Study Of Marker Assisted-selection(MAS) On The Selective Breeding Of Tan Sheep In Gansu

Polyacrylamide gel electrophoresis(PAGE)was used to analyse the genetic polymorphism of 7 blood protein loci which were hemoglobin(Hb),transferrin(Tf),albumin (Alb),erythrocyte protein 1 and 2(Ep-1,Ep-2),arylesterase(Es)andα-amylase(α-Amy)in 5 Tan-sheep populations sampled from Gaolan County,Jingtai County and Jingyuan County of Gansu Province to study their genetic variations and differentiations.The loci of Hb,Tf and Es appeared polymorphism except Amy,A1,Ep-1 and 2,though there was little difference caused by distribution and selection level.3 genetypes were found on Hb and Es loci respectively which were controlled by 2 allelic genes and Hb^B was superior allelic gene among 3 populations. According to the gene frequence variations of Hb,a result was known that the gene frequency of Hb^A was increased gradually with the development of fat-lamb technique.Es^-was dominant gene in Gaolan and Jingtai populations as well as Es⁺ was dominant gene in Jingyuan population.For Tf locus,there were 21 genetypes which were controlled by 8 allelic genes,Tf^B and Tf^C genes,TfBC and TfCC genetypes were superior in 3 populations.Meanwhile,correlationship of blood polymorphism and 2 economic traits,body-weight and body-size,were analyzed. Nei's average gene heterozygosity(H)of 3 Gansu Tan-sheep populations were 0.2037,0.2021 and 0.2254 respectively along with the average genetic diversity(G_ST)and genetic differentiation(D_ST)of total Tan-sheep population were 0.0019,0.0090.The results indicate that there is little variation(0.9%)among Gansu Tan-sheep and the genetic differentiation is very limited between Gansu Tan-sheep populations.Hb and Es have significant correlationship with body-weight and body-size,HbAA and Es++ are the best genotypes to be assistant marker to improve meat production of Gansu Tan-sheep.