When making haylage/silage you are dealing with two kinds of bacteria. anerobic and aerobic. First one multiplies without oxygen and converts starch to sugars. the second needs oxygen and composts. Making it can be any way of getting the feed into a container[ wrapped plastic, silo or pits, preferably with walls]and getting the oxygen out as soon as possible. The bacteria can start multiplying immediately after the plant is cut and so therefore speed is of the essence. With round bales it is preferable if someone can gather and wrap while someone is baling. worse case is bale one day and wrap the next, this will almost guarantee that some feed will mold.
Why feed it to sheep. ensiling can save a lot of protein and other nutrients from the plant that could otherwise be lost and when feeding any animal you must remember that their stomach is only so big. In this kind of weather if the animals are exposed to the elements then you want to get as much bang per bite into them that you can especially if they might be in the last stage of pregnancy or lactating. haylage if done properly will come as close as stored feed can get to the living plant for nutrition. If done wrong you can get into listeriosis and other ailments that are not too good to have. It costs more to do but in certain circumstances it costs more to not do it. Just my opinion.