Mary Allen
If you cross a black silkie rooster with a splash-colored hen, all the offspring will be blue feathered. Mendel’s rules explain why this is so.
Within a few millennia, humans bred several hundred breeds of chicken from the Bankiva chicken. They differ in appearance in shape, size, plumage coloration, or crest. Some breeds arose because the hereditary characteristics adapted to the respective environmental conditions. That’s why today, inheritance is almost like mixing colors: a black rooster and a white hen produce grayish-feathered offspring, known in the technical jargon as blue. The natural scientist Gregor Mendel found out why this is so and established three rules.
The first rule is about the uniformity of the offspring. If two breeds are crossed, which only differ in one feature such as color, the offspring in the first generation is in a middle position, i.e. a mixture between the parents. The example with the black rooster and the white hen (picture) is ideal for this. This is not a pure white hen, but a hen that occasionally has black feathers and is therefore also called splash.
In the Second Generation, There are Different Appearance Types
However, this first Mendelian rule does not apply when there is a dominant trait in one parent. For example, when a rooster with curly feathers is crossed with a hen with normal feathers. The offspring of the first generation does not take a middle position but takes over the dominant trait.
Which young animals result from a cross between two blue-feathered animals that arose according to Mendel’s first law? The second Mendelian rule, the splitting rule, states that the regularity is lost in the second generation. The juveniles of the blue-feathered parents split into several appearance types. According to the law of division, 25 percent of the offspring in the second generation are colored like their grandfather and therefore have black plumage. Another 25 percent of the offspring carry the trait of the grandmother and have splash-colored plumage. According to this theory, the remaining 50 percent have blue plumage like their parents.
But there is a third Mendelian rule for inheritance. This describes the law of the free combination of genes. It deals with the cases in which the parents differ in two or more characteristics. It is no longer just about the plumage color, but also about its texture, i.e. silky feathers or curly feathers. Other important features are the different variants of the combs.
Inbreeding Can Also Reinforce Negative Traits
The application of Mendel’s third rule requires a detailed study for the respective case. These three rules form the basis of the theory of heredity and they already give the breeder an idea of what the offspring of a certain cross will look like. The different characteristics and properties are stored in the individual genes. Through targeted mating, the characteristics of the parents can be passed on to the offspring.
If the rooster comes from a mother who lays eggs well and is crossed with a hen who also lays a lot of eggs, this trait will be strengthened over the generations. You can influence performance, egg weight, growth, dwarfism, or even the aggressiveness of the animals. There are always two rows of chromosomes in the hereditary system. During fertilization, the duplicated chromosomes are separated. In each egg cell, there is one chromosome from the father and one from the mother.
If you cross related animals or even siblings with each other, then either the characteristics of the father’s or the mother’s line are strengthened. With inbreeding, there is, therefore, a risk that not only positive traits but also negative traits will increase and a skeletal deformity or an increasing lack of vitality will become noticeable as a result. In order to find out which characteristics are dominant over others and which colors result from different crosses, one should consult specialist literature.