What Is the Difference Between Adult and Kitten Food?

What is the difference between adult and kitten food?

The main difference between adult and kitten food is that kitten food contains higher levels of protein, fat, calcium, phosphorous, omega oils and trace elements for rapid growth and development.

Resting energy requirements (RER) is how many calories the cat needs at rest, at a controlled temperature. You can see below that kittens have considerably higher RER requirements than adults on a maintenance diet.

  • Kittens: RER x 2.5
  • Adult cats (desexed maintenance): RER x 1.2

Kitten food for optimal growth

The first six months of a kitten’s life see rapid growth, and the kitten requires high-quality, easily digestible food with the right balance of protein, fats, vitamins and minerals. Kitten food is more calorie-dense as a kitten’s stomach is not able to hold a large volume of food, so the food must provide the kitten with high calories in small but frequently fed portions. Dry kitten food (kibble) pieces are smaller than adult dry which helps small kitten teeth and mouths to easily chew the food.

  • Protein: Proteins are the building blocks of life and cell in the body contains protein. The Association of American Feed Control Officials (AAFCO) nutrient profile has a minimum crude protein of 30% for kittens, pregnant and nursing mothers and a minimum of 26% for adult maintenance. Protein is necessary for muscle building lean muscle.
  • Single meat source: Most kitten foods contain a single source of meat, usually chicken, which is easier for the kitten to digest.
  • Fat: Crude fat is required for energy, and a gram of fat contains 9 calories.  Minimum crude fat is 9% for both adults and kittens, however, most kitten foods contain higher levels of fat than adult maintenance. Iams contains a minimum of 18.5% crude fat for kittens and 13% for adult maintenance. Eukanuba kitten contains 23.75% fat and adult (sterilised cat) contains 12.75%.
  • Essential fatty acids: The cat cannot produce omega-3 and omega-6 fatty acids and therefore must obtain them from their diet, making them essential. Docosahexaenoic acid (DHA) is an omega-3 fatty acid found primarily in marine sources that is supplemented in kitten diets to support optimal retinal function and brain development.
  • Calcium and phosphorous: Calcium and phosphorous are important for growing bones and teeth during kittenhood. Most kitten food diets contain 1.5% calcium, and 1.2% phosphorous, compared to 1.2% calcium and 0.9% in the adult diet.
  • Trace elements: Kitten food contains slightly higher levels of the fat-soluble vitamins A, D and E. Vitamin A is important for normal growth, helps vision and tissue repair. Vitamin D is needed for the body to absorb calcium from the intestines, and vitamin E is an antioxidant that protects the cells from oxidative damage.

AAFCO cat food nutrient profiles for cats and kittens

Growth and reproduction (minimum) Adult Maintenance (minimum) Maximum
Crude protein % 30.00 26.00
Arginine % 1.24 1.04
Histidine % 0.33 0.31
Isoleucine % 0.56 0.52
Leucine % 1.28 1.24
Lysine % 1.20 0.83
Methionine % 0.62 0.20 1.5
Methionine-cystine % 1.10 0.40
Phenylalanine % 0.52 0.42
Phenylalaninetyrosine % 1.92 1.53
Threonine % 0.73 0.73
Tryptophan % 0.25 0.16 1.7
Valine % 0.64 0.62
Crude fat % 9.0 9.0
Linoleic acid % 0.6 0.6
alpha-Linolenic acid % 0.02 Not determined
Arachidonic acid % 0.02 0.02
Eicosapentaenoic + Docosahexaenoic acid % 0.012 Not determined
Calcium % 1.0 0.6
Phosphorous % 0.8 0.5
Potassium % 0.6 0.6
Sodium % 0.2 0.2
Chloride % 0.3 0.3
Magnesium % 0.08 0.04
Iron mg/kg 80 80
Copper (extruded) mg/kg 15 5
Copper (canned) mg/kg 8.4 5
Manganese mg/kg 7.6 7.6
Zinc mg/kg 75 75
Iodine mg/kg 1.8 0.6 9.0
Selenium mg/kg 0.3 0.3
Vitamins and others
Vitamin A IU/kg 6668 3332 333300
Vitamin D IU/kg 280 280 30080
Vitamin E IU/kg 40 40
Vitamin K mg/kg 0.1 0.1
Thiamine mg/kg 5.6 5.6
Riboflavin mg/kg 4.0 4.0
Pantothenic acid mg/kg 5.75 5.75
Niacin mg/kg 60 60
Pyridoxine mg/kg 4.0 4.0
Folic acid mg/kg 0.8 0.8
Biotin mg/kg 0.07 0.07
Vitamin B12 mg/kg 0.020 0.020
Choline mg/kg 2400 2400
Taurine (extruded) mg/kg 0.10 0.10
Taurine (Canned) mg/kg 0.20 0.20

How long should a kitten eat kitten food?

A kitten should be introduced to kitten food when he or she begins to wean which is usually around four weeks. During this transition phase, the kitten will continue to nurse, but will gradually consume more solid food and less milk. The kitten will remain on kitten food until twelve months of age.

The Maine Coon, Norwegian Forest Cat and Siberian are large breeds that are slow to mature and should remain on kitten food for 2 years.

Is it safe for an adult to eat kitten food?

An adult can eat kitten food, however, as it contains more calories, it is not recommended for long term feeding as it can lead to weight gain. If you have a kitten and an adult cat in the same home, feed in separate locations so that each cat is able to consume an age-appropriate diet.

Can kittens eat adult food?

A kitten can eat adult food in the short term, ie; if you run out of kitten food but can buy more the following day. Adult cat food doesn’t contain the correct nutrients a kitten needs for optimal growth and development. If the food says ‘for all life stages‘, it is safe for kittens and adults to eat.

What to look for in kitten food

Learn to read pet food labels, which provide important nutritional information. Always choose a premium food that adheres to the guidelines set in place by The Association of American Feed Control Officials.

Does the brand employ a nutritionist to formulate the food? Appropriate qualifications are a PhD in Animal Nutrition or Board Certification by the American College of Veterinary Nutrition (ACVN) or European College of Veterinary Comparative Nutrition (ECVCN).

Choose diets formulated to meet AAFCO or European Pet Food Industry Federation (FEDIAF) guidelines.

The food should include ingredients (food and supplements) validation, final diet nutrient analysis, toxicology, bacteriology and packaging/shelf-life screening during the entire manufacturing process.

Does the label include a Nutrition Adequacy Statement? Is it a complete diet? Labels should state that the food is a ‘complete’ diet that contains all the required nutrients. Does the food meet the nutritional needs of the different life-stages? Kitten, reproduction, maintenance?

Look for brands that provide immediate contact information such as a phone number or an email address for additional questions pet owners may have.

Does the manufacturer offer product guarantees?


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio

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