Might be worth mentioning that half of that will be water content.
It's probably not an accurate comparison, but I don't find any consolation in the fact that a lot of the bulk/weight of cleaning my cat's litter box is water. I don't know if it meaningfully changes anything about the task for a cow though.
its a large amount of waste, but its not 150lbs of solids
Compare to horse manure which is relatively dry, easy to shovel.