| Broiler production is a very important pillar industry in China’s livestock development,and growth traits,as one of the important economic traits in broiler production,play a key role in animal production and breeding programs.Insulin like growth factor 2 m RNA binding protein 1(IGF2BP1)plays an important role in chicken growth traits and is the master effector gene affecting growth/body size traits.Our group found that there were two mutant alleles,L1 and L2,in the upstream 1-3kb promoter region of chicken IGF2BP1 gene,and the transcriptional activity of L1 allele was significantly higher than that of W allele,resulting in significantly higher expression and growth rate of IGF2BP1 gene in L1L1 genotype than WW genotype.In this study,the heterozygous genotype individuals(L1W)of “Yunong M-line” broiler chickens were hybridized,and the growth traits of homozygous individuals(L1L1 and WW)were analyzed from three aspects: conventional phenotype,histological phenotype and microbial phenotype,so as to elaborate the effect of structural variation of IGF2BP1 gene on chicken growth trait phenotype.The main research works and results carried out are as follows:1.The establishment of “Yunong M-line” broiler resource group and phenotypic analysis of growth traitsA comparison of body weight,body size,slaughter traits and feed conversion ratio among IGF2BP1 genotypes showed that chickens with the L1L1 genotype had a significant advantage in growth trait phenotypes compared to those with the WW genotype.The specific performance was that the L1L1 genotype had high body weight,large body size,excellent slaughter performance and high feed conversion efficiency,and the expression of IGF2BP1 gene L1L1 genotype in different tissues such as liver,spleen,duodenum and leg muscle was significantly higher than that of WW genotype(P < 0.05).2.Histomorphometric analysis of breast muscle and duodenum of L1L1 and WW genotypes in “Yunong M-line” broiler resource groupThe histomorphology of duodenum and pectoral muscle of different genotypes of IGF2BP1 was compared.The results showed that compared with WW genotype individuals,L1L1 genotype individuals had higher duodenal intestinal villus height and lower crypt depth,and larger diameter and area of pectoral muscle fibers.3.Analysis of cecal microbial diversity of L1L1 and WW genotypes in “Yunong M-line” broiler resource groupThe cecal microbial community structure was different in different periods and genotypes.Compared with 1-day-old,the cecal content richness and diversity of 6-week-old and 12-week-old were higher,and the microbial richness and diversity of 6-week-old were better.In different genotypes,the microbial richness of L1L1 genotype individuals in different periods was higher than that of WW genotype individuals.In summary,the growth traits of “Yunong M-line” broiler different genotypes of chicken IGF2BP1 gene were studied in detail from three aspects : conventional phenotype,histological phenotype and microbial phenotype.The results showed that the individuals with L1L1 genotype had higher body weight,larger body size,better slaughter performance and higher feed conversion efficiency than those with WW genotype.The villus height of duodenum was higher and the crypt depth was lower.The diameter and area of chest muscle fiber were larger,and the cecal microbial richness was higher in different periods.In addition,IGF2BP1 gene expression was significantly higher in individuals with L1L1 genotype than WW genotype in different tissues such as liver,spleen,duodenum and leg muscle(P < 0.05).This study was conducted to elucidate the effect of structural variation of IGF2BP1 gene on chicken growth traits through growth phenotype refinement,which is important for improving broiler production efficiency and achieving sustainable development of livestock industry. |
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