i have two adult boars(male guinea pigs) and i noticed they are not taking to their hay anymore? they eat oxbow essentials for adults and have a mixture of fruits and veggies once a day. they also get 1 tablet of vitamin c a day. i have switched back and forth from timothy to orchard grass from kaytee and oxbow and they wouldnt eat as muc h then i tried sundried sweet hay and they took to that. but i just bought a new food dispenser (the fillup kind) and i dont know they have 2 hayracks and usually they would be done with it by 2 days? now it just sits there and takes forever to finish? they eat fine are healthy popcorning responsive they squeek and play in there cage(57inch by 27inch +a second level whichi is28by 28) any suggestions? i dont get it?