Genome-wide Association Studies For Growth And Meat Production Traits In Sheep

Growth and meat production are significant economic traits in sheep, but a few investigations areemployed to identify genes associated with growth and meat production at genome level. Motivated bymining major candidate genes across ovine genome, the present study is to perform genome-wideassociation studies （GWAS） to detect genes associated with growth and meat production traits.Using Illumina OvineSNP50BeadChip, we performed a GWA study in329purebred sheepphenotyped for11growth and meat production traits （birth weight, weaning weight,6-month weight,eye muscle area, fat thickness, pre-weaning gain, post-weaning gain, daily weight gain, height atwithers, chest girth, and shin circumference）. A total of319sheep and48,198single nucleotidepolymorphisms （SNPs） were fitted using the TASSEL program with a mixed linear model，meanwhile,we considered population stratification assessment and relationship between any two individuals in thepopulation.36chromosome-wise significant SNPs were identified for7traits, and10of themconsistently reached genome-wise significance level for post-weaning gain. Gene annotation wasimplemented based on the latest Ovis_aries_v3.1genome sequence （released October2012）, and, in themeantime,we referenced genomic information of human, bovine, mouse and rat. More than one-thirdSNPs （14out of36） were located within ovine genes, some others were located close to ovine genes（878bp-398165bp apart）. The strongest new finding is5genes were thought to be the most crucialcandidate genes associated with post-weaning gain: s58995.1was located within the ovine genesMEF2B and RFXANK, OAR3₈4073899.1, OAR3₁15712045.1and OAR9₉1721507.1were locatedwithin CAMKMT, TRHDE, and RIPK2respectively. GRM1, POL, MBD5, UBR2, RPL7and SMC2werethought to be the important candidate genes influencing post-weaning gain too. Additionally,25genes（NLGN1,EPB41L3,C1ORF87,CHMP5,LRPPRC,TGIF1,STT3A,ADAMTS2,TRPS1,SRP68,HYDIN,LSM3,MYO10,CCDC15,MSL1,NTN1,ZWINT,PLA2G6,PFKFB4,TRDN,OXSM,RARB,LRRC2,ADK,andSHISA9）at the chromosome-wise significance level were also forecasted to be the promising genes thatinfluencing the sheep growth and meat production traits. In this study, we did not detected anysingnificant SNPs at genome-wise or chromosome-wise level that associated with birth weight,height atwithers,fat thickness and eye muscle area.This study is one of the earliest GWA reports which simultaneously related so many growth andmeat production traits based on the latest Ovis_aries_v3.1genome sequence. The results will contributeto identify quantitative trait locus（QTL）and candidate genes for growth and meat production traits. Ourfindings also provide an insight into the additional novel functions of genes that is previouslyconsidered having no relationship with growth and meat production traits. It will facilitate the potentialutilization of genes involved in growth and meat production traits in sheep in future.