I’m currently reading お休みなさい、お月様 to my little kid (she’s 25 days old…^_^)
Anyway, there is a cow, and it jumps over the moon in a picture. In the beginning it is mentioned like so:
And then later is
I get that the second is good night Mr. Cow jumping over the moon.
But, what is the function of 牝? Why is it in one but not the other?