End of the debate: studies on the nutritional value of food for snakes

[Raymonde]

Hi, I am relatively new to captive husbandry of reptile and have been doing a lot of reading on this forum. I have come across the debate about whether pinkie rodents or adults have better nutritional value. A lot of people have comments like "show me the proof" or "where is the research/studies to backup your opinions". So i decided to see if i could find any research on the topic.

I found several peer reviewed journal articles, most of which are actually quite old (from the 90's) but it won't have changed in the last 15-20 years. A lot comes from zoos and i think it is all from USA but that doesn't mean the data doesn't apply to us in Australia.

I found this review (not sure where it is published but it uses other literature so i believe it is trustworthy) which compares a whole lot of studies. They found that "neonates have lower body fat concentrations than do older prey animals" and that "Mineral concentrations in whole prey vary considerably, depending upon prey type and, to some extent, age. Neonates often, but not always, contain a lower proportion of total ash(mineral concentrations) compared with adults"

here is the full pdf version if you want to actually look at the values. It covers rabbits, quails and chickens along with a long list of other animals, including wild caught
View attachment Dierenfeld et al; 2002; nutrient composition of whole vertebrate prey (excluding fish) fd in zoo.pdf

i also found several of the papers mentioned in the review particularly the ones relating to mice and rats
View attachment Douglas et al; 1994; Vitamins E and A, and proximate composition of whole mice and rats used as .pdf
View attachment Clum et al; 1996; Effects of diet on nutritional content of whole vertebrate prey.pdf
View attachment Dierenfeld et al; 1996; Mineral concentrations in whole mice and rats used as food.pdf

I hope this helps to settle the debate somewhat, but i doubt it will

Raymonde

 

[Flaviruthless]

I highly doubt that it will have any influence on people's opinions. Good to see that you took the initiative after our conversation earlier today Thanks for the info

 

[Raymonde]

Hi Rahni, I was wondering if you were on here and who you were. I agree, I don't really think it will change peoples minds but its still nice to have some scientific research to refer to, especially since that is my area.

 

[chase77]

Good job. But I've got one question? In short, can you tell us what it says?

Chase.

 

[Raymonde]

Good job. But I've got one question? In short, can you tell us what it says?

Chase.

i did

They found that "neonates have lower body fat concentrations than do older prey animals" and that "Mineral concentrations in whole prey vary considerably, depending upon prey type and, to some extent, age. Neonates often, but not always, contain a lower proportion of total ash(mineral concentrations) compared with adults"

but that was in general for all the animals on the list

here is a summary of what they found in relation to rats and mice (my interpretation of the tables in the review paper):

mice
-they only measure neonates, juveniles and adults
-neonates have most protein, juveniles the least (20% difference)
-juveniles have the most fat, while neonates have the least (inversely related to protein) (13% difference)
-adults have the most mineral concentrations, juveniles the least (only 3.3% difference)
-adults have the most vitamin A, juveniles have the most vitamin E
-adults have the most calcium (only by 1.8%) and magnesium (difference 0.7%), but have the least copper, iron and zinc
- neonates have the most copper, iron and zinc, while juveniles have the most manganese

rats
-adults have most protein, juveniles the least (5.7% difference)
-adults have the most fat, while neonates have the least (inversely related to protein) (8.9% difference)
-juveniles have the most mineral concentrations, adults the least (only 2.4% difference)
-adults have the most vitamin A, neonates have the most vitamin E
-adults have the most calcium (only by 0.8%) and manganese, but have the least copper, magnesium and zinc
- neonates have the most magnesium, copper, iron and zinc


adult mice vs neonatal rats
-adult mice and neonatal rats have almost equal amounts of protein (difference 2%) and fat (difference 0.1%)
-and also have almost equal mineral concentrations (difference 0.4%)
-adult mice have 4x the amount of vitamin A while neonatal rats have a little more vitamin E
-adult mice have greater percentage calcium (1.1% difference) and slightly more manganese, while neonatal rats have double the amount of magnesium, copper, iron and zinc




wow, not really a very short summary....
but then there were a lot of different variables and i didn't want to generalise too much...

 

[dozerman]

Great post Raymonde! Im a simple kinda guy... at what age does a neonate become a juvenile , juvenile become an adult ? does the neonate mouse become a juvenile by definition when it is weaned?

 

[chase77]

thanks

 

[Raymonde]

Great post Raymonde! Im a simple kinda guy... at what age does a neonate become a juvenile , juvenile become an adult ? does the neonate mouse become a juvenile by definition when it is weaned?

i'm not entirely sure myself, but i believe that neonatal is referring babies or pinkies (maybe fuzzies as well). I think it refers to when they are still suckling milk from their mothers... Juveniles would be weiners and sub-adults, and possibly also hoppers.

actually the review did have weights with the categories, maybe that will help work it out, although their rats seem to be much smaller than the ones you can buy around here... maybe its a different species
Mice: Neonatal <3g, Juvenile 3-10g, Adult >10g
Rats: Neonatal <10g, Juvenile, 10-50g, Adult >50g

 

[Bluetongue1]

Hi Raymonde and welcome.

You seem keen on a baptism of fire stepping into the minefield of nutritional values of comparative food items. Much of the difficulty emanates from the fact that there are a number of variables over which you have no control. A major one is the various breeds and lines of rats and mice that are utilised as feed items. Different breeds have differing physical characteristics, including maximum size and body composition. What rodents are fed on influences the total minerals and the fat content. So it is not unusual to have significant differences between separate studies even if the assay methods are identical.

The developmental stages provide the easiest way to accurately identify progression in size with any given line of feeders. This is why it is used instead of weight. Any each stage would have to state a range of weights and again, weight for stage in a given line is going to be influenced by what they are feed and what amount of exercise they get.

Following would be the equivalent groupings used by most people with their feeder mice...
Neonates (new born) are pinkies = up to 3g;
Juveniles are Fuzzies & Hoppers = 3g to 10g;
Adults are Weaned and older = 10g & above.

Following would be the equivalent groupings used by most people with their feeder rats...
Neonates (new born) are pinkies = up to 10g;
Juveniles are Fuzzies, Pups & Weaned young = 10g to 50g;
Adults are Young Adults and older = 50g & above.

I thought that was most generous of you to provide the summary that you did. You mentioned that it is your area. Might I be so forward as to enquire just what that is? I shall be quite open with you – I do have an ulterior motive. Nutrition is an area that I am struggling to get a better handle on.

Blue

 

[Raymonde]

Hi Blue,
I do realise that there is a lot of variation between different species, and depending on what the animals were fed, but at least for the studies that were done by the same researcher you can compare within their results to make generalisations of whether neonates or adults are better. So if you are purchasing or breeding your own you will know that relatively speaking (as in you won't know the actual levels) adults or neonates will have higher/lower levels of fat/protein/minerals/vitamin/etc.

when i said my area, i was more referring to scientific research side of things, i don't actually study nutrition (hence the need to look it up). I am doing a phd on the biodiversity of urban lakes (including turtles, frogs, fish and birds).

 

[PMyers]

Thank you thank you THANK YOU. I found this chart a while back on another website and bookmarked it, but after the typical computer issues wiped my drive I have been searching for it since to no avail. You, ma'am, are a pure-bred champion!

 

[wokka]

other side of the equation is.....What do snakes need in the way of nutrition?
Is fat relevant? what about protein?
Do gravid females have a different nutritional requirement?
what about snake age, Does that effect optimen nutritional requirements?

 

[Waterrat]

I am also surprised that no one takes roughage into consideration. I realise that roughage is indigestible, therefore has no nutritional value but it a very important component of diet. I firmly believe that snakes fed purely on lean meat, without fur, feathers, gut contents, etc., would have healthy digestive function seriously compromised. Juvenile snakes on pinkies more than often have diarrhoea but it stops once they start heeding on hairy rodents. So, how much roughage is enough and how much is too much?
Some predators cough up hairballs (e.g. owls), other pass them their through their digestive system (e.g. crocodiles) but you take that component out of their diet and they'll be some undesirable consequences.

 

[Bluetongue1]

You are quite correct Waterrat. Vertebrate digestive systems are geared to dealing roughage. Without it, vertebrates develop severe health issues. There are a number of vitamins that would not be produced and absorbed. The ions secreted in conjunction with the digestive fluids will not be absorbed. A significant amount of fluid will not be absorbed and will be therefore lost through elimination. Clearing of the cloaca would not be effective. These are some of the short term effects. The long term effects are much more serious.

When you start looking at the diet of any organism, there are certain questions you want to be able to answer. What range of substances is required to meet the animal's nutrient needs? What effects will an excess of any give nutrient have? How much is sufficient? How much is too much?

What is really required is the answers to the question translated into the actual feed items animals are fed. Those who have extensive keeping experience have already answered these questions in practical term for the animals they keep. Not surprisingly, there are multiple answers to the same end result – healthy animals. So while charts of relative nutrient values are interesting and worth looking at, the acid test is whether or not the requirements of your animal are met by a particular prey item for the particular age of the animal.

Blue