35 replies to this topic

[Taxonomist]

Protein Nutrition of the Golden Hamster

Charles A. Banta, Richard G. Warner and James B. Robertson

The Journal of Nutrition 105: 38-45, 1975

 

This was a very good and interesting paper linked to me by missPixy.  However, I didn't find that it suited my purposes.  The title makes it sound VERY promising, but it turned out to be more about the quality of protein fed, rather than the quantity.  This is something that's very important in rats.  In fact, laboratory rats often have diets that are supplemented with specific amino acids (the smaller compounds that make up proteins) to ensure that they get adequate nutrition.

 

The paper found that, for hamsters, it really didn't make any difference whether they were fed the amino acids or not.  The proposed explanation for this is that hamsters, due to the fact that they have ruminant-like stomachs (as opposed to rats, which have simple stomachs), process protein and amino acids differently.  The conclusion of this paper was that the type of protein is less important for hamsters than it is for rats.

 

That said, there were comments made about the overall protein requirements:

 

"Diets 10 and 15 produced gains equal to those obtained by others, while gains of animals fed diets 20 and 25 are superior to any reported in the literature (1,3).  Arrington et al. (1) concluded that the protein requirement for the hamster was between 12 and 16%.  The restults of this study indicate that when the protein source is composed of common feed ingredients, the requirement is over 15% of the diet." (pg 41)

 

 

Furthermore:

"The protein requirement for the hamster is thus similar to the rat and conceivably the actual requirement for net protein would approach 10 to 12% as it does for the rat (8).  using the National Research Council amino acid requirement levels for rat growth (8) as a basis for comparison, the 12% protein diet of Arrington et al. 91) and diets 10 and 15 used in this work are limiting in sulfur amino acids." (pg 41)

 

 

 

It's all well and good, but part of the problem here is that these experiments were done on weanling hamsters.  That is...babies.  However, this paper does serve to establish the importance of protein in growth and development.

 

Growth, Kidney Disease, and Longevity of Syrian Hamsters (Mesocricetus auratus) Fed Varying Levels of Protein

Donald B Feldman, Ernest E McConnell, and Joseph J. Knapka

Laboratory Animal Science © 1982 Academic Press

 

This was an excellent and extremely interesting paper to read.  Its beauty is in its simplicity:

 

Four groups of hamsters that were fed foods with 4 levels of protein throughout their lives: 6%, 12%, 18%, 24%.  The scientists monitored the death rates and nephritis (swelling of the kidneys) rates in these groups over time.

 

1) Hamsters fed on a diet of 6% protein were found to have significantly shorter lifespans than those fed on higher protein diets.

 

This shouldn't come as much of a surprise to anyone--6% protein is inadequate at any age.  It was assumed that this was because of malnutrition--several of these hamsters died of diseases that they were presumably too weak to fight off.  Many of the younger ones died of enteritis (wet tail or something similar to it).

 

2) Statistically speaking, there was no difference in lifespan between the hamsters fed 12%, 18%, and 24% protein. 

 

As for the other levels, there simply wasn't enough difference in the lifespans of the hamsters to be sure that it wasn't just random chance.   They all had similar lifespans regardless of the amount of protein they were fed, even at levels as high as 24%.

 

Hamsters fed on diets with high levels of protein did not die sooner than those fed lower levels of protein.  And actually, of the group of hamsters that lived to be the oldest, half of them (7 out of 13) were from the group fed 24% protein.

 

3) Hamsters fed on higher protein diets had higher levels of nephritis (kidney swelling).  However, this did not contribute to higher death rates (as stated above).

 

High-protein diets did appear to contribute to kidney swelling.  However, this paper did delve into what that actually means for the hamsters:

 

"Paradoxically, seven of the 13 hamsters that survived longer than 20 months were those fed the highest level of protein.  Most of these animals had moderate to severe nephritis, but renal function apparently was adequate for survival." (pg 617)

 

"Furthermore, the blood urea nitrogen was markedly elevated in only a few animals with advanced nephritis, whereas others with comparable lesions had values that fell within the normal range.  Consistently higher blood urea nitrogen values in hamsters fed 18% and 24% protein compared to those consuming lower levels of protein at all time points probably reflected the degree of nitrogen metabolism from available protein rather than the inability of the kidney to remove waste products, at least prior to 20 months." (pg 618)

 

Basically, what this is saying is that while these hamsters had kidney swelling, it didn't seem to actually have any effect on kidney function in most cases. Their kidneys were still functioning normally.  Furthermore, when blood urea nitrogen was high, it could have been from the simple fact that these animals were eating more protein, rather than their kidneys failing (basically, more goes in, more comes out).

 

I also thought this point was very interesting:

 

"Females fed either 18% or 24% protein had heavier kidneys (p<0.05), than those females fed either 6 or 12% protein (Table 3).  The kidneys of females fed 12% protein were in turn heavier (p<0.05) than those females fed 6% protein." (pg 615)

 

Yes, females with 12% protein had more swollen kidneys.  But they still had a much better survival rate than the hamsters fed 6% protein. So kidney swelling does not necessarily equate to an earlier death.

 

4) Significant differences in kidney size were not noted until 20 months of age or more

 

"After adjusting for differences in body weight, significant differences in kidney weights were not evident until the hamsters reached 20 months of age." (615)

 

This makes me question the recommendation of dropping protein as early as 1 year.  If hamsters fed 24% protein (which is way more than we ever recommended for any age) didn't show any significant kidney swelling until 20 months...well, I'm not sure that not reducing protein from a mere 17% - 18% at only 12 months is absolutely essential.

 

Assorted Recommendations 

Various Sources

 

"Commercial rodent feed is generally used as the basic diet for omnivorous hamsters, sometimes in combination with alfalfa cubes, to provide 16% - 24% protein, 60 - 65% carbohydrates, and 5 - 7% fat."

 

Biology and Diseases of Hamsters

F. Claire Hankenson and Gerald L. Van Hoosier Jr.

LABORATORY ANIMAL MEDICINE 2nd Edition

 

"The results of this study indicate that when the protein source is composed of common feed ingredients, the requirement is over 15% of the diet." 

 

Protein Nutrition of the Golden Hamster

Charles A. Banta, Richard G. Warner and James B. Robertson

The Journal of Nutrition 105: 38-45, 1975

 

"Although the nutritional requirements have not been determined specifically, a pelleted rodent diet that contains approximately 16% protein and 4 - 5% fat is typically provided and appears to proved a nutritionally adequate diet."

 

Biology and Medicine of Rabbits and Rodents 5th Ed.

John E. Harkness, Patricia V. Turner, Susan VandeWoude & Colette L. Wheler

© 2010 Blackwell Publishing

 

Thoughts

Taxonomist

 

There is no clear answer to all of this.  I apologize if you were looking for concrete answers, but this time, I have none to give.  The literature is limited, and there simply hasn't been too much research done.  

 

Our previous protein recommendation is relatively modest--it's about the middle of the ranges recommended in literature.  If we recommended the absolute highest level of protein, that would be one thing.  But 18%?  I don't know that it's too much to worry about, considering the results of the second study I mentioned.

 

I also think not enough thought has been given to the opposite side of the story.  Yes, high levels of protein can increase the risk of kidney disease.  But having inadequate protein could have consequences that are just as bad.  Think about the 6% protein group in the second study.  It's not as if hamsters stop needing protein once they're full grown--it is still necessary in even the oldest hamsters.

 

Consider these two statements for a moment:

 

"We don't really know how much protein is too much and will cause kidney strain, so it's best to err on the side of feeding less."

"We don't really know how much protein is too little to support life function, so it's best to err on the side of feeding more."

 

I think these statements are two sides of the same coin.  The second one was the initial attitude of the forum, the first is the current thoughts.  I think both of these are kind of extremist thoughts.  This actually tends to be how many on this forum look at issues--something is either good and we need more of it, or bad and we need less.  Instead of looking at one side or the other, I think we should look at it this way:

 

"What is the amount of protein I can feed that will both support my hamster's life functions and be healthy for his/her kidneys and liver?"

 

And of this statement, I do personally think some of the current recommendations are a bit protein-shy.  I have no specific recommendations yet, but I am working on them.

 

I also think the possibility of "cutting" a high-protein food with a lower-protein one to reduce the overall protein content has been totally ignored!  It's as if any food with too much protein is flat-out unsuitable, where as the opposite is considered fine (Low-protein foods are fine as long as you add protein).  It is just as easy to reduce protein as it is to add it in.  And really, food mixing is all but essential anyway.

Edited by Taxonomist, 26 June 2014 - 12:28 AM.
Formatting

[BCPets]

I just read this whole thing, and it blew my mind!

So basically, too little protein can cause shorter lifespan but higher protein can cause kidney problems? Sorry there were lots of words that I had no clue what they meant, and I had to look them up on an online dictionary.

 

Thanks Tax!

[Taxonomist]

I just read this whole thing, and it blew my mind!

So basically, too little protein can cause shorter lifespan but higher protein can cause kidney problems? Sorry there were lots of words that I had no clue what they meant, and I had to look them up on an online dictionary.

 

Thanks Tax!

 

What confused you, if I may ask?  I did try really hard to write this to be understandable, but I probably missed a few things.  I'd like to revise to make it easier to read if needed.  

[BCPets]

What confused you, if I may ask?  I did try really hard to write this to be understandable, but I probably missed a few things.  I'd like to revise to make it easier to read if needed.  

Oh no you did it fine! Just a few words I didn't know, but I understood it.

[OakleyAmong]

When i first saw this i was like "oh my God, so much words" (lol)
Then i read it and saw so much information that was usefull

[PinkPumpkinGirl]

Thanks so much for posting this! I understood 90% of it luckily. I find this research very intriguing!

[Cindy 2014]

This is amazing work on your part Tax!!! Thank you so much. You sure do have my brain turning and working overtime. Can't wait to see more of what you uncover. Great job!

[HoppingHammy]

Thanks, Tax, for taking your time to research and share all of your findings with us! Hamster Hideout is blessed to have your contributions.

[Ravynn]

Wow, what a great pile of information. It's really interesting. Thanks for sharing.

[Biscotti]

Excellent summary of the papers. I do feel like a lot of nuance is missing in the protein discussions, and perhaps in the way of a game of telephone, and personal preference are taken as facts and being recommended as a guideline. The papers basically demonstrated that there's an acceptable range of protein %, but it doesn't tell us what the optimal %.

 

I do take several issues with the second paper, and don't think it gives a very good overview of how high protein effects kidney function. First, the sample population is on the small side, so the margin of error is likely to be quite large with one single experiment.

 

Secondly, the paper had defined the longest living group as 20+ months old. 20+ months old is barely over 1.5 years old, and while that may be considered long-lived by laboratory standard, it is very poor going by pet standard. I'm not sure that having a majority of of hamsters showing signs of kidney swelling by 20 months old is something we can dismiss as insignificant. In my opinion it is very telling that the 24% protein diet is having an actual physical impact on hamsters going into their elderly stage. 

 

Thirdly, the experiment's qualification of what's considered acceptable doesn't align with what pet owners should strive for. In one of your quotes, the paper says "Most of these animals have moderate to severe nephritis, but renal function apparently was adequate for survival." As a pet owner, I don't want my hamsters to just "survive", I want them to thrive. Nephritis might not kill directly, but it does impact other bodily function that bring about a slow decline.

 

I have put my robos on long term high protein diets before (in the 22.5% to 24% range) and a few had developed symptoms of kidney failure by roughly 16 to 18 months old. They "survived" for another few months, some longer than others, but it wasn't quality time and their condition deteriorated faster than those that didn't show the signs. Granted, my sample size is also on the small side, but that's what I experienced, and I personally think there's more damage done than whatever advantage an overly high protein diet can afford. I know nobody is pushing for that, but I don't think it's entirely accurate to say that it doesn't hurt either.

 

I've posted my preference for a slow ramp down of protein % starting from 1 to 1.5 year old, but this is only a personal preference as I start from a 22.5% protein diet for my young pups. In case anyone feels this way, this is not a direct recommendation or guideline, but rather me just sharing what had worked for my hamsters. I've said many times that a range of protein % are acceptable according to the literature, and it's fine to feed a 18% protein diet throughout a hamster's life if they wish. And I don't think anyone has suggested that we go very low on the protein yet.   (But I'm actually kind of perplexed at how 14% protein at 6 months old+ keep coming up as recommendations.  )

 

 

I also think the possibility of "cutting" a high-protein food with a lower-protein one to reduce the overall protein content has been totally ignored!  It's as if any food with too much protein is flat-out unsuitable, where as the opposite is considered fine (Low-protein foods are fine as long as you add protein).  It is just as easy to reduce protein as it is to add it in.  And really, food mixing is all but essential anyway.

 

I don't think this problem has come up yet, as far as I know. During the "18% protein or bust" era (for lack of better term), most if not all commercial hamster mixes are considered unsuitable due to being <18% protein. Some of us who are feeding primarily high protein lab blocks are already using this method of "cutting" the protein value by adding seed mixes. But more often it is the other way around, by using high protein lab blocks to boost the %. Same difference, really.

Edited by Biscotti, 26 June 2014 - 02:35 PM.

[pawlove]

Yes! I've been waiting for this. Thank you so much, Taxonomist! 

 

I had a question about how come kidney swelling isn't a problem if the hamster lives on, since they would be in pain for the rest of their lives. I guess Biscotti answered the most part of the question. 

 

Also, I know there really isn't a concrete answer from this research but I'm guessing (and just guessing) ideal protein % is around 12-18% ? Or 18% is still too high? There's a lot I get from this thread, but in the end it kind of leave me confused. 

 

edit: I have another question... in the first paper it stated that the type of proteins isn't that important for hamsters, so does it mean if they don't get animal proteins they will be fine? 

Edited by pawlove, 27 June 2014 - 01:01 AM.

[Taxonomist]

 

Excellent summary of the papers. I do feel like a lot of nuance is missing in the protein discussions, and perhaps in the way of a game of telephone, and personal preference are taken as facts and being recommended as a guideline. The papers basically demonstrated that there's an acceptable range of protein %, but it doesn't tell us what the optimal %.

 

Exactly, and a large part of the reason I chose to look into this.  I felt as if things were being taken out of context, exaggerated, etc.

 

don't think it gives a very good overview of how high protein effects kidney function. 

 

 

Agreed wholeheartedly, and that really was unfortunate.  I really did wish the paper went into more detail about the nephritis and its symptoms.  As it was, it was more about presence and absence than anything. 

Thirdly, the experiment's qualification of what's considered acceptable doesn't align with what pet owners should strive for. In one of your quotes, the paper says "Most of these animals have moderate to severe nephritis, but renal function apparently was adequate for survival." As a pet owner, I don't want my hamsters to just "survive", I want them to thrive. Nephritis might not kill directly, but it does impact other bodily function that bring about a slow decline.

 

 

 

Again, agreed.  This is always something that's really difficult with using scientific papers in regards to pet care.  For example, several of the resources I read suggested specifically against feeding seeds...because they cause unavoidable variation in diet (no good for science!).  Not terribly relevant to us as pet owners.

 

Secondly, the paper had defined the longest living group as 20+ months old. 20+ months old is barely over 1.5 years old, and while that may be considered long-lived by laboratory standard, it is very poor going by pet standard. I'm not sure that having a majority of of hamsters showing signs of kidney swelling by 20 months old is something we can dismiss as insignificant. In my opinion it is very telling that the 24% protein diet is having an actual physical impact on hamsters going into their elderly stage. 

 

 

Would you be willing to share your experience regarding lifespan?      I had previously done a (quite imperfect) survey of hamster lifespans as reported by forum members.  The average lifespan as reported was just over 1 year old.  While I certainly agree that 20 months is by no means super-elderly, I'm surprised that it is considered to be "very poor" as an age of death.      (Granted, I again admit that my survey was quite imperfect for a number of reasons--limited sample pool, self-reported data, etc.).

 

(For the sake of clarity, the oldest hamster in the experiment lived to approximately 2 years, 1 month.)

 

First, the sample population is on the small side, so the margin of error is likely to be quite large with one single experiment.

 

This is the one part of your post that I do wholly disagree with.  A sample size of 30 is considered adequate for almost all statistics-based studies.  At a sample size of 200, I felt that this experiment covered sample size pretty well.  I'm curious as to your reasoning that the sample size was "on the small side" to the extent that it had a serious effect on the results.  

 

I do admit that overall, I did like that paper.  It certainly has its flaws, but I'm reluctant to look a gift horse in the mouth.  It's an experiment that studied the long-term effects of protein on kidney health in hamsters simply for the sake of doing exactly that.  I don't know that I'll ever find a more relevant paper on the matter (heaven knows I've tried...).

 

(But I'm actually kind of perplexed at how 14% protein at 6 months old+ keep coming up as recommendations.  )

 

 

Are you referring to recommendations on the forum?  As in, members recommending 14% at "older" ages?

[Lillias]

Thanks for posting these studies! They are definitely interesting, as are everyone's comments here. Another complication is that these studies are done on Syrians, which leaves dwarf owners wondering where they stand in all this.

[pinksodamousse]

This so interesting! I've been trying to figure out how much protein to give my ham. I went to Pet Valu today, thinking I would get some dog treats, and the lady working there seemed very confused by this idea and said she'd never given her hamster extra protein and it's lived a long life. Lots to think about. Thank you for posting!

[Biscotti]

Would you be willing to share your experience regarding lifespan?      I had previously done a (quite imperfect) survey of hamster lifespans as reported by forum members.  The average lifespan as reported was just over 1 year old.  While I certainly agree that 20 months is by no means super-elderly, I'm surprised that it is considered to be "very poor" as an age of death.      (Granted, I again admit that my survey was quite imperfect for a number of reasons--limited sample pool, self-reported data, etc.).

 

(For the sake of clarity, the oldest hamster in the experiment lived to approximately 2 years, 1 month.)

 

 

This is the one part of your post that I do wholly disagree with.  A sample size of 30 is considered adequate for almost all statistics-based studies.  At a sample size of 200, I felt that this experiment covered sample size pretty well.  I'm curious as to your reasoning that the sample size was "on the small side" to the extent that it had a serious effect on the results.  

 

I do admit that overall, I did like that paper.  It certainly has its flaws, but I'm reluctant to look a gift horse in the mouth.  It's an experiment that studied the long-term effects of protein on kidney health in hamsters simply for the sake of doing exactly that.  I don't know that I'll ever find a more relevant paper on the matter (heaven knows I've tried...).

 

 

Are you referring to recommendations on the forum?  As in, members recommending 14% at "older" ages?

 

Hm... I realized that I'm very biased when I said that 20 months old is considered "poor".    I think it comes from being heavily invested in the "2-3 years average life span" that I always hear people mention, so it's something that I unconsciously use as the standard. I'm still hearing a lot about hamsters that live beyond 24 months (mostly on hamster forums), so that's likely to have colored my perception of the real average. As far as something to strive for, I'd like to think that we all prefer our hamsters to live beyond 20 month old though.

 

My first generation and a few of the second generation robos were the ones on the high protein diet for roughly 12 months. Out of 9 of the first generation robos, 4 showed mild to moderate signs of nephritis (increased thirst, weight loss, elevated ketone in urine). One of which is Bumpy who passed away at 22 months old. The other was Minty, who passed away at roughly 13 months old, likely due to a combination of slightly poor health and an accidental fall.

 

The two severe cases are actually my 2nd generation pups who were on the high protein diet once they're able to eat solids, and show symptoms as early as 5-6 months old (Kit and Tikki). With these two I switched their block to 18% at 8 months old with increased amount of seed mix so their protein intake averages out to around 16-17%. Unfortunately Tikki deteriorated very quickly and passed by 10 months old, a gross necropsy was done and showed enlarged kidneys and lesions. Kit is still alive and well at 13 months old, his symptoms eased up but he continues to drink a lot of water (I refill his bottle at least twice as often as other robos).

 

As I said, a very small sample size from my recent population, so I'm not sure if that's helpful. But it's enough for me to reconsider feeding the same high protein diet well into their adult age.

 

Regarding sample size, I admit it's more of a gut feeling since I don't have any formal statistics training.    But the link you gave makes a lot of sense, so thanks for setting me straight.   And I agree with you that that paper is certainly very helpful, we could really use more like it.

 

And yes, I'm referring to the very specific (but somehow still feels quite random) protein % recommendations that some members are giving out, typically for 6 months old+ hamsters. I can't say if it's a good recommendation or not, just that it seemed to have sprung out of nowhere.

 

 

<off topic> By the way, how do you split the qutoes like that? </off topic>