How much Energy?

[richierich]

Has anyone ever done a calorimetry to find out the exact values of the food the newt/sals eat to find out which is best? I plan on doing one this week and I will determine out of the following which have the most energy:

Earthworms from the baitshop
Earthworms from my yard
Pillbugs
Blackworms
Bloodworms
Crickets
Maggots

Nerdy enough?

 

[Jennewt]

The values for some of those feeders can be found in this article:
http://www.nagonline.net/Technical Papers/NAGFS00397Insects-JONIFEB24,2002MODIFIED.pdf (PDF)

I would also be interested in knowing whether the head end of the worm is very different from the tail end (it seems to be fattier).

Let us know how your results compare. Have fun!

 

[John]

This is interesting, I grant you, and I wish you luck with it but I what I would really like to know is the protein percentage of foods and other percentages. However please let us know how your experiments go.

 

[HanP]

Other publications on this subject are:


http://www.emys-home.de/EmysGERNaehrwertFrame.htm

http://www.chameleonnews.com/year2002/sept2002/nutrition/nutrition_sept_02.html

Han.

 

[richierich]

well I still need to obtain all these materials so I will probably start on friday when my exams are over. The question was more directed to the people of the forum as whether they partake in such experiments.

 

[invertkurt]

Cockroaches are another good food source to add. I think you also have to consider the cost:benefit of each good. Earthworms may take less energy to catch but may also take more energy to process. Feeding the most "nutritious" food doesn't make it the best food energetically.

I should also add that there are some famous studies about this sort of thing. For instance, certain birds (the type escapes me) will only try to take medium sized mussels even though larger, and more nutritious, ones abound because of the great energy it takes to open a larger one.

 

[richierich]

sorry i had to disappear for the summer before i could do my calorimetry experiment. I had lots of out of town stuff and work to do, so i plan to do the experiment within the week. I will test the ends of the worm for differences, and I dont think there is anywhere i could get my hands on cockroaches around here, sorry.

 

[Ed]

The nutritional aspects of earthworms have been well analyzed both as wild collected and as those purchased from a supplier..
Another article to check out on it is Barker, Dayna; Fitzpatrick. Marianne P.; Dierenfeld, Ellen S.; 1998, Nutrient composition of selected whole invertebrates; Zoo Biology 17:123-134
(this article covers mealworms (Tenebrio molitor), Mighty Mealys (trademarked) (T. molitor), Superworms (Zoophobas morio), Crickets (Acheta domestica), Waxworms (Galleria mellonella), Fruit Flies (Drosophilia melanogaster), Earthworms (Lumbriculus terrestris) wild caught, and commerical)

The simple energy results from a calorimetry result is not all of the information needed to get an idea of how much nutrition an invertebrate actually as you also need to figure out how much nitrogen (for protien) is available and how much is bound up in the chitin. (Most insectiverous animals can digest some chitin but the values vary from close to 0% to a high of about 85% in sea gulls and the current methods take the conservative lower end approach (until data shows otherwise) and utilize about 10-25% of the N in chitin).

Some comments,

Ed

 

[Jennewt]

Since your previous posts, Rich, I've put together a bunch of data that I was able to assemble:
http://www.caudata.org/cc/articles/foods2.shtml

 

[richierich]

Jen - Thats a great table and a wonderful addition to the site. I especially like the protein and calcium/phosphorus ratio parts of the chart.

Ed - i never thought of the chitin(or the nitrogen for the proteins), and I feel that jen's chart will satisfy me. I do not know how to calculate the influence of the proteins. I think that i will forgo the experiment if all I am going to attain is a flawed value. Thanks for your input Ed.

Sorry for wasting everybody's time