Screening Of NSP Enzyme Combination And Dose-response Of Metabolizable Energy In Broiler Diets

The experiments aimed to study the dose-response of four Non Starch Polysaccharides (NSP) enzymes (xylanase; β-glucanase; cellulose; pectase) on the energy in broiler diet and screen the optimum enzyme combination by in vitro method. Furthermore, the dose-response of the NSP enzyme complex on Apparent Metablizable Energy in diet was investigated by in vivo methods and in vitro method. And the correlation between AME_N and in vitro digested energy (IVDE) was further discussed.The first experiment investigated the dose-response of the NSP enzyme on the energy in diet using One-way randomized erperimental design, then, sreened the optimum enzyme combination using quadratic regress-orthogonal rotary design by in vitro method. The result showed that the optimum enzyme combination was xylanase 54605.2U/kg,β-glucanase 9665.2U/kg, cellulose 757.0U/kg and pectase 222.4U/kg, and that the mutual effects were detected and the marked synergy effect exists between xylanase and cellulose(P<0.05). The effect of NSP enzyme on manipulation of energy in diet: xylanase> β-glucanase> cellulose>pectase.The second erperiment evaluated the dose-response of the NSP enzyme complex on Nitrogen-corrected apparent metalbolizable energy (AME_N), apparent protein digestibility (ACPD) and growth performance for broilers fed corn-soybean meal (SBM) diet, at the increasing levels of 0, 300, 400, 500, 600, 700, 800 & 900 mg/kg diet, using One-way randomized blocks erperimental design. The NSP enzyme complex contained 78 000 U/g xylanase, 13 800 U/g β-glucanase, 320 U/g cellulase and 1 080 U/g pectinase. The in vivo experiment was conducted at 8 treatments, using in 8 21-day-old Arbor Acres male broilers per pen and 6 replicate treatments. The experimental period was 21 day (21d to 42d). The in vitro experiment was conducted as the two-stage in vitro method, and IVDE was determined in four replicate per treatment. The result suggested NSP enzyme complex improved performance and nutrients digestibility of the broilers; average daily gain (ADG), feed conversion ratio (FCR), AME_N and ACPD increased linearly (P<0.01) with increasing levels of enzyme supplementation; however, increasing to 700mg/kg resulted in no significant additional response. AME_N increased linearly with increasing level (P<0.01) of enzyme supplementation from 300 mg/kg to 700 mg/kg, as the regression equation: AME_N (MJ/kg) = 0.0018×enzyme complex + 11.2570 (R~2 = 0.94, P<0.01, RSD=0.0475).The in vitro procedure accurately predicted AME_N in broiler diet adding NSP enzyme complex. The close relationship was detected between AME_N in vivo and in vitro digested energy (IVDE): AME_N (MJ/kg) = 0.8730×IVDE + 2.3883 (R~2 = 0.94, P<0.01, RSD=0.0622).