Test And Selection For Improving Feed Efficiency Of Junmu No.1White Pig

Feed efficiency is a very important economic trait in pig industry. Especiallywith the intensification of the global energy crisis in recent years, how to improve thefeed efficiency of pigs has become a focus point in pig industry and pig breedingorganization. Improve feed efficiency can not only reduce feed cost, but also reducedung and greenhouse gas. In recent years, studies proved that residual feed intake(RFI)as the selection trait can improve feed efficiency of animals in U.S. and Europe.Residual feed intake (RFI) is a new trait for feed efficiency defined as the differencebetween the observed feed intake and that predicted from the average requirementsfor growth and maintenance. Animals with a more negative residual feed intake aremore efficient. RFI has been extensively explored as a trait to study the genetic andphysiological basis of feed efficiency in cattle and poultry, the research of RFI in pigis also gradually increasing. In addition, some researches had reported that usedresidual body weight gain(RG) as the selection trait in the program of breeding forimproving feed efficiency in beef cattle. RG was calculated as the difference betweenactual ADG and expected ADG, with expected ADG derived using linear regressionmodel of actual feed intake.The object of the paper was to improve swine feed efficiency by test some traitsrelated to feed efficiency，such as feed intake、body weight gain、backfat depth, andestimated their genetic parameters. Those traits were tested in60Junmu NO.1boarsand estimated genetic parameters. Feed efficiency values were investigated fromresidual feed intake(RFI), residual body weight gain, feed conversion ratio(FCR). AsRG has great genetic correlation with ADG, and the genetic colrrelation of RFI withADG, BF were not siginificant, RFI as the main selection trait with ADG and BF as aconstraint traits, the weights of RFI,ADG and BF were0.7,0.2,0.1, and get acomprehensive breeding value (Z-EBV) for every pig, and choose the two separategroups according to the Z-EBV, the first10pigs named high feed efficiency group, and the last10pigs named low feed efficiency group. Finally, the breeding programwere based on kinship coefficient of boars with sows for avoiding inbreeding.Results: the mean of FCR in Junmu NO.1boar population was2.61, and thestandard deviation of RFI was77.52, the standard deviation of RG was34.7. Theestimated heritability of RFI, RG, FCR were0.45,0.46,0.33；the genetic correlationsof RFI with ADFI, ADG, BF were0.89,0.04,-0.05; the genetic correlation of RGwith ADFI, ADG, BF were-0.01,0.79,-0.17; the genetic correlations of FCR withADFI, ADG, BF were0.55,-0.65,-0.11. RFI and RG, The genetic correlation of RFIwith RG, FCR were-0.41,0.82; the genetic correlation of RG with FCR was-0.79.The groups of high and low feed efficiency that selected through the method ofcomprehensive Index, compared with the original population, the estimated breedingvalues of ADG and BF were almost unchanged, and the estimated breeding values ofRFI were changed greatly.Conclusion: Use RFI and RG as the value of feed efficiency to evalute thegenetic parameter respectively, and confirme a great genetic difference inJunmu.NO.1boar group. RFI as the main selection trait with ADG and BF as aconstraint traits can selecte the two separate groups of high and low feed efficiency.