What Else Are By-Products Used For?

In the last post, we talked about what animal by-products are. And we focused on the edible by-products. The truth is, there are lots of parts of the cow (or goat, or sheep, or pig) that are not edible. And many of those parts are used for other things.

This picture has been circulating the internet for a long time. I found it most recently on Snopes.com, and wanted to discuss it a little bit here.

products made from cattle

First, let’s start with the brain. As we mentioned before, neurologic tissue from cattle (like the brain and spinal cord) can not be used for food because it is possible that it may contain the prion that causes bovine spongiform encephalopathy (BSE). Since the recognition of BSE, the brain and spinal cord (and other major neurologic tissues) of ruminants are not allowed to be used at all.

The term “blood” is a little misleading as well. One of the proteins in blood is called albumin, and this is the “blood product” that is used in many of the things listed in this diagram. Albumin is the major protein in blood (in all animals and people). It can be removed from the rest of the blood (purified) and used in other food products or for other things like medicine or laboratory research. Blood can also be dried into “blood meal” that can be used as a nitrogen-rich fertilizer.

The hooves and horns of animals are rich in keratin, a protein that is commonly used in hair care products. “Pet food” is also listed as something that uses hooves and horns. This is sort of true… but not quite. The hooves and horns of animals can be rendered – which is a heating process that pulls any fats out of the material being rendered (hooves, horns, skin, meat, and bones can all be rendered). So, inedible products (like hooves, horns, and bone) can be rendered to remove fats, and these fats can be used in pet foods. After bone is rendered, the solids that are left are ground into bone meal and can be used in pet foods. So, yes, pet food may contain hooves and horns… sort of… but not exactly. Pet food may actually contain fats that were taken out of the hooves and horns.

I know it says that bones are used to make refined sugar. Just like the “horns and hooves in pet food,” that’s an oversimplification.  Don’t worry – there’s no bone in your sugar. But the bones can be used to make filters used in the refining process. Not all types of sugars use this process, but some do.

I know this sounds strange, but the internal organs can  be used to make instrument strings and racket strings. It’s actually the outside part of the intestines that can be used for this.

In addition to what is listed above under “skin,” the skin of cattle is also used to make leather. The skin from other animals, like pigs and sheep, can also be used for leather.

So. Edible by-products include things like skin (from poultry), liver, and kidneys. Inedible by-products include things like skin (from cattle), bone, hair, and hooves.

I’ll admit that this is only scratching the surface of by-products and how they are used. It’s difficult to do much more in a single blog post! Let me know what your questions are in the comments (or email me directly), and I’ll address them below.


Large animal veterinarian, cattle farmer, pet owner, grocery buyer.


  1. Interesting.

    I’d be interested in seeing how we use by products from other animals like chickens and fish.

  2. Pingback: The Ridiculousness of it All | Sarah Sums It Up

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