Study On Molecular Markers Of Feed Convertion Efficiency In Simniental

The pursuit goal for beef operations was how to minimize the input costs and maximize theprofitability of beef cattle production. Residual feed intake had been proposed as assessment ofefficiency of individual cattles. MALDI-TOF-MS and Mixture DNA pools sequencing techniques wereapplied to detect6candidated genes (UCP2、 UCP3、 PIT-1、 MC4R、 NPY and IGF2) in118Simmental. The objects were to analysis the genetic diversity of these genes as well as the associationwith growth traits, with the purpose of indentifying the molecular markers with significant effects onfeed convertion efficiency traits. The main results were as follows:1. Association between genetic variation of UCP2gene and feed convertion efficiency traits inSimmentalThe variations of4SNPs(G118A、C161T、C305T、C215G)in intron2of UCP2gene wereindentified. Except for C215G locus, the SNPs were in moderate polymorphic (0.25<PIC<0.5) in thepopulation. And the distributions of frequency and genotype frequency were at Hardy-Weinbergequilibrium(P>0.05).The results of association with growth traits showed that G118A、C161T andC305T were significantly associated with FCR and ADG traits (P<0.05).Compared with thehomozygotes’, the FCR values of the heterozygotes were significantly higher (P<0.01). Meanwhile,individuals with homozygote of TT genotype had a significantly higher average value than that of AAgenotype (P<0.01). Association analysis of haplotypes indicated88haplotypes had the lower FCR valueand higher ADG value which was similar to the results of SNPs.2. Association between genetic variation of UCP3gene and feed convertion efficiency traits inSimmentalThe locus G820A in exon3and G1099A in intron3was detected in UCP3gene. And the locus ofG820A replaces Alanine with Threonine. Both of the two SNPs were in moderate polymorphic(0.25<PIC<0.5). The association showed that AA genotypes of G820A locus had significantly lowerFCR value and higher ADG value (P<0.05), while the site of G1099A was not significantly associatedwith growth traits. The LD value was so low that there was no haplotype existed between them.3. Association between genetic variation of PIT-1gene and feed convertion efficiency traits inSimmentalThe locus of C15636G was indentified in exon6of PIT-1gene. And the frequency of GG genotypewere superior than of CC genotype, so the allele G were the superiority gene type. In addition, the SNPwas moderate polymorphic (0.25<PIC<0.5). The association between genotypes and growth traitsshowed that GG genotype in PIT-1gene were with lower FCR and higher ADG value than that of CC orGC genotype (P<0.05).4. Association between genetic variation of MC4R gene and feed convertion efficiency traits inSimmentalThe locus of C1069T was found in exon1of MC4R gene, which replaced leucine acid with valineacid. However, the difference in FCR、ADG and RFI was not significant (P>0.05). 5. Association between genetic variation of NPY gene and feed convertion efficiency traits inSimmentalThree genotypes (TT, TC, CC) were detected in NPY, which were at3032bp position in intron2.And genotype CC were predominant genotype and C were predominant alleles. But there was nosignificant difference among the genotypes (P>0.05).6. Association between genetic variation of IGF2gene and feed convertion efficiency traits inSimmentalA total of4SNPs (C2209T、G18587C、A22950T and G26920T) of IGF2gene were indentifiedin test population, which respectively were at5′regulatory region,18587bp position of intron3,22950bp position of intron7,26920bp position of exon7. Only the locus of G18587C was moderatepolymorphic (0.25<PIC<0.5). The results indicated that only the locus of G18587C was significantlyassociated with ADG and individuals with CC and GG had higher value than that of GC genotype(P<0.05). No significant difference was found between polymorphism of C2209T、A22950T andG26920T and growth traits. The LD value was so low that there was no haplotype existed between them.