Gut Loading Feeder Insects (or how to turn your feeders into health food)
A main concern of reptile keepers is feeding food that is high in calcium and low in phosphorous. This is essential as a part of the way we prevent metabolic bone disease (MBD). The most commonly fed insects are just the opposite...high in phosphorous and low in calcium. Many dust the insects and worms with calcium powder to correct this.
While dusting works well, there is another method that works better if done properly...Gut Loading. Gut loading is a term for a technique for increasing the calcium content in an insects stomach prior to feeding. There are many that feel this is worthless but research shows that it is very effective.
The most common method is to feed the crickets, mealworms superworms etc a high calcium food a day or two before feeding the insects to the reptile. The most common food is calcium fortified chicken egg laying mash.
A far better way is to raise the feeders on high calcium food. I have found that greens such as turnip greens and dandelions are great for this (the insects feces is actually bright green). I also feed cactus powder and have made a "gel" out of cactus powder and agar that serves as a water source as well as food. An added benefit is a more balanced amino acid content and a higher omega 3 fatty acid.
In the wild insectivores and omnivores don't have the calcium deficiencies that we see in captivity. I believe this is for 2 reasons. One is the insects don't live on wheat bran or corn meal. Instead they eat a wide variety of food and greens. The other reason is the animals eat a wide variety of bugs.
In captivity we can mimic this (to some degree) by avoiding "mono" diets and gut loading.
Finke MD. 2002. Complete nutritional composition of commercially raised invertebrates used as food for insectivores." Zoo Biology 21:269-285
INCREASING THE CALCIUM CONTENT OF
Issn: 1042-7260 Journal: Journal of Zoo and Wildlife Medicine Volume: 31 Issue: 4 Pages: 512-517
Authors: Klasing, Kirk C., Thacker, Paul, Lopez, Melvin A., Calvert, Christopher C.