Best hay for guinea pigs: timothy hay and the alternatives

Why hay matters so much to guinea pigs

Hay is not a side dish for a guinea pig, it is most of the diet. PDSA and Burgess both put hay and grass at around 85 to 90% of what a guinea pig eats, with a cup of fresh vegetables and a small portion of pellets making up the rest. Our guinea pig diet guide covers the full daily plan.

There are two reasons. A guinea pig's teeth grow all its life, and long strands of hay grind them down as it eats. And the long fibre keeps a guinea pig's gut moving: their digestion is built for grazing almost all day, and it slows down badly when there is not enough fibre going through. The RSPCA says hay should be available at all times, so the simplest rule is that the hay rack is never empty.

Timothy hay for guinea pigs: is it the best?

Timothy is the standard choice and a very good one. It comes from a single grass species, is high in fibre and low in calcium, and has long, coarse stems with feathery seed heads. Burgess calls it "the gold standard" for adult guinea pigs, rabbits and chinchillas, and VCA's vets call hay the most important part of a guinea pig's diet.

It is not the only good hay, though. Orchard grass and meadow hay do the same job and many guinea pigs prefer one over another. What matters most is that it is a grass hay rather than alfalfa, and that it is fresh.

Types of hay for guinea pigs compared

First, second or third cut timothy: which one?

US hay is often sold by cut, meaning which harvest of the year it came from. UK bags rarely say, and are more often labelled "long stem", "meadow" or "dried grass", so this matters most if you buy US brands.

• First cut: the coarsest, with the most stalk and seed heads and the most fibre. Great for teeth, but some guinea pigs won't eat enough of it.
• Second cut: a balance of leaf and softer stem. Small Pet Select calls it the gold standard for healthy adults, and it is what we would start with.
• Third cut: the softest and leafiest, with less fibre and more protein and fat. It suits older guinea pigs, ones with a sore mouth and ones that need to gain a little weight, ideally after a vet check.

For a healthy adult, our pick is second cut as the main hay, with a handful of third cut mixed in for a fussy eater. Moving a healthy adult entirely onto third cut swaps away some of the coarse fibre their teeth need.

Alfalfa hay: who should have it

Alfalfa is a legume plant, not a grass, and it is richer in protein, calcium and energy than grass hay. That is exactly what growing babies and pregnant or nursing sows need, so they can have it as the main hay, mixed with grass hay. Our diet guide gives the age rule: alfalfa to about 6 months, then a slow switch to grass hay.

For other adults, keep it to a small treat. Guinea pigs are prone to bladder stones. VCA's vets recommend unlimited timothy "or other low-calcium hay" for adults, and Burgess says alfalfa is not suitable for adults because of its higher protein and calcium. Some thin older guinea pigs are moved onto a little alfalfa by their vet, and that is the vet's call.

How much hay does a guinea pig need?

More than most new owners expect. Burgess says each guinea pig should have at least a pile of hay roughly its own body size every day, and that it is not really possible for them to eat too much hay. For two guinea pigs, that is two guinea-pig-sized piles, topped up whenever it runs low.

• Fill the rack or pile in the morning and again in the evening.
• Put hay in more than one place, including inside or next to their hides.
• Pull out hay that has been weed on, trodden flat or gone damp, every day.
• Count roughly the droppings: plenty of large, round droppings means plenty of hay is going through.
• Keep pellets to the small daily portion so they don't fill up on them instead of hay.

How to tell good hay from bad

Buy hay with your nose and eyes, not by the bag. Good hay smells sweet and grassy, looks green to pale gold and has long, unbroken strands. Burgess advises looking for hay that is "dust extracted", because dust is especially hard on a guinea pig's airways, and poor hay tends to be dusty, yellow or brown.

1. Look. Green to pale gold is good. Bleached, brown or very yellow hay has lost much of its goodness.
2. Smell. Sweet and grassy is good. A musty, damp or sour smell means it has been stored badly.
3. Shake a handful. A little dust is normal; a cloud is not. Very dusty hay can make guinea pigs sneeze and wheeze.
4. Feel it. It should be dry and springy. Damp, heavy or clumped hay can be spoiling inside.
5. Check for rubbish. Sticks are fine, but take out anything sharp, any rubbish and any plants you can't name.

Store it somewhere cool, dry and out of direct sunlight, where air can move around it. A cardboard box or a breathable sack in a cupboard works well. Throw out any hay that smells musty or shows damp growth, and buy in amounts you will use within a few weeks.

Getting a fussy guinea pig to eat more hay

Most guinea pigs that "don't like hay" don't like that particular hay. Try a fresher bag first, then a softer cut or a different grass. Mixing in a handful of dried grass, oat hay or a herb blend works for many. The RSPCA suggests racks and hanging baskets to keep hay clean, and it helps to scatter some loose too, so they can forage for it. Fresh grass is a good extra if it is safe and unsprayed: see our page on whether guinea pigs can eat grass.

A guinea pig that suddenly eats much less hay is a different matter. The RSPCA says a pet that refuses hay should see a vet, to check its teeth and gut. Don't wait to see if it passes.

The best hay for guinea pigs to look at

Rabbits eat much the same hays, with a few differences: see our guide to the best hay for rabbits. For everything else on looking after guinea pigs, start at our guinea pig care guide, and check any fresh food in what guinea pigs can eat.