round bale be bout 1/3 of a ton i think so at a guess it sould last just under month. the weight will depend how tightly packed the bales are, the supplier shld know
Last year our round bales of haylage (equivalent to 8 small bales) lasted approx 10 days to 2 weeks for two stabled horses depending on how much turnout they got.
Hay wouldn't be a problem on how long it lasted, but I would be a bit worried about feeding haylege if its been opened for longer than 7 days, and in the process of heating up.
Quite a while, and you have to think about it getting hot in the middle if it's unwrapped for too long. If you unravel it all it lasts a bit longer but thats not very practical!
why not get the big oblong bales where the haylage comes off in slices, easier to get the haylage off them and you can split the bale into piles so it does head up and go off as quick, the main thing with haylage is that if you are not going to use the whole bale within 3 days you must take all the plastic off it to let it air.
We managed to get through one big bale in one week for three stabled horses (turned out during the day), but found it was better to unwrap the whole bale right from the first day to allow it to breathe. Anything longer than the week and the haylage will start to go off, which is a real pain, you've paid for the haylage and then you have to throw it away (time consuming, heavy work and can cost too!).
Many companies do small bale haylage, although it is clearly more expenssive. I use EH Haylage which is great stuff http://www.ehhaylage.co.uk/