In order to understand how sex-linked crosses work, an understanding of avian genetics is required. The first thing to note is that the genetic basis for sex determination is different from that for mammals, as shown below. Specific breeds or strains of chickens can be developed where it is possible to tell male and females apart at hatch based on their physical appearance, often plumage color.
BackYard Chickens. Sex Linked Chickens for Beginners, What they are and how to breed them. Rating: 4.
By Don Schrider — At Backyard Poultry we get questions all the time asking for help identifying the breed of various chickens. Such poultry can be very productive and useful for the backyard fancier but cannot be considered a breed. In other words, a breed breeds true. The advantage of pure breeds is that each generation of offspring can be counted on to look and perform in the same way as the previous generation.
In a mating, the parents each contribute one sex chromosome. As a result, it is the male that, genetically, determines the gender of the offspring. In birds, however, the sex chromosomes are referred to as Z and W, with females having ZW chromosomes and males having ZZ.
Sex-linked barring is a fascinating plumage pattern in chickens recently shown to be associated with two non-coding and two missense mutations affecting the ARF transcript at the CDKN2A tumor suppressor locus. It however remained a mystery whether all four mutations are indeed causative and how they contribute to the barring phenotype. Here, we show that Sex-linked barring is genetically heterogeneous, and that the mutations form three functionally different variant alleles.
The sex-linked barring gene of the chicken Gallus gallusfirst identified inproduces an alternating pattern of white and black bars in the adult plumage. More recent studies have shown that melanocytes in the developing feather follicle of the Barred Plymouth Rock experience premature cell death, whereas initially it was thought that melanocytes remained viable in the region of the feather devoid of pigmentation but were simply inhibited from synthesizing melanin. In an attempt to reconcile these 2 different hypotheses at the molecular level, we have taken a gene mapping approach to isolate the sex-linked barring gene variant.
If you want chickens that lay lots of brown eggs, and that are distinguishable as male or female upon hatching, Black Sex Link Chicks are the way to go! Production: You can expect as many as brown eggs per year, per hen from Black Sex Links. They are primarily kept as laying birds, although many people raise them as dual purpose birds. Temperament: Black Sex Links are hardier than many breeds.
Use the link below to share a full-text version of this article with your friends and colleagues. Learn more. Previous studies have indicated that the white bands are caused by an absence of melanocytes in the feather follicle during the growth of this region.
Sex-linked barring is a plumage pattern on individual feathers in chickens, which is characterized by alternating pigmented and apigmented bars. Male chicken of traditional sex-linked barred breeds like the Barred Plymouth Rock usually show much wider and clearer white bands than females of the same breed. Sex-linked barring has been established as the dominant locus B by traditional mendelian genetics in the beginning of the 20th century. Females are always hemizygous at this locus ZW.