Husbandry has nothing to do with being a husband, and a lot to do with being a farmer. If you cultivate the land or breed animals, you are practicing husbandry.
Long before husbands were hen-pecked guys who cut the grass on weekends and played with the kiddies after school, they were robust men of the Earth — farmers, in other words. That meaning died out, but its current meaning survives as a remnant of it. Today, you most often hear of "crop husbandry", which refers to raising crops; however, if you practice toad husbandry — you must be raising toads.