Beyond cow, sheep, goat and buffalo there are other milks that become cheese. But not every milk will.
Almost all cheese comes from four animals
Cow, sheep, goat and buffalo. Essentially every cheese in a shop falls into one of the four. They were not chosen because their milk tastes better, but because people domesticated them early and then bred them, generation after generation, for yield. Today's dairy cow is what thousands of years of that selection produced. Made the same way, each of those milks still gives a different colour, aroma and richness.
One from each milk, worth tasting side by side:
The rest were decided by the land
The Himalaya makes a yak's-milk cheese dried until it is as hard as stone. The S\u00e1mi of northern Scandinavia have long made cheese from reindeer milk. Camel's-milk cheese belongs to the Middle East and North Africa, and a very rare donkey's-milk cheese comes out of the Balkans. None of these milks was chosen for flavour — it was simply whatever the land could keep. One thing links them all: none of these are places where cattle do well. Which milk a cheese is made from is decided less by taste than by what survives on that ground.
Not every milk will turn into cheese, though
Camel's milk shows why. Cheese sets because the coagulant clips one particular part of the casein — kappa casein — and the proteins then bind to each other. Camel's milk holds only a third as much kappa casein as cow's (0.3% against 1%), its casein clusters are larger, and an enzyme naturally present in the milk called plasmin keeps cutting the protein even after it has set. Ordinary rennet therefore produces either no curd at all or one so fragile it collapses when handled. Proper camel's-milk cheese only became practical once a coagulant made specifically for it existed. Donkey's milk does set, but the curd stays soft, so fresh cheese is as far as it goes.
Can you make cheese from alpaca milk?
You can. In 2018 a Peruvian team hand-milked ten alpacas and made cheese from what they got, and it worked rather well. The yield was 21.6% — about the same as sheep's milk (21.4%) and well above cow's (12.7%). It came out low in moisture, firm enough to class as a hard cheese, and of a hundred tasters 74% liked the aroma and 65% the texture. So why can you not buy it? Volume. An alpaca gives between 0.3 and 1 litre a day, and in that study ten mothers with crias at foot yielded just over a litre between them. On top of that, alpacas in the Andes are kept for fleece and meat, as they always have been, so they have never been selected for milk — a dairy cow is the product of thousands of years of exactly that selection. Alpaca cheese is not an impossibility; it is an industry that does not exist.