How Gut Loading Works

Crickets eating lettuce.
Vegetables can be used as gut load food and the insects can be dusted with calcium powder.

Getty Images / Evgenia Chiley

If you care for a reptile or amphibian, you may be feeding it live insects. These insects act as food for your pet, but what's inside the insect will determine how nutritious a meal it really is. Gut loading provides assurance that you are feeding your pet nutrient-dense insects and can help prevent some serious issues from developing due to malnutrition.

What Is Gut Loading?

Gut loading is the act of feeding your pet's live food before your pet eats it. This is done so that your pet will eat a more nutritious meal. Crickets, mealworms, superworms, and other insects that are commonly used as food don't have a lot of nutritional value to them if they haven't recently eaten a meal. By gut loading these prey items, your pet will consume not only the insects, but everything the insects just ate as well.

How Do You Gut Load Prey?

A good insect gut load should consist of nutritious fruits, fish flakes, vegetables, grains, or chicken starter feed along with a calcium supplement. Products marketed as gut load can also be purchased and fed to your prey items; calcium powders can be sprinkled on the gut load prior to feeding it. Simply putting the insects in a container with some of these items will entice them to eat and gut load themselves.

Calcium supplementation is the main focus of gut loading and research has been done to examine the amount of time between gut loading and feeding your pet. While it depends on the type of insect and gut load, as a general rule, gut loading should be done within 24-72 hours of feeding the prey to your pet in order for it to receive the full benefits. If you wait more than two or three days to feed the gut loaded prey to your pet, then it isn't much different than if you hadn't gut loaded them at all. Additionally, feeding a variety of types of insects is beneficial to your pet, so you should rotate gut loading crickets, mealworms, superworms, and other insects to your reptile or amphibian.

Vitamins A and D may also need to be added to your gut load. Many insectivores need to consume these vitamins in their diets, especially if they don't have a UVB light, so depending on the type of gut load you use, you may also need to sprinkle a vitamin A and D supplement on the gut load or prey.

Why Is Gut Loading Important?

Reptiles and amphibians that primarily eat insects rely on the nutrition these insects provide to grow and stay healthy and strong. If they do not consume the appropriate nutrients from their diet, they can develop a variety of health issues.

Metabolic bone disease, also known as nutritional secondary hyperparathyroidism, is one common health issue that can affect pets that don't eat gut loaded insects. Since gut loading should include a calcium supplement and food that contains adequate vitamins, insects that don't contain these minerals and don't have a source of UVB lighting won't provide your reptile or amphibian with enough beneficial calcium and vitamin D to keep its bones strong. Bones can then become soft, bowed, and break, muscle tremors can occur, and even paralysis can develop if the disease gets bad enough. This can be avoided if calcium is provided in a gut load, proper UVB lighting is available, and vitamin D is present in the food either naturally or as a supplement.

Hypovitaminosis can also occur if insects aren't gut loaded prior to feeding them to your pet. While low vitamin D levels can contribute to metabolic bone disease, low vitamin A levels can cause skin issues, lethargy, and a decrease in appetite. Low vitamin B and E levels may also occur, but is more common in reptiles and amphibians that eat fish instead of insects. Hypervitaminosis, the opposite of hypovitaminosis, may also be seen but if the recommended amounts of vitamins are used, this is not a major concern. Ensuring that prey items are being fed nutritious gut load food is important, otherwise supplemental vitamins need to be added in addition to the calcium.

Article Sources
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  1. Finke MD, Oonincx D. Insects as food for insectivores. In: Mass Production of Beneficial Organisms. Elsevier; 2014:583-616.

  2. Boyer TH, Scott PW. Nutrition. In: Mader’s Reptile and Amphibian Medicine and Surgery. Elsevier; 2019:201-223.e2.