Ask the Vet: Byproducts in Pet Food Provide Nutrients Missing From Muscle Meat
Q: I heard that byproducts are bad for pets, so I want to buy cat food that is free of them. What brands do you recommend?
A: Actually, byproducts are full of nutrients, and it would be unwise to forgo them.
A byproduct is something produced or left over when something else is made. In the U.S., most people who eat meat consume only the animal's skeletal muscle, so its liver, pancreas, stomach, spleen, kidneys, lungs, intestines (excluding the partially digested food inside), blood and bones are byproducts.
These body parts contain abundant taurine, an important amino acid for cats, while skeletal muscle contains very little. Amino acids are the chief constituents of proteins, the building blocks of the body. Cats deprived of taurine suffer from heart failure due to cardiomyopathy and blindness from retinal degeneration.
Organ meats are also rich in protein as well as vitamins and minerals, which are lacking in skeletal muscle.
Some foods we Americans consider unappetizing byproducts are enjoyed by people in other countries. For example, I am of Scottish ancestry, and when I visited Scotland, I dined on haggis, the country's national dish. Haggis is sheep's stomach filled with the animal's heart, lungs and liver, as well as oatmeal, onions and spices.
Another common pet food ingredient is brewer's yeast, a byproduct of beer production. Brewer's yeast is rich in B vitamins, minerals and amino acids.
Vitamin E is a byproduct of soybean processing. Other useful byproducts are wheat germ, bran, molasses, tomato pomace, whey and fat.
Human meals also contain byproducts. You probably eat gelatin, bouillon and broth, all of which are meat byproducts.
You'll be relieved to know that U.S. pet food regulations prohibit the use of hides, hooves, horns, teeth, hair, feathers and intestinal contents in pet foods.