Genetic Parameter Estimation And Evaluation Of Important Economic Traits In Alpine Merino Sheep

Alpine Merino Sheep is a new type of Merino Sheep bred in China,which is adapted to the alpine cold and drought ecological area with an altitude of 2400~4070 m.In order to explore the genetic assessment scheme for Alpine Merino Sheep and optimize the current breeding program,it is urgent to conduct a comprehensive genetic assessment for the current core group of Alpine Merino Sheep.In this study,the R language was used to statistically analyze the phenotypic data of important economic traits of 20720 Alpine Merino Sheep aged 14 months from 2003 to 2018.Through a comprehensive analysis of the population structure and genetic characteristics of Alpine Merino Sheep,it lays a theoretical foundation for the optimization of breeding programs and the improvement of breed structure.Based on pedigree integrity,the production data of Alpine Merino Sheep were divided into data set 1 and data set 2,and the significance test of fixed effects was carried out by R language.Non-genetic effect significance test results showed that the identification assess year and flock were extremely significant for all traits,birth type was extremely significant for weight and greasy fleece weight,in data set 1,and gender only had an extremely significant reaction to weight.Four animal models for genetic parameter estimation were constructed according to different random effects and data sets.The variance component was estimated by ASReml4 software.The model was evaluated by AIC criterion,BIC criterion and LRT test.It was found that,the individual permanent environmental effect had no significant effect on the important economic traits.Under the condition of the same model parameters,the score of the small data volume with complete genealogy is better than that of the large data volume with incomplete genealogy.Based on the optimal model,the heritability of weight,greasy fleece weight,clean fleece yield,clean fleece weight,wool fiber diameter,coefficient of variation of fiber diameter,and the staple length were estimated to be 0.2392,0.3253,0.4394,0.2893,0.4222,0.3174,0.3669,respectively.Based on the single character animal model BLUP,the software ASReml4 was used to estimate the breeding value of each important economic trait.According to the linear regression analysis of the estimated breeding values from 2003 to 2018,weight,greasy fleece weight,clean fleece yield,clean fleece weight,wool fiber diameter,coefficient of variation of fiber diameter,and the staple length selection progress were 0.0223 kg,0.0014 kg,0.0098%,0.0004 kg,-0.0151?m,0.001%,0.0032 cm,respectively.The results showed that the selection progress of weight,greasy fleece weight,clean fleece yield and staple length were significant.Selection progress of wool fiber diameter and coefficient of variation of fiber diameter was not significant.The genetic and phenotypic trends showed that the important economic traits were developing towards the expected breeding direction.After nearly 20 years of breeding,the production indexes of important economic traits have been stabilized.