Effects Of Enzyme Supplementation Of Rice Bran Diets On Nutrient Metabolizability Coefficients In Growing Layers

The objective of this experiment was to evaluate the individual or combined effects of xylanase,phytase,feruloyl esterase,cellulase and pectinase on in vitro dry matter(DM)degradation of rice bran and the nutritive value of diets containing 35 and 65%rice bran in growing layers(Hy-line grey).Experiment 1.An optimization study of enzyme supplementation for in vitro dry matter disappearance(DMD)coefficients of rice branIn the present study,the in vitro DMD coefficients of rice bran was determined using a Simulated Digestion System(SDS-?).Within a certain range of enzyme activities,the DMD coefficients of rice bran showed a gradual increasing tendency with increasing each enzyme activities.With the highest DMD coefficients,the enzymeactivities of xylanase at 9 U(from 0 to 13.5 U),phytase at 0.8 U(from 0 to 1.0 U),feruloyl esterase at 0.1 U(from 0 to 0.2 U),cellulase at 0.76 U(from 0 to 1.14 U)and pectinase at 1 U(from 0 to 1.5 U)g-1 rice bran,respectively,when they were added individually.An optimization study on the in vitro DMD coefficients of rice bran was based on sixteen well-planned orthogonal experiments(OA16 matrix),which is an orthogonal array of five factors(five enzymes,as shown above)and two levels(the activity of each enzyme alone in the highest DMD coefficients and without enzyme addition).It was found that the order of significant factors for DMD coefficients is xylanase>phylase>feruloyl esterase>cellulase>pectinase.Based on the results of the analysis of variance(ANOVA),there was an interaction(P<0.05)between xylanase and feruloyl esterase for DMD coefficient increasing.There were significant differentce between the optimized enzyme combinations with different factors for DMD coefficient.The enzyme combinations which containing xylanase,phytase,feruloyl esterase and/or cellulase resulted in a greater DMD coefficients(P<0.05).Experiment 2.Effects of enzyme supplementation on nutrient matabolizability coefficients in growing layers fed rice bran based dietsBased on the results of the in vitro experiment,four different enzyme combinations were chose,i.e.,xylanase + phytase(XP),xylanase + phytase + feruloyl esterase(XFP),xylanase + phytase + feruloyl esterase + cellulase(XFPC)and xylanase + phytase +feruloyl esterase + cellulase + pectinase(XFPCp),to investigate the effects of enzyme supplementation on the nutrient value of diets containing 35 and 65%rice bran in a total of 640growing layers(9-wk-old,Hy-line grey).Each diet was fed in a mash form(containing 35 or 65%rice bran,with or without enzyme supplementation,respectively)to 8 replicates of 8 broilers.The results showed that feed intake was markedly reduced(P<0.001)by the increased level of rice bran in the hen diets.The inclusion of 35%of rice bran into the hen diets had greater(P<0.05)matabolizability coefficients of dry matter,amino acid,mannose,galactose and uronic acid,but significant lower(P<0.01)matabolizability coefficients of mineral,ash,xylose,glucose,cellulose and total non-starch polysaccharide(NSP),compared to the diet containing 65%rice bran.There were no significant difference in ether extract and crude protein(CP)matabolizability coefficients between 35 and 65%rice bran diets.A comparison of the data that enzyme addition to the rice bran diets improvedsignificantly nutrient matabolizability coefficients(P<0.05).The layers fed diets supplemented with XFP had greater DM,ash and CP matabolizability coefficients(P<0.001).Significant greater amino acid matabolizability coefficients were observed for hensfed diets with XFP or XFPC addition(P<0.05).The effects of enzyme supplementation on the non essential amino acids matabolizability coefficient was greater than the essential amino acids and total amino acids matabolizability coefficients(P-value,<0.001 vs.<0.01).Addition of XFPC or XFPCp had a significant(P<0.001)increasing of monosaccharide and total NSPmatabolizability coefficients,compared to others,and the maximum with XFPC addition.In this study,there was an interaction between the diets containing rice bran and enzyme supplementation for nutrient matabolizability coefficients(P<0.05).The result of in vitro experiment is in agreement with the results of in vivo experiment,which found that XFP and XFPC had a better effect on DMD coefficients and nutrient matabolizability coefficients.In consideration of the diets containing high NSP content,supplementation of xylanase + phytase + feruloyl esterase + cellulase(XFPC)was a good idea and could be continued to study in depth as suggested.