| MEF2A and MEF2 D genes play a regulatory roles in the growth and development of skeletal muscle,and have an important influence on the yield and quality of skeletal muscle in livestock and poultry.Studies have shown that polymorphisms in the MEF2 A and MEF2 D genes are associated with multiple production traits.Skeletal muscle is the main product of meat duck production.To explore the polymorphisms of MEF2 A and MEF2 D genes and their effects on production performance,it is helpful for molecular marker-assisted selection and breeding of new high-quality duck breeds.However,there is still a lack of research on the polymorphisms of CAG repeats and SNPs in the flanking sequences of MEF2 A and MEF2 D gene coding regions and their effects on production performance.In addition,the Sheldrake-Nonghua GF2 strain is a newly developed high-quality duck line of the research group and its production performance is still lacking in measurement and analysis.Therefore,this study determined and analyzed the multiple production performances of Sheldrake-Nonghua GF2 strain.The CAG repeat sequences and its two flanking sequences in the coding region of duck MEF2 A and MEF2 D genes were cloned,and their polymorphisms in Sheldrake-Nonghua GF2 strain were identified.Preliminary analysis of the relationship between CAG repeat polymorphism and SNPs in its flanking sequences.finally,the combination of CAG repeat genotypes and flanking sequences with SNP loci,SNP haplotype combinations,and multiple production performances were performed Correlation Analysis.The main findings are as follows:(1)At the age of 9 weeks,the body weight,breast muscle weight,leg muscle weight,slaughter rate,breast muscle ratioand leg muscle ratio of the Sheldrake-Nonghua GF2 strain male duck reached 347,658 mg,38,625 m g,24,971 mg,87.72%,15.81%,and 10.22.%.The female duck reached 300,941 mg,35,862 mg,22,408 mg,89.96%,16.31% and 10.19%.The chest muscle colour L value,leg muscle colour L value,chest muscle shear force and leg muscle shear force of the male duck were 41.23,39.77,39.90 N and 43.86 N,and the female ducks were 42.17,38.04,34.71 N and 40.26 N.(2)During 0-8 weeks of age,the body weight of both Sheldrake-Nonghua GF2 strain male and female ducks increased significantly(P<0.05),but there was no significant difference between 9-week-old body weight and 8-week-old body weight.Between 0 and 9 weeks of age,the daily weight gain of both male and female ducks first increased and then decreased.The average daily weight gain of ducks was 4-5weeks old,and the highest was the daily gain of female ducks at 5-6 weeks old.The body traits of 9-week-old male ducks were higher than that of female ducks,and the chest width and length were significantly different(P<0.05).The A-values of leg muscle color of 9-week-old male and female ducks were significantly different(P<0.05),and the other 7 meat quality traits were not significantly different.The nine-week-old ducks had significantly higher body weight,half-net weight,net weight,lean meat weight,leg muscle weight,leg muscle strength,and abdominal fat rate than the mother ducks(P<0.05).The remaining 10 slaughtered ducks.Male and female traits have no significant difference.(3)In this trial population,no polymorphism was detected in the CAG repeat and its flanking sequences in the coding region of the MEF2 A gene.There are three alleles of CAG in the coding region of MEF2 D gene,named A(40 repeats,allele frequency 0.931),B(49 repeats,allele frequency 0.054),and C(37.repeats,allele frequency 0.016)and three genotypes,named AA,AB,and AC(genotype frequencies0.846,0.108 and 0.046).Nine SNPs(named SNP1-9),three haplotypes(named H1,H2 and H3)and three haplotype combinations(named H1H1,H1H2 and H1H3)were detected in the CAG repeat flanking sequence within the coding region of the MEF2 D gene.There were only 2 alleles and 2 genotypes in all 9 SNP loci.SNP1/8/9 was completely linked and SNP2-7 was completely linked.H1 and H1H1 are major haplotype and haplotype combinations.(4)In this trial population,the mutation frequency of each SNP site in the flanking sequence of the CAG repeat AC type was significantly different from that of the AA and AB types,while the difference between the AA and AB types was very close.At the same time,the CAG repeat genotype has a certain correspondingrelationship with the combination of SNP haplotypes in its flanking sequences.Individuals with CAG repeats of AA,AB,and AC genotypes exhibited more H1H1,H1H1,and H1H3 haplotype combinations.(5)In this trial population,the CAG repeat polymorphism of the MEF2 D gene was significantly associated with 2-week-old body weight,9-week-old sputum length,chest muscle A value,and breast muscle thickness(P<0.05).CAG Repeated with AA genotypes individuals at 2,3,5,6,and 7 weeks of body weight,daily gain of 0-1,1-2,and 2-3 weeks of age,and 9-week-old chest width,sputum length,and chest muscle color A Value,chest muscle thickness,and sebum weight were all significantly greater than those of AC individuals(P<0.05).CAG Repeated with AA genotypes individuals at 3,5,6,7,and 8 weeks of body weight,daily gain in 2-3,5-6,and 6-7 weeks of age,and chest width,sputum length,and chest muscle color A The values,carcass weight,carcass weight,sebum weight,and chest muscle rate in 9-week-old were significantly greater than those of AC individuals(P<0.05).There was no significant difference in all traits between CAG repeat AA individuals and AB individuals.The above shows that CAG repeat AC genotype of MEF2 D gene is not conducive to meat duck performance.(6)In this trial population,the SNP1/8/9 of the CAG repeat flanking sequence of the MEF2 D gene was significantly correlated with the L value of the thoracic muscle(P<0.05),and there was no significant correlation between the remaining SNP loci and the production traits.At the same time,the haplotype combination had a significant effect on the value of thoracic muscle A(P<0.05).The Individuals with H1H1 on 1,2,3,5,6,7 and 8 weeks of weight,daily gains of 0-1,1-2,2-3 weeks of age,and 9-week-old chest width,length,and chest muscles Color A value,leg muscle weight,and sebum weight were significantly greater than H1H3 individuals(P<0.05).The Individuals with H1H2 on 1,2,3,5,6,and 7 weeks of weight,daily weight gain at 0-1,2-3 weeks of age,9-week-old chest width,sputum length,chest muscle A value,sebum weight,The rate of chest muscles was significantly greater than that of H1H3 individuals(P<0.05).However,there was a significant difference between the H1H1 and H1H2 individuals in terms of the semi-permutation rate and the total netnevus rate(P<0.05).The above indicates that the combination of H1H3 haplotypes in CAG repeat flanking sequences of MEF2 D gene is not conducive to meat duck performance.In summary,the production performance of 9-week-old Sheldrake-Nonghua GF2 strains was good.The polymorphism of the CAG repeat and its flanking sequences in the MEF2 A gene coding region was low,and the CAG repeat in the MEF2 D gene coding region was low.The polymorphisms of the flanking sequences were abundant.The polymorphism of the CAG repeat in the coding region of the MEF2 D gene had a certain effect on the combination of SNPs and SNP haplotypes in its flanking sequences,and the CAG repeat polymorphism in the MEF2 D gene coding region.The combination of SNP haplotypes in their flanking sequences has a significant effect on a number of production performances.The results of this study can provide a theoretical reference for the molecular marker-assisted selection in the breeding of new high-quality duck breeds. |
