Study On The Evaluation Of Metabolizable Energy Of Rapeseed Meal From Different Sources And Effect Of Protease On Its Energy Value In Meat Duck

Rapeseed meal is an important protein feed,and its metaboliable energy value of meat ducks may be affected by the origin of rapeseed meal and the week age of the duck,so it needs to be determined accurately.The purpose of this paper is to study the effect of week age of meat duck on the metabolizable energy(ME)of rapeseed meal,and to determine the suitable week age for evaluating the metabolizable energy of rapeseed meal of meat duck.On this basis,the metabolizable energy values of 25 different sources of rapeseed meal were accurately evaluated,and the regression equation was constructed to predict rapeseed meal ME based on the conventional nutrients of rapeseed meal.The effect of adding exogenous protease on the metabolizable energy value of rapeseed meal of meat ducks with five different protein solubility was further investigated.The results of this study can provide basic data for the establishment of rapeseed meal nutrition value database and provide technical support for the efficient utilization of rapeseed meal in duck feed.Experiment 1.Effects of week age of meat duck and rapeseed meal source on metabolizable energy of rapeseed mealThe purpose of this experiment was to study the effect of the week age of the meat duck on the metabolizable energy(ME)of three kinds of rapeseed meal and to determine the appropriate week age of meat duck for evaluating the metabolizable energy of rapeseed meal.Three kinds of rapeseed meals(RSM1,RSM2 and RSM3,respectively)were used in the experiment,and three weeks-old meat ducks were selected:7 weeks old(weight2.7±0.3 kg),13 weeks old(weight 3.0±0.5 kg)and 19 weeks old(weight 3.1±0.3 kg).The metabolizable energy value of rapeseed meal was evaluated by TME method combined with the encrustation algorithm.Rapeseed meal replaced 40%corn to form the diet to be tested,while soybean meal replaced 35%corn.The metabolizable test was conducted in 3batches,with 1 corn group,1 corn soybean meal feeding group,1 hungry endogenous group and 3 rapeseed meal feeding groups to be tested in each batch.Each was processed with 12 replicates,1 duck per repeat.Healthy male cherry valley drake was selected for the metabolizable test.The strong feeding amount was 2%of the test duck’s body weight.The emptying time and fecal collection time were both 36h.The results show that:1)The weekly age of meat duck,source of rapeseed meal and their interaction had significantly different effects on apparent and true availability of crude fat and crude protein in rapeseed meal diets(P<0.05).The effects of weekly age and interaction between weekly age and rapeseed meal sources on apparent and true availability of dry matter were significantly different(P<0.05).From the source of rapeseed meal,the apparent availability of dietary crude fat was the highest in RSM2,the lowest in RSM1 and the middle in RSM3,with significant difference(P<0.05).The apparent availability of crude protein was highest in RSM1,which was significantly different from RSM2 and RSM3(P<0.05).The rule of true availability of crude fat and crude protein of rapeseed meal from the three sources was the same as that of apparent availability.From the influence of weekly age of meat ducks on nutrient availability of diet,three weekly age of meat ducks had no significant influence on EE and DM apparent and true availability of RSM1 diet(P>0.05),but there were significant differences between CP apparent and true availability(P<0.05).With the increase of weekly age of meat duck,the apparent CP and true availability of RSM1 diet decreased first and then increased.The apparent and true availability of EE,DM and CP in RSM2 diets were significantly affected by the age of three meat ducks(P<0.05).With the increase of weekly age of meat duck,EE apparent availability of RSM2 diet increased significantly,DM apparent availability,CP apparent availability and true availability all decreased first and then increased.The apparent and true availability of EE,DM and CP in RSM3 diet were significantly affected by the age of three meat ducks(P<0.05).With the increase of weekly age of meat duck,EE apparent availability of RSM3 diet increased first and then decreased,while CP and DM apparent availability decreased first and then increased,and the rule of true availability was the same as apparent availability.2)The week age of meat duck,source of rapeseed meal and the interaction between them all significantly affected the AME,TME,AMEn and TMEn values of rapeseed meal(P<0.05).From the source of rapeseed meal,the values of AME,TME,AMEn and TMEn were the highest in RSM3 rapeseed meal,the values of AME and TME were the lowest in RSM2 rapeseed meal,and RSM1 rapeseed meal was in the middle.There were significant differences between RSM3 rapeseed meal and RSM1 rapeseed meal and RSM2 rapeseed meal(P<0.05),but no significant differences between RSM1 and RSM2 rapeseed meal of AMEn and TMEn values(P>0.05).From the influence of weekly age of meat duck on the metabolizable energy value of rapeseed meal,three weekly age of meat duck had no significant influence on RSM1,RSM2 rapeseed AME,TME,AMEn and TMEn values(P>0.05).The values of RSM3 rapeseed meal AME,TME,AMEn and TMEn of three meat ducks were significantly affected(P<0.05),and the values of RSM3 rapeseed meal AME,TME and AMEn were the highest at 19 weeks,significantly higher than that at 7 weeks and 13 weeks,while the values of TMEn were significantly increased with the increase of the weekly age of the meat ducks.The above results indicated that adult duck(19 weeks and above)should be used to evaluate the metabolizable energy of rapeseed meal.The difference of metabolizable energy value of rapeseed meal was related to the difference of nutrient composition.Experiment 2.Establishment of metabolizable energy assessment and prediction equation of canola meal from different sourcesThe purpose of this study was to evaluate the AME,TME,AMEn,and TMEn of 25different sources of rapeseed meals and to construct a prediction equation for AME,TME,AMEn,and TMEn using their conventional nutrients.metabolizable tests were carried out on healthy cherry valley meat ducks aged 19 weeks above.A total of 3 batches of metabolism tests were conducted.The first 2 batches of metabolism tests were all set with13 treatments:corn group,corn soybean meal group,hungry endogenous group and 10rapeseed meal groups.The third batch of metabolism test was set with 8 treatments:corn group,corn soybean meal group,hungry endogenous group and 5 rapeseed meal groups.The diet to be tested is composed of soybean meal or rapeseed meal replacing corn,in which soybean meal replaces corn at 35%and rapeseed meal replaces corn at 40%.Each process 12 replicates,1 duck for each replicate.The results show that:1)The apparent availability of DM in rapeseed meal from different sources was not significantly different(P>0.05),while the availability of EE,CP,NDF,ADF,CF,Ash,Ca,P was significantly different(P<0.05).The mean values of apparent availability were DM70.42%,EE 73.29%,CP 54.37%,NDF 24.75%,ADF 2.06%,CF-6.27%,ASH-5.61%,CA-9.38%,and P 1.27%,respectively.The true availability of DM,EE,CP,NDF,ADF,CF,Ash,Ca and P of rapeseed meal from different sources were significantly different.The mean values of true availability were DM 76.56%,EE 78.26%,CP 65.94%,NDF 30.72%,ADF 5.70%,CF 1.01%,Ash 38.98%,Ca 20.54%and P 56.41%,respectively.2)The values of AME,TME,AMEn and TMEn of rapeseed meal from different sources were significantly different(P<0.05).The metabolizable energy values of AME2.44 Mcal/kg(1.98～2.99 Mcal/kg,SD 0.25)、TME 2.62 Mcal/kg(2.15～3.20 Mcal/kg,SD 0.25)、AMEn 2.16 Mcal/kg(1.74～2.57 Mcal/kg,SD 0.23)、TMEn 2.32 Mcal/kg(1.88～2.75 Mcal/kg,SD 0.23)were respectively.3)The prediction equations of AME,TME,AMEn and TMEn were established by stepwise regression analysis.AME=0.5454GE+0.0220EE(R~2=0.9976,P<0.01),TME=0.5935GE+0.0181EE(R~2=0.9979,P<0.01),AMEn=0.4716GE+0.0294EE(R~2=0.9974,P<0.01),TMEn=0.5110GE+0.0263EE(R~2=0.9977,P<0.01)。The results showed that the average metabolizable energy of 25 rapeseed meal was AME 2.44 Mcal/kg(1.98～2.99 Mcal/kg,SD 0.25)、TME 2.62 Mcal/kg(2.15～3.20Mcal/kg,SD 0.25)、AMEn 2.16 Mcal/kg(1.74～2.57 Mcal/kg,SD 0.23)、TMEn 2.32Mcal/kg(1.88～2.75 Mcal/kg,SD 0.23),respectively.Experiment 3.Effect of protease on metabolizable energy of canola meal in meat ducksThe purpose of this experiment was to evaluate the effect of adding exogenous protease on improving the metabolizable energy value and nutrient true availability of rapeseed meal in meat ducks,and to construct a technique to improve the utilization of rapeseed meal.In this experiment,cherry valley meat duck over 19 weeks of age was selected and the metabolizable energy value of rapeseed meal was evaluated by TME binding algorithm.Five rapeseed meals with different protein solubility(A1,A2,A3,A4and A5)were selected,and rapeseed meal was used to replace corn at 40%and soybean meal was used to replace corn at 35%.Fifteen treatments were set up,including 1 corn non-protease group,1 corn soybean meal non-protease group,1 corn protease group,1 corn soybean meal protease group,1 hungry endogenous group,5 rapeseed meal non-protease group,and 5 rapeseed meal protease group(the addition level of protease was 200 mg/kg,and the enzyme activity in protease preparation was 1×10~5U/g).The results show that:1)Adding protease can significantly improve the true availability of DM,EE,CP,NDF,ADF,Ash and P(P<0.05),and the improvement degree is DM(+3.73%),EE(+9.92%),CP(+8.51%),NDF(+15.78%),ADF(+17.09%),CF(+2.12%),Ash(+8.55%),Ca(+2.81%)and P(+12.96%),respectively.2)The values of AME,TME,AMEn,and TMEn in rapeseed meal were significantly increased by adding protease(P<0.05),and the improvements were AME(+0.48Mcal/kg),TME(+0.48 Mcal/kg),AMEn(+0.43 Mcal/kg),TMEn(+0.43 Mcal/kg).The above results indicated that adding protease could improve the metabolizable energy value and nutrient availability of rapeseed meal.In summary,the metabolizable energy of rapeseed meal was assessed as the optimum week age of the meat duck at 19 weeks.The prediction equation of the metabolizable energy of the meat duck was established by using the conventional nutrients of rapeseed meal,which had certain reliability and reference value,and protease could improve the metabolizable energy value of the meat duck rapeseed meal.