The Chitin debate!!!

[Pixie]

Since my introduction to lizards and their diets (leos for now), I've read and heard from almost everyone in the hobby that too much chitin in a lizard's diet can cause problems with digestion that can be serious: impaction.

Everyone says it is preferable to feed freshly molted mealworms as they contain less chitin and are easier to digest.

That is what I have a very hard time understanding!!!

How does the chitin level change from regular mealworm to freshly molted mealworm? Both have chitin, the latter's is just softer and not hardened yet.

Freshly molten mealworms will turn back to the "normal" color in a very short period of time, 2 to 4 hours. So how does the mealies that just molted have less chitin than one who is regular color that molted 3 hours ago???

The only real difference I could see is between a mealie that is about to molt and one that has just molted. The first having two layers of skin and therefore having more chitin because it hasn't shed yet.

Otherwise the only difference I can think of is in the freshly molted mealie, the chitin is still soft and "wet" and hasn't hardened yet. Would the actual texture of chitin (wet versus dry) be a factor in it's digestibility?

Any opinions???

Pixie

[Rich]

Hello,
That would be a yes. Chitin is the hard exterior of the shell. When that layer is shed, the inner,softer layer is exposed. That is much more digestible than the outer shell.

[eyespy]

Pixie, entomologists laugh at most herpers for their fear of "chitin" as most of the hard shells of insects are actually toughened proteins that are merely bound together by small amounts of chitin and it's those proteins we often find in the digestive tracts after an animal is brought in for bowel resection due to an impaction. Sure, there's some chitin that makes up the blockage, but it's just a fraction of the problem.

Most bugs only shed the cuticle portion of the exoskeleton, not the membranes which contain the chitin. Cuticles are primarily protein, not chitin.

Chitin is found in greater concentrations in soft body tissues than in the shells of many common feeder insects, such as crickets and mealworms so shedding does not make much difference as to how much is ingested. But all those melanized proteins that form the hard shells of a mealworm do shed off, and that's what actually makes the difference.

Some animals get impacted on high-chitin feeders whether or not they've recently molted. Freshly-molted mealworms are very commonly found blocking the small intestines of bearded dragons, for example. But this sort of thing is relatively rare, it's the proteins that present the major problems.

http://www.faculty.ucr.edu/~insects/pages/teachingresources/tmlectures/01cuticle.html

[Pixie]

Eyespy: Thank you so much for your response! I kept hearing of how bad chitin is for lizards and how hard it is to digest that I wanted to know more about it.

I loved the link you included, was quite informative. Would you happen to have other links of the sort on insects or reptiles? I love learning about what is going on health wise other than seeing the food just being gobbled up!

Pixie

[eyespy]

Sorry, no! One of my vet friend's entomologist buddies shot me that link back when I was warning somebody of the chitin levels in mealworms to basically show me not to believe all the "herper's old wives' tales" but that's the only one I've ever seen that was like that.