Nowadays it comes in bags of dryish loose material good for the typical small garden. Already composted it is relatively clean and ready to use. You can also get pelleted chicken / poultry manure. This often comes in tubs. This too is clean and very easy to handle and apply at any time. Alternatively 6X is concentrated natural fertilizer from chickens N-P-K=5.8-3.5-3%. Easy to manage and very light - bags sizes are weighted for ladies to easily lift. It goes a long way and less storage is needed for fewer bags.
Manure is especially rich in nitrogen and in phosphates as well as other elements. Apply it before growing nitrogen hungry leafy crops like potatoes, cabbage, sprouts, or kale.
Timing Of Application
Early spring is the best time to dig it into sandy soils as they will loose lots of nutrients during the winter rains of temperate climates. Sandy soils are not as wet or difficult to work in spring.
Some crops prefer it to be applied for a previous crop e.g. carrots, onions, and runner beans. This may be because some crops prefer firm ground not recently dug. Carrots have a reputation for forking if it is applied fresh. I believe this also applies to pelleted chicken manure. Your particular soil type and conditions will effect exactly what you do.
Many crop rotations include composted animal dung once every 3 or 4 years. But your garden can only benefit by applying it more often. My rotation tries to include it twice in 4 years. And now it is so readily available in easy to manage bags I will be applying it around my garden on a regular basis. That includes the flowers, fruit beds and lawns and hedges too.
Avoid Putting With Lime
How To Apply It
I sometimes lay down an inch or so over a bed that I've just forked over to about 3 - 6 inches. Then I use my long-handled garden claw to mix it together. That treatment would be adequete to prepare most flower beds.
More Than Fertilizer
The dung is usually mixed with straw or wood shavings. Their high carbon content helps stabilise the nitrogen in the dung and make humus. Composting produces a hot heap that kills weed seeds. Keep the heap under a cover sheet to reduce leaching of nutrient liquid. When ready for use it has a pleasant earthy smell. The added woody bits should not be identifiable.
Making Liquid Fertilizer
Find more on organic fertilizers here.