The Mechanism Of Arginine On Regulating Feed Intake In Pekin Ducks

Six experiments in3parts were conducted to study the effect of arginine on performance andmechanism of arginine in regulating feed intake in Pekin ducks.Experiments1and2were conducted to investigate the effect of dietary arginine on growthperformance and carcass quality in Pekin duck. In experiment1, six hundred thirty1-d-old male Pekinducks were randomly allotted to10dietary treatments with7replicate pens of9birds per pen. Birds ineach group were fed corn-corn gluten meal diets containing0.71,0.84,0.95,1.03,1.17,1.27,1.39,1.47,1.62, and1.72%arginine, respectively. Arginine deficiency in diet could decrease average daily feedintake, body weight gain and breast muscle yield (P <0.05). Based on quadratic broken-line regressionanalysis, the arginine requirement for male Pekin ducks from1to21days of age is0.95,1.16and0.99%of the diet for maximum weight gain, feed/gain and breast muscle yield, respectively. In Experimant2,sixty14-day-old Pekin ducks were allotted to one of three dietary treatments. Birds were keptindividually and fed diets containing0.60,0.85or1.70%arginine for3weeks. Ducks that were fed thediet containing0.60%arginine had lower feed intake, body weight gain, and feed conversion ratio (P <0.05) than those fed the diet containing1.70%arginine. Breast muscle yield increased with eachincrement of dietary arginine content (P <0.05), the birds fed the diet containing1.70%arginine hadhighest leg muscle yield (P <0.05); in contrast, the abdominal fat yield was not affected (P>0.05) bydietary arginine. These results have shown that dietary arginine dificiency inhibite appetite in Pekinduck starter and grower.In Trials3and4, the proteome changes in hypothalamus and liver under dietary arginine dificiencywere investigated using isobaric tags for relative and absolute quantitation and Mass spectrometry tofind functional protein by which arginine dificiency inhibited feed intake in Pekin ducks. A total of16differentially expressed protein were identified in hypothalamus, which were involved in proteinsynthesis, carbohydrate metablism and energy production, transporter, cytoskeleton, immunity andneuronal development. Among of them,9proteins were up-regulated and7down-regulated. Proteinassociated with energy production (glycine amidinotransferase, aldolase B fructose-bisphosphate,aconitase1,6-phosphofructokinase type C-like，transaldolase) and transporter (hemoglobin subunitalpha-A) were down-regulated in dietary agrinine-dificiency group. The results of liver proteomicsindicated that36differentially expressed proteins were identified, in which,11proteins wereup-regulated and25down-regulated. These proreins were involved with regulation of transcription andtranslation, carbohydrate metablism and energy production, transporter, cytoskeleton, immunity andneuronal development. Expression of the proteins associated with energy production (pyruvate kinase,cytochrome C), transporter (sterol carrier protein-2,voltage-dependent anion-selective channel protein3,hemoglobin subunit alpha-A, zipcode-binding protein), cytoskeleton (tubulin beta-3chain, spectrin betachain, brain1, vimentin-like,tubulin beta-4chain, desmin, collagen alpha-1) and neuronal development(glial fibrillary acidic protein-like, myristoylated alanine-rich C-kinase substrate, myelin proteolipidprotein, neurofilament heavy polypeptide, collapsin response mediator protein-2A, Syntaxin1-binding protein) were down-regulated under dietary agrinine dificiency. Arginine dificiency inhibits appetite ofPekin ducks, presumably by decreasing energy production and transporting of oxygeon in hypothalamus,and changing energy metabolism,cell structure integrity and neuronal development in liver.The objective of Experiments5and6was to investigate the effect of dietary arginine on nitric oxide(NO) content and the effect of NO dificiency on feed intake in Pekin ducks. In experiment5, onehundred and forty four1-d-old male Pekin ducks were randomly allotted to3dietary treatments with6replicate pens of8birds per pen. Birds in each group were fed corn-corn gluten meals diet containing0.60,0.95and1.45%arginine, respectively. Ducks that were fed the diet containing0.60%arginine hadlower feed intake (P <0.05) than two other groups in1-7,8-14,15-21and1-21days of age. Thehypothalamic contents of neuropeptide Y and leptin at21days of age were not affected by dietaryarginine levels (P>0.05), and no differences in plasmic concentrate of ghrelin, insulin and growthhormon were found amoung three arginine-treamented groups (P>0.05). However, the plasmic NOcontent in low-arginine group (0.65%) was lower than that in groups fed diets containing0.95or1.45%arginine (P <0.05). In experiment6,2011-day ducks with near body weight were alloted to one of twotreaments. After2-hours fasting, Ducks in control and treamented group were intraperitoneallyadministreted saline and L-NAME（NG-nitro-L-arginine methyl ester）for3days,respectively. Theresults indicated that feed intake(P <0.05) and plasmic NO content(P <0.06) in L-NAME treatmentedgroup postinjetion2hours were lower than those of control group. The low dietary arginine leaded toNO dificiency,which inhibited appetite in Pekin ducks.In conclusion, feed intake and muscle development (especilally for breast muscle) were insentive todietary arginine content. The arginine requirement of male Pekin ducks from1to21d of age was0.95,1.16, and0.99%for weight gain, feed/gain, and breast meat yield, respectively. Dietary argininedificiency inhibits appetite of Pekin ducks, presumably by decreasing energy production andtransporting of oxygeon in hypothalamus, and changing energy metabolism,cell structure integrity andneuronal development in liver. In addition, low dietary arginine also inbibited feeding behaviour forlow-content NO in Pekin ducks.