Genesis 30:37-43

Jacob, however, cut green branches of poplar, almond, and plane trees and peeled back part of their bark, to expose the white inner wood of the branches. Then he set the partially peeled branches inside the water troughs where the goats would see them when they came to drink. For they mated when they came to the water troughs, and as they lowered their heads to drink, they saw the stripped branches in front of their eyes. Miraculously they gave birth to streaked, speckled, and spotted young. But with the mating ewes, on the other hand, he made them face the streaked or completely black animals in Laban’s flock. By doing this, he produced his own special flocks, which he didn’t allow to mingle with Laban’s. Moreover, every time the stronger females were in heat, Jacob laid the partially peeled branches in the water troughs in front of the flock, so that they would mate among the branches. But he didn’t place the branches in front of the scrawny goats when they mated, leaving the feeble animals for Laban and the stronger for himself. In this way, Jacob quickly grew very wealthy and owned large flocks, a great number of camels and donkeys, and many male and female servants.