The round bales are the primary feed/forage, since it's grass hay and also cheap; round bales of grass are usually the cheapest hay available. The bright green stuff in that picture is alfalfa, which is too rich to feed as the main forage and also more expensive than grass unless you're in California. Whoever had the alpacas probably found a good deal on the alfalfa and bought it to give to the females with... whatever the hell baby alpacas are called, but had no use for it once they got rid of them and offloaded it onto the troons.
It has also probably spoilt by now, since it clearly was allowed to get wet.