LEV742 Do not crossbreed animals. Hashem created His world with wisdom and understanding. He gave each creature its own purpose and place in the grand scheme. Knowing what every creature requires to serve its purpose, He commanded each species to reproduce only with its own kind, so that each one retains its uniqueness and will not be missing any of the traits that are needed for the achievement of its purpose. Mixing of the species undermines the grand scheme and Hashem’s blessing will not rest upon the resulting creature. Therefore, the crossbreeding of animals is forbidden. This also is one of the reasons for the Torah prohibition on grafting fruit trees and mixing seeds.