One cow can be exchanged for three sheep, one sheep can be exchanged for three rabbits and nine sheep can be exchanged for six rabbits.

One cow can be exchanged for three sheep, one sheep can be exchanged for three rabbits and nine sheep can be exchanged for 27 rabbits. According to relevant public information, one cow can be exchanged for three sheep, one sheep can be exchanged for three rabbits and nine sheep can be exchanged for 27 rabbits, so one cow can be exchanged for three sheep, one sheep can be exchanged for three rabbits and nine sheep can be exchanged for 27 rabbits.