Effects Of Adding Compound Enzyme Preparation To Diet On The Performance, Utilization Of Nutrients In Broilers

In order to provide theoretical and practical supports for the applications of compound enzyme preparations in lower-energy diet, this current study was conducted to evaluate the effects of compound enzyme preparations supplemented to corn-soybean meal diet and wheat diet on the performance, utilization of nutrients, slaughter performance, serum biochemical indexes and caecum microflora population in broilers.Eight hundred forty one-day-old AA broilers were selected and randomly placed into 7 treatments(20 birds per replication, 6 replications per treatment). Two diet types(corn-soybean meal diet and wheat diet) were adopted to this thesis, and the group 1, 2, 3, 4 were fed on corn-soybean meal diet and group 5, 6, 7 on wheat diet. As the positive control treatment, the metabolizable energy value of Group 1 was 80 kcal/kg more than others. Group 2 and 5 were as negative control Group. Group 3 was fed on corn-soybean meal diet + 200 g/T HT201, Group 4 on corn-soybean meal diet + 200 g/T US enzymes, Group 6 on wheat diet + 200 g/T HT201, and Group 7 on wheat diet + 200 DSM wheat enzyme. The results were as follows: There was no significant difference between the ADFI of positive and negative control treatments(P > 0.05), however the F:G of positive control treatments was less than the negative control treatments significantly(P < 0.01), when birds in starters(1-21 d), finishers(22-42 d) and full stage(1-42 d) on the whole. The ADG of positive control treatments was higher than the negative control significantly(P<0.01), when birds in finishers(22-42 d) and full stage(1-42 d). There was no significant difference between the ADFI, ADG and F:G of the positive and enzyme added treatments(P > 0.05). The ADM, ACP, TDM and TCP of positive control were greater than the negative and enzyme added treatments(P < 0.01). The positive control resulted in higher empty yield than the negative, but the laughter yield, empty yield, half empty yield, breast muscle yield and leg muscle yield were was similar to enzyme added treatments(P > 0.05). For 21 d broilers, the GLU and TP of positive control were significantly greater than the negative(P < 0.01), but the effect was reversed for α1-AGP(P < 0.01). For 42 d broilers, the TP of positive control were extremely more than the negative(P < 0.01), and there was an increasing trend of GLU(P = 0.0993), while be reversed for α1-AGP(P < 0.01). There was no significant difference(P > 0.05) between the positive control and enzyme added treatments for the TP, GLU and α1-AGP of 21 d and 42 d broilers. The population of lactic acid bacteria of positive control were extremely more than the negative(P < 0.01), while be reversed for E. coli(P < 0.01). The population of lactic acid bacteria of positive control were significantly greater than the enzyme added treatments(P < 0.05), but had no effect on E. coli(P > 0.05). For the treatments of corn-soybean meal diet(-80 kcal/kg): The enzyme had no effect on the ADFI in starters(1-21 d) and full stage(1-42 d). There was an increasing trend of ADFI(P = 0.078) between enzyme and no enzyme in finishers(22-42 d). The ADG and F:G of enzyme were greater than no enzyme, and the effects were significant(P < 0.01), when birds in starters(1-21 d), finishers(22-42 d) and full stage(1-42 d). The enzyme improved the apparent and true utilization of DM, OM and CP(P < 0.05), laughter yield, half empty yield(P < 0.05), GLU and TP of 21 d(P < 0.05), TP of 42 d(P < 0.01), the population of lactic acid bacteria(P < 0.05), while extremely reduced the α1-AGP of 21 d and 42 d(P < 0.01), the population of E. coli(P < 0.01),had no effect on GLU(P > 0.05). For the treatments of wheat diet(-80 kcal/kg): The enzyme had no effect on ADFI in starters(1-21 d) and finishers(22-42 d), but had an increasing trend(P = 0.0748) in full stage(1-42 d). The enzyme improved the ADG and F:G(P<0.05), the apparent and true utilization of DM and CP(P < 0.05), and there was an increasing trend(P = 0.08) for the apparent and true utilization of DM, but had no effect on slaughter performance(P > 0.05)when in starters(1-21 d), finishers(22-42 d) and full stage(1-42 d). The enzyme improved the TP in 21d(P < 0.05), and had an increasing trend(P = 0.0756) for the GLU, however extremely reduced the α1-AGP(P < 0.01). The enzyme improved the GLU and TP in 42 d(P < 0.05), but extremely reduced the α1-AGP extremely(P < 0.01). The enzyme had an increasing trend for the population of lactic acid bacteria(P = 0.0764), while extremely reduced the population of E. coli(P < 0.01).All these results indicate: The decreasing of dietary energy concentration(-80 kcal/kg) had significantly reduced the utilization of DM and CP and performance. The enzyme may improve the utilization of DM, OM and CP, and performance as the normal energy concentration. The enzyme improved laughter yield and half empty yield in corn-soybean meal diet(P < 0.05), but had no effect in wheat diet(P > 0.05), when the dietary energy concentration decreased 80 kcal/kg. The decreasing of dietary energy concentration(-80 kcal/kg) had significantly reduced the TP and GLU, but improved the α1-AGP, and the enzyme can reverse this trend and to achieve the normal energy concentration. The decreasing of dietary energy concentration(-80 kcal/kg) may reduce the the population of lactic acid bacteria, while extremely improve the population of E. coli. However, the enzyme can improve the environment of gut microflora.