Studies On Candidate Genes Of The Carcass And Feather-down Characteristics In Goose

F₁ population was established by Wanxi White gander×Sichuan White goose. 40 carcassand feather-down traits were tested in parents and their F₁ populations, from which 12common factors were abstracted by factor analysis. Based on the common factors, allindividuals were divided into 6 groups by cluster analysis. Using the method of comparativegenome between chicken and other animals, three candidate genes (lipoprotein lipase, LPL;Melanocortin-4receptor, MC4R; and Myogenin, MyoG) of goose important economic traitswere cloned, and SNP of LPL gene was tested by PCR-SSCP, and SNPs of MC4R and MyoGgene at Hinfâ… , Earâ… , Pstâ… and Pvuâ…¡sites by PCR-RFLP associated with sequencing. Thegenetic effects of SNP genotypes on carcass and feather-down traits were estimated by bestlinear unbias estimation dealling with SNP effect and 6 individual group effects. The genotypiccontribution percentage and gene major effect index on the trait were estimated.The results showed as follows:1. The heterosis on carcass and meat quality trait was not significant in F₁ population, butthere was higher heterosis on feather-down traits in which the heterosises of down wetnessproportion and down proportion were 4.7160% and -10.1685%.2. LPL, MC4R and MyoG genes were cloned and sequenced, and their G-enBank accessionnumbers were DQ105795～DQ105799, DQ482582 and DQ294735 respectively. Sequenceanalysis showed that the percent similaritys of DNA sequences between goose and chickenwere 92.4%, 95.3% and 91.9% in LPL, MC4R and MyoG gene respectively.3. SNPs in 5 exon fragments of LPL gene were found using PCR-SSCP and combined to 8SNP genotypes. The effects of different genotypes on carcass and feather-down traits showedthat S₁ genotype was dominant genotype in decreasing fiber diameter of leg muscle, S₂ wasdominant genotype in decreasing fat power, S₄ was dominant genotype in decreasing crude fatof leg muscle, S₅ was dominant genotype in increasing leg muscle weight, chest-leg musclepercentage and 1000-downs weight, and also decreasing fiber diameter of leg muscle, S₇ wasdominant genotype in decreasing down wetness proportion, and S₈ was dominant genotype inincreasing crude fat of leg muscle. From the major effect index, LPL gene could be regarded asa major effect gene on crude fat of leg muscle, down wetness proportion, and evisceratedweight (with giblet).4. There were 3 Hinfâ… sites in MC4R gene in F₁ population. H and h Alleles were tested by Hinfâ… -PCR-RFLP in which h Allele was caused by G373A and T915C nucleotide substitution.G373A resulted in Asp125Asn in MC4R substitution. The effects ofnucleotide substitution oncarcass and feather-down traits showed that Hh genotype was dominant genotype in increasingfat power and fatty acid quality, and HH genotype was dominant genotype in increasing meatpower.5. By Earâ… - and Hinfâ… -PCK-RFLP in MyoG gene, there were E and e alleles at Earâ… site,and H and h alleles at Hinfâ… site in F₁ population in which e allele was caused by G276A andG288T substitution, and h allele by A164T. A164T and G288T resulted in Asp55Val andLys96Asn substitution respectively in MyoG. From the effects of different genotypes on goosecarcass and feather-down traits, Eehh was dominant genotype in increasing meat performance,and EEHH was dominant genotype in improving meat water holding capacity. The effects ofSNP on feather-down trait at Earâ… and Hinfâ… sites were not significant. Based on the majoreffect index, Earâ… and Hinfâ… sites in MyoG gene could be regarded as major effect sites onmuscle water loss percentage, crude fat of leg muscle, heart percentage and stomach weight.