This is a variation on a common assertion. The usual formulation is something along the lines of, the largest domesticated animal in the Americas prior to the arrival of Europeans was the guinea pig.
Here's an online variant:
"The Aztecs and Maya kept dogs, domestic turkeys, ducks and bees. The Inca raised alpaca for wool and kept guinea pigs (cavies) for food. Other than that, 'animal husbandry' as such just wasn't an issue, and their main source of meat was game (fish, duck, turkey, deer). The Aztecs were also fond of eating tadpoles, larvae, ants, worms, newts and lizards. Some North American Indians used dogs to pull small loads, and the Incas did the same with llamas."
It's difficult to know how 'animal husbandry' wasn't an issue, given the size of the alpaca and llama (for that matter, you might include guanaco and vicuna populations, since they were at least managed if not domesticated by native Americans) population prior to the arrival of Europeans, and the various uses they were put to. I'm going to ignore all birds and fish, on the basis that lots of people understand "animal" to not include "birds" and I just don't even feel like getting into it.
This would be a much more reasonable assessment of domesticated animals of the Incas:
I don't like it when an assertion gets to be so common that it burrows into one's consciousness without inspection. Fortunately, R. caught this one for me.
ETA: If you are wondering about statements you might have seen about Incas/Americas and not having draft animals, I think the trouble involves the definition of "draft". Certainly, with appropriate equipment, llamas can be used to pull a cart or, presumably, a plow. If the Incas weren't using llamas for this purpose, it wasn't because they lacked an appropriate animal.