Rabbit and Guinea Pig Diet Basics: Why Hay Comes First

If you take one thing from this guide, make it this: hay should make up around 80% of what your rabbit or guinea pig eats every single day. Pellets and fresh greens matter, but they sit on top of an unlimited supply of good grass hay. Get the hay right and you head off most of the dental and gut problems these animals are prone to.

Why hay matters so much

Rabbits and guinea pigs have teeth that grow continuously throughout their lives. The long, fibrous strands in hay force lots of side-to-side chewing, which grinds those teeth down naturally. Without enough hay, the back teeth in particular can develop sharp spurs that cut into the cheeks and tongue.

Hay also keeps the gut moving. A rabbit's digestive system is built to process a near-constant trickle of fibre, and when that stops, things can go wrong quickly.

A rabbit that stops eating, or stops passing droppings, for more than around 12 hours is a genuine emergency. This is practical husbandry advice, not veterinary advice, so please see a vet for any sudden loss of appetite.

How much hay does a rabbit need?

The simplest rule is the one that surprises new owners most: unlimited. Your rabbit should have access to fresh hay at all times, and a good benchmark is a pile roughly the size of their own body every day. Guinea pigs are the same, eating their own body size in hay daily.

They won't eat all of it. A lot gets trampled, slept on and used as a toilet corner, and that's completely normal. The point is that fresh hay is always there when they want it. Top it up morning and evening rather than letting it run flat.

Best hay for rabbits and guinea pigs

For adult animals, the staple is a grass hay. Look for these types:

• Timothy hay is the gold standard for most adults. Coarse, fibrous and not too rich.
• Meadow hay is softer and more varied. Many rabbits prefer it, and it's a fine everyday choice.
• Orchard or ryegrass hay are good alternatives if your pet turns its nose up at timothy.

Avoid making alfalfa (lucerne) the everyday hay for adults. It's high in calcium and protein, which suits babies and pregnant or nursing animals but can contribute to urinary problems in grown rabbits. Choose hay that smells sweet and looks green, never dusty, yellow or musty.

Guinea pigs have one extra need: they cannot make their own vitamin C, so they rely on fresh vitamin-C-rich vegetables and sometimes a supplement alongside their hay.

Building the rest of the diet

Once hay is sorted, the rest falls into place:

• Fresh leafy greens daily, such as kale, spring greens, herbs and romaine. Introduce new ones slowly.
• A small measured portion of pellets, roughly an eggcup per rabbit per day. Pellets are a supplement, not the main meal.
• Treats kept tiny. Skip the sugary shop treats and offer a slice of carrot or a sprig of herbs instead.

Making hay interesting is half the battle. Stuffing it into a hay rack, a cardboard tube or under a puzzle feeder encourages foraging and slows fast eaters down. Boredom feeds destructive chewing, so good rabbit toys earn their keep here too.

Storage and everyday feeding

Hay is only as good as how you keep it. Store it somewhere cool, dry and airy, never sealed in plastic, which traps moisture and breeds mould. A breathable bag or a slatted box works well, and buying in sensible quantities means it stays fresh.

If your hutch hygiene is good, your hay supply will last longer because less gets soiled. Keeping a clean, dry living space is part of the same picture as a healthy diet, and the right rabbit hutches make daily spot-cleaning quick. For more on feeding, housing and companionship, our Small Pets hub and the wider small pets range pull it all together.

If your pet shares its home with a friend, watch that both are eating well. Our guide to guinea pig housing covers space and pairing, while do rabbits need company explains why bonded pairs tend to eat and thrive better than singles. And because a bored rabbit eats less hay, the ideas in beating small-pet boredom are worth a look.