The 217th prohibition is that we are forbidden from crossbreeding different species of animals.

The source of this commandment is G‑d's statement,1 "Do not crossbreed your livestock with other species."

The punishment for crossbreeding an animal is lashes, provided that the person actually placed the organ of the male animal in that of the female by hand, [as the Talmud puts it,] "like an applicator2 in its tube." Our Sages3 said this clearly: "For adultery, [the witnesses] only need to see them in the position of sexual relations. For crossbreeding, they must see 'like an applicator in its tube.' " Only then does the person receive lashes.

The details of this mitzvah are explained in the eighth chapter of tractate Kilayim.