Study On The Effects Of ?-Ketoglutaric Acid On Nitrogen Utilization And Its Regulation Mechanism In Growing Pigs

The imbalance of nutrients in feed and the low utilization rate of feed are the reasons for the high content of nutrients in livestock and poultry waste,which will cause serious pollution to the surrounding soil,air and water.In the livestock and poultry farm excreta,the main environmental impact of nitrogen and phosphorus.Studies have shown that dietary nutrition intervention can reduce the content of nitrogen and phosphorus in livestock and poultry waste,thus reducing the pressure on the ecological environment caused by large-scale livestock and poultry farms.Alpha-ketoglutarate?AKG?is the central substance of Tricarboxylic acid?TCA?cycle.It plays an important role in maintaining total nitrogen balance,reducing nitrogen loss and promoting protein synthesis in the body,and plays an important role in physiological processes such as bone development and bone mineral deposition in the body.In view of this,this paper intends to use growing pigs as research objects to explore whether dietary AKG can reduce nitrogen and phosphorus emissions in growing pigs through growth and digestion and metabolism tests,and on this basis,add AKG to low-protein diets to explore the effects of it on intestinal microbial ecology in growing pigs,and its possible mechanisms for nitrogen nutrient utilization,the main results were as follows:1?Growth performance,nitrogen balance,and metabolism of calcium and phosphorus in growing pigs fed diets supplemented with alpha-ketoglutarateSixteen healthy animals?Large×White×Landrace?of similar initial weight?40.08±0.78 kg?were randomLy assigned to two dietary groups.The pigs were fed a basic diet containing either 0?control?or 10 g AKG kg^-1 for 28 d.Their faeces and urine were collected continuously from days 23 to 25.On Day 28,all of them were killed and their right rear femurs and tibias were removed.Pigs fed diets with AKG tended to have higher average daily gain?ADG;P=0.088?,but their urinary-N levels and excretion of total N were 24.50%?P=0.012?and 23.67%?P=0.011?lower,respectively,when compared with corresponding values measured from the control group.However,their apparent N-digestibility and net protein utilization were increased by 2.43%?P=0.044?and 11.84%?P=0.002?,respectively,over the control.Furthermore,supplemental AKG decreased faecal-and urinary-Ca levels by29.56%?P=0.045?and 24.54%?P=0.001?,respectively,while enhancing P-retention,apparent Ca-digestibility,and apparent P-digestibility by 27.10%?P=0.002?,14.51%?P=0.041?,and 16.62%?P=0.010?,respectively.The addition of AKG also elevated the concentrations of ash,P,and Ca?P=0.012,P=0.002,and P=0.004,respectively?in the femur samples,and increased bone density?P=0.003?,but did not affect those parameters in the tibias.These results indicate that dietary supplementation with AKG can improve the utilization of N,Ca,and P;while effectively reducing N,Ca,and P emissions;and promoting N-,Ca-,and P-metabolism in growing pigs.2?The effects of dietary supplementation with?-ketoglutarate on the intestinal microbiota,metabolic profiles,and ammonia levels in growing pigsSixteen healthy animals?Large×White×Landrace;84±1 d of age?of similar initial weight?40.08±0.78 kg?were randomLy assigned to two dietary groups?n=8?.The pigs were fed a basic diet containing either 0?control?or 10 g AKG kg^-1?supplemental diet?.After a 28-d trial period,the luminal digesta of the cecum and ileum were collected to analyze the amounts of short-chain fatty acids and ammonia,as well as populations of gut microbiota.Supplementation with AKG decreased?P=0.043?the pH value of the digesta in the ileum.Moreover,the AKG concentration in the ileal digesta was significantly higher in pigs fed the supplemented diet than in control pigs?P=0.009?.The addition of AKG also significantly increased the amounts of Lactobacillus?P=0.002?and Bifidobacterium?P=0.021?in the cecum,and Lactobacillus?P=0.029?and Firmicutes?P=0.045?in the ileum,but decreased the amounts of Escherichia coli in the ileum?P=0.034?and in the cecum?P=0.082?when compared with the control group.Dietary AKG also increased the concentrations of valerate?P=0.026?in the caecal digesta and butyrate in both the caecal digesta?P=0.017?and the ileal digesta?P=0.022?.Concentrations of ammonia also declined in the caecal?P=0.042?and ileal?P=0.038?digesta in response to AKG.Therefore,our results suggest that this dietary supplement has the potential to promote the growth of beneficial bacteria,improve intestinal microbial populations,increase the concentrations of butyrate and valerate,and decrease the level of ammonia in the gut of growing pigs.3?Study on the effects of supplementation with?-ketoglutarate to a low-protein diet on nitrogen utilization and its regulation mechanism in growing pigs.A total of 27 growing pigs?Large×White×Landrace?with an initial body weight of11.96±0.18 kg were assigned randomLy to one of the three diets:control?normal recommended 20%CP,NP?,low CP?17%CP,LP?,or low CP supplemented with 1%AKG?ALP?.The pigs were fed their respective diets for 35 days.Free amino acid?AA?profile and hormone levels in the serum,and the expression of genes implicated in protein metabolism in skeletal muscle were examined.Results showed that although no significant differences were found in performance among the diet groups,pigs fed the ALP diet had greater average daily gain?ADG?when compared with those in the LP group.Compared with the control group or LP group,low-protein diets supplemented with AKG enhanced serum and intramuscular free AA concentrations,the mRNA abundances of AA transporters,and serum concentrations of insulin-like growth factor-1?IGF-1?,activated the mammalian target of rapamycin?mTOR?pathway,and decreased serum urea concentration and the mRNA levels for genes related to muscle protein degradation?P<0.05?.In conclusion,these results indicated that addition of AKG to a low-protein diet promotes amino acid synthesis in tissues and improves protein metabolism in skeletal muscle.4?Alpha-ketoglutarate in low-protein diets for growing pigs:Effects on cecal microbial communities and parameters of microbial metabolismTwenty-seven young pigs?Large×White×Landrace?with an average initial body weight of 11.96±0.18 kg were randomLy allotted into three groups?n=9?:a normal protein?NP?diet containing 20%crude protein?CP?;LP diet formulated with 17%CP?LP diet?;or LP diet supplemented with 10 g kg^-1 of AKG?ALP diet?.After a 35-d trial period,the digesta of the cecum were collected to analyze the concentrations of ammonia and short-chain fatty acids?SCFAs?.We also performed a microbial analysis.Experimental diet did not affect cecal bacterial richness or diversity,as determined by Chao1 and ACE species richness measures and Shannon and Simpson indices,respectively.The predominant phyla Firmicutes,Bacteroidetes,and Proteobacteria increased in relative abundances in the cecum of pigs fed ALP diet.At the genus level,compared to the LP diet,the ALP diet significantly increased the abundances of Lachnospiraceae UCG-005,Lachnospiraceae NK4A136 group,Phascolarctobacterium and Parabacteroides,while decreased Vibrio and Maritalea.Pigs fed the ALP diet increased Oribacterium and Lachnoclostridium when compared with the NP diet.Nonmetric multidimensional scaling analysis revealed that the distribution of microbiota at each group was distinctly clustered separately along principal coordinate.In addition,quantitative PCR revealed that the ALP diet was associated with increases in the amounts of Bacteroides,Bifidobacterium,and Lactobacillus,but a decrease in the level of Escherichia coli.Compared with the NP diet,the ALP diet enhanced the concentrations of valerate and propionate.This ALP diet also increased the concentrations of valerate and isobutyrate when compared with the LP diet.Moreover,the ALP diet was linked with a significant decline in the concentration of ammonia in the cecum.These results indicate that a low-protein diet supplemented with AKG can alter the balance in microbial communities,increasing the population of SCFA-producing bacteria and the amounts of Bacteroides and Bifidobacterium,while reducing the counts of Escherichia coli and the amount of ammonia in the cecum.In conclusion,the addition of AKG in diet can reduce the excretion of nitrogen,calcium and phosphorus in growing pigs,increase the density of femur,increase the number of some beneficial bacterial species in caecum and ileum and the content of SCFAs in intestinal cavity contents,and reduce the number of Escherichia coli and the concentration of ammonia in caecum and ileum.In addition,the addition of AKG to low-protein diets improved the colony structure of cecum microflora and increased the content of SCFAs in the cecum.Moreover,the addition of AKG in low-protein diet promoted the synthesis of amino acids in muscle tissue,improved the protein metabolism of the body,and thereby improving the nitrogen utilization rate,thus improving the growth performance of growing pigs.