Here is some good wholesome stuff: alpaca dung. My father purchased eight sacks of it from a lady on a market stall who keeps a small herd of them. Too much muck too fresh can have an adverse effect on the soil so I let it sit in the bags for a number of weeks (it doesn't smell!). Then I've been spreading it thinly on the allotment as a winter mulch.
 It takes the form of pellets (rather like sheeps' droppings) which seem to take weeks and weeks to decompose. That's a good thing because the nutrients will filter into the soil slowly. I have high hopes for the efficacy of free range organic alpaca poo...