Albert Barnes Commentary 1 Kings 4:28

"Barley also and straw for the horses and swift steeds brought they unto the place where [the officers] were, every man according to his charge." — 1 Kings 4:28 (ASV)

Barley is to this day in the East the common food of horses.

Dromedaries - Swift horses. The animal intended is neither a camel nor a mule, but a swift horse.

The place where the officers were - Rather, “the places where the horses and swift horses were,” that is, the different cities where they were lodged.