Another characteristic that has been used in some commercial strains is the silver (S) and gold (s) color genes.Common breeds used as the non-barred male include Rhode Island Red or New Hampshire. Crossing a barred male with a non-barred female will not work. It is this specific cross that must be used. At hatch, both sexes have dark-colored down, but the males have a white spot on the top of their head. When a non-barred male is crossed with a barred female, the resulting females will be non-barred like their father, while the resulting males will be barred like their mothers (see Figure 3). The sex-linked trait of barring has been used in such sex-linked crosses.It is the female, therefore, that, genetically, determines the sex of the offspring (see Figure 1). In birds, it is the other way around-females carry a Z and a W chromosome, and males carry two Z chromosomes. It is the male that, genetically, determines the sex of the offspring. In mammals, males carry an X and a Y chromosome, while the females carry two X chromosomes. Most breeds do not have this type of sex-linked characteristic, but crossing certain breeds can result in different feather characteristics for the offspring. The mother contributes one sex chromosome to the offspring, and the father contributes the other. It takes a pair of sex-related chromosomes to determine the sex of the offspring. To understand how this works, it is important to have a basic understanding of the genetics involved. Sex-linked crosses are based on the color or growth rate of feathers, characteristics carried on the sex-determining chromosomes of chickens. Barred Plymouth Rock male chicken (Photo by Michael Shake on ) Barred Plymouth Rock female (Photo by By Veroja on ) The spot is much smaller and narrower in females (image by Dr. Photograph of a Barred Plymouth Rock chick with a white spot on top of the head. This has been found to be about 80% accurate. The spot is much smaller and narrower in females. The sex of purebred Barred Plymouth Rocks chicks can be determined on the basis of the size and shape of a light-colored spot on the top of the head. As a result, males are overall lighter in color. In adults, the male, with two barring genes (BB), has feathers with broader white bars than those of the female, who has only one of the barring genes (B_). The gene is incompletely dominant over the non-barring gene (b). This gene produces a white bar on an otherwise black feather. The Barred Plymouth Rock breed carries a gene for barring (B) that is carried on the Z chromosome (see Figure 2). However, there is considerable normal variation in the size of the spot, so sexing in this way is not always accurate. This spot is lost when the chick down is shed and replaced with feathers. The Rhode Island Red and New Hampshire breeds can be sexed by wing color at hatching. Male chicks have a white spot on the down over the wing web. There are very few schools that still teach chick sexing.įeather sexing is possible for some chicken breeds. To accurately sex chicks in this way, you need to be well trained and to have had a great deal of practice. This process sounds much easier than it actually is. The producer can then look for the presence or absence of a rudimentary male sex organ. It involves holding the chick upside down in one hand, expelling the fecal material and everting (turning outward) the vent area. Vent sexing is a skill that takes a long time to develop.
Vent sexing was developed in Japan and brought to North American poultry producers in the 1930s. There are two methods of sexing chicks that can be used at hatcheries: vent sexing and feather sexing. This makes sexing newly hatched chicks difficult In male birds, the reproductive organs are inside the body cavity. The male reproductive organs are located on the outside of the body and are relatively easy to see, even in newborns. With most animals, it is relatively easy to determine the sex of the newborn. Genetic basis for sex determination in mammals and birds (Image created by Dr.
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