Can you interchange food for specific rodents?

[TJ's Rodent Ranch]

Hi there, I'm wondering if you can interchange rodent food. (Such as giving gerbils rat & mouse, or hamster, or even guinea pig food). 
I know that a lot of times some of the big problems are that rat and mouse food, for example, may not provide all the nutrition that a gerbil needs... but is there anything in these foods that could harm gerbils? I'm wondering, because surprisingly I have not been able to find an affordable food in my area. (I don't like to get it online). I've been spending 20$ for a 1lb bag, and with over ten gerbs I'm going through it at alarmingly quick rates. (ten at the current moment, including babies. So soon to go down, but still). 
I'm wondering if it would be okay for the gerbils if I were to mix a proper gerbil food so they get the specific things, and some that are for different rodents. 

I've currently got 3 different foods that aren't for gerbs... I'll list the ingredients below. If you see any that are harmful and don't mind replying that would be great. It's pretty long so if not don't worry about it.
  

Kaytee Food (for mouse and rat). 
Corn, Sunflower seeds, Oats, Peanuts, Alfalfa meal, Barley, Milo, Millet, Wheat, bananas, carrots, raisins, pumpkin seeds, Papaya, Split peas, Beet, Dried egg, Sesame seed, Honey. 


PURE (for hamsters).
Corn, Oats, Wheat, Peas, Buckwheat, Sunflower seed, Carrot, Bean Flakes, Puffed rice, Raisins, Safflower seeds, Dried banana, dried egg, dried flax seed, Bell pepper, Buffalo worms, Parsnip, rosehips, peanuts, Sunflower oil, Apple, Papaya, Nettle, Celery, Merigold. (they've had this one a few times, and have taken to it quite a bit). 


Tropical Carnival (For Rabbits... definitly the most odd, but surprisingly seems most acceptable).
Timothy Hay, Flaked peas, Hibiscus flower, Merigold flowers, Rose petals, Nettle leaves, Raspberry leaves, Blue Cornflowers, Chamomile Flowers. 


Anyway, if you did take a read over them thanks so much!

[LilyandDaisy]

A lot of rodent foods can be interchanged between species, with certain considerations taken into account. There's certainly not likely to be anything harmful for gerbils in any rodent food.

The first big thing to be aware of is that rabbits and guinea pigs have very different digestive systems to gerbils, mice, rats and hamsters. Rabbits, guinea pigs are adapted to a very high fibre diet consisting mostly of vegetation, whereas other rodents are adapted to eat a wider range of foods, but gerbils in particular naturally eats lots of seeds plus vegetation. This means that a diet that is well-suited to rabbits or guinea pigs shouldn't be used as a gerbil's main diet but could be used as a supplement/forage mix. I would say the Tropical Carnival mix would be suitable only a forage mix for gerbils.

Most commercial rodent foods aimed at gerbils, hamsters, mice or rats are fairly generic, including the Kaytee and Pure foods you've listed. Although they might be marketed for a specific species, for the most part they aren't that different. In some cases they are actually identical, for example Science Selective Hamster and Science Selective Gerbil are the exact same product in different packaging. So if you find one and the ingredients and nutritional analysis seem suitable for gerbils, there's probably no major reason you shouldn't feed it to gerbils.

Some higher end brands (mainly European) have more thought and research put into them and there may actually be intentional differences between foods marketed for each species. A dwarf hamster food would be slightly different to a gerbil food, for example. Using these foods interchangeably is still fairly unlikely to cause any health issues, though the manufacturers would claim certain benefits of using the exact right food for each species. Rodipet even has different food for short-hair and long-hair Syrian hamsters, although I find their reasoning for that a bit dubious!

Have you considered mixing your own food from single ingredients? I do, and it works out cheaper than buying food of similar or even lesser quality.

[TJ's Rodent Ranch]

Okay, that's good to hear. I was worried that one might not be okay...
That is definitely something I had noticed, but I wasn't sure if there might have been something in there that was a red flag, so I thought it was a good idea to ask and be on the safe side. I think it also says something to that effect, that many foods are for 'hamster and gerbil' or 'mouse and gerbil' or sometimes even hamster mouse and gerbil. It seems to show how similar their digestion actually is, that they can be blocked into the same bag of food. But yes, the rabbit was the one I was mainly concerned about... although compared to all the others it had only a few ingredients and none that proved troublesome to pronounce! (I didn't put all the little things such as dyes, supplements, etc, into the ingredient list for the others, since that's interchangeable with almost every food).

Interesting... I could see foods for different species for sure, although a lot of people interchange here in the US and haven't had many, to any, obverse side effects. Though I suppose Europeans might just be a bit more on top of things regarding rodent food... although different foods for long-haired and short-haired Syrian Hamsters does seem like a stretch. I wonder how much of a difference there really is to change up their food at all, and what prompted that?

I did mix my own food for a short time, but I could never get a good mix that seemed to have everything they needed in it. So I switched to getting them several different foods, and mixing those. I figured if I got foods that were different enough it would provide an interesting varied diet for them... what do you usually use in your mix?

Oh! Also, a small side note... are salt blocks OK for gerbils? I know for most animals it's really great and can help them get extra minerals that they might not easily get from normal food and whatnot... but I'm just worried about overloading their little bodies.

[LilyandDaisy]

I asked Rodipet about the different food for long-haired Syrians once and they said it had more fibre because long-hairs swallow more hair when grooming? But when you look at the actual nutritional analysis, it has slightly less fibre and the only major difference seems to be that the protein is much higher.
"Teddy" (long-haired) Syrian food
Normal Syrian food

My mix has the following ingredients:
Barley, Millet, Oats, Sorghum, Wheat, Buckwheat, Grass seeds, Maize yellow
Dill seeds, Flaxseeds, Hemp seeds, Milk thistle seeds, Niger seeds, Pumpkin seeds, Rapeseed, Sesame seeds, Safflower seeds, Calci worms, Dried carrot, Dried peas, Almonds

I've found through trial and error that these ingredients mostly go down well with most gerbils.

Salt blocks are very unpopular these days. On groups people will just tell you they're dangerous, same with mineral stones. Personally I don't think either of those things are nearly as dangerous as people say. I always provide my gerbils with a calcium-based mineral stone and often a salt stone too, just in case they feel the need of the extra minerals, though I find they use them very sparingly. I think they're generally ok to provide as long as you keep an eye on how much they're using it (especially with the fruit-flavoured mineral stones).