I absolutely LOVE these bags!!!! Not only do they reduce the waste, but it helps with dust control too. The horses can't get their heads into the middle of the bales so they aren't breathing in any dust or possible mold spores. Even though the nets do develop a hole once and a while, they are extremely simple to fix. If you can tie a square knot, you can fix these things. They're not always the easiest to put on by yourself, but if you have a tractor and a rake, it turns into a one-man task pretty quickly.
Case and point:
Round bale with net
Round bale in feeder
Even though the netted bale is a few days newer than the feeder bale, you can tell how the net will hold the bale together a lot better than a feeder. (Sorry for the bad quality pictures! Taken after sunset with my phone, the flash can only go so far!).
It's really fun getting up on the bales and watch the horses work the hay through the holes in the net:
Koda says hi!
Work those lips! The net is about a 1" square.
Koda trying to nibble my boot
As always, I don't have any affiliation with nag bags or slow feed hay bags, I just like their product :)