The Silver
Dutch bantam is truly a beautiful color variety. The colors are identically
presented as in the Light Brown, Blue Light Brown or Cream Light Brown
patterns except that the red feathered areas in these varieties are replace by
white. The black areas are excatly the same. When you breed outside silver
into another variety there are some important thing that you need to know in
order to achieve success.
Silver is a sex-linked color variety, the
other mentioned varieties are not! What this means is that the Silver gene is
located on the sex chromosomes. The sex chromosomes are so named by the fact
that they determine the sex of a bird. In addition to the determination of
sex, the sex chromosomes also carry other genes that reside on the chromosomes
not necessarily related to sex but to color or pattern or some other trait
such as rate of feathering. The fact that these genes reside on the sex
chromosomes means that when a bird receives the sex chromosomes at conception
then they also receive all of the genes that reside on these chromosomes.
These genes that are riding on the sex chromosomes are known as sex-linked.
Then a bird is showing silver in it's plumage it is showing a sex-linked
trait.
How do you know what traits are sex-linked? There are breeding
tests to prove them, but it is not really practical because sex=linked traits
are published in many books and are easily researched for this information.
The main concern of the fancier should be how to work with it effectively.
I have worked with only two sex-linked traits since I started breeding
Dutch bantams. These two are silver plumage and white legs. Both of these
color traits are dominant. Dominant means that if a bird inherits a dominant
gene from one parent, then it will show that particular trait; for example
when a bird has silver plumage, one or both parents had to have it. The same
is true of white legs or any other dominant trait. All sex-linked traits are
inherited in the same way and they can be either dominant or recessive. Any
recessive trait that expresses or shows itself needs two genes to show the
trait. A dominant trait will show itself when only one gene is present for the
trait. So, any bird that show a recessive trait (red plumage, for example, as
in Light Brown or Blue Light Brown plumage color) has to have two genes to
show it. The bird got one gene for red from each parent. A Silver bird on the
other hand could have received its gene from one or both parents. If only one
parent gave it a silver gene, then the bird would be Silver since silver is
dominant to red or gold. It is possible that a Silver bird can also carry a
gene for red or gold, if one of the parents were Light Brown or Blue Light
Brown. A Light Brown cannot carry Silver because if it did, it would be
Silver.
All traits are inherited with at least two genes for each
trait (one gene from Pappa and one from Momma, so 1+1=2). If the male and
female parents pass the same gene for any trait to the offspring, then the
offspring is said to be "pure" for that trait. Another term often used is
"homozygous". If the two parents pass on genes that are not equal for a given
trait, then a dominant gene of either parent will show itself and the bird
might appear to be pure but this is only because the dominant gene wins the
battle for showing or, as we say, "for expressing". The impure, but "pure
looking" bird also has the opposite recessive gene which it is "carrying". It
is "heterozygous" or not pure for that trait. One individual bird can be
homozygous for one trait and heterozygous for some other traits. The fancier
who understands this can build his strain with reasonable certainty toward
whatever goal he has in mind.
Chickens have hundreds and maybe
thousands of genes which reside on about seventeen pairs of non-sex
chromosomes and one or two sex chromosomes. Now, when we talk about
"sex-linked" genes (as in the case of silver plumage or white legs), we can
know that the gene is residing on the sex chromosome and we can observe the
illustration and understanding of how these sex-linked genes are passed on to
the chicks (offspring).
Pictured is a Silver cock
bird. Artist: Aaron Hamilton