Study On Linear Evaluation Method Of Body Shape Of Duolang Sheep

The traditional evaluation of body shape and appearance of livestock only evaluates the single character of body weight,while the linear evaluation evaluates the traits of body type in turn,which is more scientific and comprehensive.Therefore,it has been widely used in the production and breeding of dairy cows,beef cattle and dairy goats.According to the standard of local sheep breeds,weight has been used to evaluate the appearance and shape of local sheep breeds,and there is a lack of scientific and comprehensive evaluation method.The establishment of a linear evaluation method for the somatotype of local mutton sheep as soon as possible can classify the meat sheep scientifically and effectively,which is of great significance for the breeding of local sheep breeds.This paper collected and recorded 13 phenotypic traits(body weight,body height,body length,chest circumference,chest depth,chest width,tube circumference,ear length,ear width,cross height,tail length,tail width,tail height)of 12500 Duolang sheep in three Duolang sheep breeding farms in Kashi,Xinjiang.13 traits were analyzed by correlation analysis,cluster analysis,principal component analysis and factor analysis in SPSS19.0software.The appearance score table of Duolang sheep,the function conversion table of each body size traits of Duolang sheep,the weight coefficient table of each body size and the grade evaluation standard of Duolang sheep were established,and the linear scoring method of somatotype of Duolang sheep was established and compared with the traditional method.The results are as follows:1.The correlation of body weight and body size of Duolang sheep was analyzed by SPSS19.0software.the results showed that:(1)the body weight of ram and ewe was positively correlated with chest circumference,tail height,chest width,tail width,cross height,body height,tail length and body length.There was a very significant positive correlation between body length index and chest circumference index(P<0.01).There was a significant positive correlation between chest circumference index and body index(P<0.01).There was a very significant positive correlation between body index and chest index(P<0.01).(2)the body weight,body height,body length,chest circumference and cross height,tail length,tail width and tail height of Duolang sheep were classified into the same category through body size cluster analysis and principal component analysis.it shows that the interaction among body weight,body height,body length,chest circumference,cross height,tail length,tail width and tail height is obvious.Conclusion: the results of correlation analysis,cluster analysis and principal component analysis reflect each other,and the traits that can comprehensively reflect the growth and development characteristics of Duolang sheep are screened out,which provides a theoretical basis for the subsequent establishment of linear evaluation system of Duolang sheep.2.(1)the appearance score table of Duolang sheep was established.based on the body size data of12500 Duolang sheep,the maximum and minimum values of body size were selected,the variation range of each character was established,and the appearance score table of Duolang sheep was established.(2)The function conversion table was established: basically following the relevant principles of the function score of Simmental cattle,referring to the function score table in the linear score of beef cattle,and combining with the body size development of Duolang sheep,the function conversion table was obtained.and the appearance score was converted into function score.(3)The weight coefficient of each body size is calculated by factor analysis,the function score is transformed into the final linear score,and the grade evaluation standard is established.3.By comparing the new linear evaluation method with the traditional method,the results show that the linear scoring standard is more suitable for the current somatotype development of Duolang sheep by comparing the results of local standard and linear scoring standard.It can accurately evaluate the somatotype and appearance of Duolang sheep.Conclusion: this experiment is the first time to evaluate the appearance of local sheep breeds.compared with the original breed grade evaluation only considering body weight,the effects of 13 traits such as body height,body length and chest circumference on body weight were analyzed,and the linear evaluation standard of somatotype of Duolang sheep was established.the purpose of this paper is to evaluate the somatotype and appearance of local sheep breeds in China more objectively and scientifically.