Study On Evaluating The NET Energy Of Cottonseed Meal(sol.) For Duck

Metabolizabal energy(ME)system is the most commonly used to evaluate available energy of poultry feed.But it can t reflect the amount and proportion used to maintenance and production of feed.Net energy(NE)consider the deduction of heat increment(HI)in metobolisom.It is accurately but complex to measure NE which could waste vast time,labor power and material resources,so it is essential to establish prediction models.The objective of this study is to evaluate the NE of cottonseed meals for Cherry valley ducks and establish prediction models by apparent meta-bolizabal energy(AME)and chemical composition,or by near infrared reflectance spectroscopy(NIRS)based on measured NE,Cottonseed meals were collected by feed standard and origin before experiment,and their chemical composition include CP,NDF,ADF,CF,EE and Ash were analyzed.The nutrient component of cottonseed meals used in this experiment met the nation feed standard(GB/T21264-2007).The factorial method was employed to evaluate the NE of cottonseed meals.The NE were divided into NEm and NEp measured through regression analysis and comparative slaughting method respec-tively.Then the NE of cottonseed meals for Cherry valley ducks can be calculated by substitution formula.Next,the measured NE combine with its AME and chemical composition were used to conduct related analysis and multiple linear stepwise regression analysis.Last,NE prediction model was established by NIRS in procedure which include a few steps as scanning spectra,spectra pretreatment,screening best spectra,and testing model finally.400 Cherry ducks with average fasted bodyweight of(130±8.5)g were selected for experiment.20 ducks were killed by cervical dislocation to determine the initial body energy for control at the beginning of the experiment.The NEm of experiment diet was estimated by fast heat production(FHP)messured by regression analysis.There were five replication and 2 ducks per replication for every treatment.The other 330 ducks were for the determination of NEp.They were divided into 33 treatments iucluding one feeded with basical diet and 32 with different diets substituted with cottonseed meals and five replications for every treatment,two ducks per replication.All ducks were killed by cervical dislocation to determine the final body energy.Metabolizable energy intake(MEI)and heat production(HP)of each treatment group in NEm experiment were calculated to establish logistic regression equation in which MEI was as independent variable and HP as dependent.Then NEm was equal to FHP when MEI is zero.The difference between final body energy with initial body enengy was NEp.The NE of experiment diet was equal to NEm plus NEp.The results of this study were as follows.The chemical composition of cottonseed meals include CP,NDF,ADF and CF were variable significantly to provide evidence for model establish.The MEI and HP of duck decreased significant(P<0.05)with feed restriction increasing except HP of 25%and 35%restriction treatments during experiment of FHP determined by regression.The model between MEI and HP was lgHP=0.157×MEI-0.233(R2=0.944,RSD=0.000,P<0.05)and FHP was equal to 580.7 KJ/(kgBW0.75.d)when the value of MEI was zero.The NEm and NEp of experiment diet were(2.97±0.15)MJ/kg and(5.22±0.12)MJ/kg respectively and the NE of experiment diet were(8.19±0.09)MJ/kg.The NE and AME of cottonseed meals were(6.12±0.6)MJ/kg and(10.05±1.02)MJ/kg respectively calculated by the substitution formula.The result about related analysis showed the NE of cottonseed meals were significantly positively correlated(P<0.01)with AME and CP and the r were 0.945,0.842 respectively.The NE of cottonseed meals were significantly negatively correlated(P<0.01)with ADF,NDF and CF and the r were 0.916,0.884,0.862 respectively.The modle stablished by chemical composition through multiple linear stepwise regression analysis was NE=0.241 AME+0.044CP-0.081ADF+3.276(P<0.01,R2=0.954,RSD =0.13MJ/kg)showing the model can predict the NE of cottonseed meal in Cherry duck accurately.In NIRS model,the relation between measured and prediction NE value was shown in figure.The coefficient of determination of internal cross-validation(R2cv),coefficient of determination of calibration(R2cal)and coefficient of determination of external validation(R2vai)were 0.945,0.861,0.828 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 0.156,0.231and 0.306MJ/kg,respectively.In a conclusion,the NE of 32 different cottonseed meals for Cherry ducks were(6.12±0.62)MJ/kg varing large from 5.04 to 7.30 MJ/kg and chemical composition and NIRS analysis technology can predict NE of cottonseed meal effectively.