Gut loading frenzy

Okay....after browsing through hundreds of pages of research (the one posted above is a solid 161 pages!) I have some interesting info to share. It would appear that studies have demonstrated a combination of the two definitions of gutloading proposed is actually in effect. The time suggested for gutloading varies as well. I will provide a few excepts from some of the studies and then discuss a summary of sorts. As a side note, challenging view points is best accomplished with data to back it up, such as the studies quoted below.
AN OVERVIEW OF THE DEVELOPMENT AND EVALUATION OF A GUTLOADING DIET FOR FEEDER CRICKETS FORMULATED TO PROVIDE A BALANCED NUTRIENT SOURCE FOR INSECTIVOROUS AMPHIBIANS AND REPTILES
- As a result, after sufficient ingestion, the insect’s gastrointestinal tract (crop and midgut) is filled (Figure 1) and hence, its nutritive composition is comprised of both the insect’s whole body nutrients and the retained diet within its gastrointestinal tract.
- The minimum target vitamin A levels were achieved, again after gut-loading for only one day, and these continued rising until the fourth day at which time they decreased but were still above the target minimum.
- This time period was chosen based on reports of other researchers who 14 found that cricket gut-loading potential was usually maximized after two days of gut-loading (Allen and Oftedal 1989; Bernard et al. 1997; Hunt et al. 2001; Finke et al. 2005).
- These values also illustrated that the target nutrient levels were achieved after gut-loading for only 24hrs (Ca: P of 1.127; vitamin A (retinyl acetate) level of 12,607 IU/kg; vitamin E level of 342 IU/kg and a linoleic fatty acid level of 4.62%). The benefits of this technique were realized over the full four day gut-loading period in that the nutrient levels attained remained above target levels and hence, above the estimated requirements of the end consumers (insectivores) throughout the duration of the experiment.

The Development and Evaluation of a Gut-loading Diet for Feeder Crickets Formulated to Provide a Balanced Nutrient Source for Insectivorous Amphibians and Reptiles
- Gut-loaded cricket analysis established its effectiveness such that the targeted level of most nutrients required by the end consumers (insectivores) were met after consuming the diet for 24 hrs (Ca: P of 1.127; vitamin A (retinyl acetate) level of 12,607 IU/kg; vitamin E level of 342 IU/kg and a linoleic fatty acid level of 4.62%), peaking at 2 days for some and remained above targeted amounts for at least 4 days.

GUT-LOADING DIET EVALUATION FOR CRICKETS (ACHETA DOMESTICUS), MEALWORMS (TENEBRIO MOLITOR), AND SUPERWORMS (ZOPHOBAS MORIO) FOR THE PURPOSES OF OPTIMIZING INSTITUTIONAL PROTOCOLS
Previously measured vitamin A values in non-gut-loaded adult crickets and mealworms has been shown to be 0.8 IU/g, and superworms had measured values of about 0.95 IU/g (Baker et al., 1998). However, gut-loaded crickets have been shown to reach levels as high as 14.59 IU/g when measuring retinol and βcarotene (Li et al., 2009). The level of accurate detection of vitamin A at the lab we sent our samples was 1.66 IU/g. Therefore, several of the samples tested showed below detectable levels. Surprisingly, the only cricket group to have detectable concentration of vitamin A was the PS diet (1.99 IU/g). There was no detectable vitamin A concentration in any of the superworm diets, and although the mealworms all had measurable levels of vitamin A (1.74-2.14 IU/g), there was no significant difference between the diets fed. When making our decision regarding which diet to choose for our protocols, this information removed vitamin A as a deciding factor.

Effects Of A High Calcium Diet On Gut Loading In Varying Ages Of Crickets {Acheta domestica) And Mealworms {Tenebrio molitor)
- A typical cricket has a Ca: P ratio of only 0.15:1 whereas, a dietary ratio of 1:1 - 2:1 is the usual recommendation for birds and mammals [Allen and Oftedal, 1989].
- Crickets and mealworms were maintained on the experimental diet for eight or seven days, respectively, and were sampled at days two, four, and eight (crickets) or two, four, and seven (mealworms) according to the sampling weights mentioned above
- WeekOldCRickets had the highest Ca: P ratio of 0.88 at day four, whereas Half GrownCRickets and ADultCR reached the highest ratios (0.67 and 0.48) at day two.
- The Ca: P ratio increased significantly in WOCR by day two and was maintained until day eight. In HGCR and ADCR the Ca: P ratio increased 96 significantly from both day zero to day two and day two to day four and was maintained throughout day eight.
- An important aspect of gut-loading is the timing involved in feeding the insects out. According to these results, small and medium mealworms reach a 1:1 Ca: P at day two and dropped significantly after that. Allen and Oftedal [1989] show that Ca levels are maintained from 48-120 h. In this study, levels were not maintained, however, this could be due to the higher terrahum temperature. Most likely, crickets and mealworms should be gut loaded and fed out between two and four days after being subjected to the diet.

From blackbirds and thrushes... to the gut-loaded cricket: a new approach to zoo animal nutrition
- The Ca content of the crickets increased progressively with an increase in dietary Ca (Fig. 2(a)), with the result that crickets consuming diets containing 80-120 g Ca/kg had a Ca: P ratio greater than 1:1. P concentrations did not change and remained at approximately 8 g P/kg (Fig. 2(b)). Radiography demonstrated that Ca accumulated in the gut rather than in the bodies (Fig. 3).

Increasing calcium levels in cultured insects
- Acceptable insect Ca and Ca: P levels were achieved by maintaining insects on commercial high‐Ca diet products for as little as 24 hours.

Evaluation of Various Calcium-fortified High Moisture Commercial Products for Improving the Calcium Content of Crickets, Acheta domesticus
- Since gut loading results in an increase in cricket calcium content due to the food retained in the crickets’ gastrointestinal tract (Allen and Oftedal, 1989), it is not surprising that commercial “calcium-fortified cricket waters” containing only 0.37 and 0.24 g/kg Ca would have no significant effect on cricket calcium content.
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Dietary Manipulation of the Calcium Content of Feed Crickets
- Experimental diets were formulated to contain 2, 4, 6, 8, 10, and 12% Ca and were provided to the crickets for 12, 24, 48, 72, 96, and 120 hr. Crickets were analyzed for dry matter, Ca, and phosphorus. Dietary treatment and duration of treatment were found to have significant effects on Ca content and Ca: P ratio of crickets, but not on P content. The Ca content and Ca: P ratio of crickets increased during the initial period of feeding, but after 48 hr these mineral levels remained stable.
- Radiographs revealed radiopaque material in the gastrointestinal tracts (GIT) of most crickets fed diets high in calcium (8, 10, or 12% Ca) but not in the GIT of crickets fed diets low in calcium. It is concluded that in order to obtain crickets with a Ca: P ratio of 1:1 or higher it is necessary to feed diets containing at least 8% Ca.

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To be continued, I exceeded the character limit for a post....
 
The Development and Evaluation of a Gut-Loading Diet for Feeder Crickets Formulated to Provide a Balanced Nutrient Source for Insectivorous Amphibians and Reptiles
- Gut-loaded cricket analysis established its effectiveness such that the targeted level of most nutrients required by the end consumers were met after consuming the diet for 24 hrs (Ca: P of 1.127; vitamin A (retinyl acetate) level of 12,607 IU/kg; vitamin E level of 342 IU/kg and a linoleic fatty acid level of 4.62%), peaking at 2 days for some and remained above targeted amounts for at least 4 days.
- After dusting, 10 g cricket samples were collected at intervals of 5 min, 3 hrs and 22 hrs. Samples analyzed for each time period yielded disappointing results since the Ca: P ratio was still 12 below the desired 1:1. The low amount of supplement used was possibly to increase palatability, but this may have facilitated its removal via grooming by the cricket. Other researchers have been more successful. For example pinhead and juvenile crickets that were sampled immediately after dusting with a high calcium supplement (39%) showed a desirable Ca: P ratio (McClements et al. 2003; Schlegel et al. 2005)
- The second supplementation technique, gut-loading, is the most utilized, tending to be more consistent and significantly more successful than the “dusting” technique (Allen and Oftedal 1989; Finke et al. 2005; Hunt Coslik et al. 2009). It offers a nutrient-dense diet to an insect prey species so that after sufficient ingestion, its gastrointestinal tract is filled. Its nutritive composition, therefore, is comprised of both the insect’s whole body nutrients and the retained diet within its gastrointestinal tract.
- Gut-loading has also played a role in supplying other nutrients besides Ca. There are reports of the use of gut-loading to enhance vitamin A and vitamin D content of crickets fed to geckos and chameleons (Finke 2003). Li et al. (2009) have incorporated vitamin A, unsaturated fatty acids and spirulina (a source of several micronutrients, particularly carotenoids) into cricket gutloading diets and have increased the growth rate, as well as doubled the feeding strike success of Wyoming toads (Bufo baxteri) suffering from squamous metaplasia syndrome due to vitamin A deficiency
- The general recommendation is for palatable gut-loading diets to contain 5 - 8%, or 50 to 80 g calcium/kg diet. If this is derived from calcium carbonate (400 g calcium/kg by weight), these diets, should be supplemented with 125 to 200 g Ca carbonate/kg diet in order to be effective as a feeding source for reptiles and amphibians (Allen and Oftedal 1989; Hunt et al. 2001; Finke 2003; Finke et al. 2004). Although, 8% diets are more commonly used, Finke (pers. comm., September 2005) suggests that diets containing 6-7% Ca should be more than adequate for gutloading.
- The dietary ingredients incorporated contained the provision of required nutrients which were expected to be retained in the GIT of the cricket, the vehicle of nutrient delivery. The retained nutrients and the cricket whole body nutrients combined were expected to provide an optimal nutrient package for the end consumers. This of course was dependent on the sufficient ingestion of the diet by the cricket.
- It would be best to gut-load the crickets before they entered mid instar i.e., before the moulting process began thereby avoiding a reduction in intake. However, as observed through most of the previous chapter’s set of experimentation, the crickets consumed comparatively more of the food offered during the first 24 hrs after delivery than during any other time period (Tables 4.14 and 4.16).
- The target minimum Ca: P ratio was achieved after they had been gut-loaded for only one day, reaching a maximum level after two days and although it did decrease over the next two days, the levels were still above the minimum.
- The minimum target vitamin A levels were achieved, again after gut-loading for only one day, and these continued rising until the fourth day at which time they decreased but were still above the target minimum
- The vitamin E levels, however, exceeded our target maximum after gut-loading for only one day. The levels of this vitamin’s addition to the diet may be too high in that it may interfere with vitamin A absorption in the end consumer
- The GLD, in combination with the recommended gut-loading methodology, has more consistent success and is an improvement over other previously tested diets. Those researchers who were able to achieve required nutrient levels through the gut-loading supplementation technique, reported that the required levels were reached, albeit inconsistently, after at least two days of gut-loading and remained at these levels for a further one to two days of gut-loading, after which the nutrient levels dropped below the required amounts
- Researchers who achieved the required nutrient levels were only able to do so for a period between 2-4 days of gut-loading (Allen and Oftedal 1989; Anderson 2000; Finke 2004; Finke et al. 2005; Hunt Coslik et al. 2009). The crickets consuming the new GLD could be used for feed after one day of gut-loading and could continue to be fed off over a maximum of four days of gut-loading which may be extended with further testing.
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Most of the studies were specifically focused on calcium levels and increasing the Ca: P ratio from 0.15:1 (the normal cricket without gutloading) to 1:1, which is more nutritionally appropriate for insectivores. None of the studies were focused directly on chameleons and determined what was "sufficient" based on an average across reptile species that have been studied. These specific studies are lacking in chameleons unfortunately. Some studies directly contradict others but there were some repeated trends seen from multiple investigators in different scenarios. So in summary, a couple of interesting things that the peer reviewed studies show:
  • Younger crickets (mid instar) gutload more effectively, as long as they are not molting, than adult crickets
  • Dry gutload formulas were more effective in increasing calcium levels as well as several other vitamins but most commercially available dry formulas are not as calcium enriched as advertised. Specifically, the Fluker products did not increase calcium content enough to be even remotely sufficient. Timberline Power food fortified with an additional 15% calcium carbonate was the only one that provided sufficient levels but Timberline Power food alone scored the lowest. But when pure calcium carbonate was provided the results were not inspiring.
  • Of some produce based gutloads, which unfortunately there were not many in these studies, a combination of apple, carrot, and sweet potato was more effective compared to apples and papaya. Which is interesting since apples and carrots are not particularly rich in calcium so it would seem the sweet potato is the most effective part. But maybe that corroborates why so many people that "gutload" with carrots don't have reptiles as poor off as expected. More research is needed there.
  • The only gutload that included vegetables was based on bok choy, broccoli, and collard greens. It was not concluded to be very successful, but that's not surprising given that bok choy and broccoli are both considered poor gutloading ingredients. More research is needed using higher calcium, more appropriate veggies to determine their efficacy.
  • An early study indicated it took 48 hours of gutloading to be effective so many subsequent studies don't even measure effects of gutloading before the 48 hour mark. However, the ones that did found sufficient levels after 24 hours in multiple cases and in the graphs posted you can see that there is already a considerable rise in just 12 hours. So perhaps the recommended interval from feeding feeders to feeding insectivores is best stated as 12-48 hours.
  • In most of the studies that tested beyond 48 hours they saw a plateau in levels so there were no additional benefits and in some cases some values decreased beyond the initial 4 days.
  • Numerous studies identified that 8% calcium on a dry matter basis is necessary to successfully increase calcium ratio sufficiently.
  • Vitamin A is inconsistently increased by an insufficient degree through various gutload formulas though some studies achieved sufficient levels for some reptiles and amphibians studied.
  • Lower calcium dry formulas were considered more palatable via higher consumption rates compared to high calcium formulas, leading some researchers to believe this is a better formula to use for “maintenance” of feeders not being fed off and then switching to a higher calcium gutloading before feeding.
  • There were no studies that gutloaded and then fasted the crickets to determine whether it was digested nutrients or those in the gut providing the improved nutrient profile. Gutload was provided over the entire test period regardless of when they were tested.
  • Several studies indicated that calcium is stored primarily in the gut of the cricket even at the 72 hour mark and thus indicate that gut contents are an important component of gutloading.
  • For most gutloads they improve calcium content but not enough to eliminate dusting. They are best used in combination, as CF recommends.
  • There are no studies that I am aware of that examine chameleon digestion specifically and how digestible various food materials are. There are also no studies specifically looking at how cricket digestion changes any available nutrients after ingestion or increases bioavailability.
Some interesting food for thought. :)
 
So with that data I evaluated some of my gutload options this morning as I was feeding my crickets. Based on 8% calcium content minimum and very small particle size (another factor investigated in several studies found to have a beneficial effect on gutload efficacy) the Mazuri Better Bug Gutloading formula does fit those criteria. It also defines gutloading as to “enhance the total body nutrients of the feeder insect” and recommends feeding 24-72 hours after ingestion, which is line with the available data. Hopefully someone does more studies on other gutload formulations, including this one. I typically do include some kind of dry ingredients when feeding my crickets so maybe I’ll use this more regularly now.

Edit: it worth mentioning that the Flukers HiCal cricket food also lists 8% calcium and it performed very poorly in the studies when used alone. Analysis of the product showed that it was regularly less than 8% as advertised. I have more faith in Mazuri as a brand based on their other diets formulated for various species but hopefully a study will be done in the future. This will be used in addition to other high calcium foods, not a sole gutload.

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ferretinmyshoes said:
So with that data I evaluated some of my gutload options this morning as I was feeding my crickets. Based on 8% calcium content minimum and very small particle size (another factor investigated in several studies found to have a beneficial effect on gutload efficacy) the Mazuri Better Bug Gutloading formula does fit those criteria. It also defines gutloading as to “enhance the total body nutrients of the feeder insect” and recommends feeding 24-72 hours after ingestion, which is line with the available data. Hopefully someone does more studies on other gutload formulations, including this one. I typically do include some kind of dry ingredients when feeding my crickets so maybe I’ll use this more regularly now.
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My vet actually recommended I add this to my gutload last visit. Nice to see it is actually worth my money ?
 
ferretinmyshoes said:
An early study indicated it took 48 hours of gutloading to be effective so many subsequent studies don't even measure effects of gutloading before the 48 hour mark. However, the ones that did found sufficient levels after 24 hours in multiple cases and in the graphs posted you can see that there is already a considerable rise in just 12 hours. So perhaps the recommended interval from feeding feeders to feeding insectivores is best stated as 12-48 hours.
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Awesome - you provided a real, evidence-based benchmark! Thanks, @ferretinmyshoes
 
Very interesting info @ferretinmyshoes - and I agree that the onus is on your to prove your own comments, if disputed or controversial!

I've read a little bit on the relation of UVB on the insects nutritional levels of Vit A (and other vitamins I'm sure). I'll have to look to find it... perhaps that plays into the vit A levels of the insects being tested (vs. wild insect diet), which seem to be lower than expected?
 
SourGrape4u said:
I dont gut load i just feed my feeders every other day and then dust with sticky tongue. Im sure some are gut loaded from not fully digesting the food and some arent. Either way what they did digest will be nutrition the chameleons will for sure get and the rest would be passed in stool if it cant be digested by the cham.

Here's my view on the whole matter I just ate chili with squash tomatoes rice and whatever else my wife put in it. Everyone else that is human on this forum I'm sure doesn't eat the same or never will eat the same as what I eat but they will live and I will live because we both get nutrients from the different types of food we eat. It doesn't matter if they have apples where they live, it just matters if they eat something that has the same nutritional value, same goes with our chameleons. If I decide to eat a Snickers bar I'm sure the nuts will be digested and half of the other crap in there will be crapped out just like if our chameleons get something they can't digest. As long as the bugs are healthy then the chameleon will be fed healthy. sometimes I get tired of seeing people say stuff about oh we should do exactly as they are in the wild when one living 10 miles away from the other one is probably most likely digesting completely different stuff than the one you're comparing it to. Healthy is healthy doesn't mean you have to eat the exact same thing as long as it has the same healthy nutritional value and vitamins.
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Now that is something that makes sense to me. I use same technique on my feeders. Feed em well and dish em up.
 
snitz427 said:
Very interesting info @ferretinmyshoes - and I agree that the onus is on your to prove your own comments, if disputed or controversial!

I've read a little bit on the relation of UVB on the insects nutritional levels of Vit A (and other vitamins I'm sure). I'll have to look to find it... perhaps that plays into the vit A levels of the insects being tested (vs. wild insect diet), which seem to be lower than expected?
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A relationship between UVB and vitamin A? That’s interesting. I’d love to read more about that if you find it.
 
ferretinmyshoes said:
A relationship between UVB and vitamin A? That’s interesting. I’d love to read more about that if you find it.
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I’ll look and see what I can find... I couldnt tell you where I saw it (here on forums vs a more official site), but if I recall, the thought was that wild insects exposed to natural sunlight could synthesize vit d from it, and that allowed them to absorb vit a from their food. Again Ive no idea where I read it or how credible but I’ll see if I can find it.

To be honest I was hoping that comment would prompt you or @kinyongia to say “oh yea, that’s ______! Read this!”
 
There is a definite "connection" between vitamin D3 and vitamin A but I think it's more of a concern with the supplements than the levels from carotene produced vitamin A and UVB produced vitamin D3....but I've never thought at looking at how UVB affects vitamin A.
I'm going to look though...now that you've forced me to think! :)
 
ferretinmyshoes said:
So with that data I evaluated some of my gutload options this morning as I was feeding my crickets. Based on 8% calcium content minimum and very small particle size (another factor investigated in several studies found to have a beneficial effect on gutload efficacy) the Mazuri Better Bug Gutloading formula does fit those criteria. It also defines gutloading as to “enhance the total body nutrients of the feeder insect” and recommends feeding 24-72 hours after ingestion, which is line with the available data. Hopefully someone does more studies on other gutload formulations, including this one. I typically do include some kind of dry ingredients when feeding my crickets so maybe I’ll use this more regularly now.

Edit: it worth mentioning that the Flukers HiCal cricket food also lists 8% calcium and it performed very poorly in the studies when used alone. Analysis of the product showed that it was regularly less than 8% as advertised. I have more faith in Mazuri as a brand based on their other diets formulated for various species but hopefully a study will be done in the future. This will be used in addition to other high calcium foods, not a sole gutload.

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I don't even own a chameleon but I would like to join in and see if a gutloading study I have read would help. There is a study where Repashy Superload was tested against Mazuri Better Bug, Timberline, Mazuri Hi calcium Cricket Diet, and a control of crickets fed fresh produce and then dusted with a supplement. I'll need to double check the rules and make sure I can post the link to this study. I have been thinking about signing in and criticizing the gutload sheet that this forum has based off of the studies that I have read. I saw how proven gutloading diets were disregarded simply for not having a good looking top ingredient list or not being "fresh" but you seem to have read pretty much everything that I have and I'd be happy to share my opinion on this subject. :)
 
TBH mazuri has very underwhelming ingredients. Ground corn? Talk about filler... I'd use it if it was given to me for free. I don't have a problem with it as much as I feel it is overpriced for what you get.
 
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I've had little time to follow along with this thread, so why is feeding calcium to feeders so important if we're dusting anyway? Did I miss this?
 
jamest0o0 said:
TBH mazuri has very underwhelming ingredients. I'd use it if it was given to me for free. I don't have a problem with it as much as I feel it is overpriced for what you get.
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I think Mazuri is well worth the price. In a gutloading diet, the top ingredients are more for palatability rather than for increasing nutrients. In the study that I want to post Mazuri increased calcium and vitamins better than Repashy Superload in medium sized crickets. A gutloading diet that effectively increases nutrients in feeders requires a lot of money and time to create. Fresh produce simply doesn't provide the necessary nutrients to increase calcium and vitamins to targeted levels.
 
jamest0o0 said:
I've had little time to follow along with this thread, so why is feeding calcium to feeders so important if we're dusting anyway? Did I miss this?
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That Finke article @kinyonga cited may be helpful here. In it, Finke questions the reliability/consistency of dusting, and found that gutloading with ~8% calcium had more consistent results in changing the ca/p ratio of bugs.
 
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