Hay for Rabbits and Guinea Pigs: Which Type, How Much, and What to Do If They Won't Eat It (UK Guide)

Short answer: Rabbits and guinea pigs should have hay available at all times. For a rabbit, the daily minimum is a pile at least as big as the rabbit (RSPCA, PDSA). Hay or grass should be around 85% of a rabbit's diet, says the Rabbit Welfare Association & Fund (RWAF), and 85–90% of a guinea pig's (PDSA).

Timothy and meadow are both fine everyday hays for healthy adults. Alfalfa is a legume, so keep it to small amounts for young, pregnant or nursing rabbits (RWAF). If an animal that normally eats hay stops, contact your vet immediately, the same day.

New to rabbits or guinea pigs? Our first-time pet owner guide covers housing and the first vet visit; this guide sticks to hay.

Why hay is most of what a rabbit or guinea pig should eat

PDSA's 2026 PAW Report, a YouGov survey, found hay and rabbit pellets tied as the most commonly reported main foods for UK rabbits, at 80% each. Of the owners who feed hay, 82% give unlimited access, but 16% give less than the recommended amount.

Hay and teeth

Teeth come first. Rabbits' teeth grow throughout their lives (RWAF), and the RSPCA says the same of guinea pigs: their teeth "are always growing, and eating hay helps wear them down to keep them at the correct length and shape".

Grass and grass hay have to be chewed "in a side to side motion and that is what wears down rabbit teeth", according to the same RWAF page. A second RWAF page adds: "There is no other food (except for straw) that rabbits use this chewing motion for." Pellets don't need that motion. Greens don't either.

Take the hay away and the teeth keep growing anyway. PDSA explains that without enough fibre, a rabbit's teeth "will overgrow and develop sharp spikes ('spurs')" that dig into the tongue and cheeks. Eating hurts, so the rabbit eats less, and the RWAF is blunt about where that ends: "Many pet rabbits die of starvation when this condition is left untreated."

Hay and the gut

The gut is the second reason. PDSA says rabbits need a high-fibre diet "to keep their guts moving and prevent a serious condition called 'gut stasis'", and in guinea pigs PDSA calls it life-threatening. The RSPCA puts it simply: guinea pigs "need hay and/or grass for their digestive systems to function properly."

The RWAF puts grass hay at a minimum of 20% fibre and 12 to 15% protein, with no split by type.

Which hay for rabbits and guinea pigs? Timothy vs meadow vs orchard vs alfalfa

Four names turn up on UK shelves: three grass hays and one different plant.

Timothy, meadow and orchard: the grass hays

Timothy is the only hay type that the RSPCA, PDSA or RWAF feeding pages name for guinea pigs. For rabbits, the RSPCA and the RWAF ask for good-quality hay and leave the type to you. The one page naming timothy and meadow side by side is PDSA's chinchilla guidance, which calls either one "perfect".

So which should you buy? For a healthy adult rabbit or guinea pig, timothy or meadow, chosen by what your animal will eat and how dusty the bag is. Nothing in the charity guidance suggests one beats the other on nutrition.

Alfalfa: the exception

The RWAF has a whole page on why alfalfa is different. "Alfalfa is not a grass hay, it's a legume, similar to peas or lentils," and its calcium levels "are too high for adults, other than pregnant and lactating females".

Even youngsters and pregnant or nursing females "shouldn't have it as a replacement for grass hay": "A small handful 3-4 times a week is plenty." It also "will not wear teeth as well as grass hay".

That's rabbit advice, and PDSA's equivalent line is written for chinchillas. For guinea pigs we'd apply the same caution, because the reasoning is about the plant itself.

What good hay looks and smells like

The RWAF's test is short: good hay "should be dry, sweet smelling and free from grit, dust and mould". The RSPCA asks for "sweet-smelling and dust-free". Before you tip a new bag into the rack, check for:

• a green colour, rather than yellow or brown

• a sweet, summery smell, with nothing musty or sour about it

• dry strands with no damp clumps

• no cloud of dust when you shake a handful

• no grey, white or black patches, which can be mould

• long strands rather than crumbled fragments

Dust matters twice over. The RSPCA asks for "dust-free hay" in a guinea pig's hutch, and dust also matters for anyone in the house with asthma, which our guide to pets for allergy sufferers covers.

Feeding hay vs bedding hay

PDSA draws the line: "'Feeding hay' is fresher, greener, smells better, tastes better, and has more nutrients in it", while "'Bedding hay' is dryer, ideal for bedding, but not so great for nibbling".

The rack should hold feeding hay. If they nibble the bedding, PDSA says "it's not a problem if your rabbits occasionally eat it". Hay as bedding is covered in our winter care guide for outdoor rabbits and guinea pigs.

How much hay should a rabbit eat a day? (And how much for a guinea pig)

Rabbits: unlimited, with a floor

All three charities say unlimited. The RWAF calls unlimited good-quality hay "the foundation of a healthy diet", and the RSPCA says rabbits "should always have unlimited access to good-quality hay or grass".

Unlimited is hard to measure, so two of them give a floor. The RSPCA: "always provide a 'rabbit-sized' bundle of good-quality hay every day (it should be as big as they are)". PDSA: "ideally they should be given an unlimited amount, but as an absolute minimum, a bundle at least as big as them per day".

Note the word minimum. A rabbit that clears its own body size in hay by lunchtime and then faces an empty rack all afternoon isn't getting the unlimited hay all three ask for.

As a share of the diet, all three land on 85% hay or grass. The RWAF feeding policy sets the split at "85% hay / grass, 10% greens and 5% pellets".

For greens, PDSA suggests "an adult-sized handful of leafy greens, vegetables and herbs twice daily". Fresh grass counts towards the hay share, and the RWAF prefers it: "Fresh grass is preferable, but hay is a very good substitute and it's available all year round." Kiln-dried grass "can be used alongside hay" too.

Guinea pigs: never an empty rack

Guinea pigs get a wider band and no body-size rule. PDSA says hay "should make up 85-90% of their diet; unlike pellets, you can't overfeed it". The RSPCA says good-quality hay "should make up the majority of your guinea pig's diet and should be available at all times", with fresh grass "as often as possible, ideally every day".

Neither gives a daily amount, so the practical rule is a rack that never runs empty. That's also why hay doesn't suit timed, portioned feeding; our automatic pet feeder guide explains why it leaves rabbits out.

Pellets: three charities, three figures

Here the charities differ:

• The RWAF puts pellets at 5% of the diet, "15g per kg bodyweight".

• The RSPCA allows "25g (approximately an egg cup-full) of nuggets per kilogram of their body weight" for a healthy adult rabbit.

• PDSA says "one tablespoon of nuggets every day" per rabbit, "or twice a day if they're over 3.5kg".

For a 2 kg rabbit, that's 30 g a day on the RWAF figure and 50 g on the RSPCA's (our arithmetic), or one tablespoon on PDSA's. Different amounts, same point: pellets are a small top-up, and PDSA warns that "If your rabbits are fed too many pellets, they will eat less hay".

PDSA's own pages differ too. Its diet page gives the tablespoon, while PDSA's 2026 PAW Report recommends "around 15g of commercial rabbit nuggets or pellets per kg of body weight each day", the RWAF's figure. Pick one figure and keep to it.

For guinea pigs there's one figure. PDSA recommends "one tablespoon of pellets per adult guinea pig each day", grass-based and "specifically made for guinea pigs". The RSPCA adds: "Ask your vet for advice on portion sizes if you're not sure."

Rabbits vs guinea pigs: where the hay advice differs

Beyond the pellet figures and the rabbit-only body-size rule, two things differ.

Vitamin C for guinea pigs

Vitamin C is the big one. "Guinea pigs need vitamin C from their diet because they can't produce it themselves," says PDSA.

PDSA's route is grass-based guinea pig pellets and daily fresh greens high in vitamin C; hay isn't part of it. If you're concerned they aren't getting enough, it recommends "a daily vitamin C supplement in/on their food"; supplements in water "aren't recommended as vitamin C is weakened by sunlight".

The RSPCA's route is a fresh daily portion of pellets, because "Vitamin C is destroyed over time and more quickly with exposure to the air", so a bag that's been open for months is doing less than you think. Follow the product's instructions and ask your vet about the right amount.

Growing grass indoors

The second is grass. For guinea pigs kept indoors, the RSPCA suggests "pots of fresh, growing grass can be offered to encourage natural grazing behaviour". A cheap trick for a flat.

Chinchillas and degus: the same rule, two extra cautions

Other hay-eaters: Chinchillas "need a constant supply of hay, so it should be the main part of their diet", says PDSA, and "A good quality, dust extracted timothy or meadow hay is perfect." Avoid alfalfa "unless your chinchilla is pregnant, feeding babies or still growing".

Keep pellets to "1-2 tablespoons" a day, a figure the RSPCA gives too, along with a warning: "Never change your chinchillas' diet suddenly, as this could upset their digestive system and make them very ill."

Degus need "constant access" to hay, which the RSPCA says is "much more important than commercial degu nuggets". If you can't get degu nuggets, guinea pig or chinchilla ones are fine only "as long as they don't contain molasses", because "degus are prone to Type 2 diabetes, so need a diet that's low in sugar and fat".

Why has my rabbit or guinea pig stopped eating hay? When it's an emergency

Two different questions hide inside this one, and they need opposite responses.

If they've never really eaten hay

A new rabbit that came home on muesli. A guinea pig that has always picked at the rack and lived on pellets. Neither is an emergency, but the RSPCA's order for a rabbit that isn't eating hay is still a vet check first, "to check there are no underlying health problems", and only then "hay from a different provider".

After that, it's a habit to build. PDSA's advice for rabbits is to "keep persevering", because "it might take them some time to start eating it": "Offer a fresh bundle every day and try different types to tempt them." In the order we'd try them:

1. Cut pellets back to the amounts above. A full pellet bowl is the first thing to rule out.

2. Move the hay. The RSPCA notes that "placing hay close to or above litter trays may encourage some rabbits to eat more".

3. Change how it's offered. Racks and hanging baskets keep hay clean, and grazing trays encourage natural foraging (both RSPCA). Keep the rack low enough for an older animal to reach without stretching; that part is our suggestion.

4. Mix a little of the old hay into the new for a few days, so the smell is familiar. Also our suggestion.

5. Make it a game. Hay stuffed into a cardboard tube, or a small box with the ends folded over, gets pulled apart, and some of it gets eaten on the way.

6. Go slowly. PDSA says to make any diet change gradually, over two to four weeks, for rabbits and guinea pigs alike.

If they used to eat hay and have stopped

This is the red flag.

See a vet immediately: PDSA's wording for rabbits is "Contact your vet immediately if your rabbit stops eating." The RSPCA's for guinea pigs: "Consult your vet immediately if you notice any changes in your guinea pigs' eating, drinking and/or toilet habits." In plain terms, immediately means the same day, weekends included. PDSA explains why: "Gut stasis is an emergency that can be fatal if it isn't treated quickly."

A rabbit or guinea pig that has eaten hay happily for months and then stops is telling you something is wrong.

For rabbits, the RSPCA names gut stasis and dental disease among the health problems a vet should rule out, and PDSA's mouth pain guidance explains the chain: a rabbit with a sore mouth "might stop eating which can rapidly turn into a very serious problem such as gut stasis". Don't try a new bag first. Ring the vet.

Signs to check for while you ring the vet

PDSA's list of signs of dental problems in rabbits is worth reading out to the vet. These are signs to act on, not a way to diagnose anything at home:

• Overgrown teeth

• Weight loss

• A dirty bottom

• Diarrhoea or soft faeces

• Weepy eyes

• Drooling

• Reduced appetite

• Tooth grinding

• A bumpy, painful jaw

• A runny nose

• Lethargy (low energy)

Guinea pig droppings: The RSPCA adds droppings to the list: "If their eating or drinking habits change, or the quantity of droppings reduces or stops, consult your vet immediately - they could be seriously ill."

Between emergencies, check the front teeth every week. PDSA says to "Check your rabbit's teeth at home, at least once a week", and the RSPCA says of guinea pigs, "Check their front teeth and nails every week - these grow quickly."

The molars at the back are the vet's job, and the RSPCA is clear that "Only vets should correct overgrown/misaligned teeth." If you're unsure what you're seeing, ring your vet and describe it.

Storing hay so it stays worth eating

Hay that passed the smell-and-dust check in the shop can fail it a month later in the garage. Our practical suggestions:

• somewhere dry with some airflow, and never sealed in plastic while it's still even slightly damp

• off the floor, so it isn't sitting in condensation or garage damp

• in amounts you'll use before it goes dusty, which argues against the biggest bale if you have one guinea pig

Hay in an outdoor hutch has a harder life: rain gets in, and wet hay is cold hay as well as hay nobody wants to eat. Keeping the hutch dry is covered in our winter care guide.

If a bag smells musty or shows grey or white patches, throw it out. The RWAF standard is hay free from mould, and picking through a bad bag won't get you there.

Common hay mistakes

• Topping up pellets all day. The RSPCA says to avoid "constantly topping up pellets and nuggets" because rabbits "might stop eating hay or grass in favour of pellets". Give a set daily amount instead.

• Muesli mixes. PDSA's vets "don't recommend muesli-style mixes", the RWAF says muesli "is known to cause dental disease", and PDSA's 2026 PAW Report found 13% of rabbits are still fed one as a main food, down from 25% in 2017.

• Lawnmower clippings. The RSPCA and PDSA both rule them out for rabbits and guinea pigs; PDSA notes mown grass "tends to ferment quickly".

The bottom line

Keep the rack full and the pellet bowl small. If an animal that used to eat hay stops, ring your vet the same day.

One honest warning. Hay gets everywhere: the carpet, your socks and, if the hutch is near the back door, the kitchen. A rack and a litter-tray corner cut the mess down; nothing removes it.

If that would drive you up the wall, a rabbit or guinea pig is going to test you, because the one thing you can't do is feed less of it.

This guide compares current feeding guidance for rabbits, guinea pigs, chinchillas and degus from the RSPCA, PDSA and the RWAF, including PDSA's 2026 PAW Report. Where the charities give different figures, as they do for pellets, we've shown each one. We didn't test any hay, rack or product ourselves.

This evening, look at the rack before you top up the pellets. If the rack is full and the bowl is empty, you've found the thing to change first.