Timothy Hay for Guinea Pigs: How Much, Which Cut, and Why

Why hay is not optional

Guinea pig teeth grow continuously throughout life. The long, side-to-side chewing needed to grind coarse hay is what keeps the molars worn evenly. Pellets and vegetables are chewed differently and do not do this job.

Hay also provides the indigestible fibre that keeps the gut moving. When hay intake drops, the gut slows, and gut stasis in a guinea pig is a same-day emergency.

How much to feed

Unlimited. A guinea pig should always have a pile of fresh hay roughly the size of its own body available, and should never run out overnight. Most adults eat somewhere around 50 to 80 grams a day, though the exact figure matters less than constant availability.

Refill at least once daily rather than topping up. Hay that has been sat on, urinated on, or flattened is usually ignored.

Timothy, orchard, meadow, or alfalfa?

• •Timothy hay: the standard choice for adults. Good fibre, moderate protein, low calcium.
• •Orchard grass: a softer, sweeter alternative, useful for fussy eaters and for owners with timothy allergies.
• •Meadow hay: a mixed grass hay, varied and interesting, quality varies more between batches.
• •Alfalfa: a legume, not a grass. High in calcium and protein, appropriate for guinea pigs under about six months, pregnant or nursing sows, and pigs recovering from illness. For healthy adults it raises the risk of bladder stones.

Judging quality before you buy

Second cut timothy is the usual all-round choice, balancing soft leaf with enough stem. First cut is coarser and higher in fibre, third cut is soft and leafy but lower in fibre.

• •Colour: green rather than yellow or brown. Sun bleaching means lost nutrients.
• •Smell: sweet and fresh. Musty or sour smells mean mould, which is dangerous.
• •Texture: long strands with visible stems, not dust and fragments at the bottom of the bag.
• •Dust: a very dusty batch irritates the airways of an animal already prone to respiratory problems.

Storage and serving

Keep hay somewhere cool, dry, and ventilated. Sealed plastic bins trap moisture and grow mould; a cardboard box or fabric bag is better. Buy quantities you will use within a couple of months.

Offer hay in a rack or pile away from the toilet corner, and consider two locations so a dominant guinea pig cannot guard the supply.

If your guinea pig stops eating hay

A sudden drop in hay consumption is one of the earliest signs of dental pain, and it often appears before weight loss. Check for drooling, dropped food, or a preference for soft vegetables only, and book an exotic veterinary dental check.

Our guide to guinea pig dental problems explains what to look for in more detail.