Study On Available Energy And Amino Acids Digestibility Of Double-low Rapeseed Cakes For Pigs

Five experiments were conducted to determine the chemical composition,digestible energy(DE),metabolizable energy(ME),and amino acids(AA)digestibility of ten double-low rapeseed cakes(DLRSC),and to evaluate the effects of dehulling and multi-enzyme on the nutritional value of DLRSC,and to develop the prediction equations for DE,ME and AA digestibility.The accuracy of the equation for ME was also validated.In Exp.1,the chemical composition,DE and ME of 10 DLRSC were determined and the prediction equations of energy value based on chemical compostion were developed.Sixty-six growing barrows(initial BW:36.6 ± 4.1 kg)were randomly allotted to 1 of 11 diets(n = 6),including a corn-soybean meal basal diet and 10 DLRSC test diets.The DLRSC in the DLRSC replaced 20%of the energy supplying ingredients in the basal diet.Results showed that the chemical composition of 10 DLRSC samples varied considerably especially for NDF,ADF,calcium,phosphorus,total glucosinolates and lysine.The DE and ME content differed(P<0.01)among the 10 DLRSC samples.On the DM basis,the DE(mean 14.51 MJ/kg)and ME content(mean 13.08 MJ/kg)varied from 12.64 to 15.77 MJ/kg and 11.93 to 14.41 MJ/kg,respectively.The best fit equations for DE and ME was DE =1.47 x GE-0.21 x ADF + 0.53 × Ash-14,72(R2 = 0.93)and ME = 9.33-0.09 x NDF-0.25 x CF +0.59 x GE(R2 = 0.93),respectively.In Exp.2,the apparent ileal digestibility(AID)and standardized ileal digestibility(SID)of CP and AA were evaluated and the equations for SID of CP and AA in DLRSC were established.Nine growing barrows(initial BW:29.7 ± 3.1 kg)were surgically fitted with a T-cannula in the distal ileum and allotted to a 6 × 9 Youden square design with 6 periods and 9 diets.The diets included a N-free diet and 8 test diets which contained 40%of each of the DLRSC samples.Results showed that there were significant differences in AID and SID of amino acids,except tryptophan and tyrosine.The AID of CP and lysine averaged 64.98%and 67.96%,respectively.The SID of CP and lysine ranged from 65.22%to 80.61%and 55.43%to 86.16%,respectively.The best fit prediction evaluated for Lys and Met was SID Lys = 0.33 x Protein solubility + 56.89(R2 = 0.78)and SID Met = 1.65 × Lys-2.40 x CF +22.07 x Met + 111.04(R2 = 0.91),respectively.Exp.3 were conducted to determine the energy value and AA digestibility of five double-low rapeseed coproducts produced by different processing technology.In Exp.3-1,36 growing barrows(initial BW:37.7 ± 4.8 kg)were randomly allotted to one of six diets(n =6),including a corn-soybean meal basal diet and five rapeseed coproduct test diets.The double-low rapeseed coproduct was added at the expense of 20%of the energy supplying ingredients in the basal diet.In Exp.3-2,six growing barrows(initial BW:69.4 ± 4.4 kg)fitted with a T-cannula in the distal ileum were allotted to a 6 x 6 Latin square design with 6 periods and 6 diets.Diets included one N-free diet and five test diets which contained 40%RSC or RSM as the only source of CP and AA.Results showed that the dehulled RSC samples(RSC-DH1 and RSC-DH2)contained the lowest NDF and ADF and the greater lysine and CP concentration among rapeseed co-product samples.On the DM basis,the ME value was greater(P<0.05)in dehulled RSC(16.15 MJ/kg)than RSC-CV(13.33 MJ/kg)and RSM(11.68 MJ/kg).With the exception of phenylalanine and valine,the SID of CP and most AA in dehulled RSC was greater(P<0.05)than that in RSC-CV and RSM.The RSC-CP had greater energy value and AA digestibility than RSC-CV and RSM.Exp.4 were conducted to evaluate the effects of multi-enzyme supplementation on the energy value and ileal amino acids digestibility in double-low rapeseed cakes(RSC)and rapeseed meal(RSM)fed to growing pigs.In Exp.4-1,36 growing barrows(initial BW:37.6 ± 1.2 kg)were individually placed in stainless-steel metabolism crates and randomly allotted to 1 of 6 test diets(n = 6).Six experimental diets were prepared in a 3 × 2 factorial treatment arrangement with 3 diet types(corn-soybean meal basal diet,RSC diet and RSM diet)and 2 levels of multi-enzyme supplementation(0 and 800 mg/kg).Two rapeseed co-products were added to replace 20%of the energy supplying ingredients in the basal diet.In Exp.4-2,30 crossbred barrows(initial BW:54.3 ± 1.8 kg)were randomly allotted to 1 of 5 diets(n = 6).Diets included a cornstarch-based diet with 40%RSC or RSM without and with multi-enzyme(800 mg/kg),and a nitrogen-free diet was used to quantify endogenous CP and AA losses.Results showed that the multi-enzyme used in the present study significantly improved(P<0.05)the ME value and the apparent total tract digestibility(ATTD)of EE,NDF and ADF,and tended to increase(P = 0.06)the ATTD of GE and DE value in rapeseed co-products.When multi-enzyme was used,the ME value(DM basis)in RSC and RSM increased(P<0.05)by 1.38 and 0.77 MJ/kg,respectively.In addition,with the exception of Phe,multi-enzyme increased(P<0.05)the SID of CP and all the AA in the rapeseed coproducts.Exp.5 was to validate the accuracy of the prediction equation(ME = 9.33-0.09 × NDF-0.25 × CF + 0.59 × GE,R2 = 0.93)by two methods.In the repeat measurement test,the difference between the measured ME and the predicted ME for the RSC-CV and RSC-CP was calculated.In caloric efficiency method,the ME utilization efficiency and performance of pigs was measured to validate prediction equation.In the experiment,144 growing pigs(29.7 ± 2.7 kg BW)were allowed to 1 of 4 treatments,with 6 pigs per pen and 6 replicate pens per treatment.Four experimental diets included 0%,7%,14%and 21%DLRSC,respectively.The ME value of DLRSC used for diet formulation was calculated by the prediction equation.Results showed that the relative deviation between the measured ME and the predicted ME for the RSC-CV and RSC-CP was lower than 5%and acceptable.The caloric efficiency of pig for ME in 4 treatments was similar.Therefore,both methods showed the prediction equation of ME can accurately predict the ME of DLRSC for growing pigs.In conclusion,the DE,ME and AA ileal digestibility in double-low rapeseed cakes differed significantly,the dehulling and multi-enzyme addition can improve the nutritional value of double-low rapeseed co-products.The prediction equations of the energy value and the amino acid digestibility can be used to evaluate the nutritional value of double low rapeseed cakes.