Study On The Relationship Of Body Image With Lactation Performance Of Xinjiang Donkeys

In this study,194 Xinjiang lactating female donkeys with 1-6 litters from Aketao Donkey Farm and Yuepuhu Donkey Farm in Xinjiang were used as the main research subjects.From February to December,the daily lactation and 13 body size trait indexes of 194 Xinjiang donkeys were measured and recorded,milk composition was collected,5 milk composition indexes were measured,and a database was established.The correlation between body size traits and total lactation was analyzed using SPSS 26.0 software,and the optimal regression model between body size traits and total lactation was established using the regression analysis method in Graph Pad Prism 8.0 software,and the corresponding program was developed to estimate the total lactation of Xinjiang donkeys by body size traits to provide a scientific basis for the selection and breeding of Xinjiang donkeys.The regression analysis method in Graph Pad Prism 8.0 software was used to establish the optimal regression models of body size traits with 4%standard milk and energy-corrected milk,respectively,to provide technical support for the selection and breeding of different types of Xinjiang donkeys.In this study,we used SAS 9.2 software to compare four models to fit the lactation curves of the 4th litter of Xinjiang donkeys,and selected the best-fit model as the basis to develop correction coefficients for different lactation periods of the 4th litter of Xinjiang donkeys.The correction coefficients for different lactation periods of the 4th litter of Xinjiang donkeys were also developed based on the 4th litter as the standard litter,and the correction coefficients for different foaling months of Xinjiang donkeys were also developed to establish a set of scientific criteria for the objective evaluation of lactation of Xinjiang donkeys.The correction coefficients for different lactation periods of the 4th litter of Xinjiang donkeys were also developed based on the 4th litter as the standard litter,and the correction coefficients for different foaling months of Xinjiang donkeys were also developed to establish a set of scientific criteria for the objective evaluation of lactation of Xinjiang donkeys.Different models in Graph Pad Prism 8.0 software were used to fit curve equations for different litter sizes on somatic cell counts to provide scientific support for farm assurance of fresh milk quality.The results of the study are as follows:1.Multiple regression equation of body structure and lactation traits in Xinjiang donkeysThe correlation between 13 body size traits and lactation of Xinjiang donkeys was investigated,and the significantly different body size traits were selected to establish the optimal multiple linear regression equation:Y=-215.2+3.14X₁+4.75X₂-3.83X₃-6.36X₄+13.85X₅+2.06X₆+0.83X₇-43.53X₈-36.55X₉,where X₁～X₉ represent nine body size traits:chest circumference,anterior segment,buttock width,buttock angle,waist strength,udder depth,udder attachment height,teat diameter,and teat length.The body size traits were used to estimate the total lactation of Xinjiang donkeys,and to provide a reference basis for the selection and breeding of Xinjiang donkeys with high lactation.At the same time,we developed a computer program to use the optimal linear regression model as a function to obtain a program that can output the lactation estimation value by inputting body size data,which can facilitate the selection and breeding of high lactation Xinjiang donkeys on farms to reduce the selection cost and speed up the breeding process.2、Relationship between body size traits and milk composition in Xinjiang donkeysThe body size traits that differed significantly from the 4%standard milk of Xinjiang donkeys were selected to establish the optimal regression equation:Y=231.7-0.28X₁-0.96X₂-5.79X₃-0.55X₄+0.37X₅+3.81X₆-4.53X₇-8.94X₈-2.63X₉.The body size traits represented by X₁～X₉ in the equation were:body length,fore part,buttock width,buttock angle,waist strength,udder depth,udder attachment height,teat diameter,and teat length.By studying the seven body size traits that have significant effects on the energy-corrected milk of Xinjiang donkeys,namely:fore part,buttock width,buttock angle,waist strength,udder depth,teat diameter,and teat length,the optimal regression equation was established:Y=231.7-0.28X₁-0.96X₂-5.79X₃-0.55X₄+0.37X₅+3.81X₆-4.53X₇.This study can provide a scientific basis for the selection and breeding of Xinjiang donkeys that produce different types of milk.3、Study on the milk yield adjustment coefficients of Xinjiang donkeysFour different models,Wood incomplete gamma function model,Nelder inverse polynomial model,sixth order polynomial model,and linear hyperbolic model,were used to fit the 4th lactation curve of Xinjiang donkeys,and the fitting effect was analyzed.The best lactation curve model is the sixth-order polynomial model:Y=-389.5+40.84X-1.46X²+0.026X³-0.0002X⁴+（1.138e-006）X⁵+（-2.090e-009）X⁶.The correction coefficients for different lactation days of the 4th litter were developed based on this model,and the correction coefficients for different litters of Xinjiang donkeys were developed using the 4th litter as the standard litter（the correction coefficient for the 4th litter was 1）,and the correction coefficients for the 1st to 6th litters were obtained as follows:1.67026,1.42149,1.07145,1.00000,1.12949,1.18883.The correction coefficient for different foaling months of Xinjiang donkeys was developed by taking the 4th foaling month as the standard.The correction coefficients for the 3rd,4th,5th and 6th foaling months of Xinjiang donkeys were developed as 1.2011,1.0000,0.9699 and 1.1303.This study provides a reference for assessing the individual lactation performance of Xinjiang donkey females at different lactation stages.4、Relationship between parity and the number of somatic cells in milk of the Xinjiang donkeyThe correlation analysis between parity and the number of somatic cells in the milk of Xinjiang donkeys was carried out,and the optimal curve for the number of somatic cells in the milk of Xinjiang donkeys at different parity was fitted using different models,and the optimal fitted curve was chosen as a cubic polynomial model,and the equation of the optimal fitted curve was Y=-35.32+48.53X-15.41X²+1.695X³.At the 7th parity and above,the number of somatic cells in the milk exceeded 1 million cells/m L,the quality of fresh milk is difficult to ensure.This study can guide the actual production to further improve the milk quality of donkey milk.Conclusion:A multiple regression equation for body size traits and total lactation of Xinjiang donkeys was established by studying the relationship between body size traits and lactation performance,and a regression equation for body size traits and 4%standard lactation and energy-corrected lactation of Xinjiang donkeys was fitted.A set of correction coefficients for different parties and different foaling months of Xinjiang donkeys was developed,and the curve equation of the parity on the number of somatic cells in donkey milk was fitted using a cubic polynomial.It provides a scientific basis for the selection and breeding of high-yielding and high-quality dairy Xinjiang donkeys.