Purely because hay can make mine cough if not excellent quality, hay/lage together she'd pick the haylage out and leave the hay....in saying that I've 150 bales of hay to use before I crack open the haylage...bet she can't wait....
I would perfer to feed hay, but we have no barn so can't store it, and my horse coughs on hay. I prefer hay as it doesn't go off once you open it, although if money was no object I could afford mini haylage.
Herb was always been on hay since i've had him (3yrs) but recently moved to a yard that just has haylage and i have to say he's put on rather alot of condition since but he hasnt fizzed up which is rather useful at this time of year