| Dezhou donkey is one of the best large-size meat and draft breeds in China.Dezhou donkey can be divided into "Three-pink donkey" and "Black-head donkey" in phenotype,except for color difference,other studies on production performance are less reported.Body length is one of the important economic traits of livestock,which directly affects the body length of livestock and further affects the economic benefit.The most important determinant of body length is the number and length of thoracic and lumbar vertebrae.It was found that VRTN and NR6A1 were the causal mutated genes of the variation of the number of vertebrae in pigs.Therefore,these two genes were selected as candidate genes for the variation of the number of vertebrae in Dezhou donkey.Genetic parameters and Hardy-Weinberg equilibrium(HWE)were tested by using Excel2010.Haploview 4.2 software was used to analyze linkage disequilibrium and haplotypes according to SNP location and genotype information.The association between genetic polymorphism and haplotype with thoracolumbar vertebra number character,production character was analyzed by general linear model(GLM)of SPSS 24.0 software.To provide molecular markers for the future breeding of a new breed(strain)of multi-thoracolumbar donkey.1 A preliminary study on the production performance of Three-pink donkey and Black-head donkeyThrough comparative study and analysis of the body size traits,slaughtering traits and organ index of Three-pink donkey and Black-head donkey populations,this paper intends to understand the similarities and differences in the production performance of the two different strains,to provide basic information for further germplasm innovation.In order to provide reliable production performance data for the development of Dezhou donkey industry,this study systematically studied the characteristics of body size,slaughter performance,organ index and number of thoracic and lumbar vertebrae of 40 Three-pink donkeys and 9 Black-head donkey.The results showed that the slaughter rate of Three-pink donkey was 54.02%,the net meat rate was 42.43%,and the net skin rate was 8.12%.The results showed that the dressed percentage of Three-pink donkey was 54.02%,the net meat rate was 42.43%,the net skin rate was 8.12%.Forthe Black-head donkey,the dressed percentage was 53.71%,the net meat rate was 40.32% and the net skin rate was 9.41%,which indicates that the Three-pink donkey is more suitable for breeding meat-used donkey strain and the Black-head donkey is more suitable for breeding skin-used donkey strain.Compared with the Black-head donkey,the Three-pink donkey had higher liver coefficient and significantly longer small intestine and cecum(p <0.01),indicating that the Three-pink donkey had better digestion and metabolism ability,which may be one of the reasons for its better meat production performance.2 Analysis of multiple thoracolumbar vertebrae in Dezhou donkeyA total of 555 Dezhou donkeys were used as experimental subjects to study the association between multiple thoracolumbar variation with body size,production traits.The results showed that the normal number of thoracolumbar vertebrae of the Dezhou donkey was T18L5(T:thoracic vertebra;L: lumbar vertebra).There were also four types of polythoracic lumbar vertebrae variation types in the population: T18L6,T17L6,T19L5,and T17L5.Through the analysis of the correlation between the different types of thoracolumbar vertebrae and body size,it was found that adding a thoracic or lumbar vertebra resulted in an increase in body length of5.14 cm and 2 cm,and a weight increase of 11.17 kg and 2.83 kg,respectively.The correlation analysis of body size traits,slaughter traits,number and length of thoracolumbar vertebrae showed that body length with length of thoracolumbar vertebrae,length of lumbar vertebrae,total number of thoracic vertebrae and total length of thoracolumbar vertebrae was significantly correlated.Therefore,individuals with multiple thoracolumbar traits can be selected preferentially in breeding.3 Analysis of association between VRTN,NR6A1 gene and polythoracolumbar character,growth traits in Dezhou donkeyAccording to the whole genome sequencing of Dezhou donkey in early stage of this research group,VRTN gene sequence was obtained.Six pairs of primers were designed to amplify the upstream and downstream 4000 bp region and the whole VRTN gene with the blood genomic DNA of each donkey as the template.The genome sequence resequenced by our research group showed that the full length of VRTN gene was 2137 bp,all of which were exonswithout introns.Eleven single nucleotide mutation were found on the VRTN gene.The correlation analysis results were shown that,the linkage sites g.3644436A>G and g.36444438G>A were significantly correlated with the number and length of thoracic vertebrae(p <0.05).g.3645735G>A polymorphism was significantly correlated with carcass weight,number of thoracic vertebrae,length of thoracic vertebrae and total length of thoracolumbar vertebrae(p<0.05).Five fully linked polymorphisms g.3648666C>A,g.3648675C>T,g.3648700T>C,g.3648729C>T,g.3649227C>T were significantly correlated with carcass weight,thoracic vertebra number and thoracic vertebra length(p <0.05),g.3650137C>T was significantly correlated with carcass weight(p <0.05),g.3652326A>T was significantly correlated with the number of thoracic vertebrae(p <0.01),and significantly correlated with the number of lumbar vertebrae(p <0.05).By linkage disequilibrium analysis and haplotype analysis,9 kinds of haplotype combinations were found in the experimental Texas donkey population.Correlation analysis showed that the number of thoracic vertebrae of H1H4,H4H4,H1H2,and H2H3 haplotype combinations was superior to other individuals,and the carcass weight,number of thoracic vertebrae and length of thoracic vertebrae of G1G1 individuals were significantly superior to other combinations(p < 0.05).NR6A1 gene sequence was obtained from whole genome of Dezhou donkey,and 13 pairs of primers were designed to amplify all exon and intron sequence of NR6A1 gene with the genomic DNA of each donkey as the template.14 single nucleotide mutation,4 deletions mutation and 1insertion deletion site were found in the NR6A1 gene.The mutation sites were all located in intron regions,but did not cause changes in protein structure.General linear model was used to analyze the correlation between production traits and gene polymorphism.Correlation analysis showed that there was a significant correlation between g.2238183 delA and chest circumference(p <0.05).g.2237358del13 bp was significantly correlated with chest circumference and thoracic vertebra length(p <0.05).g.2230648G>T was significantly correlated with body height and carcass weight(p <0.05).g.2230404T>C was significantly correlated with body height,chest circumference and tare weight(p <0.05).g.2229161C>G was significantly correlated with body height and lumbar spine length(p <0.05).g.2213153G>C was significantly correlated with body height(p <0.05).g.2211668 delT was significantly correlated with body height and chest circumference(p <0.05).g.2208980A> g was significantly correlated with the number of lumbar vertebrae,the length of lumbar vertebrae and the total number of thoracolumbar vertebrae(p<0.01).g.2208714T>C was significantly correlated with chest circumference and the number of lumbar vertebrae(p <0.05),and was significantly correlated with the total number of thoracic and lumbar vertebrae(p <0.01).Haploview software is used to predict NR6A1 gene haplotype,using the general linear model analysis of haplotype combination and the correlation of body measurements,slaughter traits,the analysis results show H1H7,H1H5 and H1H6 haplotype the number of lumbar vertebrae,lumbar vertebrae length and the total number of thoracolumbar significantly greater than other combination(p < 0.01),G1G3 and G4G4 length is superior to the other combination of the lumbar spine(p < 0.05).In conclusion,NR6A1 and VRTN genes were considered to be candidate genes for the variation of the number of vertebrae in Dezhou donkeys,leading to the variation of the number of thoracic and lumbar vertebrae,which resulted in the increase of body length and carcass weight.Therefore,it can be used in future breeding of Dezhou donkey to improve the efficiency and accuracy of seed selection as marker assisted selection. |
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