Mechanism Of Avian Gout Induced By High Calcium And High Protein Diets In Poultry

Avian gout is a common avian disease with complex etiology.The purpose of this experiment was to study the effects of high calcium and high protein diets on growth performance,serum inflammatory factors and endogenous small molecule metabolites,intestinal flora,XDH and ABCG2 expression in tissues of poultry.The aim of this study was to investigate the mechanism of avian gout induced by high calcium and high protein diets.One hundred and sixty one-day-old broilers were randomly into four groups,each group had 5 replicates and each replicate had 8 broilers,which were control group,high protein group,high calcium group,and high protein and high calcium group.Seventy two one-day old goslings were randomly divided into control group(CP),high protein group 1(HP1)and high protein group 2(HP2),respectively,each group was fed with diets containing 18%,23% and 28% crude protein,with 3 replicates in each group and 8 geese in each goslings.Blood samples were collected to separate serum for detection of serum antioxidant indexes,inflammatory factors,serum related liver and kidney indexes,and serum total metabonomics.The cell structure of liver and kidney was observed by transmission electron microscope.RT-PCR,immunohistochemistry and Western blot were used to detect the expression levels of XDH and ABCG2 genes and proteins in tissues of 14 day old goslings.1)The results of experiment in broilers were as follows :At 21 days of age,ABW,ADG and ADFI of the broilers in the control group were significantly higher than those in the other three groups(P<0.01),ABW,ADG and ADFI of the control group were significantly higher than those of the other three groups(P<0.01),and F/G was significantly lower than that of the high calcium high protein group(P<0.01);ABW and ADFI of the high protein group were significantly higher than those of the high calcium group and the high calcium high protein group(P<0.05);ABW,ADG of the high calcium group were significantly higher than those of the high calcium high protein group(P<0.05)and F/G was significantly lower than that of the high calcium and high protein group(P<0.05);High calcium and protein diets could lead to abnormal activity or contents of serum AST,ALT,UA,CREA-S,UREA,GSH-Px,SOD,MDA,T-AOC and XOD in broilers.Illumina Miseq high-throughput sequencing results showed that the species richness of Firmicutes,Proteobacteria,Barnesiella,Alistipes,Faecalibacterium,Rikenella,Porphyromonas,Clostridium＿XVIII,Alkaliphilus,Oscillibacter and Clostridiumin the intestines of broilers changed significantly(P<0.01 or P<0.05).The liver and kidney tissues of broilers in control group were normal and the structure was clear,while the liver and kidney tissues of broilers in the other three groups had different degrees of pathological changes.2)The results of experiment in goslings were as follows :Transmission electron microscopy showed that the organelles structure of gosling liver and kidney in CP was complete,whereas,some mitochondria of liver in HP1 and HP2 groups appeared to be swollen and vacuole degeneration,the endoplasmic reticulum was dilated,and glycogen levels were decreased.Some mitochondria of kidney cells appeared to be swollen and vacuole degeneration,and the nuclear membrane space increased.At 7 days of age,the ABW of HP2 was significantly lower than that of CP group(P<0.05),and extremely significantly lower than that of HP1(P<0.01);ADG of HP1 group was significantly higher than that of HP2 group(P<0.05).At 14 days of age,ABW,ADG and ADFI of CP group were extremely significantly higher than HP1 and HP2(P<0.01).The content or activity of serum 1L-1 β,IL-6,TNF-α,XOD,AST,ALT,TP,UA,LDH,GLB,TBIL,IBIL,UREA and CREA-S were abnormal in Goslings at 7 and 14 days of age.Results showed that Aminoacyl-t RNA biosynthesis,lysine degradation,urine metabolism,yrimidine metabolism,nositol phosphate metabolism,eta-Alanine metabolism,antothenate,and Co A biosynthesis changed significantly.The difference of metabolite content between high protein group and control group was visualized by heat map.The expression of XDH gene and protein in liver,kidney and duodenum of HP2 group was significantly higher than that of CP group(P<0.05 or P<0.01);The expression of XDH gene and protein in liver and kidney of HP2 group was significantly higher than that of HP1 group(P<0.05 or P<0.01);The expression of XDH gene and protein in liver and duodenum of HP1 group was significantly higher than that of CP Group(P<0.05 or P<0.01).The expression of XDH gene and protein in jejunum among the three groups were no significant difference(P>0.05).The expression of ABCG2 gene and protein in duodenum and jejunum in group HP1 was significantly or extremely higher than that in CP group and HP1 group(P<0.05 or P<0.01),and the expression in kidney was significantly or significantly lower than that in CP group And HP1 group(P<0.05 or P<0.01);The expression of ABCG2 gene and protein in goose in HP1 group was significantly higher than that in CP group(P<0.05),and the expression in kidney was significantly lower than that in CP group(P<0.05).High calcium and high protein diet could reduce growth performance and antioxidant capacity,impair liver and kidney function,and cause hyperuricemia and cecum flora disorder in broilers.Excessive protein intake can lead to the decrease of growth performance,the damage of liver and kidney cells,the damage of kidney and liver function,the disorder of amino acid and nucleotide metabolism,the occurrence of inflammatory reaction,the increase of expression of XDH,and the decrease of expression of ABCG2.The results showed that the increase of serum uric acid level caused hyperuricemia and gout in gosling.