Its bad form to answer a question with a question
but:
Are they your sheep?
Do you have permission to collect? Remember sheep are not always friendly, especially when with young.Many flocks are kept just to impart fertility into pasture
Freshly gathered they are best composted.They will contain grass and weed seeds .If you know the farmer, doubtless he could supply some older material . Ideally you want composted droppings,(or compost from your heap )which may be 2 or more years old. The simple method would be to fill a sack* with this and immerse in a waterbutt for some weeks.This will give you a liquid similar in appearance to Tomorite. Some folks go to the bother of aereating the drum with a pump. However, the object is to feed/boost the microbes in the soil and within the root. This is the way to get nature working faster.Be cautious in applying to new growth without further dilution.
*a porous bag of a size you can easily lift, could be hessian although polypropylene is longer lasting. 'Nora Batty' stockings would do! Personally, I collect a 'free' onion sack from the local takeaway.