| As an excellent lean meat duck,black Muscovy ducks has the advantages of fast growth rate,high feed compensation,easy feeding and good meat production performance,and has broad market prospects.However,due to the strong nesting performance and low annual egg production rate of female Muscovy ducks,the production performance of Muscovy ducks is seriously restricted.In addition,the black Muscovy duck has not been systematically bred,which provides abundant material for the breeding of the black Muscovy ducks.With the rapid development of molecular biology technology,traditional breeding methods have gradually been replaced by scientific and efficient breeding methods,providing a more powerful way to screen functional genes or molecular markers of high fecundity traits.In this experiment,the black muscovy ducks were studied,and the performance of different feeding methods of Muscovy ducks was compared.The genetic mechanism of laying traits of Muscovy ducks was also investigated by RNA-seq and PCR-RFLP techniques.The main contents and results of the study are as follows:1.Comparative study on the production performance of black muscovy ducks under cage and flat conditionsIn this experiment,1800 black Muscovy ducks were selected,which were divided into cage group and flat group.From the age of 31 weeks,the starting age,number of eggs laid,number of broken eggs and number of times laid were recorded,and production indexes such as egg yield rate,breaking rate,number of broken eggs,cumulative number of eggs laid and maintenance time of ? 60% egg yield were calculated,the test recorded a total of 19 weeks of data.Egg quality of duck eggs was measured for 3 consecutive days from the age of 300 days.The following conclusions were obtained:(1)The egg laying rate,cumulative egg production and egg breaking rate of the black muscovy ducks in the cage group were better than those in the flat group,which had extremely significant differences(P < 0.01).The egg weight and egg transverse diameter of the cage group were significantly different from the flat ratio(P < 0.05),and the egg-laying rate of black muscovy ducks in the cage mode was also higher than that of the flat-raising group.(2)The rate of eggs in the flat group was significantly lower than that in the cage group(P < 0.01),and the age at the start of production(222 days)was slightly earlier than that in the cage group(224 days).2.Differential expression of mRNA in ovarian tissue of high and low yield black muscovy ducksThree high-yield(> 90%)and low-yield(25% ~ 30%)black muscovy ducks were selected at the peak of egg production(40 weeks old),and the transcriptome of Muscovy duck ovary tissue was sequenced by Illumina sequencing platform.Get the following results:(1)Differential expression analysis identified a total of 619 differentially expressed genes(DEGs).Compared with the low-yield group,356 DEGs were up-regulated and 263 DEGs were down-regulated.(2)Analysis of DEGs revealed that the key genes associated with reproductive traits were: TGFB2,FGF18,EFNA5,POSTN,SMOC1,ESR1,and SLIT2.(3)GO analysis showed that 12,682 annotated genes were involved in the 64 small GO categories of the GO database,506 DEGs were annotated by GO function,and DEGs were mainly concentrated on cellular components and molecular functions.Involved in the integral component of membrane,nucleus,plasma membrane,ATP binding,zinc ion binding and calcium ion binding.(4)The KEGG database enriched 13371 functional annotation genes,involving 265 pathways,and 41 pathways were significantly enriched.The KEGG database analyzes differential genes mainly in the Pathways in cancer,the PI3K-Akt signaling pathway,the cell adhesion molecules(CAMs),and the Rap1 signaling pathway.TGFB2,FGF18,EFNA5,POSTN and SMOC1 were mainly concentrated in the pI3k-akt signaling pathway related to reproduction.(5)The 7 DEGs screened were verified by qPCR and consistent with the results of RNA-seq sequencing.3.Polymorphisms of MTNR1 B,BMP6,NSG1 and MC4 R genesFrom the beginning of the experiment(31 weeks old),the number of eggs produced by Muscovy ducks in 65 days was counted,and the weight of Muscovy ducks was weighed at the end of the experiment.Using MTNR1 B,BMP6,NSG1 and MC4 R genes as research objects,the polymorphism of Muscovy ducks was studied and correlated with egg production traits.Five SNP sites were detected.The results are as follows:(1)One polymorphic locus(g9880654 C > T)was detected in exon 1 of MTNR1 B gene,which was significantly correlated with the number of eggs laid by black muscovy ducks(P < 0.05).The number of eggs produced by CC alleles was significantly lower than that of TT.Individuals,the T allele is a dominant gene in the population,and the TT allele frequency is significantly higher than the CC and CT genotypes.The MTNR1 B gene mutation site has high genetic diversity(PIC=0.256)and can be used as a candidate gene for Muscovy duck reproductive traits.(2)A SNP locus(g67793146 G > A)was detected in the 5'UTR region of BMP6 gene.The BMP6 mutation site was digested and found to have no significant correlation with the number of eggs laid by black muscovy ducks(P > 0.05).The number of eggs produced by AG type individuals was significantly higher than that of the other two genotypes,and it was dominant in the population.Among them,the homozygosity and the heterozygosity were the same,indicating that the distribution of alleles in the group was relatively uniform.The polymorphic site PIC value is 0.375,which is moderately polymorphic.(3)NSG1 gene detected two polymorphic loci,SNP1(g63052875 A > C)and SNP2(g63058214 C > T),which were located in intron 4 and intron 5,respectively.Among them,the SNP2 polymorphic locus(g63058214 C > T)CT genotype frequency is lower,but the number of eggs produced by CT genotype is significantly better than other genotypes.The PIC values of SNPs found in this experiment ranged from 0.250 to 0.500,which showed high genetic diversity.In addition,there was no significant correlation between the three genotypes obtained by enzyme digestion and egg production(P > 0.05).(4)There is one SNP in the 3' untranslated region of the MC4 R gene(g76929165 A>T).Genotype-phenotype association analysis showed that there was no significant correlation between the SNPs of MC4 R gene and the number of eggs laid by black muscovy ducks(P > 0.05).The T allele frequency in the population was significantly better than the A allele frequency,and the number of eggs produced by the AA genotype was significantly higher than that of the AT and TT genotypes.The MC4 R gene mutation site has a PIC value greater than 0.025 and is in a moderate polymorphism.(5)There were no significant correlations between the SNPs mutation sites of MTNR1 B,BMP6,NSG1 and MC4 R genes and the weight of black muscovy ducks(P > 0.05). |
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