The end of realistic animal sounds :'(

We were reading a story the other day and in it were a bunch of farm animals.  Any of you who have heard HT's animal sounds will know just why this is my favorite part of reading stories.  I pointed to the cow and asked him what it says and he said, "moooooo" like he usually does.  Then I pointed to the horse and asked what it said.  He said, "neigh."  I paused for a second and asked him to repeat it and sure enough, he said "neigh" again.  Then I asked him what the pig said and he said, "oink-oink."  I was able to coerce him into doing the realistic sounds that we've come to know and love but it wasn't easy.  In fact, it was hard enough that I kind of think they must have been doing animal sounds at school and he got embarrassed or something by doing his usual sounds.  It broke my heart to hear those 'ordinary' animal sounds coming out of his mouth.  I guess I didn't expect our influence over him to wane quite so quickly.  :'(  Big little guy.