You can use a dog our simply open a gate and cows will respond well. I grew up on a mid sized dairy farm and a good incentive to have a human go and fetch the c

You can use a dog our simply open a gate and cows will respond well. I grew up on a mid sized dairy farm and a good incentive to have a human go and fetch the cows was (and has always been) to have eyes on the herd. You can't see her ears or how hard it might be to get up when you just issue vibrations.