Fat frogs

[JL-Exotics]

Originally Posted by Ed

How does just weighing and measuring them indicate level of fat deposition?

I think you made a very good case for this actually...

Originally Posted by Ed

Unlike other animals we don't see significant changes in body morphology such as changes in bone structure, fat deposition, musculature and so forth. The fat depositon sites (and musculature) is going to stay the same resulting in a scalable animal. This would allow people to compare pictures of froglets with adults of the same species allowing for a comparision.

And...

Originally Posted by Ed

This is why I made the argument about adults being scalable comparisions for the froglets... as without a series of random sacrifices and necropsies from different feeding regimens it is going to be hard to quantify.

Originally Posted by Ed

As I think I noted early on.. a lot of these issues are conserved across taxa so if we are willing to look outside of dart frogs (or frogs), I think we can come up with some genealizations.....
Ed

Yes, would you be willing to give us a starting point (with some generalizations)?

[JL-Exotics]

Originally Posted by Ed

No.. while I did the calculation with the statement needed to supply the energy for 24 hours, unless the frog(let) has no reserves left, the feedings can be concentrated into a several feedings a week for several reasons. One of these is that the frog's can reduce thier metabolic needs by simply reducing thier movement or seeking a cooler microniche (this can significatly change the metabolic needs), and that when provided with food, tend to overeat..

Ed

Most people rear froglets in smaller tanks to make food easier to find, where microniches tend to be hard to come by. Especially if there are several other froglets competing for that resource. A larger tank would certainly help in this regard - or a consistently available food source.

I was a bit surprised at your answer to be honest. I'll admit the principal and reasoning make sense - but this is contrary to some of my personal observations. In my experience, a froglet that is without food for even a few days will "stunt" it's growth for an extended period of time. In some cases they may never catch up to siblings that did not endure a similar shortage.

This would leave me to speculate that either it takes much much longer to replace a froglets fat reserves before it can redirect that energy back to growth or the average looking froglet just doesn't carry a significant store of fat reserves and they can be delpeted in just a few days. Or both.

Either way, consistent feeding seems to be pretty important for a frog to reach it's full growth potential.

I'm curious if anyone else has made similar observations?

[Ed]

[QUOTE=JL-Exotics;567216] I think you made a very good case for this actually...[QUOTE]

Actually it gives a profile we can use to get an idea that the froglet approaches "a normal" profile.. not the amount of fat the frog is actually carrying.


[QUOTE=JL-Exotics;567216] Yes, would you be willing to give us a starting point (with some generalizations [QUOTE]

I wish we could just submerge the froglets and weigh them like we do people... as we should be able to get thier composition that way...

Let's see what we can come up with in the next couple of days. I need some time to think about this more... I'm starting to think we may be restricted to using profiles.. at this time.

[Ed]

Originally Posted by JL-Exotics

Most people rear froglets in smaller tanks to make food easier to find, where microniches tend to be hard to come by. Especially if there are several other froglets competing for that resource. A larger tank would certainly help in this regard - or a consistently available food source.

If one looks at the calculations on metabolic needs, even a couple of degrees one way or the other results in major changes in the daily metabolic needs of the animals..

Originally Posted by JL-Exotics

I was a bit surprised at your answer to be honest. I'll admit the principal and reasoning make sense - but this is contrary to some of my personal observations. In my experience, a froglet that is without food for even a few days will "stunt" it's growth for an extended period of time. In some cases they may never catch up to siblings that did not endure a similar shortage.

And your observation is opposite mine.. (and some of the literature).. particularly that of amphibians (see discussion in Amphibian Medicine and Captive Husbandry on metabolism) but this sort of growth couldalso be due to factors that result from a fator or factors during the tadpole period (see http://www.popbiol.ebc.uu.se/pdf/Jou...4%20(2009).pdf as one example of tadpole exposures carrying over). We also can't rule out that the delay of growth was due to a lack of calories (as this is opposite the metabolic data) and not a lack of vitamins needed for proper growth. We now know that historically most supplements did not contain appropriate or sufficient pre-vitamin A sources or vitamin A (as retinly palmitate).....
We also can't rule out enviromental plasticity from housing see for example http://www.popbiol.ebc.uu.se/pdf/Tej...43%2031-39.pdf

I'll have to get the papers together where differences in metamorphic size between cohorts were rapidly made up by the froglets.

Originally Posted by JL-Exotics

Either way, consistent feeding seems to be pretty important for a frog to reach it's full growth potential.

I'm curious if anyone else has made similar observations?

Consistent doesn't have to be daily..

Ed

[JL-Exotics]

Originally Posted by Ed

If one looks at the calculations on metabolic needs, even a couple of degrees one way or the other results in major changes in the daily metabolic needs of the animals..

I tried to find a source for the gross energy (kcal/gram) provided by fruit flies and found a few undocumented citations similar to what you provided in another post (5.12 kcal/g). The Amphibian Medicine and Captive Husbandry book suggests that most feeder insects range between 1-2 kcal/gram and they suggest 1.5 kcal/gram as a good rule of thumb for calculating metabolic needs. Obviously, that makes a pretty big difference in the calcs. Can you recall your source? I would like to be certain I am using the most accurate information available if possible.

Originally Posted by Ed

And your observation is opposite mine.. (and some of the literature).. particularly that of amphibians (see discussion in Amphibian Medicine and Captive Husbandry on metabolism)

I wasn't able to find anything in the Amphibian Medicine and Captive Husbandry that supports this - but it's quite a novel and I could have easily missed it. Do recall the chapter specifically? I did see in section 5.7 (Nutrition) a statement that said "The recommended frequency of feeding varies with species, age, and activity level... of the amphibian. Young, growing animals, and active foragers thrive on daily feeding.... In general, larval amphibians shoud be fed small amounts daily, rather then several large meals weekly." It didn't go on to detail why this was recommended though.

Originally Posted by Ed

Consistent doesn't have to be daily..

Agreed, but 2-3 times a week may not be ideal either.

Thanks Ed, I appreciate your input and discussion.

[Ed]

Originally Posted by JL-Exotics

I tried to find a source for the gross energy (kcal/gram) provided by fruit flies and found a few undocumented citations similar to what you provided in another post (5.12 kcal/g). The Amphibian Medicine and Captive Husbandry book suggests that most feeder insects range between 1-2 kcal/gram and they suggest 1.5 kcal/gram as a good rule of thumb for calculating metabolic needs. Obviously, that makes a pretty big difference in the calcs. Can you recall your source? I would like to be certain I am using the most accurate information available if possible.

The number suggested by Kevin there is actually less than either crickets or mealworms.. as both of those are close to 2 kcal/gram so using the recommendation in text can result in an undercalculation or overcalculation. There can be a lot of variation between feeders so if available an exact number is better than the estimate. I can rework it with the lower calories if you are more comfortable with those numbers. (we also need to keep in mind that these calculations are for an enviroment that is devoid in other feeders such as springtails, mites or other microfauna).

I have reposted that calculation several times now so the original citation was probably lost. I think the reference for the kcal/gram is from http://www.nagonline.net/Technical%2...02MODIFIED.pdf as that was the best available data at the time. I'd have to look at my library to see if a different result has since been obtained.

Originally Posted by JL-Exotics

I wasn't able to find anything in the Amphibian Medicine and Captive Husbandry that supports this - but it's quite a novel and I could have easily missed it. Do recall the chapter specifically? I did see in section 5.7 (Nutrition) a statement that said "The recommended frequency of feeding varies with species, age, and activity level... of the amphibian. Young, growing animals, and active foragers thrive on daily feeding.... In general, larval amphibians shoud be fed small amounts daily, rather then several large meals weekly." It didn't go on to detail why this was recommended though.

Okay bear with me..

I am going to refer you page 84 left hand column discussing the feeding needs for starved animals.. The time line for working with feeding starved animals is handled in seven day increments and that feeding does not have to occur on a daily basis as long as the caloric needs (and that includes the excess to meet an increased metabolism) are met within that seven day period... Now if a starved animal can have its metabolic needs met within a seven day period without daily feedings, it is a pretty big jump to make the requirement that healthy animals with fat reserves require feedings on a daily basis..

This is also before we understand how the frogs manipulate thier own metabolism between feedings. During periods where there is a lack of stimulation from food (or being fed), the frogs tend to remain more stationary, and reduce thier metabolism, access to cooler microniches can further reduce this metabolic rate. This means they can actually reduce thier SMR below that used in the calculations. (this is mentioned briefly in Kevin's book but is taken from elsewhere and I would have to look for the specific reference). The impact of lack of nutrition on the frog typically takes 4-6 weeks before it manifests as the fat reserves are reduced (summarized on page 81 1.12) (See Grably, S. and Peiry, Y.; 1981, Weight and tissue changes in long term starved frogs, Rana esculenta.; Comparative Biochemistry and Physiology 69A: 683-688 for more details). This metaboloc plasticity and long time before starvation impacts set in are why we have to be suspicious of the reports on the impact of non-daily feedings on froglets as they don't match with what we know about thier metabolism. It may however point towards the carried over impacts from the tadpole stage (and I'm not done reviewing the literature on that to give a more coherent response on that as of yet). It is possible that the daily feedings were masking an underlying issue with the frogs which could be a carry over from the tadpole size.

This is also before we begin to discuss the impacts of the enviroments on the froglets development. It is apparent that across taxa, enviromental impacts can manipulate physical form as the animals grow...

Some thoughts,

Ed

[Woodsman]

Hi Chris,

Just my opinion.

Richard.

Originally Posted by Chris Miller

How is it cruel? Also, I must have missed it, but how do you know springtails were a main food item?

[PeanutbuttER]

So smaller daily feedings though unnecessary would result in more consistently active frogs?

[JL-Exotics]

Originally Posted by Ed

Now if a starved animal can have its metabolic needs met within a seven day period without daily feedings, it is a pretty big jump to make the requirement that healthy animals with fat reserves require feedings on a daily basis..

Just for clarification - my observation was that froglets left without food for more then 3 or 4 days appear to lag in growth compared to froglets fed more regularly. I am not proposing that daily feedings are required, rather I am proposing feeding 1-2x per week does not appear to promote optimal growth rates in the froglets I keep. Lots of variable can come into this with microfauna, temps, competition, stress etc. Just wanted to clarify I did not suggest daily feeding was required, but am questioning what is the ideal feeding schedule for optimal growth - given the above mentioned variables that answer will probably vary from hobbiest to hobbiest and even tank to tank. That is the reason i was interested in a matrix or body mass index of sorts, so folks can feel confident that what they are doing is producing froglets and juveniles that fall into that "ideal" threshold.

Originally Posted by Ed

This metaboloc plasticity and long time before starvation impacts set in are why we have to be suspicious of the reports on the impact of non-daily feedings on froglets as they don't match with what we know about thier metabolism. It is possible that the daily feedings were masking an underlying issue with the frogs which could be a carry over from the tadpole size.

Again, the idea is not to keep the froglets alive - but to see them thrive and fulfill their optimal growth potential. A 2 week old froglet would not make it to week 6 without food. They are too small and lack enough fat reserves for that kind of sustained starvation. The long time to starvation impacts appears to be related to adult frogs and not juveniles that are actively growing and it does not reflect the desired optimal growth potential.

I had not considered an underlying issue as I have seen it across many species and in froglets I have received from other breeders. I have also spoken to other breeders that have made similar observations. An underlying issue is always a possibility however, and you make a good point to raise that variable.

Originally Posted by Ed

This is also before we begin to discuss the impacts of the enviroments on the froglets development. It is apparent that across taxa, enviromental impacts can manipulate physical form as the animals grow...

Whew! Lets try and get a firm grip on the feeding aspects before we tackle environmental variables please!

[Ed]

Originally Posted by JL-Exotics

Just for clarification - my observation was that froglets left without food for more then 3 or 4 days appear to lag in growth compared to froglets fed more regularly. I am not proposing that daily feedings are required, rather I am proposing feeding 1-2x per week does not appear to promote optimal growth rates in the froglets I keep. Lots of variable can come into this with microfauna, temps, competition, stress etc. Just wanted to clarify I did not suggest daily feeding was required, but am questioning what is the ideal feeding schedule for optimal growth - given the above mentioned variables that answer will probably vary from hobbiest to hobbiest and even tank to tank. That is the reason i was interested in a matrix or body mass index of sorts, so folks can feel confident that what they are doing is producing froglets and juveniles that fall into that "ideal" threshold.

Sorry, there was an implication in the discussion that feedings needed to be on a daily basis and that is what I was addressing.

Originally Posted by JL-Exotics

Again, the idea is not to keep the froglets alive - but to see them thrive and fulfill their optimal growth potential. A 2 week old froglet would not make it to week 6 without food. They are too small and lack enough fat reserves for that kind of sustained starvation. The long time to starvation impacts appears to be related to adult frogs and not juveniles that are actively growing and it does not reflect the desired optimal growth potential.

While the reference was done on adults.. there isn't any indication in the literature that I have seen that indicates thier metabolic responses are different... (contextually, a lack of the plasticity seen in the adults in juveniles would be very counter adaptive..). Time scale may be different due to body mass but the theory should hold and should also be scalable. I have more on this below.

Originally Posted by JL-Exotics

I had not considered an underlying issue as I have seen it across many species and in froglets I have received from other breeders. I have also spoken to other breeders that have made similar observations. An underlying issue is always a possibility however, and you make a good point to raise that variable.

The more I look at the literature, the more I see across anuran taxa how significant impacts on the tadpole stage carry over into the metamorphs and beyond. Nutritional, time to hatching, competition, exposure to predators, temperature, and/or water quality/exposure as tadpoles can fitness and survivorship up to a year later (this is in no way an all inclusive list).. I'm starting to really think we cannot decouple this metamorphs and the tadpole stage is probably where we really need to start...

Originally Posted by JL-Exotics

Whew! Lets try and get a firm grip on the feeding aspects before we tackle environmental variables please!

The more I review the literature and refresh myself on it, the more I'm starting to think, that it may be impossible to seperate them...

Ed