What vet?!
What are you feeding in the first place? What is their current age? Did the vet ask these things before saying it wasn't needed?
My preferred duck feed (at my location in the US) is Purina, Flock Raiser. Not required to be listed in the guaranteed analysis, I called the company and they confirmed 55mg/kg
niacin in this product which IS labeled for use in duckling and chickens... My main bird is chickens, I breed them. But I have also raised ducks very well on this feed.
Ducklings DO need to have 55mg/kg of niacin in their feed. If the feed has a sufficient amount of niacin then they *should* not need extra added... except for giant Peking can use 70m/kg of niacin in feed (wouldn't surprise me if some standard Pekin did also need more than other slower growing standard duck breeds, which duck had the issues, did it resolve yet?). Check out this RELIABLE resource (I linked nutrition requirement but there is MUCH more under the info tab)...
https://www.metzerfarms.com/NutritionalRequirements.cfm?affiliate=undef&CustID=25143148
Maybe a crested black Swedish.. do you know which hatchery the feed store uses?
In most duck (not Muscovy, which yours aren't), the quack strength can be a HUGE indicator of gender... hens being loud quackers and drakes having more of a raspy whisper (like Donald duck come to think of it).
I don't see ANY Silkies in your photo, I presume whoever told you that, was not extremely experienced with Silkies and gave you their best assessment based on the feathered legs/feet. Mix ups are not uncommon.. But in the US all Silkies are considered bantam even if not nicely bred. In the UK they have 2 standards for Silkies to include large fowl and bantam. That feather legged bird may be a Cochin or Brahma. Silkies should have five toes and dark skin. I would need to see a better pic that includes comb type.
At this age it's all in the comb/wattle color and development and not the tail feathers (yet)... I'm not seeing anything screaming cockerel yet. Most feed store bantams will NOT be sexed. Better pic of white bird also needed if breed ID is requested. Tail differences are seen across the board depending on breed and genetics more so than gender. The gender differences may start about 10 weeks at earliest usually around 12 and often not later than 14 weeks when saddle feathers will show major differences on most breeds (some rooster breeds are hen feathered, and Silkies are a tad more challenging).
Red wattles and combs will develop on many breeds starting around week 4-6, with some holding off until 8 weeks+ (not much more)... in the BOYS. girls should not have faces, wattles, or combs turn red (not oink or flushing red) before 14-16 + weeks... give or take depending on season and genetics... maybe even artificial lighting or other factors.
Oh ya... Welcome to BYC, hope you love it here!
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