Study On Evaluating The Net Energy Of Wheat For Duck

Compared to the metabolizable energy normally used by poultry,Net energy(NE)system can more accurate reflect truly available energy of feed ingredients and provide the energy closest to animal maintenance and production.At present,some progress have been made in the research of the NE content of corn,soybean meal,rapeseed meal and cottonseed meal in ducks.However,there is no study about the NE content of wheat in ducks.At the same time,the actual measurement net energy was low efficiency,processing method tedious,time-consuming and hard sledding.The study was conducted to determine the NE content of wheat samples for growing ducks.Using chemical characteristics or Near Infrared Spectroscopy(NIRS)to establish rapid determination of available NE prediction equations or models,that provide the reference data and method for growing ducks in feed formulations.40 wheat samples were selected from the wheats producing areas of China and bulk weight based on《Wheat》(GB-1351-2008).its concentration was determined by chemical composition analysis in the laboratory.The net energy value of wheat for ducks was measured by the factorial method.A total of 480(mean =67.43 ± 3.32g)1-wk-old ducks were chosen.At the beginning of the experiment,20 ducks were selected and slaughtered to determine the initial body composition;The remaining 460 ducks were randomly assigned to 1 of 46 diets,including a basal diet,5 restricted feeding diets and 40 test diets.Each diet contained 5 replicates of 2 ducks per replicate.The basal diet and restricted feeding diets was corn-soybean meal,forty test diets were formulated by mixing the basal diet with 20%wheat.The levels of restricted feeding were calculated as 0%,15%,30%,45%and 60%of their estimated ad libitum intake,respectively.First,the purpose of restricted feeding treatments was to determine the fasting heat production(FHP)using linear regression method;Comparative slaughter method was used to calculate the net energy for production(NEp).Then,the NE、NEm and NEp of each wheat source were calculated using the method of substitution.Finally,linear regression analysed the correlation between NE of wheat and its chemical constituents,apparent metabolizable energy(AME)to develop prediction equations for NE content of wheat based on the results of stepwise regression analysis;The 40 samples spectral were obtained by using Fourier transform near infrared spectrometer and established prediction models between the net energy values of wheat and NIRS.The main results of the experiment are as follows:The content of Neutral detergent fiber,Acid detergent fiber,Ash and Ether Extract ranged from 6.80%to 12.15%(mean =9.56 ± 1.10%),1.69%to 3.92%(mean = 2.58 ± 0.69%),1.31%to 2.32%(mean = 1.90 ±0.25%)and 1.31%to 3.29%(mean = 1.76 ± 0.31%),respectively,which were the coefficient of variation(CV)more than 10%.The content of Gross Energy(GE),Mistore,Crude Fibre(CF),Crude Protein(CP)and Bulk Weight were ranged from 15.71MJ/kg to 16.54 MJ/kg(mean = 16.21± 0.19 MJ/kg),9.93%to 13.89%(mean = 12.02 ± 0.89%),2.65%to 3.73%(mean = 3.07 ± 0.27%),10.66%to 16.16%(mean = 14.46 ± 1.09%)and 660.4 g/L to 863 g/L(mean =775.30 ± 38.84g/L),respectively;The CV of GE,Mistore,CF,CP and Bulk Weight were 1.16%,7.42%,8.76%,7.56%and 4.95%,respectively.Using comparative slaughtering and regression obtained the equation in the period 8～14 d of age for duck:LnHP = 0.4719MEI-0.570(R2=0.9951,P<0.001),the NEm was 566MJ/kg BW0.75 d-1 by extrapolation.AME and NE contents of 40 wheat samples ranged from 11.03 MJ/Kg to 14.34 MJ/Kg(mean=13.15 ± 0.73 MJ/Kg,CV=5.67%)and 6.81 MJ/Kg to 9.12 MJ/Kg(mean=8.15 ± 0.52 MJ/Kg,CV = 6.40%),respectively;NEm and NEp contents of wheat samples ranged from 2.07 MJ/kg to 3.86 MJ/kg(mean = 3.14 ± 0.45 MJ/Kg,CV =14.44%)and 4.63 MJ/kg to 7.05 MJ/kg(mean = 5.72 ± 0.52 MJ/Kg,CV = 9.07%),respectively.The results show that main nutrient content and energy value of 40 difference wheats varied to a great extent.Using correlations and stepwise regression analysis show that the NE value of the wheat was significantly correlated with the chemical composition and AME(P<0.01).The highest correlation coefficient was NDF among chemical composition and correlation coefficient of AME with NE of wheat was 0.833.Using stepwise regression analysis,a series of NE prediction equations was generated.The best fit equations were as follows:NE = 0.380 AME-0.147 NDF-0.274 ADF + 5.262(R2 = 0.874,RSD = 0.19MJ/kg,P<0.01).In this experiment condition,the model of NIRS to prediction NE value of wheat was shown:The coefficient of determination of internal cross-validation(R2cv),coefficient of determination of calibration(R2cal)and coefficient of determination of external validation(R2val)were 75.03、83.42and 82.93 respectively;The root mean square error of calibration(RMSEE),the root mean square error of internal cross-validation(RMSECV)and the root mean square error of external validation(RMSEP)were 0.080 MJ/kg、0.090MJ/kg and 0.059MJ/kg,respectively;Relative Standard Deviation of cross-validation(RSDcv)and relative Standard Deviation of validation(RSDv)were 2.251%and 2.143%;Ratio of performance to deviation of cross-validation(RPDcv)and ratio of performance to deviation of validation(RPDv)were 2.136 and 3.030.In conclusion,the chemical composition of 40 difference wheats varied to a great extent.The mean of NE contents for wheat samples was(8.49 ± 0.30)MJ/kg in growing duck.The NE value of wheat has correlation with its chemical ingredients and AME.Using chemical characteristics and AME or NIRS to establish prediction equations or models of NE for rapid determination of NE in wheat was feasible.