well rotted horse is the best all round general fertiliser and soil conditioner, you cant get enought of it!
poultry is very concentrated, the nitrogen is contained in the urea, the white 'dab' on top... its great as a compost activator. the cucurbits love it, i make a liquid feed using chicken manure, and feed cucumbers and courgettes with it all summer.
cow is better than nothing but low in nutrients, something to do with their digestive system being v efficient.
pig and sheep are good too but i cant remember the figures for them, ill have a look in lawrence d hills's famous book in a mo.