Genesis 30:39

³⁷And Jacob took to himself green rods of storax tree and walnut and plane tree; and Jacob peeled in them white stripes; and as he drew off the green, the white stripe which he had made appeared alternate on the rods.

³⁸And he laid the rods which he had peeled, in the hollows of the watering troughs, that whensoever the cattle should come to drink, as they should have come to drink before the rods, the cattle might conceive at the rods.

— Genesis 30:39 —

⁴⁰And Jacob separated the lambs, and set before the sheep a speckled ram, and every variegated one among the lambs, and he separated flocks for himself alone, and did not mingle them with the sheep of Laban.

⁴¹And it came to pass in the time wherein the cattle became pregnant, conceiving in the belly, Jacob put the rods before the cattle in the troughs, that they might conceive by the rods.