Sex Determination Of The Plumage Of Holdobaggy Goslings And The Expression Of Melanin In Embryonic Feather Follicles

The Holdobaggy goose is a Hungary goose breed with excellent meat and down production performance,and it has the characteristics of high down content,large down and high fluffiness,that has been included in the latest National Catalogue of Livestock and Poultry Genetic Resources in China.The dorsal feathers of Holdobaggy goose during the gosling stage are gray-black.Based on the preliminary production practice,we found that the black feathers on the dorsal of female goslings are darker than the dorsal feathers of male goslings,and it is presumed that there may be a companion inheritance of feather color.Therefore,the present study was conducted with the Holdobaggy goose as the study subject.Firstly,by turning the anus to identify the sex of the goslings,and the correlation analysis of the results of the sex difference comparison of the goslings’ plumage color.Therefore,the relationship between the color of the dorsal plumage and the sex of the goslings can be initially determined.Then,the distribution of melanin in the feathers follicles of the dorsal skin of embryonic stage of Holdobaggy goose and the expression content of related genes involved in melanin synthesis in different sexes were further investigated by histochemical staining,ELISA,q PCR and WB experiments to investigate whether the shades of dorsal black feathers in embryonic stage of Holdobaggy goslings is related to sex,to further elucidate the relationship between the shades of black dorsal feathers and sex during the goslings stage,and to provide a theoretical basis for the sex identification of firstborn plumage of Holdobaggy goose.The study content and results are as follows:Ⅰ A total of 2,000 newborn Holdobaggy goose were randomly selected,grouped according to the color shade of black feathers on their backs,and correlation analysis was performed by anal flip sex identification.The results showed that the rate of female goslings in the dark black feather group was over 99.1%,and the rate of male goslings in the light black feather group was also over 99.1%,and identification of the sex of the fledgling geese by the depth of the black feathers on the back is feasible.Ⅱ The structure and melanin distribution of the dorsal skin follicles of goose embryos were studied by HE staining and melanin-specific staining.The results showed that melanin is mainly distributed on the surface of feather buds at E13;At E18 and E23,melanin is mainly distributed in the inner and outer feather sheaths of feather follicles and in the feather crest.At E28,melanin mainly accumulates in the tips of feather follicles.In turn,the melanin content was measured by ELISA.The results showed that melanin content tended to increase and then slightly decrease at four time points during the embryonic period,where females were higher than males,with significant differences at E13,E18 and E23(P<0.05)and non-significant differences at E28(P>0.05).Ⅲ The m RNA as well as protein expression levels of melanin-related genes(TYRP1,ASIP)were measured in the feather follicles of the dorsal skin of goose embryos of different sexes by q PCR and WB.The results showed that the m RNA relative expression of TYRP1 gene increased first and then decreased during embryo development,in which E18 was significantly different from E13,E23 and E28 during female embryo development(P<0.05),while E28 was significantly different from E13,E18 and E23 during male embryo development(P<0.05).At E13 and E23,the relative expression of TYRP1 m RNA was not significantly different between male and female goose embryos(P>0.05),and at E18,the relative expression in female goose embryos was at significantly higher than that in males(P<0.05).But the m RNA relative expression of ASIP gene in female embryos showed a trend of decreasing and then increasing,with significant differences in the relative expression of E28 and E18 and E23(P<0.05).The relative expression in male embryos showed an increasing trend,with non-significant differences between E23 and E18 and E28(P>0.05),but significant differences between the two at all other time points(P<0.05).There was no significant difference in ASIP m RNA between male and female goose embryos at E18 and E23(P>0.05),but the relative expression in female goose embryos was significantly higher than that in male embryos at E13 and E28(P<0.05).TYRP1 protein was expressed only in E18(P<0.05)and the relative expression level was significantly higher in female than in male goose embryos at this time point(P<0.05).