There are live brine shrimp hatcheries, but that would do you no good for these guys! (you asked on a system that could feed live food 24/7)
1 week is a long time, so other then stocking the tank with live food, you really do need someone to come out & feed them daily.
When I went on vacation last year, I had my best friend who can't keep a goldfish alive feed my tanks. I cried as I pulled out of the driveway, but hey, rinsing off frozen food isn't to hard to teach someone! He did good, no deaths, I was impressed! Give a call to any family or friends, even if they don't have hobby experience, at least that way, your horses will be fed!
Good luck & I hope you enjoy your trip!