Genesis 30:38-43

38 Then he set the rods he had peeled upright in the watering troughs, so that the animals would see them when they came to drink. And since they bred when they came to drink,
39 the animals mated in sight of the rods and gave birth to streaked, speckled and spotted young.
40 Ya'akov divided the lambs and had the animals mate with the streaked and the brown in the flock of Lavan. He also kept his own livestock separate and did not have them mix with Lavan's flock.
41 Whenever the hardier animals came into heat, Ya'akov would set up the rods in the watering troughs; so that the animals would see them and conceive in front of them;
42 but he didn't set up the rods in front of the weaker animals. Thus the more feeble were Lavan's and the stronger Ya'akov's.
43 In this way the man became very rich and had large flocks, along with male and female slaves, camels and donkeys.
Complete Jewish Bible Copyright 1998 by David H. Stern. Published by Jewish New Testament Publications, Inc. All rights reserved. Used by permission.