The accredited examination is carried out for the orders Parrots (Psittaciformes), birds of pray (Falconiformes), cuckoos (Cuculiformes), pigeons and doves (Columbiformes), fowl-like birds (Galliformes), wading birds (Ciconiiformes), perching birds (Passeriformes), owls (Strigiformes).
The determination of sex in young birds by morphological features is absolutely impossible for most species. The adults of the half of bird species do not show any morphological differences between adult males and adult females or the morphological differences are at such a level that excludes reliable sex determination. The gender can be determined by vent sexing. However, this method represents high risk of bird injury and mistakes in sex determination. The sex determination by DNA-analysis based on PCR-method is a modern, exact, quick, reliable and non-invasive alternative. The method is also suitable for examination of nestlings, in which the sex organs are not still developed. This method can be also used for determination of sex on shell membrane immediately after hatching of the chick.
The sex in birds is determined by sex chromosomes Z and W. The female birds are heterogametic (contrary to humans) and their chromosome set contains combination of sex chromosomes ZW. The males are homogametic and their chromosome set contains two Z chromosomes (ZZ). The sex determination in an unknown bird is based on proving the absence or presence of W-chromosome or a specific sequence of W-chromosome.
The first gene described on W-chromosome was CHD1-gene (chromo-helicase DNA binding protein). This gene is very similar to the human gene CHD1 (abbreviated as CHD1W). Generally, the CHD genes among various animal species are conservative. Another copy of CHD1-gene was found on Z chromosome (abbreviated as CHD1Z). The sequence of CHD1 gene is interrupted by intron and the length of the intron differs for CHD1W-gene and CHD1Z-gene. The sex determination in birds using the PCR method is based on amplification of homological sequences of CHD1Z and CHD1W genes incl. the inserted intron that determines the length of PRC products. This method can be used for the most birds with the exception of the superorder Ratite (Ratitae). For determination of sex in ratite birds, you have to place a separate order.
For determination of sex with PCR method, primers are often used that are based on the following publications:
Griffiths et. al. 1998 - Restrictions on the representatives of the swift order (Apodiformes) and the owl order (Strigiformes)
Kahn et. al. 1998 - Restrictions on the representatives of the swift order (Apodiformes) and the owl order (Strigiformes) and falcon and caracaras family (Falconidae)
Fridolfsson and Ellegren 1999 - Restrictions on the representatives of family of passerine birds (tits, chickadees and titmice) (Paridae) and some representatives of sparrows (Passeridae)
In the case of sex determination in birds of pray (Falconiformes), waders (Ciconiiformes), owls (Strigiformes) is frequently used alternative method PCR-ARMS (amplification refractory mutation system) that uses the differences in sequence between CHD1W and CHD1Z (Ito et al. 2003).
In case of the first two publications, the PCR-products in the representatives of the orders and families mentioned have CHD1Z and CHD1W genes of identical length. If primers according to the publication Fridolfsson and Ellegren 1999 are used, it is only performed the PCR-amplification of the CHD1Z gene.
The accredited examination is carried out for the orders Parrots (Psittaciformes), birds of pray (Falconiformes), cuckoos (Cuculiformes), pigeons and doves (Columbiformes), fowl-like birds (Galliformes), wading birds (Ciconiiformes), perching birds (Passeriformes), owls (Strigiformes).
The determination of sex in young birds by morphological features is absolutely impossible for most species. The adults of the half of bird species do not show any morphological differences between adult males and adult females or the morphological differences are at such a level that excludes reliable sex determination. The gender can be determined by vent sexing. However, this method represents high risk of bird injury and mistakes in sex determination. The sex determination by DNA-analysis based on PCR-method is a modern, exact, quick, reliable and non-invasive alternative. The method is also suitable for examination of nestlings, in which the sex organs are not still developed. This method can be also used for determination of sex on shell membrane immediately after hatching of the chick.
The sex in birds is determined by sex chromosomes Z and W. The female birds are heterogametic (contrary to humans) and their chromosome set contains combination of sex chromosomes ZW. The males are homogametic and their chromosome set contains two Z chromosomes (ZZ). The sex determination in an unknown bird is based on proving the absence or presence of W-chromosome or a specific sequence of W-chromosome.
The first gene described on W-chromosome was CHD1-gene (chromo-helicase DNA binding protein). This gene is very similar to the human gene CHD1 (abbreviated as CHD1W). Generally, the CHD genes among various animal species are conservative. Another copy of CHD1-gene was found on Z chromosome (abbreviated as CHD1Z). The sequence of CHD1 gene is interrupted by intron and the length of the intron differs for CHD1W-gene and CHD1Z-gene. The sex determination in birds using the PCR method is based on amplification of homological sequences of CHD1Z and CHD1W genes incl. the inserted intron that determines the length of PRC products. This method can be used for the most birds with the exception of the superorder Ratite (Ratitae). For determination of sex in ratite birds, you have to place a separate order.
For determination of sex with PCR method, primers are often used that are based on the following publications:
Griffiths et. al. 1998 - Restrictions on the representatives of the swift order (Apodiformes) and the owl order (Strigiformes)
Kahn et. al. 1998 - Restrictions on the representatives of the swift order (Apodiformes) and the owl order (Strigiformes) and falcon and caracaras family (Falconidae)
Fridolfsson and Ellegren 1999 - Restrictions on the representatives of family of passerine birds (tits, chickadees and titmice) (Paridae) and some representatives of sparrows (Passeridae)
In the case of sex determination in birds of pray (Falconiformes), waders (Ciconiiformes), owls (Strigiformes) is frequently used alternative method PCR-ARMS (amplification refractory mutation system) that uses the differences in sequence between CHD1W and CHD1Z (Ito et al. 2003).
In case of the first two publications, the PCR-products in the representatives of the orders and families mentioned have CHD1Z and CHD1W genes of identical length. If primers according to the publication Fridolfsson and Ellegren 1999 are used, it is only performed the PCR-amplification of the CHD1Z gene.