Growth Curve Fitting Analysis And Model Optimization Of Australian White Sheep

In this study,2007 Australian White sheep were used as test subjects.Through the study of their growth and development laws,a growth and development model of Australian White sheep was established.Experimental analysis and research on the correlation of the growth and development law of Australian White sheep with gender,developmental stage and data structure,aims to provide a theoretical basis for the breeding management and late breeding of Australian White sheep.The test group included 856 Australian White sheep rams and 1,151 ewes.The weight measurement process was carried out in accordance with the"Cotton and Goat Production Perfor-mance Measurement Specification"(NY/T 1236-2006).After the data is preprocessed,it is divided into 12 day-age groups(newborn weight,weaning weight,90-120d,120-150d,150-180d,180-240d,240-300d,300-360d,360-420d,420-480d,480-540d,540d and above),using Brody,Von Bertalanffy,Logical and Gompertz fits the growth curve of the four models,and establishes the best fit model for groups and individuals based on different data structures.The results of the study are as follows:1.Analysis of the growth and development of Australian White sheep in different time periods:After collating and analyzing the data set of the Australian White sheep population,linear regression,power function and exponential function regression,and generalized linear regression were used for data analysis.It was found that the first two are nonlinear regression R~2is 0.854,which is significantly higher than linear regression(0.816),indicating that nonlinear regression can better describe the growth and development of Australian White sheep;Generalized linear regression analysis found that the influence coefficient of gender effect on the weaning weight of Australian White sheep was-3.97(P<0.05),the weaning weight of rams was significantly higher than that of ewes,and the weaning weight was also positively correlated with the weaning age and newborn weight.2.Growth and development fitting of Australian White sheep:The growth fitting model was used to analyze the growth fitting of Australian White sheep groups,individuals,and male and female sheep respectively.It was found that the optimal fitting models of Australian White sheep groups,individuals,and male and female sheep classified by weaning weight are all Brody models.The weight growth results are more relevant to the actual observations.The fit of the Australian white ram is0.955,and the fit of the Australian white ewe is 0.933.The results prove that the Brody curve can better fit the dynamic growth process of the Australian White sheep.3.Optimization of the growth and development of Australian White sheep:Based on the variance of the prediction error of the growth model,the weight of the growth fitting model is obtained.After optimizing the combination of the four growth models according to the weight,it is found that the combination of Brody and Von Bertalanffy has the best fit,and it is improved compared with the original optimal fit model.The fit of the Australian white ram is 0.959,and the fit of the Australian white ewe is0.949,which proves that the combined model of Brody and Von Bertalanffy has the best description effect on the growth and development of the Australian White sheep.