Molecular Mechanism Of Growth And Development In Lveyang Black-bone Chicken By Regulating Of Dietary Protein Based On The Transcriptional Analysis

Protein is an important material basis that constitutes animal tissues and organs.Protein nutrition is an important nutrient in poultry nutrition research.In this study,three experiments were conducted to investigate the effects of different dietary protein levels on growth performance,serum biochemical indexes,organ indexes,intestine nutrient transporter gene expression,and liver transcriptome of Lveyang black-bone chickens during the brood period,in order to determin dietary protein requirement of Lveyang black-bone chickens during the brood period,to investigate the molecular mechanism that dietary protein could regulate the growth and development of Lveyang black-bonechickens,then to deep insight into domestic fowls,to more reasonably feed the birds.Trial 1 The Effects of Dietary Protein Levels on Growth Performance,Serum Biochemical Indexes,Organ Indexes of Lveyang black-bone Chickens during the Brood Period.In this trial,four hundred and twenty healthy Lveyang black-bone chickens were selected and randomly divided into 5 groups with 6 replicates and 14 chickens in each replicate.The five groups were fed with the same metabolic energy of 11.9 MJ/kg and protein levels of 13.23%,14.87%,16.34%,18.69% and 20.88% respectively during brood period.The results showed:i)Dietary protein levels had significant effects on the average daily gain,average daily feed intake,and feed-to-weight ratio of the Lveyang black-bone chickens during the brood period(P<0.01).With the increase of dietary protein level,ADG and ADFI showing a first increased and then decreased trend,trend of F/G showing a decreased first and then increased.ii)Dietary protein concentrations had no significant effect on liver,spleen,bursa,thymus,and gizzard index,the heart indexes of birds fed with 18.69% and 20.88% protein were lower than others.iii)Dietary protein concentrations had no significant effect on the serum total protein,albumin,globulin,uric acid,urea nitrogen,total cholesterol,triglyceride indexes of the Lveyang black-boned chickens during the brood period(P>0.05).The present results suggest that the optimal CP requirement of Lveyang black-boned chicken during the brood period was 18.69%.Trial 2 The Effects of Dietary Protein Level on the Expression of Intestinal Transporter Genes of Lveyang black-bone ChickensIn this trial,One hundred and sixty-eight healthy Lveyang black-bone chickens were selected and randomly divided into 2 groups with 6 replicates and 14 chickens in each replicate.The two groups were fed with the same metabolic energy of 11.9 MJ/kg and protein levels of 13.23% and 18.69% respectively from 1 to 6 weeks.The results showed: i)Average daily weight gain and average daily feed intake of the 13.25% CP group were slightly lower than the 18.69% CP group(P<0.01),and the feed-to-weight ratio was significantly higher than the 18.69% CP group(P<0.05).ii)Dietary protein concentration had no significant effect on serum biochemical indicators of Lveyang black-bone chickens from 1 to 6 weeks.iii)Dietary protein concentration had no significant effects on the expression of PepT1?EAAT3?CAT-1 and B0 AT genes in the duodenal of the Lveyang black-bone chickens during the brood period(P>0.05).Trial 3 The Effects of Dietary Proteins on the Liver Transcriptome of Lveyang black-bone ChickensIn this trial,One hundred and sixty-eight healthy Lveyang black-bone chickens were selected and randomly divided into 2 groups with 6 replicates and 14 chickens in each replicate.The two groups were fed with the same metabolic energy of 11.9 MJ/kg and protein levels of 13.23% and 18.69% respectively from 1 to 6 weeks.The results showed:Compared with the suitable protein group,there were 1391 significant differentially expression genes in the deficient protein group,with 489 genes were up-regulated and 902 genes were down-regulated.Analysis of differentially expression genes showed that: Histidine metabolism,Tyrosine metabolism,Phenylalanine metabolism,Cyanoamino acid metabolism,Arginine and proline metabolism pathways were significantlly enriched(P<0.05),which were related to amino acid metabolism.Steroid biosynthesis,Steroid hormone biosynthesis,Metabolism of xenobiotics by cytochrome P450,PPAR signaling pathway and Butanoate metabolism pathway were significantlly enriched(P<0.05),which were related to lipid metabolism.In summary,it can be concluded that the dietary protein mainly regulates the growth and development of Lveyang black-bone chickens by changing the expression of genes related to lipid metabolism and protein metabolism.