Study For Effects Of Supplementing Traditional Low-protein Diets With Pyruvate On Nitrogen Excretion And Amino Acid Utilization Of Growing-finishing Pigs

Amino acids are fuel substances preferred by most tissue cells,especially in the portal drained viscera,which is an important reason for the high nitrogen and total nitrogen emissions from pigs.Therefore,it is an important strategy to reduce the emission of pig nitrogen by providing amino acid metabolic fuel substitutes and reducing the energy supply of amino acid.This study was performed to investigate the effects of supplementing low-protein diets with pyruvate on nitrogen emissions,AA metabolism in the portal-drained viscera and liver,and urea synthesis in the liver,providing theoretical reference for improving the technology of porcine nitrogen reduction.Experiment 1:Cell test.The experiment in vitro was carried out to investigate the effects of culturing the porcine small intestinal epithelial cell line?IPEC-J2?with 110mg/L or without 400 mg/L pyruvate on the oxidation and consumption of amino acids.The results showed that when compared to the control group?110 mg/L pyruvate?,supplemention with 400 mg/L pyruvate significantly reduced the number of glutamate oxidation?P<0.001?and total amino acid consumption?P<0.05?.Experiment 2:Nitrogen balance test.Six healthy Duroc×Landrace×Large White three-way cross hybrid barrows weighing 40.0±1.0 kg were randomly allocated into three groups using the 3×3 Latin square design.The diets of the three different crude protein levels were respectively:18%crude protein?CP??control?,15%CP+0.8%pyruvate,and 13%CP+1.6%pyruvate.Feces and urine were collected to measure nitrogen content.The results showed that addition of pyruvate to traditional low-protein diets significantly decreased the nitrogen intake,fecal nitrogen,urine nitrogen,and total nitrogen excretion?P<0.05?,and significantly increased the ratio of nitrogen retention to nitrogen intake?P<0.05?in growing-finishing pigs;After the addition of pyruvate,there was no significant difference in the nitrogen retention between the low protein group and the control group?P>0.05?.Experiment 3:Blood intubation test.Eighteen healthy Duroc×Landrace×Yorkshire?DLY?pigs?40±1.0 kg?,which were surgically fitted with permanent catheters in the portal vein,carotid artery,mesenteric vein and hepatic vein,were used to investigate the effects of supplementing traditional low-protein diets with pyruvate on the net portal fluxes of AA and the consumption of AA in the liver.After recovery from surgery,pigs in three treatments were fed a maize-soybean meal diet containing18%CP?control?,15%CP+0.8%pyruvate,and 13%CP+1.6%pyruvate,respectively.During the experiment,food and water were provided ad libitum.Pigs were fed at 0800,1600 and 2400,respectively.Blood samples were collected from hepatic vein,portal vein and carotid arterial at 0730,0930,1130 and 1430 for amino acid analysis.The results showed that when compared to the control group,there was no significant difference in the concentration and fluxes of TAA,essential AA?EAA?and non essential AA?NEAA?in portal vein,hepatic artery and hepatic vein of growing-finishing pigs when pyruvate was added to the the low protein diet?P>0.05?.Addition of pyruvate to traditional low-protein diets significantly reduced the net portal fluxes of NH₃,Gly and Ala?P<0.05?;This diet modification reduced the net portal fluxes of NH₃,Gly,and Ala,as well as the consumption of TAA,EAA,NEAA,urea production rate in the liver?P<0.05?.This study results show that pyruvate can effectively reduce the consumption of amino acid and oxidative metabolism in IPEC-J2 cells.Supplementing low-protein diets with pyruvate can decrease the level of dietary protein by 5%without affecting the nitrogen retention of growing-finishing pigs.Addition of calcium pyruvate to traditional low-protein diets significantly decreased the release of urea precursorand urea production rate in the liver.