I don't count any "work" that is physical. My brother told me years ago that it simply does not count in a true fitness program. Through the years, I have decided that he was right. Besides, that's something I do on a regular basis so isn't an added thing to promote fitness and use of calories in excess or my norm. There is someone on here who says that mucking stalls is counted as about 500 per hour - so that means that it's a pretty significant calory burn.

Amber,

I have added my own catagory to the cardio exercises of "cleaning stalls" 30 min = 120 calories burnt. I chose that cal burn level because you can see raking leaves already in cardio exercises at that burn level. Yes, I clean 5 stalls daily, BUT I usually only add it to cardio on the weekends, when I have NOT done any other cardio. I too, do believe, your body begins to ignore your 30 minutes (or whatever #) of stall cleaning because you do it EVERY DAY & the body gets used to it....so I don't count THAT as cardio.

For heavy liffting, like unloading a truckload of hay by myself, I will use the cardio that is already in the MFP list of exercises - it says Strength Training (weight lifting/heavy lifting), I think it is 60 min = 242 calories burnt. Since I don't buck hay but once a month or so, I consider that "above & beyond" my daily chores & I do add it into my exercise log.
Everyone is different, & imho, if your barn chores are difficult enough that it makes you sweat, then I would add it into your exercise log. Do what works for you.

J