Avian Genetics Determination
How Can I Determine the Sex of a Baby Chick?
There are a number of tests that can be done for determining the sex of the chicken. It is
quite difficult to do this if you are new to chickens. The best thing to do when you go out
to purchase your chicks is to take an experienced chicken breeder with you. If you do this
you will be able to do the butt bump test. This is a test that hatcheries and professionals use.
They gently squeeze the chick to find out if it has a bump at the butt, if they do this indicates
that the chick is a cockerel, or young rooster. An absence of the bump means that the chick
is a pullet, or young hen. If you are not familiar with chickens, it is wise to let someone who
is more experienced to do this to avoid harming or hurting the chick.
As the chicks grow you will find that the roosters develop a bigger comb and wattles than
the hens. You will be able to determine this when the chicks are about 6 to 8 weeks old.
With some breeds you can do the wing test. Females grow feathers faster than the males so
will have uneven feathers on their wings. Both these tests will be for older chicks.
With some breeds you can tell their sex by color. This is simple to do with the Red Star Sex
Link as the cockerels will be yellow and the pullets will be red in color. Some breeds will
have slightly lighter chicks as males and darker ones as females.
Components of Chicken Chromosomes and Chicken Chromosomes Structure
Chickens have pairs of 78 chromosomes, with the majority being microchromosomes. There
are 2 ways that scientists classify them. Some say that they have 8 pairs of macrochromo-
somes, 1 pair of sex chromosomes and 32 pairs of microchromosomes. The “International
Chicken Genome Sequencing Consortium” classifies the chicken chromosomes into 5 pairs
of macrochromosomes, 5 pairs of chromosomes that are intermediate and 28 pairs of micro-
chromosomes. These microchromosomes form 1/3 rd of the size of the genome and have a
much higher gene density.
Because the majority of the chicken's chromosomes are microchromosomes they have the
capacity to be very diverse genetically. The chromosome 16 in chickens which is a micro-
chromosome is one of the most diverse genetic chromosomes in some breeds of chicken.