Effects Of Different Lysine Levels On Growth Performance And Feed Intake Regulation Mechanism Of Guizhou Yellow Chickens

Lysine is the second limiting amino acid in poultry corn-soybean meal diets,and it is a research hotspot in poultry nutrition.In this experiment,the effect of lysine level on the growth and feeding of Guizhou yellow chickens was explored to determine the optimal dietary lysine requirement for Guizhou yellow chickens of 0-6 weeks of age.At the same time,RNA-Seq and metabonomics techniques are used to analyze the key genes and marker metabolites of lysine regulating feed intake,and to explore the molecular mechanism of dietary lysine regulating poultry feed intake through the hypothalamus,in order to improve the feed intake of poultry Regulation provides a theoretical basis.Experiment 1 Study on the lysine requirement of Guizhou yellow chickens aged 0-6 weeksA total of 400 1-day-old Guizhou yellow chicken chicks were selected and randomly divided into 4 groups,each with 5 replicates,and each replicate with 20 chickens.They were fed with 0.7%,0.9%,1.1%and 1.3%lysine.For diets with acid levels,accurately record body weight and feed intake.The analysis of the results showed that the weight gain of the 0.9%group was significantly higher than that of the 0.7%and 1.3%groups(P<0.01),but it was not significantly different from the 1.1%group(P>0.05);the 0.9%group had the highest average feed intake,which was extremely significant The high 1.3%group(P<0.01)is not significantly different from the 0.7%and 1.1%groups(P>0.05);the 0.9%group has the lowest material-to-weight ratio,which is extremely significantly lower than the 0.7%group(P<0.01),but is different from 1.1%%,1.3%groups are not significantly different(P>0.05);0.7%,0.9%,1.1%and 1.3%groups have no significant difference in the crude protein content of the 0-6 weeks old carcass and feathers of Guizhou yellow chickens(P>0.05).Through regression analysis,the quadratic regression models of Lys and average daily gain,average daily feed intake and feed-to-weight ratio were established respectively.The models were y=-7.84+39.05x-19.98x~2(R~2=0.96),y=-4.22+64.41x-34.62x~2(R~2=0.89)and y=4.02-3.41x+1.62x~2(R~2=0.67),based on average daily gain,average daily feed intake,feed weight ratio of Guizhou yellow chicken lysine The appropriate addition amount of acid is 0.98%,0.93%and 1.05%respectively.Experiment 2 Based on RNA-Seq technology to study the mechanism of lysine regulating the feed intake of Guizhou yellow chickensSelect the group with the highest feed intake of 0.9%(group b,n=3)and the group with the lowest feed intake of 1.3%(group c,n=3)6-week-old Guizhou yellow chickens,collect hypothalamic tissue,extract total RNA,and construct transcription Sequencing the library,and using the Illumina Hi Seq 2500 sequencing platform to perform transcriptome sequencing analysis on the hypothalamus,screening Guizhou yellow chicken feed intake-related candidate genes and candidate regions,and verifying the functions of some candidate genes and candidate regions.The results showed that a total of 2006 differentially expressed genes were obtained,including 1275 up-regulated genes and 731 down-regulated genes.The genes related to feed intake are PTGFRN,GH,GRM 1,GRM 3,GRM 7,TRHDE,CGA,THRB,HCRT,CCKAR,CARTPT,AGRP,NPY,RXFP1,RLN3,PMCH,CCKBR,SS 2,THRB,NPBWR1.The results of enrichment analysis of KEGG and GO found that differentially expressed genes were enriched into 139 signal pathways,5794 terms,and 6 terms related to feeding.Lysine regulates CARTPT,SS 2,CCKAR,CCKBR,and CCKBR through the hypothalamus.The expression of genes such as NPY/AGRP acts on the neuroactive ligand-receptor interaction pathway and regulates the feed intake of Guizhou yellow chickens from0 to 6 weeks of age.Experiment 3 Studying the key metabolites of lysine regulating the feed intake of Guizhou yellow chickens based on metabonomics technologySelect the group with the highest feed intake of 0.9%(group b,n=3)and the group with the lowest feed intake of 1.3%(group c,n=3)6-week-old Guizhou yellow chickens,collect hypothalamic tissue,extract metabolites,and pass the LC-MS technology for metabolomics testing.A total of 678 metabolites were obtained,and 25 differential metabolites were obtained through PLS-DA analysis,of which 9 were up-regulated and 16 were down-regulated.The marker metabolites that affect the feed intake of Guizhou yellow chickens are 5-hydroxytryptophan and L-Valine.The results of KEGG enrichment analysis found that the differential metabolites between group b and group c were mainly enriched in 26 pathways,and significantly enriched in the ABC transporter pathway map02010.Under the experimental conditions,the suitable lysine requirement of 0-6 weeks old Guizhou yellow chickens is 0.9%,and the feed intake of each test group is different during the brooding period.Guizhou yellow chickens regulate central induction through hypothalamic feeding The level of lysine in the diet regulates the expression of neuropeptides CARTPT,NPY/AGRP and SS 2,CCKAR,CCKBR and other genes,resulting in changes in the expression of metabolites such as 5-hydroxytryptophan and L-valine.These molecules bind to specific receptors to initiate the signal cascade of specific neuron groups in the hypothalamus,thereby regulating the feed intake of Guizhou yellow chickens during brooding period,and further affecting its growth,development and production performance.