Identification Of Candidate Genes Associated With Feed Efficiency Traits In Meat-type Ducks

Feed cost constitutes about 60%-70% of the total cost of meat-type duck production.Selection of more efficient animals reduces production cost,improves economic benefits,and reduces the environmental impact of nitrogen and phosphorus excretion during digestion/metabolism.Male meat-type ducks of Huangshan Qiangying Duck Co.,Ltd.were furnished as experiment material.Healthy ducks with complete genealogy record were unified fed to 21 days of age.At 21 days of age,1000 male meat-type ducks with similar body weight were selected and raised according to the unified breeding procedures.Body weight gain and feed intake from 21 to 42 days of age were recorded,then calculated daily gain,daily feed intake,FCR(feed conversion ratio)and RFI(residual feed intake).Based on residual feed intake twelve individuals with high and low RFI(6 HRFI vs.6 LRFI)were selected randomly for RNA-Seq.Transcriptome sequencing analysis was conducted on the liver tissues of the ducks by RNA-Seq to further explore the candidate genes and pathways affecting the feed utilization efficiency of the meat-type ducks.1.Descriptive statistical analysis of feed efficiency traits showed that daily feed intake,FCR and RFI of LRFI group were significantly lower than those of HRFI group(P<0.05).Transcriptome sequencing results showed that a total of 33,842 transcripts were identified.There were 29,306 transcripts in HRFI and LRFI groups,of which 2,030 were unique transcripts in HRFI group and 2,506 in LRFI group.A total of 1297 differentially expressed genes were screened in this study,including,including 686 up-regulated genes and 611down-regulated genes in LRFI group.Function annotation and pathway enrichment analysis were carried out on the above differentially expressed genes.GO analysis revealed that these differential expressed genes are involved in the regulation of biological processes related to biosynthesis and metabolic processes.KEGG analysis showed that the pathways involved in these differentially expressed genes mainly included amino acid metabolism,carbon metabolism,TCA cycle,2-oxidized carboxylic acid metabolism,mTOR signaling pathway,insulin signaling pathway and material metabolism.Based on functional analysis,ACLY,GSK3β,SORBS1,ACOX1,LPCAT1,LPIN2 and OSBPL8 genes were related to nutrient metabolism,energy metabolism and insulin signaling pathway in the body,which could be chosen as potential candidate genes for feed efficiency traits in meat-type ducks.2.Analysis of transcription factors related to feed utilization of meat-type ducks showed that 116 transcription factors were unique in HRFI group and 146 transcription factors were unique in LRFI group.Meanwhile,12 transcription factors with significant differences were common in HRFI group and LRFI group.Among them,three significantly different transcription factors,ZNF423,E4F1 and ESRR,may affect the differences in RFI traits between different individuals by regulating the expression levels of genes related to the metabolism of energy substances of body and cell proliferation and differentiation.In this study,RNA-Seq was used to identify important functional genes and signaling pathways related to RFI traits of meat-type ducks,which will provide valuable reference for breeding of feed utilization traits and molecular marker-assisted breeding of meat-type ducks.