Also sounds like I need to read up about the sex-linked silver, and how that works. I have watched some videos but not sure if/how it applies to my D'Uccle flock yet. Though your description helps. Is the white base vs yellow-ish base easy to see in chicks, or what age would one expect to be able to differentiate between male and female based on the silver gene?
A gene that's sex linked means that it is carried by the chromosome which determines the sex. In chickens and other birds it works the opposite as mammals: males have two copies of the same chromosome (ZZ) and females have one copy of each (ZW). The "W" chromosome is much shorter than "Z", so many alleles (an allele is a form of a gene) which are on Z, don't have the space to stay on W.
This is the case of silver ("S" is the silver allele, "s+" is the gold allele, the + means that it's the wildtype allele). So, males can either be S/S (pure silver), S/s+ (impure silver, they can have a range of yellow to yellowish white colour) or s+/s+ (gold).
Hens, on the other part, can only be S/- (silver) or s+/- (gold), because their W chromosome can't carry the other silver allele.
Depending on which crossings you are doing, yes, you could get sex-linked chicks, but not always. to make things easier, now I'm referring at only the silver gene, not the whole color genotype of millefleurs. In this case, you have S/S males and s+/- females.
I'll make a Punnett square.
| s+ | - |
| S | S/s+ | S/- |
| S | S/s+ | S/- |
The first column on the left is the father's genotype, the first row on the top is the mother's one. The 4 other spaces refer to the offspring genotype, the left ones are the males (they have 2 alleles), the right ones are the females (they have only one). You will get all the females with a white background color and males that will be impure, so they could have a range of yellowish background color. In this case, you won't probably be able to sex the chicks, since the males could also be almost white. You'll have to wait until they are old enough to be sexed normally (by paying attention to comb and/or saddle feathers)
If you used, instead, a millefleur male and a silver millefleur female:
| S | - |
| s+ | s+/S | s+/- |
| s+ | s+/S | s+/- |
Then, yes, you will get chicks which can be sexed at hatch: you will still get impure silver males, but all the females will be gold, so at hatch they will have a more reddish-buff fluff.
So, if I understand correctly, I am in need of a Millefleur rooster, I really love the colour, and if I breed a Millefleur that carries the Lemon gene to the Lemon rooster, I will get all-Lemon chicks... right? And same story for the Porcelain, if I'd like to do a Porcelain line, I'll need a correct rooster, since mine don't carry the Lavender gene?
Lemon and lavender are both recessive genes, so they need both the alleles to be present for them to be shown in the phenotype. You can't tell if a bird is carrying them by only watching at it, the only way to know is to make some test-breedings.
They both aren't sex-linked, so both males and females carry two alleles.
Let's talk about lemon, first. Lemon is a gene that inhibites only the gold color, making it a lemon-color. Its symbol is ig (from inhibitor of gold), the wildtype allele is Ig+. Of course, if you breed lemon x lemon, you get all lemon chicks.
If you breed a lemon (ig/ig) with a millefleur that carries lemon (ig/Ig+):
| ig | ig |
| ig | ig/ig | ig/ig |
Ig+ | Ig+/ig | Ig+/ig |
Then, you will get half chicks that are lemon (ig/ig), and half that are millefleur that carry lemon (Ig+/ig). The sex of the parent that is lemon/the one that's lemon-carrier doesn't change anything.
The same thing is with lavender, lav symbol, the wildtype allele is Lav+. This gene dilutes both gold (making it cream) and black (making it pale grey). Also in this case, if you breed lavender x lavender you get only lavender chicks.
If you breed a lavender (lav/lav) with a millefleur that carries lavender (lav/Lav+):
| lav | lav |
| lav | lav/lav | lav/lav |
| Lav+ | lav/Lav+ | lav/Lav+ |
Then, you will get half of the chicks that are lavender (so porcelain) and half that are millefleur carrying lavender.
If you want to only breed true (so chicks that are the same color as the parents), then yes, you should pair roosters and hens that are the same color. There's nothing wrong in playing with genetics, if you are willing to learn how it works you can create lots of interesting colors. For example, with what you have right now, you could also create some silver porcelains in few generations. Silver porcelain has both silver and lavender, so each feather has white background color, pale grey pearl and white tip.
I hope this is easier to understand, genetics can be hard to learn. Let me know if you have other questions.
