Analysis Of Growth And Development Characteristics Of Duolang Lamb

Taking Duolang sheep as the research object,441 Duolang lambs(220 male lambs and 221 female lambs)were randomly selected to measure their body weight and body size;The fastest growth stage was analyzed by statistical method;Analyze the correlation between 9 body sizes and body weight,judge the main body size indexes affecting body weight in each stage,and judge the main influencing factors through principal component analysis;Three nonlinear models were used to fit the growth curve of Duolang sheep from birth to one year old,and the best growth curve model was determined.The fastest growing period of Duolang sheep was analyzed to provide a theoretical basis for production practice.The results are as follows:Experiment 1:the body weight of male and female Duolang sheep increased fastest at the age of 2months,decreased rapidly at the age of 3～4 months,and decreased gently at the age of 4～12 months.The growth rate of body height and cross height was the fastest in 2～5 months,the growth rate of body length was the fastest in 2～6 months,the growth rate of chest circumference was the fastest in 4～6 months,and the ear length,ear width,chest depth and tube circumference increased steadily.At weaning,the body weight of Duolang sheep was significantly positively correlated with body height,body length and cross height(P<0.01).At the age of half a year,chest circumference mainly affects body weight.Body weight is positively correlated with body length,chest circumference,chest depth,chest width and ear width(P<0.01).At the age of one year,body weight is positively correlated with body height.It shows that Duolang sheep has the characteristics of fast growth and development before and after weaning.In the process of seed selection and breeding,the body size indexes that mainly affect body weight at each stage should be given priority.Experiment 2:through the fitting analysis of the weight of Duolang sheep from birth to one year old,the three models can fit well,and the determination coefficient(R~2)is greater than 0.98.The predicted values of the three models are consistent with the measured values,which can well describe the growth and development process of Duolang sheep.The Gompertz model curve has a good fitting effect on rams and the von Bertalanffy model has a good fitting effect on ewes.It has more advantages in predicting weight.The theoretical prediction value of the model:the inflection point months of male and female lambs are 3.347Vmonths and 2.969 months,the inflection point weight is 24.84kg and 21.81kg,and the maximum daily gain is 198.68g and 190.64g.The results show that Duolang sheep has the characteristics of rapid growth and development in the early stage,and the body size index has a certain impact on the body weight,which can provide a theoretical basis for the selection and breeding of Duolang sheep.