Unfortunately you are not that well versed in actual feeding practices of cattle operations. Poultry litter was widely accepted as an additive to cattle feed in just the ways that
@greybeard listed. There were several operations around here that used to do it alot.
NOW before I go any further...... I DO NOT LIKE THE PRACTICE of feeding poultry litter....
BUT, it is still done by some. It is often fed to "feeder cattle" and is a percentage of the feed they get. Most of the time it is mixed in with silages of some sort..... It is perfectly legal to use it. Cattle will then go from there to finishing lots when they are in the 800-1,000 lb size and fed on whatever grain/silage mixtures that the feedlot company uses; to the accepted slaughter weights in the 1200-1500 lb size.
Yes it does have a "chocolatey" smell to it. Our cattle go nuts to eat it if they get a chance. We get poultry litter delivered to use on pastures as fertilizer. One place we have it dumped in piles... the tractor trailers hold 30 + tons... in a "walking trailer", that is a big "box" trailer that has a moveable floor... and when they bring it the manure comes off the back as the moving floor continues to feed it to the back of the trailer and off... Anyway, this one place we often have them put it is close to several different fields that we spread it on. We can close a couple of gates and the cattle that are wintered in this pasture, then cannot get into it... they will get acting like silly goat kids and lambs, and run up and down and jump and play in it....like teenagers.... but a few times over the years they have managed to get a gate open and we will find them standing there eating it like it was candy.
I think it is gross, they see nothing wrong with it.
I am not sure what USDA inspected facilities that you are referring to. For all of us out here with cow/calf operations... and feeder operations, there is no one coming around to do any inspecting. There are certain things we are not allowed to use and most every one of us follows those guidelines.... mostly pertaining to antibiotics in the feed or used in injections.... because if you have an animal sampled for any reason that winds up getting killed instead of going on a feed lot for further feeding, and they test positive for any type of antibiotic, you could be bankrupted by fines and penalties and all sorts of other sanctions. The poultry operations have composting sheds that they put all their dead birds into, and the carcasses are composted in the litter sheds and it all gets spread on the pastures. Or used for a percentage of feeding rations. That is the PREFERRED way to dispose of dead poultry carcasses..... and the most economical for a farmer to do.
The ONE thing that has been banned is the feeding of any type of blood meal in rations.... due to the "Mad cow disease" and the prions.... any blood meal that is produced is strictly for fertilizer use.... as well as restricting anyone from getting back any cut of meat from an animal over 27 months with a backbone or spinal column or brain tissue..... So if you want T-bone steaks, the animal has to be under 27 months when it is killed.... otherwise you get NY strips and filets and such, but no bones from the backbone area. No "ox-tail" bones or anything from the whole length of the spinal cord.
Although I do not use and don't like the idea of using poultry litter for feeding... saying that any "self respecting" cattle rancher is not dumping manure and garbage in the feed troughs is an unfair statement. There are rules for feeding any food wastes to any animals... and some places it is allowed under some circumstances.
Years ago there was a very good business of collecting and selling food wastes from restaurants for hogs... but then it was discovered that you could cause trichinosis in pigs by feeding them meat wastes that were infected with the larvae and then humans eating the pork that is undercooked. So for awhile there was a requirement that anyone collecting food wastes had to "cook it" before it could be incorporated into hog feed. I don't think that is even allowed anymore....
But the whole thing is that there are practices that you may not like, and I don't like feeding poultry litter... but once composted and it goes through the heating phase, it is allowed in certain percentages. And that doesn't make a farmer a bad farmer.
That said, if you are ever around cattle much, you can tell by their smell if they have had been fed any amount of poultry litter. Their manure has a particular odor and they even seem to have that odor emanate from the live cattle. I have been at the stockyard and had cattle come through the ring and can tell if they have been fed a percentage of litter just from their own odor.... I have also been told that you can taste an "off taste" in the meat also. This is something that has to be fed to them for a prolonged period of time though.... it permeates their whole body tissues.