After Jesus healed a blind man, he went to make one of the most well-known analogies -- the one on sheep.
In the analogy, Jesus talks about how robbers do not use the door when accessing sheep but the doorkeeper (or shepherd) enter via (or on account of) the door (10:2-3). Then the doorkeeper calls the sheep and leads the sheep. In fact, the sheep follow the doorkeeper because the sheep are aware of the doorkeeper's voice, but they flee from strangers because they are unaware of the strangers' voices (10:4-5).
Jesus is NOT making an absolute claim on raising sheep because he is using a figure of speech (his audience is likely aware of farming life anyway). In particular, Jesus is using an illustration based on a familiar general scenario (kinda like making an analogy on an athlete). The sheep refers to a specific group of people who distinguish different voices. The purpose of making the illustration is to provide connections of concepts. The audience at that time did not understand the meaning, but Jesus would shortly explain the analogy.