Hi Glen, partly it depends how much time you have as the heap is all there for you, also it depends if the heap is fresh or older manure, if the latter it is more interesting.
Straw takes longer to decompose than pure manure. Ideally you want some straw or other bedding to keep air in a heap of fresher manure while it composts, but many horse owners use a lot of bedding, more than ideal for gardening!
So you could collect some of each and mix them – although if there are parts of the heap with brown straw and older manure, keep them separate to use first.