Mouse Nutrition
How Much do Mice Eat and Drink?
A large fancy mouse will eat around 8g of food and drink around 8ml of water per day while a small pet mouse will eat 5g and drink 5ml. But it would be silly to measure out these tiny portions. Since mice don’t naturally overeat (i.e. they will not eat just because there is food available) you can just let your mice help themselves to what they want. However, you should be aware that topping up the mouse's food too much will result in a plentiful supply of the fattier parts of the mix, which they may favor in comparison to the healthier portions. To make sure that your mice eat all parts of the mix make sure you give a good balance and do not top up if unnecessary (i.e. if the bowl is still almost full). Also, try to avoid giving a large supply of food at once, but top up with small amounts more often. Food consumption varies with the quality of the food(s) offered, the age, health and breeding status of the individual, the environmental temperature and the time of day. Mice tend to feed at night, though daytime feeding is quite common. Mice are voracious feeders and consume proportionately more food per day than rats. This is because of their smaller body size and relatively high metabolic rate. If you only have a small number of mice you may not notice the food diminishing in the same way as with larger colonies, but take it from me, mice can actually eat quite a lot in a night or two between them!
Vegetables
In the wild mice eat various vegetables: but then your mice are not likely to be wild, so you have to be careful to feed with caution since they are domesticated and will be sensitive to certain things. If you are feeding a new vegetable, like anything else only feed it in moderation at first. After a couple of days if there have been no adverse effects (e.g. diarrhea) then you know that you should be able to carry on feeding this food to your mice. Always make sure that any vegetables (and other fresh food) is washed and peeled as it would be if you were going to eat it yourself. This will help to remove any pesticide residue or bacteria that may be present.
Seeds
Mice don't eat any one particular sort of plant or seeds exclusively and will enjoy eating a range of different foods if presented to them. Many different kinds of seeds suitable for consumption by mice are available either at the pet shop, supermarket or health shop. These include yellow millet, budgie seed, mixed corn and sunflower seeds. Just remember to check the ingredients and be creative with your mix! And although seeds are a good constituent of a mix, they should not make up the whole thing - just think variety.
Balanced Diet
Getting back to a balanced diet, some owners recommend mouse/rat lab blocks because every bit tastes the same. The idea here is that mice cannot pick out the tastiest parts, which are usually the fattening seeds. The blocks also contain all the vitamins and trace elements a mouse needs. However, mice can also find this diet boring and enjoy searching through their food mix. A versatile seed mix is suitable for the basic constituent of a mouse's basic diet, but should not be its exclusive make up. Mice do not like the 'rabbit pellets' alfalfa (which are just hay pellets) found in many mixes, and will leave them uneaten. Because of this it may be better to choose a seed mix without these pellets if you can find one. Some seed mixes have been constructed to please the eye of the owner more than the stomach of the mouse. Therefore, it pays to take a close look at the contents of the seed mix and make sure it is not mainly composed of colored corn flakes or sunflower seeds.
An ideal mixture will have a variety of ingredients such as seeds, grains, flaked peas, sunflower seeds (but not too many), dried sweetcorn, corn flakes and dry dog food pieces to name a few. A substantial portion of the mix is likely to be seeds and grains which mice enjoy. I have not seen many mixes that are specifically made for mice, but this is OK because they will eat mixes sold for hamsters (but not other animals such as rats, rabbits or guinea pigs as a general rule). Just remember to check that the food looks appetizing - if it looks old and crumbly and the bag is full of dust do not even consider it.
Click here for some safe food ideas
DIY Mixes
You can also make your own food mix. If you live in a rural area, it is quite easy to buy seeds from farm shops. You can vary the contents of your own seed mix according to what is easily available at the time. If you use a self-made seed mix, you should add dry dog or cat food in the mix. This contains protein and other vitamins and minerals, but be careful not to put too much in as this is not good for the mice as it can be quite rich (especially cat food). The more mice you have, the more food they will consume. When you have more than 20 mice, it is no longer practical to feed them with small bags of food available at pet shops. It's better to buy in bulk or make your own seed mix.
When Should You Feed?
Mice should be fed once a day. Larger groups of mice or does with litters are better fed twice a day if possible, but will be OK with one feeding/change of food if this is not possible as long as you make sure to leave plenty spare. Each feeding time, give enough food so that there is some left over at the next feeding time to ensure your mice won’t go hungry.
What NOT to Feed Mice and Why
- Citrus fruits (cause the runs)
- Peanuts (They are fattier than other nuts and may provoke a skin reaction in susceptible mice, although a few peanuts in the mouse’s food mix may be ok. I would give them complete with shell, which the mice will also eat.)
- Chocolate (can be toxic to rodents in large amounts)
- Unwashed fruit/vegetables (These may contain pesticides. A simple rule is not to feed your mice anything that you wouldn't eat yourself.)
- Wheat (can cause skin problems in susceptible mice)
- Cheese (despite the stereotype of mice, cheese is not good for them and many don't like it!)
- Milk (Only offer milk products (kitten milk replacement formula) if there is a medical reason or the mice are being hand-reared. Milk is unnecessary and can cause health problems in both the short and long term.)
- Lettuce (causes diarrhea) *Too many watery vegetables, such as lettuce, can cause runny stools.
- White millet (this is too fatty, use yellow millet instead which is sold for birds)
- Maize (see wheat)
- Fizzy drinks (can be fatal - see below)
If you are feeding bread to your mice you may want to let the bread dry out first. This is because some breeders say that their mice react badly to the enzymes in the bread, giving them spots. However many owners frequently feed bread to their mice with no problems, including myself. If you want to give extra nutrients to a sick mouse, bread soaked in stock or gravy may be a good solution.
Chocolate
It seems to be a generally held belief that chocolate can be toxic to mice and rats, although I have never seen any research to support this. But it is best to be safe, so if you want to give your mouse a treat, use special mouse chocolate drops or another kind of treat.
Fizzy Drinks
Mice and rats cannot burp (or pass wind I suppose) so they do not have the capability to get rid of excess gas that may result from drinking carbonated drinks. This build up of gas can be dangerous and even a small amount can kill a small animal like a mouse, so please don't give your mouse fizzy drinks. They will be much happier drinking water and much safer too.
Mice Can't Be Sick
Mice cannot physically be sick so it is impossible for them to get rid of bad food if they happen to eat any. This means that it has to go all the way through their digestive system and will do whatever harm it may be able to do on the way. This is also the reason why rat/mouse poisons work - once the animal has eaten the poison they can't get it out of their system and it does its job. Because of dangers like this, mice usually eat a small amount of a new food and then wait a while to see if they feel ill before eating any more. If after a while they do not feel ill then they can reasonably assume the food is safe to eat and go back to it.
Corn
There has recently been some worry about giving mice and rats too much corn in their diets. The reason for this is that corn can contain certain contaminants that may cause illness in rodents.