GEN 30:40

40 Furthermore, Jacob separated the female sheep in his flock from the other sheep and goats in Laban’s flock. And when his female sheep mated, he made them look toward the animals that belonged to Laban that had black and white stripes on them, and the dark-colored animals. He did that so that the female sheep would give birth to animals that were striped or dark-colored. By doing that, he made bigger flocks for himself, and he kept them separate from Laban’s flocks.