# Nutrition Advisory Group - Insectivores



## Magpye (Jan 26, 2007)

Not sure if a moderator wants to make this a sticky, but here is the link to the Nutrition Advisory Group Handbook on feeding insectivorous species:

http://www.nagonline.net/Technical%20Papers/NAGFS00397Insects-JONIFEB24,2002MODIFIED.pdf

It details the nutritional content of numerous insects (although not locusts surprisingly), and illustrates the benefits of feeding a commercial high-Ca diet to the insects a couple of days before offering them as livefood. Note this removes the requisite to dust (doing so may lead to toxicity).

[Edit] - Just checked the figures again, crickets still need dusting as their Ca ratio is still poor, however king mealworm larvae and wax moth larvae wouldn't need dusting.


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## Magpye (Jan 26, 2007)

I did some maths using the figuers available:

*Standard metabolic rate of a reptile = 32W.77kcal/d* (Donoghue)
[when W is body weight in kg]

A 300g bearded dragon would therefore require 73.92 kcal/g Metabolizable Energy (ME) for maintenance.

If we work on the assumption that approximately 30% of the gross energy (GE) of kcal/g of a cricket is lost through feces (I'm too tired and too lazy to try and calculate actual ME from GE), then a single adult cricket provides around 3.696 kcal/g ME. A 300g bearded dragon would therefore require around 20 crickets a day to maintain its weight.*



* As stated, this is an assumption on the amount lost through excretion. If no GE is lost (impossible) then only 13 crickets a day would be required, whereas if 60% of GE is lost then around 45 crickets a day would be required. Theres some homework if you get bored - find out the ME of a cricket to a bearded dragon.



Donoghue, S. Nutrition of Pet Amphibians and Reptiles. _Seminars in Avian and Exotic Pet Medicine_ *7*(3):148-153.


P.S.
I know bearded dragons are omnivores, but used them as an example to illustrate how useful the other numbers (not just Ca and P) on the paper can be.


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## HadesDragons (Jun 30, 2007)

Magpye said:


> [Edit] - Just checked the figures again, crickets still need dusting as their Ca ratio is still poor, however king mealworm larvae and wax moth larvae wouldn't need dusting.


Waxmoth larvae have a Ca ratio of approx 1:4, and King Mealworm larvae have a ratio of approx 1:6 - they definitely need dusting, unless they've been fed a high-Ca diet. To get that amount of calcium into them would take at least a week or two on a highly-soecialised diet - usually they are fed off long before that time. Assuming that they haven't been fed whilst in the petshop, any shop-bought insects will have lower nutritional contents than those stated.

The "king mealworm" larvae that they are referring to aren't readily available in the UK - they are a _Tenebrio_ species, like regular mealworms, often pumped full of growth hormones. The larger ones we get over here are a _Zoophobas_ species, which have a different nutritional content.

The tables are useful if you breed your own livefood, but IMO shouldn't be taken as "gospel" because of the number of different factors involved.


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## AshMashMash (Oct 28, 2007)

Nice thread. I have saved the link, ta!

I did a very similar thread the other day, with the calulations, but on snake nutrtion. 

The equation I got for snakes was:

10(W^0.75), compared with your 32(w^0.77)... I guess its different for BD's and snakes eh?!

This was my one:

http://www.reptileforums.co.uk/snakes/82906-how-much-should-i-feed.html


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## Magpye (Jan 26, 2007)

It's interesting that 2 different equations exist. In the paper written by Donoghue there was no indication as to where she got the 32(w^0.77) formula. But I wouldn't discount it on the face of the snake formula you have being different - snakes are generally less active than most lizards so its reasonable to conclude they require a lower food intake. 

Don't forget to account for the fact that not all of the energy (GE) in the prey is available for metabolisation (ME) - some of it is lost through faeces but I couldn't find any figures on this for invertebrates so made a rough estimate of 30%. Not sure if the kcal you have used is GE or ME.

I don't have any snakes but I do have monitors, however I'm not sure how well they would do on 1 fuzzy a week!


Hades - the figues on quoted in the paper for crickets, mealworms and waxmoth larvae have values both with and without the high Ca diet. The literature also states that if the high Ca diet is fed for more than a few days it is likely to result in high invertebrate mortality, so 1-2 weeks is probably a no-no. The mineral values were also obtained through emission spectrometry so they're aren't estimates. I should have been clearer in the [edit] - which is referring to the values post high Ca diet.


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## AshMashMash (Oct 28, 2007)

Magpye said:


> It's interesting that 2 different equations exist. In the paper written by Donoghue there was no indication as to where she got the 32(w^0.77) formula. But I wouldn't discount it on the face of the snake formula you have being different - snakes are generally less active than most lizards so its reasonable to conclude they require a lower food intake.


Oh yeh, definitely! I wasn't discounting it! Sorry if my post implied that. I definitely think that there would be seperate formulae for snakes and lizards, they are very different. 



Magpye said:


> Don't forget to account for the fact that not all of the energy (GE) in the prey is available for metabolisation (ME) - some of it is lost through faeces but I couldn't find any figures on this for invertebrates so made a rough estimate of 30%. Not sure if the kcal you have used is GE or ME.


Yeh, I know. But, snake poo is pretty much _only_ hair. Few other bits, but thats it. So, I was discounting it... as I couldn't give a proper estimate as to how many calories come out in it.


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## Magpye (Jan 26, 2007)

Sorry lol! I wasn't suggesting you implied discounting it - I agree there will be different formulas.

Snakes are pretty efficient at making maximum use of their prey. I used to temporarily accomodate non-native snakes found in the wild but never was a fan of cleaning up after them. Their crap was usually quite messy - probably a result of digestion problems from being outside in our climate.


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## AshMashMash (Oct 28, 2007)

Magpye said:


> Sorry lol! I wasn't suggesting you implied discounting it - I agree there will be different formulas.
> 
> Snakes are pretty efficient at making maximum use of their prey. I used to temporarily accomodate non-native snakes found in the wild but never was a fan of cleaning up after them. Their crap was usually quite messy - probably a result of digestion problems from being outside in our climate.


Ah, cool. 

Wow, rehabilitating would be really interesting. My snakes are small... so poo's not that bad!


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## Magpye (Jan 26, 2007)

I've spotted a deliberate mistake with my maths when working out the ME kcal/d requirement. A 300g lizard actually needs 7.392 kcal/d according to Donoghue's formula, which to me sounds a bit low if 1g of crickets have a GE of 5.34. 

I'm going to get some 0.1g pocket scales to experiment with invert weights to validate the formula, until then I would ignore the kcal/d calculations.


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## AshMashMash (Oct 28, 2007)

Magpye said:


> A 300g lizard actually needs 7.392 kcal/d according to Donoghue's formula, which to me sounds a bit low if 1g of crickets have a GE of 5.34.


My 326g snake needs 4.31kcal/day. So your calculations seem of the right sort of order...

Would a 300g lizard not eat 1.5 crickets a day? That seems about right to me? (I dont keep lizards though, so maybe not : victory: )


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## Magpye (Jan 26, 2007)

Depends how much a cricket weighs. Common guidelines to feeding are as much as can be eaten in 10 mins and then to remove uneaten food. Some beardies will eaten more than 2 dozen crickets in 10 mins. However, condensing feeding into a single 10 minute session isn't ideal for a species that would spend considerable time in the wild searching for food.

I'll see how my beardie's weight progresses if I feed on a weight basis according to Donoghue's formula once I have the pocket scales to weigh out the diet.

If it turns out to be accurate I'll throw together a spreadsheet with invert and salad nutrient content to see if a diet can be formulated without the need to dust with calcium (Spring Greens have a Ca of 14:1 or similar so it should be possible).


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