Wool Production And Growth Performance Measurement And Related Molecular Markers Screening Of South African Mutton Merino×Gansu Alpine Fine Wool Crossbred Sheep

644 individuals of South African mutton merino(?)× Gansu alpine fine wool(?)crossbred Sheep(SG)and South African mutton merino(?)× SG(?)crossbred sheep(SSG)were selected for the study and wool production and growth performance were measured;To screening the corresponding molecular marker,DNA pool sequencing and SNPscan methods were used to scan SNPs in KIF16 B,KRTCAP3,FGF5,GPRC5 A and PTPN3,and the correlation of SNPs with wool and growth traits was investigated to find significant SNPs.Meanwhile,the haplotypes of significant SNPs were constructed and the correlation analysis of combined genotypes of strong linkage SNPs with wool and growth traits were also constructed.The study could supply guidelines for selection of elite sheep at early stage.The main results are as follows:1.The wool lengths of adult female SG,yearling male SG and yearling male SSG were 6.17±0.87,8.37±1.40 and 7.62±1.37 cm on shoulder site,6.56±1.15,8.11±1.95 and 7.86±1.56 cm on body side,6.27±0.88,8.17±1.42 and 7.50±1.14 cm on thigh site,6.37±0.94,8.67±1.58 and 7.86±1.45 cm on notum site,and 4.53±1.08,5.31±1.32 and 5.33±1.17 cm on the abdomen site,respectively.The wool fiber diameters of adult female SG,yearling male SG and yearling male SSG were 22.06±2.18,21.30±2.16 and 21.00±2.32 ?m,with a standard deviation of 4.55±0.71,4.88±0.76 and 4.05±0.76 ?m,and coefficient variation of 20.63±2.74%,22.99±3.20% and 19.32±3.00%,respectively.The crimp ratio,curl recovery rate and crimp elastic rate of yearling male SSG were 12.45±3.3%,11.82±3.36% and 92.59±2.85%,respectively.The strength index,including breaking force,elongate length,breaking strength,fracture,and the elongation of yearling male SSG were 7.4±2.36 cN,3.63±0.44 mm,1.48±0.48 cN/dex,31.92±4.37% and 94.15±41.6 ?J,respectively.The body weight of adult female SG,yearling male SG and yearling male SSG were 38.54±5.09,41.31±8.69 and 47.54±7.58 kg,the chest girth were 81.16±5.22,87.83±6.83 and 92.78±7.24 cm,body height were 64.56±3.63,73.20±3.47 and 71.71±3.78 cm,body length were 68.14±5.27,75.58±4.15 and 74.19±4.49 cm,shin circumference were 7.39±0.72 ? 10.40±0.71 ? 10.01±0.97 cm,respectively.The greasy wool weights of mature female SG and SSG were 3.36±0.72 kg and 3.86±0.70 kg,respectively.The relationship between wool and growth traits was investigated.The results revealed that there were significantly positive correlations between the wool length at the shoulder,side,thigh,notum and abdomen site with greasy wool weight(P<0.05);the wool fiber diameter had a strong positive correlation with related indicators of wool crimp elasticity and single fiber strength(P<0.05).2.A total of 45 SNPs in KIF16 B were detected by DNA pool sequencing,including 7 missense,1 synonymous,1 promoter,and others were intron region;KRTCAP3 had 1 SNPs in intron 2;10 SNPs were identified in FGF5,of which 5 were located in the promoter region,5 were in intron 1;GPRC5A had 7 SNPs were located in intron 3;PTPN3 had 6 SNPs,2 were missense,1 were synonymous,and the remaining were intron.3.After primer evaluation,53 SNPs detected above could be genotyped using the SNPscan method.48 SNPs were significantly correlated with the growth and wool traits.In KIF16 B,five SNPs(SNP21,SNP22,SNP23,SNP32,SNP42 and SNP49)had significant correlations with wool length,five SNPs(SNP29,SNP30,SNP31,SNP35 and SNP36)has significant correlations with related indicators of wool quality(P<0.05),4 SNPs(SNP4,SNP8,SNP9 and SNP21)were significantly correlated with growth traits such as body weight and body size(P<0.05);In FGF5,SNP49 was significantly associated with natural wool length at five body sites;SNP46 of KRTCAP3,which was significantly correlated with wool length and wool quality(P<0.05);In GPRC5 A,four SNPs(SNP57,SNP61,SNP62 and SNP63)in intronic region were found to be significantly associated with growth traits;In PTPN3,four SNPs(SNP65,SNP66,SNP67 and SNP68)were significantly associated with growth traits(P<0.05).4.A total of 18,3,1 and 1 "haplotype block" were found in KIF16 B,FGF5,GPRC5 A and PTPN3,respectively.In addition,the haplotype analysis of strong linkage SNPs found 62,10,2 and 2 haplotypes in KIF16 B,FGF5,GPRC5 A and PTPN3,respectively.Among them,the haplotype TATG comprised of significant SNPs(SNP10,SNP12,SNP16 and SNP20)that correlated with natural wool length at abdomen site in KIF16 B has the highest frequency,which was a dominant haplotype.Correlation analysis of SNP4,SNP8 and SNP9 loci of KIF16 B were significantly correlated with the greasy wool weight,wool length and growth traits(P<0.05),multiple combined genotypes of the SNP29,SNP30,SNP35 and SNP36 loci were significantly correlated with wool quality indicators(P<0.05).In summary,the SSG has better performance in fiber diameter of wool,and reveals lager body weight and chest circumference than SG.Five genes,including KIF16 B,KRTCAP3,FGF5,GPRC5 A and PTPN3 could be used for the candidate genes for marker assisted selection.