Gosling is growing slower than hatchmates

[picalowpiepi]

So the geese are 3 months old now. When he was 1 month old, he was finally starting to get his wing feathers. The others already grew most of their adult feathers, although they looked pretty scraggly. At 2-3 months, the other geese looked like adults already, while the gander still had the downy bits stuck at the ends and is noticeably smaller. I am giving them 1 romaine head each and a whole lot of kale, 3 times a day. Is he going to be smaller when he's an adult? Or is he going to catch up, but slowly? Should I help or give him vitamins?

 

[Kiki]

I'm not sure if this proper feed article would be of any interest to you and I honestly don't know what the proper diet for geese is but I'd like to share it with you anyways:
http://articles.extension.org/pages/69065/feeding-chickens-for-egg-production