Dwarf chickens with low monocytes/macrophages phagocytic activity show low antibody titers but greater performance

A selection method of chickens with blue-eggshell and dwarf traits by molecular marker-assisted selection

The blue-eggshell and dwarf traits have an important economic value in poultry production. Using a genetic aggregation-based strategy, the molecular marker-assisted selection technology was jointly used to provide a rapid breeding method for pure strain chickens simultaneously with hens exhibiting the blue-eggshell and dwarf traits. Overall, 80 male dwarf chickens and 1,000 hybrid blue-eggshell hens (F0) were used for the hybridization experiment. Subsequently, the crossing of F1 or F2 chicks was performed in succession. The F1 and F2 chicks were respectively detected by the joint molecular markers of the solute carrier organic anion transporter family, namely, 1B3 (SLCO1B3) and the growth hormone receptor (GHR) genes, which relate to blue-eggshell and dwarf traits. Meanwhile, the selection of blue-eggshell and dwarf phenotypes was used to validate the data obtained by the molecular markers. The results showed that F1 chicks included the heterozygous and wild-type of SLCO1B3, as well as the homozygous (hens) and heterozygous (roosters) of GHR. However, F2 chicks included 3 different genotypes of both SLCO1B3 and GHR. Ultimately, 196 F1 roosters (concurrently with heterozygous genotype of SLCO1B3 and GHR) and 1,073 F1 hens (concurrently with heterozygous genotype of SLCO1B3 and homozygous genotype of GHR) were obtained from the initial 10,040 F1 chicks. Further, 27 F2 roosters and 345 F2 hens, which simultaneously carried the homozygous genotype of SLCO1B3 and GHR, were screened from the initial 6,000 F2 chicks. Data obtained on the blue-eggshell and dwarf phenotypes were consistent with the results by molecular markers. Similarly, the purity verification of the strain obtained through 2 crossing experiments (F0♂ × F2♀ and F2♂ × F2♀) revealed that all chickens had the blue-eggshell and dwarf traits, supporting that the obtained F2 strain was pure. In summary, for the first time, we successfully bred a pure strain chicken with blue-eggshell and dwarf traits by jointly using the molecular markers of the SLCO1B3 and GHR genes. Our study provides a new method for the rapid cultivation of new chicken strains.