Timothy: the coarse workhorse
Timothy hay earns its place as the default because of its texture. Its long, coarse strands and firm seed heads demand real chewing — the side-to-side grinding that keeps continuously growing teeth worn and drives fibre through the gut. For a healthy adult rabbit or guinea pig with no issues, second-cut timothy (leafier, a little softer) or first-cut (stalkier, maximum chew) should make up the bulk of the hay on offer, available at all times in quantities bigger than the animal. If you choose one hay and never think about it again, timothy is the one. Its only real drawbacks are practical: some animals pick through the stalky pieces, and its dust bothers some animals and some owners.
Orchard grass: the softer alternative
Orchard grass is a different grass with a softer, flatter leaf and a sweeter smell, and it suits the animals timothy fails. Picky eaters who sort timothy and eat only the soft fraction often eat orchard grass more completely, which matters more than any small nutritional difference — the best hay is the one the animal actually consumes in quantity. Orchard grass is also the usual recommendation where timothy dust aggravates a sensitive animal's airways or an owner's allergies. It is slightly less abrasive than coarse timothy, so for an animal with a known tendency to dental trouble, many owners serve it alongside timothy rather than instead of it, letting the animal take the chew it needs from both.
Meadow hay: variety with a caveat
Meadow hay is not one grass but a mixture cut from mixed pasture — several grass species plus whatever herbs and flowers grew among them, seed heads and all. That variety is its strength for enrichment: the changing textures and smells give rabbits and guinea pigs something to sort through and investigate, and a fussy animal bored by a single hay sometimes eats meadow hay with real enthusiasm. The caveat is consistency: because the mix depends on the field and the season, one bale can be leafy and rich and the next mostly stalk, so meadow hay works best as part of a rotation rather than the sole supply. Whichever bale you open, it should smell sweet and feel dry, never musty or damp.
The exceptions: alfalfa, and guinea pigs' extra need
Alfalfa is a legume hay, visibly different — leafy, rich and high in calcium and protein. That richness is wrong for healthy adults, in whom excess calcium is a genuine concern, but right for young growing animals, pregnant or nursing mothers, and animals rebuilding condition under a vet's eye; think of it as a supplement hay for specific life stages, not a rack filler. Guinea pigs add one more consideration whichever hay you choose: hay alone does not supply the vitamin C guinea pigs cannot make for themselves, so their diet still needs its daily vitamin C source from suitable fresh vegetables and their pellets, with the hay providing the fibre and chewing foundation underneath.
Storage and serving decide more than brand debates
More hay is wasted by storage than by choosing the 'wrong' grass. Keep hay somewhere dry, airy and out of direct sun — a breathable bag or box rather than a sealed plastic bin it can sweat in — and serve it generously from a rack, a pile on the floor or both, topping up at least daily so the animal always meets fresh-smelling hay at the top of the pile. An animal who goes off its hay entirely, whatever the type, is telling you something beyond fussiness and deserves a health check. Since constant availability is the whole point, keeping the top-up as a daily duty in KinsLe's Care Teams makes sure the rack is refilled morning and evening, whichever hay your rabbits and guinea pigs do best on.