Feeding baby animals

Lately I have noticed that you can now feed baby animals. When you feed them, you get the same animation as when you use bonemeal on a plant (little green stars).

But so far, that's it. I fed a baby chicken an entire stack of seeds, and I'm sitting here, staring at the same baby chick.

Am I doing it wrong? Am I meant to feed them other things? Or is the RNG just not on my side?

According to the Wiki, feeding the "Breeding Item" for that animal takes of 10% of the remianing time for them to grow up

Baby animals grow into full sized animals after twenty minutes (one game day, beds notwithstanding). Their growth can now slowly be accelerated using the animal's breeding item, where each use takes 10% off the remaining time to grow up.

Source

What would be happening if that each time you have fed the animal the remaining time for them has been reduces by 10%, but since it's affecting the remaining time the amount it's being reduced by is getting smaller each time.

100 - (100 / 10) = 90           - 10 was taken away
90 - (90 / 10) = 81             - 9 was taken away
81 - (81 / 10) = 72.9           - 8.1 was taken away
72.9 - (72.9 / 10) = 65.61      - 7.29 was taken away
65.61 - (65.61 / 10) = 59.049   - 6.561 was taken away

get the picture? mind you i just started with 100 cause it's easier, the 20 minutes would actually be worked out as 24000 ticks in Minecraft (so replace the 100 i used)

you probably just need to wait a little while, since the original time is one full day you wont have to be up so long

after twenty minutes (one game day, beds notwithstanding)