Effects Of Dietary Supplementation Of Guanidinoacetic Acid And Betaine On Meat Quality And Body Metabolism Of Finishing Pigs

This work sought to evaluate the effects of guanidinoacetic acid(GAA)and combination of GAA and betaine on growth performance,energy metabolism,postmortem glycolysis,meat quality and metabonomics analysis of finishing pigs.This work explores the mechanism of GAA to provide useful information for the further research in actual production and application of livestock and poultry.This paper consists of three parts as follows:The first part primarily studies the effects of GAA and combination of GAA and betaine on growth performance,carcass traits,chemical composition and meat quality.According to the effects of GAA and combination of GAA and betaine on average daily gain and average daily feed intake,we discuss the mechanism of weight gain and fat loss.A total of 180 cross-bred,castrated male pigs were randomly assigned to one of three experimental diets(pigs were adapted to the control diet for 7 days and experimental diets were given for 15 days):a control(CON;basal diet consisting of a ground corn-soybean base),a GAA diet(GAA;basal diet supplemented with 1 g of GAA),and a combination diet(CGB;basal diet supplemented with 1 g of GAA and 0.5 g of betaine per kg of feed).Each treatment was replicated in 3 pens with 20 pigs each.Compared with the CON group,GAA and CGB supplementation increased the average daily feed intake(P<0.05)and average daily weight gain(P<0.05),reduced back fat thickness(P<0.01).However,feed to gain ratio,dressing percentage,loin muscle area and carcass lean percentage were not significantly affected by GAA supplementation or CGB supplementation(P>0.05).Moisture,crude protein,crude fat and crude ash showed no statistical differences in longissimus dorsi(LD)and semitendinosus(ST)when fed with GAA supplement or CGB supplement compared with the CON group(P>0.05).In LD,the two dietary supplements GAA and CGB each increased pH45min value(P<0.05)and pH24h value(P<0.05)compared with the CON diet.Moreover,GAA supplementation and CGB supplementation significantly reduced drip loss(P<0.05),cooking loss(P<0.05),hardness(P<0.05)and shear force(P<0.01).However,no significant changes were observed in cohesiveness,elasticity,adhesiveness,chewiness,L*,a*and b*values(P>0.05)for either GAA or CGB diets.In ST,the two dietary supplements GAA and CGB each increased pH45min value(P<0.05)and pH24h value(P<0.01)compared with the CON diet.Moreover,GAA supplementation and CGB supplementation significantly reduced drip loss(P<0.01),cooking loss(P<0.05),hardness(P<0.05)and shear force(P<0.01).However,no significant changes were observed in cohesiveness,elasticity,adhesiveness,chewiness,L*,a*and b*values(P>0.05)for either GAA or CGB diets.There were no significant differences between GAA group and CGB group in growth performance,carcass traits,chemical composition and meat quality(P>0.05).These results showed:supplementation of 1 g/kg GAA in diet in the period pre-slaughter increased growth performance,pH value,water holding capacity and tenderness,as a result of fact,improved meat quality.The second part primarily studies the effects of GAA and combination of GAA and betaine on energy metabolism,postmortem glycolysis and the mRNA express of GAA metabolism related enzymes and discusses the mechanism of them.In LD,dietary GAA and CGB reduced the activity of hexokinase(P<0.05)and the content of lactic acid(P<0.05),increased the mRNA expression of creatine transporter(CrT)(P<0.01),the content of creatine(Cr)(P<0.01),phosphocreatine(PCr)(P<0.01),adenosine triphosphate(ATP)(P<0.01)and the activity of creatine kinase(P<0.05).However,no obvious differences in the contents of glycogen(P>0.05),the glycolytic potential(P>0.05),activities of lactate dehydrogenase(P>0.05)and pyruvate kinase(P>0.05),the content of adenosine diphosphate(ADP)and adenosine monophosphate(AMP)(P>0.05),and the mRNA expression of L-arginine:glycine amidinotransferase(AGAT)and N-methyltransferase(GAMT)were observed(P>0.05).In ST,The GAA and CGB diets reduced the activity of hexokinase(P<0.05)and the content of lactic acid(P<0.05),increased the contents of glycogen(P<0.05),the mRNA expression of CrT(P<0.05),the content of Cr(P<0.05),PCr(P<0.01),ATP(P<0.01)and the activity of creatine kinase(P<0.01).No significant changes were observed in the glycolytic potential(P>0.05),activities of lactate dehydrogenase(P>0.05)and pyruvate kinase(P>0.05),the content of ADP and AMP(P>0.05),and the mRNA expression of AGAT and GAMT were observed(P>0.05)for either GAA or CGB diet.In addition,both GAA and CGB diets increased the content of Cr(P<0.05)in liver.Dietary supplementation with GAA and CGB could also increased the content of Cr and the mRNA expression of CrT(P<0.05)in kidney.There were no significant differences between GAA group and CGB group in energy metabolism,postmortem glycolysis and the mRNA express of GAA metabolism related enzymes(P>0.05).These results indicated that the dietary supplementation with GAA and CGB could delay muscle glycolysis via regulating some aspects of energy metabolism and the mRNA express of GAA metabolism related enzymes.The third part primarily studies the effects of GAA and combination of GAA and betaine on small molecule substance metabolism in plasma and discusses the mechanism of them.In plasma,there were obvious differences between CON group and GAA group,which reflected on the aspect of protein biosynthesis,ammonia recycle and urea cycle.Compared with the CON group,GAA group reduced the content of leucine,lactic acid,taurine,ornithine,phenylalanine,isoleucine,glycerol,linoleic acid,histidine,lysine,11-eicosaenoic acid,cystine,urea,oleic acid,methionine,palmitelaidic acid,asparagine,valine,serine,aminomalonic acid and tyrosine,increased the content of glucose,lactose and creatinine.In addition,the contents of small molecule substance in plasma were also different between CON group and CGB group,which reflected on the aspect of Compared with the CON group,GAA group reduced the content of protein biosynthesis,betaine metabolism and aspartate metabolism.Compared with the CON group,GAA group reduced the content of leucine,alanine,lactic acid,isoleucine,tyrosine,urea,glycerol,histidine,lipid,taurine,creatinine,cholesterol,ornithine,cysteine,cystine,phenylalanine and glycine,increased the content of glucose,lactose,and creatinine.These results indicated that the dietary supplementation with GAA and CGB could help with protein biosynthesis and delay muscle glycolysis via regulating small molecule substance metabolism in plasma.Then,it further increased growth performance,reduced body fat content and improved meat quality.