Optimal Selection Of Environmental Factors Combination And Construction Of Comprehensive Selection Index For Homefly

This paper aims to provide theoretical basis and practical guarantee for breeding and production,promote the factory standard production of domestic fly breeding,and promote the sustainable development of breeding industry.The specific research contents are:through the previous literature review,three main factors of milk powder addition,medium humidity and feeding density were selected.Four levels of each factor were used for cross-combination test.There were 64 treatments with 3 replicates for each treatment.The indexes of maggots weight,maggots length,pupa weight and pupa length were observed in order to evaluate the effects of these factors on growth and reproduction performance of maggots.To understand the growth characteristics of fly maggots,Gompertz、Logistic and Bertalanffy 3 models were used to fit and analyze the body weight of 1 to 4 days old fly maggots.According to the financial statements of He Dao Agricultural Development Limited and the comprehensive market situation of family fly products in 2019,the economic weighted value of family fly breeding target was assigned to estimate the genetic parameters of family fly by REML method,and the comprehensive selection index was constructed by using the breeding value of family fly and the economic right of each trait.The following conclusions were drawn from the study:（1）The feeding conditions of domestic fly larvae were 30 g fermented wheat bran+3g brown sugar base medium,milk powder 6 g,medium humidity 80%,feeding density60～90,the growth traits of maggots,maggots,pupa rate and reproductive traits pupa weight,pupa length and other indicators are more ideal,and when the humidity of the medium was 50%,the Eclosion rate was the highest,and with the increase of the humidity of the medium,the Eclosion rate showed a downward trend.（2）According to the research,Gompertz model is most suitable for the growth and development of maggots at 1-4 days of age,and can provide reference for the development and utilization of maggots resources,breeding and breeding practice,the regression equation of fitting curve is as follows:W_t=28.001exp^{[-13.241exp（-1.693t）]},the inflection point of weight is:W_t=A/e=28.001/e=10.30（mg）,the age of inflection point is:ln B/K=ln（13.241）/1.693=1.53（d）.（3）Genetic parameter estimation of housefly mainly studied growth and development traits,including the weight of fly maggots,body length of fly maggots,body maggots,body length of pupa,pupa,pupa rate of fly maggots and pupa emergence rate.The heritability（h2）was 0.013,0.028,0.132,0.452,0.071,0.025 respectively,with the exception of pupae,all traits were within the low heritability range.Except for the negative correlation between the eclosion rate and maggots length,pupa length,pupa rate（-0.299～-0.407）and pupa length and pupa weight（-0.163）,the rest were positive correlation（0.004～0.732）.（4）According to the financial statements of Hedao Agricultural Development limited company and the comprehensive market situation of family fly products in 2019,the economic weighted value of family breeding target was assigned.The economic weight of each target trait was maggots,pupae,maggots,pupation,Eclosion and pupa,accounting for47%,18%,12%,11%,9%and 3%of the total weight,respectively.The selection indices constructed are:I=2.97QZ+1.67QC+2.30YZ+0.24YC+2.36HYL-0.23YHL,accuracy RHI 65%,can more accurately evaluate the comprehensive breeding value of housefly.