I'm not sure about the vitamin deficiencies being more prominent in Silkies compared to other breeds but I have never had any problems with it ( my chickens are my babies, they get the table scraps, I buy pet mince for them, they get extras like bird seed and a good mixture of other stuff like greens, fruits etc) . The main problems I've had with Silkies is the wet and cold of the random weather in NZ and sinus infections. huh that's interesting if the sizzle is a sizzle prone to seizures, but I've never had any other chickens have seizures so I assumed it was a once off. I've heard about house chickens but where I live I'm not allowed ( chickens must be outside) but I can imagine how cute that is