Kick Kibble to the Curb “Revisited” - How Digestible Is Your Pet’s Diet?

Have you ever wondered if the food you feed your pet is highly nutritious and easily digested? It is important to consider digestibility when choosing any food for your pet. If you buy a commercial product, it is important to carefully read the ingredient labels and to know whether those ingredients provide optimum nutrition.

Digestibility (also referred to as bioavailability) is defined as how easily and completely a food or ingredient can be absorbed and used by the body.

What factors affect the digestibility/bioavailability of food?

  • Quality of ingredients – This factor is the most important. High quality easily digestible ingredients (i.e., whole foods) will result in a more highly digestible food. Organic or free-range ingredients are more likely to have higher digestibility.
  • The type of food - Animal-based protein is better digested than plant-based sources of protein for dogs and cats. Be warned of the following inferior ingredients that are purported to be excellent sources of protein:
    • Plant gluten (corn) protein, also known as “corn gluten meal”
    • Pea protein
    • Soy protein
    • “Egg Product” is an inexpensive way to add protein when the meat content of the food is inferior.
  • Degree of processing – A raw diet is more digestible than a kibble diet because it is minimally processed. When food is processed at high heat (kibble), the proteins can become “denatured” and the molecular structure is altered, resulting in a less digestible food. Dry food is (on average) 75% digestible while raw food is 95%-100% digestible. 
  • Amino acids - Studies in rats show that foods with an entire array of amino acids are more digestible than foods where amino acids are added back in after processing. Essential amino acids such as lysine, cysteine, taurine, and methionine are added back to food. It’s hard to trick mother nature in this instance!  Proteins are scored 0-100 based on the amino acid profile.  Eggs (score of 100) and meats (score 60-75) are at the high end of the amino acid profile. Beans and lentils score around 50. The biological value of a food is much lower for plant-based protein. 

What ingredients supply the most digestibility in dog food?

  • Egg whites contain all the essential amino acids your pet needs
  • Animal muscle meat and organ meat
  • Dairy products, particularly raw and fermented milk (pasteurized dairy is not recommended)

What ingredients and other factors can affect digestibility in dog food?

  • Cereal grains (wheat, corn, and oats) - Studies show the addition of grains and soy products into dog food will reduce digestibility. However, if grains are an ingredient in your dog’s food, it’s digestibility is improved with cooking. Inadequate cooking of any plant material can reduce its digestibility.
  • Soy products
  • Meat products (such as those in kibble) lose bioavailability when processed.
  • Fiber – A study showed adding fiber to dog food reduces the digestibility by 2-20%. Fiber content greater than 7.5% has been shown to be acceptable; however higher levels can create adverse effects on digestion. Some fiber is beneficial in a highly digestible diet; however too much can result in less digestibility.
  • Additives such as fillers and preservatives
  • Poor quality ingredients
  • Vitamins and minerals that are heat sensitive can be damaged by cooking

Do puppies and kittens need a highly digestible diet?

Puppies and kittens have a shorter and more acidic digestive tract than adults since their systems are not fully developed. As a result, they are not able to digest food as well as adults. They also have higher metabolic rates than adults, meaning they need more nutrients than adults for proper growth and development. Feed them a high-quality food that is highly digestible, and feed them more often, 3-4 times a day until about 6 months old.

What are the benefits of a highly digestible diet?

  • Reduced digestive problems (diarrhea, constipation, gas)
  • Increased nutrient absorption
  • Improved weight management: a highly digestible food contains more calories that are available for use by the body.
  • Reduced environmental impact: less waste (feces) is produced when an animal is consuming a highly digestible food.
  • Highly digestible foods have a higher moisture content, allowing the food to move easily through the digestive system.

What are the consequences of feeding a less digestible diet?

  • Gastrointestinal problems (diarrhea, constipation, IBD - Irritable Bowel Disease): processed foods like kibble are harder to breakdown in the body. The additional effort needed to break down the food in the digestive tract can place stress on the body and cause gastrointestinal problems.
  • Vomiting
  • Nutritional deficiencies
  • Weight gain – many calories are empty calories
  • Environmental impact: more waste is produced because the food cannot be utilized by the body efficiently.
  • Weight loss due to poor nutrition
  • Lack of energy

A few parting thoughts…

  • For animals with sensitive stomachs the digestibility score of the ingredients, the quality of those ingredients, and the fiber content are especially important. Add fiber gradually to allow the digestive system to adjust. 
  • A species appropriate diet (high meat) is recommended.
  • Large breed dog owners – feeding a species appropriate diet does not have to be cost prohibitive. Look for co-ops in your area. Do you have friends who are hunters?  Ask them for any part of the animal they do not want to keep for their families.
  • When purchasing gently cooked commercial food, read the label as certain brands have a high carbohydrate content. Your dog’s stool should be small, firm, and well formed. Large, bulky, messy and frequent (more than 1-2 times daily) bowel movements are a sign of high carbohydrate content.









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