No. Haylage contains 25percent (maybe a bit more) more water than hay. so on a weight for weight basis you have to feed more haylage than hay, otherwise horses won't get enough fibre.
You should feed one and a quarter to one and a half times more haylage than hay. (in my opinion)
also a lot depends on how wet your haylage is i suppose. but in any case, you need to feed more haylage than hay on a weight for weight basis.
