Genesis 30:37-39

Young's Literal Translation

³⁷ And Jacob taketh to himself a rod of fresh poplar, and of the hazel and chesnut, and doth peel in them white peelings, making bare the white that [is] on the rods,

³⁸ and setteth up the rods which he hath peeled in the gutters in the watering troughs (when the flock cometh in to drink), over-against the flock, that they may conceive in their coming in to drink;

³⁹ and the flocks conceive at the rods, and the flock beareth ring-straked, speckled, and spotted ones.