Every new guinea parent at some point asks “Can Guinea Pigs Eat Grass”?
As you can tell from the photo above, we’ve been exploring this question for some time. Milo & Oreo have been helping us experiment to find the answer (alright, maybe this bowl also contains a couple of dandelions and springs of mint too!)
Anyway, since you’re at GuineaMates – and not just any random old blog – we are here for you with our comprehensive and fully faceted guide to guinea pig grass.
Can Guinea Pigs Eat Grass?
Yes! Yes, they can! Guinea pigs can eat grass, should eat grass and love to eat grass!
In fact, this question is a little bit like asking “can squirrels eat acorns?”, “can cats eat mice?” or “can birds eat worms?”. Grass is the natural diet of wild guinea pigs… and their domesticated cousins.
If you’ve been feeding your little friends any of the many guinea pig hay products out there, then you’ve actually already been feeding them grass – just dead, dried grass.
In any case, you’ve probably got a bunch more questions. So let’s explore the topic of grass for guinea pigs in more depth.
The Anatomy Of A Piece Of Grass
If you’re dumb like me maybe you used to think grass was just short green stuff that lives in your back yard. Well, that’s not strictly true. The reason most of the grass we see is short, is simply because we cut (mow) it!
What’s the difference between the short stuff in our yards, around sidewalk and in parks – and the long wavy stuff with seeds on the end in the endless fields that you drive past when you go on a road trip?
Well basically nothing. The only difference is that the latter has been allowed to continue growing until the seed head has sprouted. Check out the diagram below:
Next time you’re picking some grass for your guinea pigs, take the time to examine just what you’re picking a little more closely. Chances are, you’ll easily identify the sheafs and nodes – parts you may not have been aware of before. This will also help you understand what stage of the growth cycle your grass is in.
The Grass Growth Cycle
As I mentioned above, while we are used to seeing grass short, this isn’t the whole story. Check out the diagram below of the various stages of grass growth.
This is useful to know, because in the wild your guinea pig will eat grass in the all of the vegetative, elongation and reproductive stages.
While the caloric and protein value of the grass plant degrades over time and is lowest in the reproductive stage (as the grass uses up its energy in the process of reproduction), ironically the seed head is actually the most nutrient dense and valuable part of the plant.
So if you are gathering grass for your piggies to eat, try to gather from across a range of these growth stages – to capture the broadest possible array of micronutrients and phytonutrients.
The Guinea Pig’s Digestive System
Guinea pigs are known scientifically as graminivorous (grass eating), alongside elephants, horses, cows, capybaras and many other well known animals.
Since grass is a relatively low-nutrient food (compared to meat, or fruit, for example) guinea pigs have a digestive system especially designed for the purposes of digesting it!
This is called ‘hind gut fermentation’ and basically means that guinea pigs have a huge (as in 10-13x the length of their body) large intestine and cecum, a type of pouch at the beginning of the large intestine. It is in this cecum where the actual digestion occurs – and it is home to a wide variety of special intestinal flora.
It is this cecum and flora that enables guinea pigs to digest the high levels of fibre that are contained in their natural, grass-based diet.
You see, hindgut fermentation is designed to allow animals to consume small amounts of low-quality forage all day long – exactly what they have in their natural environment – grasslands.
In other words, your guinea pig’s digestive system is especially made to digest fresh grass all day long.
Does Grass Have Vitamin C?
One of the biggest questions for guinea parents is does grass have vitamin C?
Yes, yes it does!
While the Vitamin C content of a given patch of grass will vary wildly depending on the species, soil, growing conditions, etc., this 2018 study found that green grasses on average have a Vitamin C content of around 14 – 25mg per 100g of grass.
Bare in mind that fresh grass is not the same as hay in this respect. Hay is devoid of Vitamin C.
What Species Of Grass Do Guinea Pigs Like To Eat?
You may be surprised to know that there is some specific research available on this topic, that tells us about the dietary preferences of guinea pigs in the wild.
I was able to find a 1998 study that took 2,000 Brazilian Guinea Pig poops under the microscope to find out what kind of food they preferred. Turns out, according to these poop analysts, grasses of Lolium sp., were consumed preferentially.
A popular grass used across Aussie back yards – Perennial Ryegrass – falls into this genus. Just be careful not to graze your guinea pigs on this particular species too hard, as it could potentially cause ‘ryegrass staggers’ a disease seen in livestock.
Although bare in mind that guinea pigs are highly adaptable creatures! In the wild, they live in habitats as diverse as dry flatlands, to moist marshes to the sides of extinct volcanos at 4,000 ft elevation.
One of their most infamous homelands, the Paramo Grasslands in South America contains over 550 different species of grass.
How Much Grass Can Guinea Pigs Eat?
Simple answer: as much as they like!
More complex answer: if your guinea pig is used to a hay and pellet based diet, you will need to tread more carefully – as if you introduce too much grass too quickly – they could suffer from gastrointestinal bloating.
We’d suggest starting with a couple of handfuls of fresh grass each day and increase by a handful every other day or so. We are now up to feeding our piggies 60% of their diet based on fresh grass.
Yes, you can feed your guinea pigs grass every day!
Can Guinea Pigs Eat The Grass Seed Head or Flowers
Yes, they can!
Our little guinea mates find the seed head the tastiest part… it’s virtually the only thing they will fight over!
The reason for this is that grass seed heads contain a dense concentration of micronutrients.
Can Guinea Pigs Eat Lawn Clippings?
No, no they can’t.
Lawn clippings begin to ferment in the hopper due to the heat and moisture involved in the mechanical mowing process. This will wreak havoc on your guinea’s digestive system and cause severe bloating – which could even be fatal.
Fertilizer and Toxic Chemicals, Pesticides, Etc.
Make sure that whatever grass you feed your guinea pigs has not been treated by any chemicals such as fertilizers, pesticides, etc. Only naturally grown grass should be provided, or those treated with organic products such as seaweed based fertilizer.
Guinea Pig Grass – Final Thoughts
There is likely some nutritious guinea pig grass lurking close to you in a spot you never imagined. A much more nutritious treat than guinea pig pellets. Try searching nearby in the wild to see what you can find!
Grass diagram by Kelvin Song, Creative Commons
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