I was at the fair on the weekend and a booth in the agricultural building claimed that we used 98% of the cow. Which parts of the cow are not used?
As I recall, from one of William Poundstone’s books – either Big Secrets or one of the later ones, that after butchering for human consumption, the only parts not ground down for animal feed, or industrial use, is the ends of the very largest bones, and the blood that has dried to the table. Dunno why they have seen fit to point out that some blood gets lost, when much of it is used for other purposes. I mean, we know some of everything is going to be lost at each step, even trimmings from the supermarket, etc.
I think the only bit they don’t use is the moo.
And the fart.
I prefer to call it the ‘bottom moo’, in polite company.
Since the advent of mad cow disease, I think the spinal column is discarded. There is no known way (short of heating to 300 deg C) of destroying the infectious agent.
I used to buy animal feed ingredients and commodities and as far as I know all parts of the animal are used for one thing or another.
After the human food products, which use quite a bit of the animal, there are uses for everything.
There are several grades of tallow from rendered fat and cooked bones. Gelatin from bones and hide. Meat and bone meal from what is left. Dried blood meal. Spleens and livers go toward the pet food flavor market.
The quantity of these products is amazing. I used to buy truck loads of this stuff every month, and we were a small company.
What about the brain? Is that used in brawn?
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Well, I was going to say the gall bladder wasn’t much use, but then a little googling showed me that there’s a big market for bovine gallbladder mucosa in the scientific community, and bovine gallstones in the crystal healing community.
These parts are called Specified Risk Materials (SRMs). First they were only banned from ruminant feed, then from all animal feeds, and then they became taboo to even have anywhere near a feed plant of any kind.
I don’t know what the current situation is but I gather from this recent article that the disposal problem continues to be debated.
http://dairywebmall.com/dbcpress/?p=2493
Incineration, burial, or composting seem to be the only accepted methods. All these methods are problematic. Compost it and then do what with it? The organic gardening industry won’t touch it with a ten foot pole. Burial means a truly huge amount of goop in the ground. And rendering plants now refuse to take the SRM’s because just processing them causes the other products they make to be unsaleable by association. Just trucking it almost requires a dedicated truck that will be used for no other purpose.
I have been away from the industry for a couple years, but the issue was a real big deal then.
In vet school we saw a video taken at a slaughterhouse, and I seem to recall that the lungs aren’t used for anything (or was it that they are merely not used for human consumption?) I was therefore a little bit surprised when I was in China and saw lung on some restaurant menus.
Bovine bile soap (produced in/extracted from the gall bladder) can be used to dissolve fat and protein stains. It used to be quite common over here for that purpose.
Turn it into fuel oil.
I’ve seen the ends of the largest bones for sale as dog bones. Beef lung can be dried for a dog treat, too.
We’ve got the hide covered - but what about the actual hair?
Carpets.
In the similar field of harvesting hogs, I worked near a meat processing line with hog carcasses hanging from a slow moving overhead chain. One man’s job was to jam his thumb into the anus, carve around it with a knife, pull it out, and sling it in a very professional and tricky manner into a chute specifically for pig anuses. I did get to go into the basement, but never saw where the pig anuses went. Still, they were getting special treatment for some reason.
[Barth]
What do you think’s in the burgers?
[/Barth]
Eyes ? Udders ? What about those ?
Gentlemen, I give you : the birth of the cockring. 
Cow eyes are a popular subject for dissection in high school biology classes. I did three of them. And a pig fetus.