Charles Ellicott Commentary Genesis 30:38

"And he set the rods which he had peeled over against the flocks in the gutters in the watering-troughs where the flocks came to drink; and they conceived when they came to drink." — Genesis 30:38 (ASV)

In the gutters ... — Hebrew, in the troughs at the watering-places. So virtually all the versions; and see Exodus 2:16, where the word rendered here “gutters” is rightly translated troughs. The idea that there were gutters through which to pour the water into the troughs is utterly modern, but all travellers describe the fixed troughs put for the convenience of the cattle round the wells.