay under the feeder and give it to them. I have done that before. Most parasites from goats will not infect the pigs, cows, or horses. In fact, I use this to my advantage in rotational grazing and graze my horses and cows behind my goats so they ingest the low climbing goat parasites and the goats don't get infested then.
you can use the hay under the feeder for goat bedding. Then when the goats
pee and poo on it, make it into a
compost pile and use it later on our garden beds, flower beds, or any other place you would normally use compost.
I don't buy bedding for my goats, I just use the hay they drop and wont eat. If it is nice hay, sometimes I take it to my horses, but if it is first cut, I use the dropped hay in their
shelters for deep litter bedding all winter. I even take the outer layers of the round bales off the hay and lay it in the goat shelters so they have plenty of bedding. The goats love it, they will pick through it and eat a bit then they lay down on it and wont' touch it.
and if anyone can't tell, it is a rainy wet day in my area or I wouldn't have any time to post on permies.
goodluck with your goats!