how much calcium does my guinea pig need

How Much Calcium Does My Guinea Pig Need?

Guinea pigs need calcium in their diet.  However, too much calcium can cause problems, like bladder stones or kidney stones.  So how much calcium should a guinea pig eat every day?

Calcium as a Percentage of Daily Calories

I asked my veterinarian friend what the ideal calcium intake should be for a guinea pig to avoid bladder and kidney stones. She said I should use a diet that was just 0.3% calcium.

I’ve also read accounts online where people state that a diet of 0.3% calcium is good for guinea pigs.

However, my question on this method is 0.3% of what? Calories?

When I do the calculations, this method of calculating calcium content does not work out.

A published report states that a guinea pig should eat around 8 grams (i.e., 8000 mg) of calcium per day. (see Just Count the mg of Calcium, below).

Let’s use an example. If I feed my guinea pig, let’s say, 100 calories per day, and I want to feed him 0.3% of those calories as milligrams of calcium, that means I am feeding him just 0.3 mg of calcium per day.  Which is not enough calcium.

Here’s an example:

100 grams of parsley has 138 mg of calcium and 36 calories.

Let’s turn everything into grams:

138 mg of calcium = 0.138 g of calcium

If I feed him 100 calories per day, and I use the guidelines that say he needs 8 grams of calcium per day,

8 grams is what percentage of 100 calories?

8%.

100 calories per day / 36 calories (per 100 grams) = 2.77 servings of parsley = 100 calories.

2.77 x .138 g of calcium = 0.38 grams of calcium in 100 calories (100 x 2.77 = 277 grams of parsley)

So, let’s say my guinea pig eats 200 calories per day.  And I still want him to eat 8 g of calcium.

8  is 4% of 200.

Now, because he’s eating 200 calories, I need to feed him 4% of that as milligrams of calcium.

So to me, this method of calculating calcium requirements is not useful.

Just Count the mg of Calcium

According to the Nutrient Requirements of Laboratory Animals (1995), a normal adult guinea pig should eat around 8g of calcium per day per kg of body weight.

A normal guinea pig weighs around 900 grams, so 8 mg per kilogram of body weight in a 900-gram guinea pig would be 7.2 grams of calcium per day.

To calculate how much calcium your guinea pig is eating, use the spreadsheet method (above). List what he eats every day, look up the amount of calcium in that amount of food, and add it up. If you’re using pellets or a food with a label, you can get the info straight from the label. Otherwise, you’ll have to do an Internet search to find the calcium content.

How Guinea Pigs Absorb Calcium

Guinea pigs absorb more calcium from their food than humans do. On average, guinea pigs absorb about 50% of the calcium they ingest. People, on the other hand, absorb about 30% of the calcium they ingest. Of course this amount varies based on several factors.  For example, excess protein in the diet lessens the amount of calcium that gets absorbed. But it’s a good guide to go by as a general rule.

Vitamin D aids in the absorption of calcium, so giving your guinea pig about 20 minutes of sunlight exposure per day can help him absorb the calcium he eats better.  If you can’t take him outside to get some sun, you can purchase a full-spectrum sunlight light bulb and use it for about 20 minutes a day.

If calcium is not absorbed by the body, it goes to the kidneys and bladder to get eliminated through urine. And once there, it can accumulate and create kidney and bladder stones.  So it’s better to increase the absorption of the ingested calcium, which again, can be aided by adequate intake of Vitamin D.

How Many Calories Does a Guinea Pig Need per Day?

This question doesn’t have much to do with how much calcium your guinea pig needs, but I wanted to know the answer anyway.  I searched the published literature, and there was no one definitive answer (that I could find).

However, there is a law known as Kleiber’s Law. This law was named after Max Kleiber who published his studies in the 1930’s.  The law states that, for the vast majority of animals, an animal’s metabolic rate scales to the ¾ power of the animal’s mass.

If q0 is the animal’s metabolic rate, and M the animal’s mass, then Kleiber’s law states that q0 ~ M¾.

Applying this law to humans, we assume the average adult weighs 70 kg (154 pounds). Using Kleiber’s Law, then, the adult human would require about 2200 calories per day.

Applying this law to guinea pigs, we assume the average guinea pig weighs 1 kg, or 1000 grams.

2200 * (1/70)^(3/4) = 91 calories.

The average guinea pig requires 91 calories per day.

That’s the best answer I came up with. If you have different information, please share it in the comments below.

Take Notice of the Calcium to Phosphorus Ratio, too!

The amount of calcium a guinea pig absorbs is interdependent on the amount of phosphorus and magnesium he ingests, as well. For example, a study published by Van Hellemond et al. (1988) observed that guinea pigs fed purified diets that contained 8.4 g Ca/kg with 7.7 g P/kg and 1.0 g Mg/kg retained more calcium than those fed the same concentrations of calcium but with less phosphorus (4.4 g P/kg) and more magnesium (1.9 g Mg/kg).

The ideal calcium to phosphorus ratio for guinea pigs is 1.33 to 1. That means he should have 1.33 times more calcium in his diet than phosphorus.

So when you’re making your spreadsheet (detailed above), you might want to make another column next to calcium (mg), and keep track of the phosphorus content of each food, as well. Then add up all the calcium mg’s he eats in a day as well as all the phosphorus mg’s he eats and divide both by the smallest number (which should be the total mg of phosphorus) to get your ratio.

Table of Calcium Content of Food

You can easily find the calcium content of the different foods that you feed your guinea pig by searching with Google.

Alternatively, you can also check out this handy list published by Guinealynx.