Research On Early Development Regulation Of Pigeon Squabs By Cationic Amino Acids

Meat-type pigeons are considered as the fourth largest source of poultry product in China due to its delicious taste.In contrast to precocial poultry,pigeon squabs are typical altricial birds,which are fed with pigeon milk by parental pigeons for a few days after hatch.Little information is available referring to the nutritional effet of cationic amino acids in pigeon squabs.Hence,this study was conducted to evaluate the transportation of amino acids in small intestine of 2 weeks post-hatch pigeon squabs by estimating the mRNA expression pattern of amino acids transporters and its correlation with pigeon milk.Furthermore,the nutritional regulation of cationic amino acids on early development of pigeon squabs was determined.The main results are listed as follows:1 Changes of pigeon milk composition during 2 weeks secretionThe present study was conducted to determine composition of pigeon milk and its changes during 2 weeks secretion.Results showed that levels of moisture(71.59～83.05%)were highest in pigeon milk on a half-dry basis.Contents of crude protein and diethyl ether extraction were 52.68～58.47%and 18.94～32.77%on an air-dry basis,respectively.Contents of crude protein were decreased with age(P<0.05),while that of ash increased with age(P<0.05).Contents of diethyl ether extraction were firstly increased,than decreased(P<0.05).12 kinds of essential amino acids(EAA)and 5 kinds of non-essential amino acids(NEAA)were determined.Contents of Met,Cys,and His were quite low,while that of Asp and Glu(15.14～22.51%)were extremely high.Contents of amino acids in pigeon mik remained constant in the first 4 d,declined abruptly at d 6,then increased dramatically from d 8 to 14.Index of EAA increased with age.2 Changes of gene expression of amino acid transporter in small intestine of pigeon squabs during 2 weeks post-hatch developmentThis study was conducted to evaluate gene expression of the amino acid transporter in 2 weeks post-hatch pigeon small intestine.Results showed that there was a significant effect of interaction between age and intestinal segments on gene expression of amino acid transporters.mRNA abundance of ATB0’+,SNAT2,LAT4,rBAT,b0’+AT,EAAT3,and PAT1 was highest in the ileum,and that of B0AT1,asc-1,and IMINO were predominate in the jejunum,and that of CAT1,y+LAT2 were greatest in the duodenum.Agerelated changes of amino acid transporter mRNA was inconsistent.mRNA levels of SNAT2,rBAT,y+LAT2,and b0’ +AT ascended with age,whereas that of B0AT1,asc-1,CAT1,LAT4,and IMINO diminished significantly.3 In ovo feeding of single cationic amino acids on early development of pigeon squabsOn the basis of correlation analysis of pigeon milk composition and gene expression of amino acids transporters in small intestine of pigeon squabs,this study was performed to investigate the effect of in ovo feeding of single cationic amino acids on early development of pigeon squabs.Concentrations of Arg,Lys,and His solutions were 5.7,10.55,and 2.75 g/L,respectively.Results showed as follows,1)hatchability was improved by feeding of Arg and His,compared with NC and SC group.Hatchability in Arg group increased 22.27%(P<0.05)and 18.19%(P<0.05),and that in His group increased 17.56%(P<0.05)and 13.64%(P<0.05),however,decreases of hatchability were observed in Lys group of 2.6%(P<0.05)and 6.04(P<0.05).2)Body weight of pigeon squabs in Arg group on DOH and D14,as well as in Lys group on D14 were increased significantly(P<0.05).In addition,body weight gain of squabs in Lys group on D14 was increased.3)Increased organ developments of squabs were observed.On DOH,indices of brain in Arg and Lys group,pancreas in His group were higher that those in NC group(P<0.05).On D7,indices of heart,gizzard,small intestine,pancreas,and spleen in Arg group,indices of gizzard,heart,leg,and small intestine in Lys group,associating with indices of leg,gizzard,proventriculus,small intestine,pancreas,and spleen in His group were improved significantly(P<0.05).On D14,indices of proventriculus,liver,pancreas,and spleen in Arg group,indices of lung,as well as indices of head in His group were higher than those in the control groups(P<0.05).4)Length and weight of small intestine,and jejunum morphology of pigeon squabs were changed significantly(P<0.05).On DOH,crypt depths in Arg group,Lys group,and His group were declined significantly(P<0.05),while villus area in His group increased(P<0.05).On D7,a significant decrease of crypt depths were also obtained in Arg group,Lys group,and His group,while ratio of villus height to crypt depth in Arg and His groups,and villus area were increased(P<0.05).On D14,weight index of small intestine,villus height,ratio of villus height to crypt depth in Arg group,crypt depth in Lys group,and villus height in His were improved,followed by a decrease of crypt depth in Arg group(P<0.05).5)In ovo feeding of Arg advanced the hatching time of squabs and improved production of pectoral muscle(P<0.05).4 In ovo feeding of combined cationic amino acids on early development of newly-hatched pigeon squabsThis study was aimed at estimated the impact of in ovo feeding of dual-combined and tri-combined cationic amino acids on early development of pigeon squabs.Results showed that in ovo feeding of dual-combined cationic amino acids decreased hatchability,proventriculitis index,serum activity of AKP,while increased villus area of duodenum(P<0.05).In ovo feeding of tri-combined cationic amino acids had a significant effect on body weight and organ development of pigeon squabs.Increased proportions of yolk-free hatch weight to hatch weight were observed,and the proportion in group IV was highest(P<0.05).In addition,squabs in group IV had higher organ indices of heart,liver,and kidney than those in group Ⅰ(P<0.05).Organ weight of heart and liver in group IV increased 33.33%(P<0.05)and 34.36%(P<0.05).Organ weights were positively correlated with the body weight,except brain,spleen,and proventriculus.In conclusion,high levels of curde protein and diethyl ether extraction were observed in pigeon milk.Index of EAA increased with age.Cationic amino acids transporters of rBAT,y+LAT2,and b0’ +AT had the highest increased ratio.In ovo feeding of cationic amino acids may improve squab early growth performance by advancing the hatching time,and increasing the hatchability,body weight,muscle production,and small intestine morphology mature,which implying that the method of in ovo feeding may be applied as a effective tool to study the nutrition requirement of pigeon squabs.