Production Performance And Intestinal Micropopulations In Laying Duck With Different Residual Feed Intake

Feed costs 60% ~ 70% of the cost of breeding,in order to solve the contradiction between people and animal competition for food,it is necessary to select and breed feed conversion efficiency,increasing production and reducing the consumption of feed.Feed conversation ration(FCR)used to be a good index but it can’t reflect the genetic background of the feed efficiency,residual feed intake(RFI)was introduced to reflect the individual metabolic differences determined by genetic background,and it also calibrated the individual metabolic weight,RFI is universally known as one of the preferred methods for feed conversion efficiency.This experiment picked up Shaoxing ducks with high residual feed intake(HFRI)and low residual feed intake(LRFI)to study the differences in phenotype,key gene expression,polymorphism,cecal contents microbiome and metabolic components,we explored the influence of RFI on the body and its regulatory mechanism.We have risen 300 Shaoxing ducks which are at 400 day for 60 days,each duck’s individual intake,egg weight,initial weight and final weight were noted to calculate RFI and sort,15 ducks of the highest FRI were chosen to be the HFRI group,15 ducks of the lowest FRI were chosen to be the LFRI group.The results showed that:1.In phenotype,there were significant differences(P< 0.05)on RFI,FIandFCR,average mass of LRFI group is 57.0 g less than HRFI group,and there were no significant difference on weight mass;RFI was only significantly correlated with FI and FCR(P<0.05).We also detected the quality of eggs,and the results showed that Yolk color in the LRFI group was significantly lower than that in the HRFI group(P<0.05),there was no significant difference in other indexes,which indicated that the selection of RFI in Shaoxing duck would not decrease product quality.2.Subsequently,the expressions of CCK,NPY and NPY5 R mRNA in hypothalamus,expression of CCK and NPY mRNA in duodenum and CCKAR polymorphism in Shaoxing ducks between the LRFI group and HRFI group were detected.It was found that the relative expressions of NPY and NPY5 R mRNA in HRFI group were 3.52 times and 2.49 times higher than those in LRFI group,respectively(P<0.05).The relative expression of CCK mRNA in LRFI group was significantly higher than that in HRFI group(P<0.05).The relative expression of CCK mRNA in the duodenum in LRFI group was significantly higher than that in HRFI group(P<0.05),and the relative expression of NPY mRNA in HRFI group was 3.3 times higher than that in LRFI group(P<0.05).3.The composition of cecum contents was detected by 16 S rDNA sequencing.The alpha diversity was different between the HRFI group and LRFI group,Chao1,Shannon and Simpson indexes in LRFI group were significantly higher than that of HRFI groups(P < 0.05).LRFI and HRFI group have significant differences in multiple biological flora classification level,the dominant flora of the two groups were Firmcutes、BacteroidetesandProtebacteria atthe phylum level,however the relative abundance of Firmcutes and Cyanobacteria in LRFI groupwere significantly higher than that in HRFI group(P < 0.05),the relative abundance of Protebacteria,Deferribacteres andSpirochaeteswere significantly lower than that in HRFI group(P < 0.05).There were 18 different flora between the LRFI group and HRFI group at the level of genus,17 of which were higher in the LRFI group than that in the HRFI group,most of them belonged to Firmcutes.Rikenellaceae is involved in the process of carbohydrate degradation.Eubacterium-coprostanoligenes can reduce cholesterol levels in the blood.Lachnoclostridium symbiosum is an important member of flora which can product butyrate,which indicated that RFI not only affects the relative abundance of intestinal flora,but also promotes the feed conversation for LRFI population.This partly explains why the LRFI group with less food intake have the same quality of production with the LRFI group.A total of 56 SNPs were found in this study,aspartic acid encoded by C1370 T transformed to asparagine,threonine encoded by A6347 G transformed to isoleucine,glutamic acid encoded by G6530 T transformed to aspartic acid,the conversion of amino acid may alter the structure of the encoded protein.The results showed that the sites A1435 T,C6164T,A6347 G and G6530 T were in Hardy-weinbreg equilibrium state,and the PIC values indicated that all 6 sites were in moderate polymorphic locus.In the linkage disequilibrium analysis,the sites C1370 T and A1435 T,A6347G,the sites A1393 G and A1435 T,and the sites G6530 T and C6164 T and A6347 G were all meaningful linkage disequilibrium.The analysis of production traits at each point showed that the sites A1393 G,C1435T and G6530 T were significantly correlated with FI and RFI.4.Rectal contents were detected by liquid chromatograph-mass spectrometer(LC-MS)technology.There are more than 90 different metabolites were found between the LRFI group and HRFI group,we could find 29 corresponding metabolic pathways in KEGG.We found that the content of carbohydrates,lipids,amino acids in the LRFI group tare lower than that in the HRFI group(P < 0.05),a large number of research results showed that the sugar metabolism,lipid metabolism and amino acid metabolism is closely linked.Rectum is the end part of the body’s digestion and absorption,it’s absorption and utilization efficiency are low,enrichment of nutrients in HRFI group may be related to absorption conversation disorder of front intestine.