If you do get offered some remember to check that the animals which produced it have not been wormed with Ivermectin wormers. These persist in the manure for a lot longer than the claimed 6 months,preventing worms from composting it properly, then Ivermectins persist in your pasture/garden killing earthworms. We made that mistake when we first arrived on our holding - the new muck heap just sat there for about 3 years before it began to shrink. Fortunately we didn't spread it on the garden. When we investigated the heap there was not a single compost/tiger worm to be seen.
There is evidence that pastures grazed by animals wormed with Ivermectins have noticeably lower earthworm counts than other pastures.