The SNPS Of Chicken OBR Gene Are Genetically Associated With Growth And Fatness Traits

Accompanying selection for rapid growth, meat-type chickens exhibit an increase in physiologica] disorder such as obesity. Production performance and fitness traits are negatively correlated in chicken and multitrah selection to simultaneously improve fitness traits and simultaneously increase production performance is, therefore, difficult to achieve by using only direct phenotype selection. Molecular marker-assisted selection (MAS) may be required and the combination of traditional genetic selection and modem molecular methods may be preferred for breeding chickens in the future. Leptin receptor (OBR) is a member of the class I cytoldne receptor family and signals via janus-activated kinases (JAK) / signal transducers and activators of transcription (STAT) pathway and plays an important role in regulating body energy stores and energy metabolism. Therefore, OBR gene can be viewed as the candidate gene that influences chicken growth and fatness traits. Three SNPs of chicken OBR gene were newly found and genotyped in the population of CAU F2 population and NEAU broiler lines divergent selection for abdominal fat by the methods of PCR-SSCP, PCR-RFLP and Direct sequencing. The correlation analysis between the polymorphisms of OBR gene and growth and fatness traits in the two populations were carried out using the appropriate mixed model. The main results are as follows:(1) Four SNPs were found in various regions of chicken OBR gene. Those are T500C, G659A in Intron8 (Accession No. AF222783), A3291G in Exon20 (Accession No. AF169827), and G3528A in 3'UTR (Accession No. AF169827).(2) In F2 population, results of association analysis between the SNPs (T500C and G659A) in Intron8 of OBR and growth and fatness traits showed that OBR gene influenced the body weight of new hatched birds (P<0.05); In the broiler lines of the fifth generation of divergent selection for abdominal fat, the experiment results show that AA and AB birds had higher LW than BB birds (P<0.05); In the broiler lines of the sixth generation of divergent selection for abdominal fat,BB birds had higher AFWthan AAand AB birds (P<0.05), and AB and BB birds had significantly higher LW than AA birds (P<0.01).In F2 population, results of association analysis between the SNP (C1167A) in Exon9 of OBR and growth and fatness traits showed that CD birds had the higher body weight at 7 wk of age than DD birds, and CC birds had lower LWP than CD and DD birds (P<0.05). In the broiler lines of the sixth generation of divergent selection for abdominal fat, CC birds had higher AFWthan CD and DD birds; CC birds had higher AFP than CD birds (P<0.01).In the broiler lines of the fifth generation of divergent selection for abdominal fat, results of association analysis between the SNP (A3291G) in Exon20 of OBR and growth and fatness traits showed that EE birds had higher LW than FF birds (P<0.05); In the broiler lines of the sixth generation of divergent selection for abdominal fat, FF birds had higher AFW than EE birds (P<0.05), and EF birds had higher LW than EE birds (P<0.05).In F2 population, results of association analysis between the SNP (G3528A) in 3'UTR of OBR and growth and fatness traits showed that GG birds had higher LW/CW than GH and HH birds (P<0.05).