We harvest our own hay, and buy the rest of what we need from local farmers. The hay we use is organic, grass mix, first cut hay - perfect forage for horses. We store it indoors.
Slowfeeders are a great way to provide 24/7 access to forage without allowing horses to gorge. They also help to prevent boredom, ulcers, colic, dust inhalation, and wastage.
When we started using the nets back in 2011, we immediately noticed a positive difference in the health of the animals. There is far less resource guarding, since the hay was available 24/7 and not near the lounging areas. The horses are always full and thus more relaxed as 'feeding time' has virtually disappeared.
Less hay wastage means that even the horses eating off of the large roundbale nets are no longer standing on loose chaff, mud, or manure - which is a breeding ground for hoof disease. Another unexpected benefit is that paddock management and clean up is a much easier task, since there is no extra wasted hay mixed in with the manure. We can then compost it down quickly with kills off any lingering parasites.