poultry litter and cow are two that i'd be hesitant to use for these reasons:
1. diet of the animal. plant or other based?
2. how was it composted -professionally, at home, treated?
so really source it beforehand - like i did not... some of those pots that have that sub-par organic cow manure and humus now have small little sprouts occasionally from left overs from cow droppings i'm sure.
-VERMICOMPOST is my solution. mostly plant diet for me leads to all plant diet for the worms and then the castings and compost should all be top-notch.
why i wouldn't use cow or poultry => animals are part of the food web but the excrement is far from the best. and some of that is again how its made.
so to me it seems not worth it when there is a possibility that the manure i use may even kill off the essential microbes i want living in it.
BUT. if you are the one taking care of them, feeding them, composting it yourself, treating it.. then that is a different story - but i would still rather more plant based.
the less degrees from where the energy first came from = the sun; the better.