we'll, he's had three of these shakes now. i've never seen him chug a cup of milk, but he did today. then kept looking for more, even making the more sign to himself when he didn't realize i was watching!
the good news is that his weight has gone from 21lb 8oz to 23lb 2oz in a month, and the ped's now happy with his weight %. he's eating a lot more now that three of his four eye teeth are through; i don't think i'll be giving him many more of these shakes. maybe a little chocolate milk instead for a treat occasionally.
thanks for all your advice!
katy