Hay for guinea pigs: what to buy and how much to give

Why there is no way around it

A guinea pig’s teeth grow for its whole life and wear down only through work. What wears them is not the hardness of the food but the chewing motion itself: the animal grinds fibrous material sideways rather than gnawing at it. A handful of hay does more for the teeth than a carrot, hard as the carrot is.

The second reason is the gut. It runs continuously and stops as soon as food stops arriving. A few hours without food are already dangerous for a guinea pig, and hay is the thing that is always right there.

How much there should be

Enough that it never runs out. An empty hay rack during the day is a problem, not a detail. Grams are beside the point here: the animal eats exactly as much as it wants and the rest becomes bedding, which is fine.

Only about half of the hay turns out to be edible. The rest is rejected — it holds coarse stems and plants the animal should not eat. That is why you must not wait for her to «finish the old one»: doing that forces her to eat what she deliberately set aside.

What good hay looks like

• Smells of dry meadow — not of dust, not of a cellar, not of nothing.
• Green-grey, not straw-yellow and not brown.
• Does not raise dust when you shake a handful over a table.
• A mix of species beats a single grass: more taste and more nutrition.
• No white or grey patches — that is mould, and such a bale goes out whole.

The most expensive hay is not always the best. Judge by smell and colour rather than by the packaging: hay pressed into a bright bag often sits in storage longer than what farmers sell by weight.

How often to change it

Daily. Hay that lies in the cage for several days takes up moisture from the air and from the animal itself; yeasts and mould start to develop, and you cannot see them until it is too late. A fresh handful every day is cheaper than one visit to the vet.

A rack or a pile on the floor — either works. What matters more is that the hay is not where the animal goes to the toilet.

Hay or fresh grass

Sources disagree here, and both positions are worth knowing. British and American veterinary references put it simply: hay is the base of the diet, eighty per cent and more. The German school, built around meadow feeding, treats fresh greens as the base and hay as an important addition, because drying costs grass its vitamins and nearly all of its water.

In practice the disagreement is smaller than it looks. Both sides say the same thing: fibrous plant food must be available at all times. If your guinea pig gets a large bowl of varied greens every day, hay works as a reserve and as an occupation. If greens are scarce, hay stays the base — and it must always be there.

What does not belong in the rack

• Hay with additives — dried fruit, pellets, coloured bits.
• Straw instead of hay: it holds almost no nutrition, it is bedding.
• Damp or warmed hay — even if it merely sat in a bag in the sun.
• Freshly cut grass piled up: it heats and spoils within hours.

In short

• Hay available around the clock, without limit.
• A fresh portion daily, even if the old one is not finished.
• Half of it becomes bedding — that is how it should be.
• Smell and colour matter more than price.
• Mould means the whole bag goes out.