hi Kevin,
Can you tell us more about your land/setup?
i have observed something similar to what you mention.
our
dairy cows dont seem to stomp in the manure piles left in the (irrigated) pasture as is seen with mob grazing. sometimes the chickens cant/dont get to them because of plant height in the pastures or a variety of other reasons.
we are trying a higher stocking density - but realize we will have limitations with this.
another option is to hold the cows in the laneway overnight (exclude from pasture) and collect the manure for other uses that way.
we have been doing this and composting the manure. we use the chickens to help in the compost mixing process. doable on my small scale, but not sure if that would fit your situation.
instead of raking, can you through some scratch on the pies? that may attract the chickens or other birds that may scratch it up more.
ive heard of mowing over them and mulching over them (to help keep them moist so they break down) as other options.