I just feel that hay wastage is part and parcel. Sometimes some pieces don’t taste as nice! If my two don’t eat all of the hay in their rack, I sometimes put it back into the back, mix it in with other hay and then put it back in the rack. They eat it eventually, or I just put uneaten hay down as bedding (and then throw it out after during the hutch clean).
As an aside though, (unless your piggies are pregnant sows), then alfalfa hay is not a grass hay and it is too high in calcium to be fed to piggies. It should really only be fed to nursing babies and pregnant sows in tiny quantities.