Could you soak some grain in water that has been treated then feed them that? I don't know if it would work - i've never tried it but it might be a solution (pardon the pun) that others in a similar situation could use as well. Or as they are geese - just put some grain in a container covered with water that's been treated - then in order to get the grain they would treat themselves.
I feel bad in that I'm taking possible attention away from BarkingChickens' possible issue. My gosling is fine, I was simply reassuring BarkingChickens that sometimes goslings can be a bit clumsy or gimpy. I have one 2 week old gosling thriving and the 5 siblings of the gimpy one are thriving. And the gimpy one is improving without my interference. For me I really do think it was a trampling situation. Not sure what BarkingChickens gosling issue might be but again, I was simply saying - sometimes goslings seem to take some time to find their legs.
That may not be the case though so if anyone has any information for BarkingChickens' issue please post that.