It’s pretty salty when added by itself. High in K, Na, Mg, Cl.
But I think when it’s appropriate nowadays is when it’s one part of a compost mix. I think the beneficial microbiology is what manure can be a great additive for. Aged manure can be used as top dressing or cultivated in. But if I were to use manure, I’d likely compost it first keeping in mind its macro/micronutrient content as part of the greater compost mix. Aiming to reduce the overall salinity of it.