| A mutant duck was found in the breeding for rice-duck fanning system by Yangzhou University and Zhenjiang tiancheng agricultural science and technology limited company, which had a prominent uplift in the feathers and rear of the head skin. According to the book shi wu gan zhu which was written by Zhengyi Huang 400 years ago (1951), crested ducks existed at that time characterized by high hair in the head, white hair and black bone. The mutant duck was used for introgression of crest phenotype to Liancheng white ducks and then selected breeding of four generations by our research group via using modern biotechnology. The new ducks bred were characterized by black mouth, white hair and crested feather and were temporarily named of Crested white ducks. To well understand the similarities and differences of germplasm characteristics between crested white ducks and Liancheng white ducks, the weight at different weeks,10-week-old body size, slaughtering, routine meat quality, breast and leg muscle nutrients were measured, the allele frequency, effective number of alleles (Ne), population heterozygosity (He), polymorphic information contents (PIC), fixation indexes (Fis) of 12 microsatellite loci were analyzed and real time quantitative PCR (qRT-PCR) was used to detect the expression of crest phenotype related genes Hoxc8, EphB2, EphA2 and EphA3 in two populations. The results were summarized as follows:1. The result of growth and development experiment of Crested white ducks and Liancheng white ducks indicated that the weight growth velocity of Crested white ducks were faster than that of Liancheng white ducks in the first eight weeks. The 10-week-old body size of Crested white ducks are larger than that of Liancheng white ducks.2. The result of slaughter performance measured in Crested white ducks and Liancheng white ducks indicated that almost all the slaughter performance indexes measured in crested white ducks were larger than in Liancheng white ducks except the leg muscle percentage. The results of meat quality showed that the conventional meat quality indexes of pH, shear force and water loss rate show no significant difference between Crested white ducks and Liancheng white ducks. The composition of meat showed that the breast muscle protein percentage and leg muscle fat percentage of Liancheng white ducks was significantly larger than that of Crested white ducks, but leg muscle protein and water percentage was significantly lower, other composition of meat show no significant difference. The Mg content in Liancheng white ducks breast muscle is significantly larger in Crested white ducks, while Fe, Cu, Zn content in the two groups show no significant difference. Together, slaughter performance of Crested white ducks is better than that of Liancheng white ducks, and the conventional meat quality, composition of meat and mental element content of two groups show no significant difference. The overall results showed that Crested white ducks had higher slaughter performance and equal meat quality.3. The detected and analyzed result of 12 microsatellite loci in Crested white ducks and Liancheng white ducks indicated that eight microsatellite loci (AY493256, CMO11, APH01, APL2, AJ515884, AJ272579, AJ272577, AY493289) of Crested white ducks possess more alleles than that of Liancheng white ducks, three microsatellite loci (AJ515887, AJ515893, AY493313) equally and one single polymorphic (AJ272578) less. The average of Ne, He, Ho and PIC in Crested white ducks was larger than in Liancheng white ducks. Besides, the Fis of Crested white ducks and Liancheng white ducks is -0.0184 and 0.0904 respectively, indicate heterozyosis excess in Crested white ducks. The overall results showed that Crested white ducks had higher genetic diversity than Liancheng white ducks in the 12 microsatellite loci.4. Hoxc8, EphB2, EphA2, EphA3 gene expression in different tissues in Crested white ducks and Liancheng white ducks:Hoxc8 gene only expressed in kidney and dorsal skin, the expression in dorsal skin was higher than the other tissues. EphB2, EphA2 and EphA3 gene express equally in the tissues of Crested white ducks and Liancheng white ducks, but express extraordinarily high in intracranial fat which was the exclusive tissue of Crested white ducks. The result showed that Hoxc8 and EphA2 may be related to the crest phenotype. |
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