Protein in Pet Food: What You Need to Know

Cat eating food
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Cats need significantly more protein than dogs because of species differences in protein metabolism.

Few pet food ingredients are more important than protein. But it’s also one of the more difficult ingredients to judge on a pet food label. Here’s what you need to know when evaluating the protein in your pet’s food.

What Role Does Protein Play?

Dietary protein is crucial to sustain daily life functions. After a meal, protein is broken down by the digestive system into amino acids. Once absorbed into the bloodstream, amino acids can be used to form new proteins that have numerous functions, such as helping to build muscle, repairing tissues, creating enzymes and hormones, transporting oxygen and iron in the blood and supporting immune function. If that’s not enough, proteins are also a source of energy and a major component of hair, skin, nails, ligaments, tendons and cartilage.

What Are Essential Amino Acids?

Amino acids fall into two categories: those that can be produced by the animal and those that can’t be made in the quantities the pet requires. The latter are considered “essential amino acids” and must be supplied in the diet. Although dogs and cats require the same 10 essential amino acids, cats also need one more called taurine. Signs of taurine deficiency in cats can range from blindness and heart failure to inadequate immune response and poor reproduction.

Are Some Proteins Better Than Others?

Pet food manufacturers generally rely on animals or plants (or both) as protein sources. Animal sources of protein include beef, chicken, lamb and fish; corn and soy are common plant sources.

But some proteins are better than others at providing essential amino acids that can be used by the animal.

In general, animal sources of protein yield a better balance of essential amino acids for dogs and cats than plants do. But if the protein source isn’t digestible, the diet won’t be effective. That’s why the highest-quality protein sources not only contain the proper proportion of essential amino acids for dogs and cats, but they’re also very digestible.

Still, even the best-quality proteins can be damaged by improper cooking during the pet food production process. That’s why it’s best to stick with a well-established, reputable pet food company experienced in proper production.

How Much Protein Is Enough?

The amount of protein your pet needs depends on her species, life stage and activity level, as well as the quality and digestibility of protein in her diet. Cats need significantly more protein than dogs because of species differences in protein metabolism.

Kittens, puppies and pregnant or nursing pets need more protein than adults. As you might expect, performance dogs involved in hunting, agility and other high-energy activities also require more protein than the dog who spends most of his day snoozing on the couch.

In the past, it was believed that older pets should be fed diets with lower protein, but veterinary nutritionists now believe that healthy older pets need protein every bit as much as their middle-aged counterparts. However, a protein-restricted diet may still be advised for older pets with severe kidney or liver disease.

Are Proteins Involved in Food Allergies?

Some pets can develop allergies to proteins in their foods. Signs may include itching, skin and ear infections, hair loss, hot spots and, less commonly, vomiting or diarrhea. Unlike some allergies that may be seasonal, food allergies (and the associated signs) tend to persist all year long.

To help resolve signs associated with food allergies, pets are usually given a special diet containing a protein they haven’t been exposed to in the past, such as rabbit, venison, salmon, turkey, duck and even kangaroo, or a diet in which the protein molecule has been hydrolyzed (broken apart) to such a small size that the pet’s immune system can’t recognize it. Pets on these special diets should not be fed other treats, including rawhides or pig ears, because they may contain proteins that could trigger allergies.

So How Do You Choose a Diet?

Start by asking your veterinarian for guidance. He or she can recommend reputable pet food companies and help you interpret and compare protein content on pet food labels.

If you choose a diet that’s tailored to your pet’s life stage (such as growth and reproduction or adult maintenance), it should be formulated to contain an appropriate level of protein for your pet.

You’ll also want to check the label to make sure the food is complete and balanced, as established by animal feeding tests using Association of American Feed Control Officials (AAFCO) procedures. Foods deemed “complete and balanced” are formulated to provide balanced nutrition when fed as the pet’s exclusive diet.

There are essentially two ways that a pet food manufacturer can substantiate nutritional adequacy. The first way is to formulate the food to meet AAFCO nutrient profiles for dogs and cats. For example, a label for an adult dog food may read, “X brand of dog food is formulated to meet the nutritional levels established by the AAFCO Dog Food Nutrient Profiles for maintenance of adult dogs.”

The preferred method requires pet food manufacturers to actually feed the finished food to dogs and cats, following AAFCO feeding trial guidelines. This provides you with the added assurance that the nutrients are properly absorbed and the diet has no significant negative effects on pets. For example, a label for a food for an adult cat may read, “Animal feeding tests using AAFCO procedures substantiate that X brand of cat food provides complete and balanced nutrition for the maintenance of adult cats.”

Finally, remember that your pet is unique and may respond differently than other pets to a particular diet. But with the right dietary proteins, your dog or cat is more likely to have a shiny coat, healthy skin and plenty of energy.

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