Evaluation Of Standardized Ileal Amino Acid Digestibility Of Rapeseed Meals From Different Sources And The Effect Of Dietary Protease Supplementation In Meat Duck

The objective of this thesis is conducted to evaluate the standard ileal amino acid digestibility(SIDAA)of rapeseed meals(RSM)from different sources by digestibility experiment,and to establish the prediction equation for SIDAA of RSM based on protein solubility(PS),proximate nutrients,and anti-nutrition-factors.On this basis,five representative RSM were selected to investigate the effect of dietary protease supplementation on SIDAA of RSM in meat duck.The results will provide technical and data support for the efficient utilization of RSM in meat duck comlete feed.Experiment l:Evaluation of the standard ileal amino acid digestibility of rapeseed meal from different sources in meat duckThe study was aimed to evaluate SIDAA of 22 kinds of RSM in meat duck,and further to establish the prediction equation for SIDAA of RSM based on chemical composition.A total of 1,168 one-day-old duck were randomly divided into 23 treatment groups(6 replicates each gruop,8 ducks each replicate)which contiains one basal diet and twenty-two RSM replacing 15%basal diet,and a nitrogen-free diet group(8 replicates each gruop,8 ducks each replicate).From 15 to 17 days of age,meat ducks were fed with experimental diets.0.5%titanium dioxide was used as an indigestible marker.Digesta were sampled on a pen basis from the section between Meckel's diverticulum and 2 cm anterior to the ileocecocolonic junction at 18 days of age.The results showed as follows:1)The chemical composition and anti-nutritional concentration of 22 kinds of RSM were:DM 91.55%(CV 2.14%),CP 36.43%(CV 4.31%),EE 7.56%(CV 49.23%),Ash 7.66%(CV 17.03%),CF 12.89%(CV 16.50%),NDF 36.45%(CV 24.57%),ADF 13.40%(CV 24.15%),GS 22.74 ?mol/g(CV 86.84%),ITC 2.18 mg/g(CV 90.19%),OZT 1.12 mg/g(CV 81.98%)and PS 53.31%(CV 52.62%).2)The essential amino acid content of22 kinds of RSM were:Lys 2.07%(CV 24.19%),Met 0.49%(CV 15.17%),Arg2.33%(CV 12.62%),Ile 1.55%(CV 10.67%),Leu 2.80%(CV 7.54%),Thr 1.76%(CV 16.30%),Val 1.90%(CV 7.98%),Phe 1.55%(CV 7.95%)and His 0.98%(CV 6.72%).The content of non-essential amino acids were:Asp 2.75%(CV 9.57%),Ser 1.67%(CV 7.45%),Glu 7.11%(CV 7.01%),Gly 2.05%(CV 7.56%),Ala 1.72%(CV 6.90%),Cys 0.39%(CV 30.83%),Tyr 1.16%(CV7.65%)and Pro 2.31%(CV 6.82%).3)The SID of all amino acids except Leu and Tyr of RSM from different sources showed significant difference(P<0.05).The SID of Lys,Met,Arg,Ile,Thr,Val,Phe and His were 66.21%(CV 9.13%),90.74%(CV 4.79%),81.42%(CV 2.57%),75.80%(CV 2.77%),73.35%(CV 4.38%),76.11%(CV 2.82%),82.94%(CV 2.45%),82.54%(CV 2.58%),respectively.The SID of Asp,Ser,Glu,Gly,Ala,Cys and Pro were 73.97%(CV 4.57%),77.51%(CV 3.19%),82.91%(CV 3.56%),75.01%(CV 4.69%),78.84%(CV 4.27%),79.78%(CV 4.18%)and 80.71%(CV 3.28%),respectively.4)Correlation analysis of the chemical constituents of RSM showed that there was a significant negative correlation between PS and CF,NDF,ADF(P<0.05),PS was positively correlated with GS and ITC(P<0.05).The CF was a significant positive correlation with NDF and ADF(P<0.05),but a significant negative correlation with GS and ITC(P<0.05).The ADF content of rapeseed meal was significantly negatively correlated with GS,ITC,OZT(P<0.05).5)Correlation analysis between SIDAA and anti-nutritional factors and PS found that the SID of lle,Val,Phe,Ser,Tyr,Lys,His,and Cys were significantly positively correlated with PS(P<0.05).The SID of Arg,Asp,Ser,Lys,Cys,Ile,Val,Phe,His,Tyr and Pro were significantly negatively correlated with CF(P<0.05).The SID of Ile,Val,Phe,Ser,Tyr,Lys,His,and Cys were significantly negatively correlated with NDF(P<0.05).The SID of His,Cys,and Lys were significantly negatively correlated with ADF(P<0.05).6)The optimal prediction equation of SIDAA of rapeseed meal as followed:SID-Lys(%)=1.231 DM-0.914 CP-1.342 EE-1.081 CF+0.334 ADF+0.131 PS+0.264(R2=0.9577,P<0.0001);SID-Ile(%)=-0.790 CF-0.602 Ash+90.568(R2=0.7169,P<0.0001),SID-His(%)=-0.220 EE-0.826 CF+95.146(R2=0.7672,P<0.0001),SID-Cys(%)=-0.140 NDF+0.071 PS+80.803(R2=0.8372,P<0.0001).R2 values of the remaining amino acids of SID ranged from 0.3484 to 0.6843.Experiment 2:Effects of dietary protease supplementation on standard ileum amino acid digestibility of rapeseed meal in meat duckThis study was conducted to investigate the effect of dietary protease supplementation on SIDAA of RSM in meat duck.A 6x2 factorial,involving 6 testing diets(one is the basal diet,five is five RSM replacing 15%basal diet,respectively)and 2 levels of protease(0 or 200 mg/kg).A nitrogen-free diet was also offered to a reference group from day 15 to 17 to determine amino acid flow at the terminal ileum and calculate the SIDAA.The 640 ducks were randomly divided into 12 groups(6 replicates each gruop,8 ducks each replicate)and a nitrogen-free diet group(8 replicates each gruop,8 ducks each replicate).0.5%titanium dioxide was added to the experimental diets.The results showed as follows:1)There were significant differences in SIDAA among 5 kinds of RSM(P<0.05).The mean SID of Met,Lys and Thr was 91.04%,66.19%and 73.54%,respectively.2)Protease could significantly increase(P<0.05)SID of Thr(+6.73%),Ile(+4.47%),Lue(+3.03%),Val(+4.60%),Arg(+2.36%),Asp(+8.46%),Ser(+7.05%),Glu(+5.97%),Gly(+9.38%),Ala(+8.44%),and Pro(+3.94%).In summary,SIDAA of RSM from different sources had significant differences.The SIDAA of RSM could be affected by its PS,CF,ADF,NDF,GS,ITC and OZT.The prediction equations of SIDAA of RSM established by chemical composition had certain reliability and reference value.Dietary protease supplenmentation could improve the SIDAA of RSM in meat duck.