Effects Of Enzyme Preparation On Growth Performance And Nutrient Digestibility In Ducks

Two experiments were conducted to investigate the effect of xylanase and phytase supplementation on the growth performance and apparent metabolisability of nutrients for ducks, and effect of xylanase and cellulase supplementation on apparent metabolisability of nutrients for ducks.Experiment one : The objective of the present study was to assess the effects of xylanase and phytase on the performance and apparent metabolisability of nutrients for Cherry Valley ducks. A total of 588 day-old Cherry Valley Ducks were randomly divided into 7 treatments with 7 replicates each treatment and 12 ducks per replicate. This experiment contained seven treatments including a positive control,a low-energy group, a low-energy low-phosphorus group and four treatments which added xylanase (500g/t) to the low-energy group,added phytase and xylanase 50g/t and 0g/t, 50g/t and 250g/t, 50g/t and 500g/t respectively to the low-energy and low-phosphorus group. The low-energy control diet contained a lower energy (reduced by 200kcal/kg) than the positive control ,and the low-energy low-phosphorus control diet contained a lower energy (reduced by 200kcal/kg), Ca (reduced by 0.12%) and phosphorus (reduced by 0.14%) than the positive control.The results showed that:(1) Adding 4 000u/kg xylanase to the low-energy diets significantly improved the weight gain of ducks by 9.81% during 0～21d,and had no significant effects on FCR and the growth performance for ducks at 22-41d(P>0.05). Supplementation of 4 000u/kg xylanase improved the metabolic rate of the Pr,energy,Ca,P and AME by 5.53%, 3.97%, 13.62%, 7.39%, 3.94% at day 0～21, separately. The metabolic rate of the same nutrients were improved by 9.99%,4.17%,19.85%,12.00%,4.50% at day 22～42.The ileal digestibility of Pr, energy, Ca, P were increased significantly by 5.71%, 5.43%, 11.71%, 11.19%, but there was no significant differences in DE in ileal(P>0.05).(2) Adding 500FTU/kg phytase in the low-energy and low- phosphorus diet,was singnificantly improved the weight gain and FCR of ducks by 9.81% ,12.77%during 0～21d , separately(P<0.05).But there were no significant differences in FCR for ducks at day 22～42(P>0.05). Supplementation of 500FTU/kg phytase improved the metabolic rate of the Pr,energy,Ca,P and AME by 4.66%,2.99%,40.17%,9.20%,2.78% at day 0～21, separately and by 8.63%,0.53%,11.81%,14.61%,0.95% at day 22～42, separately. The ileal digestibility of Pr,energy,Ca,P and DE were increased significantly by 8.53%, 1.42%, 20.23%, 9.48%, 1.86%, separately.(3) The low-energy and low-phosphorus diet with 500FTU/kg phytase and 2 000u/kg xylanase was singnificantly improved the metabolic rate of the Pr, energy, Ca, and the ileal digestibility of energy, Ca and P,and the ileal digestibility of energy, Ca and P at day 42(P<0.05). The low-energy and low-phosphorus diet with 500FTU/kg phytase and 4 000u/kg xylanase was no singnificantly improved the metabolic rate of nutrients at day 0～21, but singnificantly improved the metabolic rate of energy and Pr,except P,and improved the ileal digestibility of nutrients at day 42 (P<0.05).Experiment two: A 2×3 faetorial arrangement of threatments was used with two levels of xylanase(2 000u/kg and 4 000u/kg) and three levels cellulase(0u/kg,1 000u/kg and 2 000u/kg). A total of 640 day-old Cherry Valley Ducks were randomly divided into 8 treatments with 8 replicates each treatment and 10 ducks per replicate. This experiment contained eight treatments including a positive control group,a negative control group and six treatment groups. The low-energy control diet contained a lower energy (reduced by 200kcal/kg) than the positive control.The results showed that:(1) Adding 2 000u/kg xylanase in the negative control group was singnificantly improved the metabolic rate of DM,Pr and AME at day 0～21 by 3.23%,2.95%,2.39%, separately(P<0.05),but no singnificantly improved the metabolic rate of energy. Supplementation of 2 000u/kg xylanase was singnificantly improved the metabolic rate of DM,Pr,energy and AME at day 22～42,and at day 42,improved the ileal digestibility of energy and DE by 4.59%,5.26%,separately,except that of DM,Pr.(2) Adding 4 000u/kg xylanase in the negative control group,the metabolic rate of energy and AME at day 0～21 and the ileal digestibility of Pr,DM,energy and DE were higher the that of the negative diet supplemented with 4 000u/kg,but no singnificantly improved the digestibility of nutrients for ducks at day 22～42.(3)Adding 1 000u/kg and 2 000u/kg cellulase in the negative diet supplemented with 2 000u/kg and 4 000u/kg xylanase were no singnificantly increased the metabolic rate of nutrients and the ileal digestibility of nutrients.The negative diet with 2 000u/kg xylanase and 2 000u/kg cellulase was more increased the metabolic rata of Pr than that with 2 000u/kg.Adding 1 000u/kg and 2 000u/kg cellulase in the negative diet supplemented with 4 000u/kg xylanase were not increased the metabolic rate of DM,Pr and AME. Xylanase and cellulase whether the additive effect needs further study.