Protein is a vital component of a cat’s diet, playing a crucial role in their overall health and well-being. As obligate carnivores, cats have unique nutritional requirements that differ significantly from dogs and humans. This article delves into the importance of protein in cat food, exploring various sources, recommended levels, and how to determine the protein content of your cat’s food.
Why Protein is Essential for Cats
Like humans, cats need a balanced diet of water, protein, fats, carbohydrates, vitamins, and minerals. Protein, fat, and carbohydrates are the primary energy sources. However, protein is particularly crucial for cats due to their obligate carnivorous nature.
Cats: Obligate Carnivores
Unlike dogs, which are omnivores, cats are obligate carnivores. This means their bodies are designed to thrive on a diet primarily consisting of meat. Their metabolism has adapted to efficiently process and utilize animal protein.
Cats need to ingest specific amino acids readily available in meat sources. While other species can synthesize certain amino acids, cats have limited ability to do so.
The Importance of Amino Acids: Taurine and Arginine
Most species require 9 essential amino acids from their diet, but cats need two additional ones: taurine and arginine. These amino acids are only found in animal tissues.
- Taurine: Essential for eye and heart health, reproduction, and kitten growth. Deficiency can lead to blindness, heart failure (dilated cardiomyopathy), reproductive issues, and developmental abnormalities.
- Arginine: Crucial for removing ammonia from the blood. Arginine deficiency can cause neurological symptoms, seizures, and even death.
Protein as a Primary Energy Source
Cats rely heavily on protein for energy. Their liver enzymes constantly break down proteins to maintain blood glucose levels. When cats don’t get enough protein from their diet, their bodies start breaking down muscle tissue to meet their needs.
Protein Sources in Cat Food
Cat food typically contains protein from animal and plant sources. While plant-based diets may appeal to some pet owners, cats cannot meet their nutritional needs with plant sources alone. Animal tissues contain essential nutrients not found in plants.
- Taurine: Only found in animal tissues.
- Methionine and Cystine: Essential amino acids required in high amounts, especially during growth. Plant sources often lack sufficient levels.
- Bioavailability: Animal proteins are more readily used by the body than plant proteins.
Animal Protein Sources
Common animal protein sources in cat food include beef, chicken, turkey, lamb, and fish. Meat meals and by-products also offer concentrated protein. Despite misconceptions, meat meals and by-products are often nutritious and beneficial for cats.
- Meat Meal: Animal protein that has been ground and had the water removed, providing a concentrated protein source.
- Meat By-Products: Organ meat, which can be a concentrated source of nutrients.
Plant Protein Sources
Plant protein sources include corn gluten meal, soybean meal, wheat gluten, and rice protein concentrate. While some plant sources contain comparable protein levels to animal-based ingredients, cats cannot digest and utilize them as efficiently. Plant sources often lack sufficient taurine or methionine. Synthetic taurine and methionine can be added, but their digestibility is lower than naturally occurring nutrients in animal tissues.
Determining Optimal Protein Levels in Cat Food
Adult cats require significantly more protein than dogs or humans. Guidelines may vary, but cats generally need a minimum of 26% protein in their diet.
A mouse, a cat’s natural prey, consists of approximately:
- 55% protein
- 45% fat
- 1-2% carbohydrate
AAFCO recommends a minimum of 30% protein for growth and reproduction and 26% for adult maintenance. However, recent studies suggest that a higher percentage of dietary protein (at least 40%) is warranted for optimal health. Cats consuming diets with less than 40% protein may lose lean body mass over time.
Increased Protein Needs for Senior Cats
As cats age, their protein requirements increase due to reduced digestive efficiency. Cats aged 12 or more may benefit from diets containing nearly 50% protein.
Calculating Protein Content: Dry Matter Basis
It can be challenging to determine the actual protein content based on the label alone due to variations in moisture content. AAFCO bases nutrient recommendations on a “dry matter basis,” while pet food labels print nutrient content on an “as-fed” basis.
To accurately compare protein content, convert the protein level from “as-fed” to “dry matter basis.”
- Subtract the Moisture (max) percentage from 100. This gives you the percent dry matter.
- Divide the Crude Protein (min) by the percent dry matter.
- Multiply the result by 100. This gives you the percent of protein on a dry matter basis.
Example:
Canned Food A:
- 12% crude protein minimum
- 78% moisture maximum
Calculation:
- 100 – 78 (moisture) = 22 (dry matter)
- 12 (crude protein) / 22 = 0.545
- 0.545 x 100 = 54.5% protein on a dry matter basis
AAFCO Standards and Protein Quality
AAFCO sets standards for pet foods in the United States. While compliance is not mandatory, veterinary nutritionists generally recommend feeding AAFCO-compliant diets. These diets have a nutritional adequacy statement.
AAFCO also has standards for protein analysis, stating that not more than 9% of the crude protein should be “pepsin indigestible,” ensuring that at least 91% of the protein is digestible.
Protein Allergies in Cats
Food allergies are relatively common in cats and are typically triggered by specific proteins. Symptoms include itchy skin, overgrooming, vomiting, diarrhea, and conjunctivitis.
Elimination Diets for Food Allergies
Diagnosing a food allergy requires a diet trial, involving a limited ingredient diet or a hydrolyzed protein diet for 8-12 weeks.
- Limited Ingredient Diets: Use proteins that the cat has not been exposed to before, such as duck or venison.
- Hydrolyzed Protein Diets: Modify the shape of the proteins, so the body does not recognize them as an allergic trigger.
Conclusion
Protein is a critical nutrient for cats due to their obligate carnivorous nature. Ensuring your cat receives adequate protein levels, from high-quality sources, is essential for their overall health and well-being. By understanding the different protein sources, recommended levels, and how to calculate protein content on a dry matter basis, pet owners can make informed decisions about their cat’s diet. Consult with your veterinarian to determine the best diet for your cat’s individual needs and life stage.
References
“AAFCO Methods for Substantiating Nutritional Adequacy of Dog and Cat Foods: AAFCO Dog and Cat Food Nutrient Profiles.” www.aafco.org, 2014.
Burns, Kara M., “Feline Nutrition – Cats Are Not Small Dogs!” Southwest Veterinary Symposium, September 21-24, 2017, San Antonio, TX.
Davenport, Gary M., “Feeding Cats as Carnivores.” Iams Company Symposium Proceedings, 2002.
Kerby, Victoria L., “Feeding Our Feline Overlords: Nutrition for the Internet’s Favorite Animal.” Western Veterinary Conference, February 16-19, 2020, Las Vegas, NV.
Scherk, Margie, “Feline Nutrition: Facts, Fun and Physiology, Cats Are Different Than Dogs!” American Board of Veterinary Practitioners Symposium, April 15-18, 2010, Denver, CO.
Thomas, Randall C., “Food Allergy in Dogs and Cats.” Western Veterinary Conference, 2005.
Verbrugghe A. and S. Dodd, “Plant-Based Diets for Dogs and Cats.” World Small Animal Veterinary Association Congress Proceedings, July 16-19, 2019, Toronto, Canada.
Zoran, Debra L., “Cats and Protein: The Conversation Continues.” American College of Veterinary Internal Medicine Forum, June 14-16, Seattle, WA.
