Genesis 30:37-42

37Jacob then took branches of fresh poplar, almond, and plane wood, and peeled the bark, exposing white stripes on the branches.

38He set the peeled branches in the troughs in front of the sheep — in the water channels where the sheep came to drink. And the sheep bred when they came to drink.

39The flocks bred in front of the branches and bore streaked, speckled, and spotted young.

40Jacob separated the lambs and made the flocks face the streaked sheep and the completely dark sheep in Laban’s flocks. Then he set his own stock apart and didn’t put them with Laban’s sheep.

41Whenever the stronger of the flock were breeding, Jacob placed the branches in the troughs, in full view of the flocks, and they would breed in front of the branches.

42As for the weaklings of the flocks, he did not put out the branches. So it turned out that the weak sheep belonged to Laban and the stronger ones to Jacob.