Primary Study On Optimal Supplemental Program Of Copper, Iron, Zinc And Manganese In Broiler Diet

Copper, iron, zinc and manganese are essential micronutrients for broiler growth and development, which are excessively supplemented into diet generally. Blind supplementation of trace minerals not only fail to improve growth performance and health condition of broiler, but also decrease total utilization efficiency of trace minerals, and cause a waste of mineral resource, environmental pollution and threats to human. This study was focused on industrial practice and optimal physiological status of broiler and explored effects of different supplemental patterns on growth performance, mineral and nutrient metabolism in broilers.Exp. 1 Effects of supplemental patterns of trace minerals on performance and mineral apparent retention rate in broilers.This experiment aimed to detect growth performance, indexes of immune organs and apparent mineral retention rate in broilers which were under different supplemental patterns of trace minerals. 900 1-d-old Cobb 500 broilers were randomly assigned to 5 treatments, each group contained 10 replicates with 18 broilers per replicate. The experimental period was 42 d. Industrial standard group(Industrial standard): Dietary Cu, Fe, Zn and Mn were added according to industrial standard NY/T33-2004. NRC standard group(NRC standard): Dietary Cu, Fe, Zn and Mn were supplied following NRC(1994) recommendation. NRC proportion group(NRC proportion): After measurement of mineral content in basal diet, the highest multiple of Cu in basal diet to NRC recommendation was found, and then the rest of minerals were supplemented to reach same multiple. Relative bioavailability group(Relative bioavailability): Bioavailability of minerals in feed ingredients was assumed 30% relative to sulfates, and then practical contents were transformed into valid content of equivalent sulfate. Finally, adding sulfates as NRC proportion group. All minerals in above treatments were in form of sulfate. MHA group(MHA): Relative bioavailability of methionine hydroxy analogue chelate(MHA) was assumed as 150% to sulfates, and then used MHA to replace sulfates in Treatment 3. According to results, different supplemental patterns did not cause significant differences on growth performance, mortality rate and development of immune organs in broilers(P > 0.05). Apparent retention rate of iron in broiler were not affected by supplemental patterns(P > 0.05). On 21 d, broilers in NRC proportion and MHA had significantly higher apparent retention rate of Cu(P < 0.05). On 42 d, except NRC proportion, MHA had remarkably higher apparent Cu retention rate(P < 0.05). On 21 d, apparent Zn retention rate of broilers in MHA group were significantly higher(P < 0.05). On 42 d, apparent Zn retention rate of broilers in NRC proportion and MHA group were not notably higher as compared with other treatments(P < 0.05). On 21 d, there were no significant differences in apparent Mn retention rate between Industrial S and MHA group(P > 0.05). While compared with the rest of groups, broilers in MHA had significantly higher apparent Mn retention rate(P < 0.05). On 42 d, apparent Mn retention rate of NRC standard group was significantly lower than that of other treatments(P < 0.05). Supplemental program of trace minerals caused obvious differences on apparent utilization ratio of trace minerals. Exp. 2 Effects of supplemental patterns of trace minerals on mineral metabolism and antioxidant capacity in broilersThis experiment was conducted to determine metal ion transporter expression of duodenum, antioxidant performance, mineral accumulation and excretion. The results suggested that copper transporter 1(Ctr1) expression was remarkably increased by NRC proportion and MHA pattern(P < 0.05), while no differences were found among all treatments on 42 d(P > 0.05). On 21 d, divalent metal transporter 1(DMT1) expression level of Industrial standard and BD +NRC was significantly decreased(P < 0.05), while broilers in Industrial standard and NRC proportion group had significantly lower DMT1 expression on 42 d(P < 0.05). Zinc transporter 1(ZnT1) and zinc transporter 5(ZnT5) expression in duodenum had no significant difference on 21 and 42 d(P > 0.05).On 42 d, broilers in MHA group had notably higher plasma total antioxidant capacity(T-AOC) as compared with other groups(P < 0.05). Activity of catalase in plasma of NRC proportion was significantly lower than that of Relative bioavailability and MHA(P < 0.05). Liver Mn concentration in Industrial standard broilers were significantly higher, and mRNA expression level of CuZn-SOD and Mn-SOD in liver of Industrial standard broilers were significantly higher than other treatments(P < 0.05). Positive correlation between the concentration of trace minerals in feces and supplemental concentration in basal diet was observed. Supplemental patterns of trace minerals might affect antioxidant capacity in broiler plasma through process of absorption in duodenum, Mn accumulation condition obviously regulated expression of antioxidant proteins in liver. Exp. 3 Effects of supplemental patterns of trace minerals on nutrient digestion and absorption, and nutrient metabolism in broiler liver.This experiment investigated nutrition absorption and utilization status of broiler under different supplemental patterns of trace minerals. The results showed that activity of trypsin was higher in Relative bioavailability and MHA than that of Industrial standard and NRC proportion(P < 0.05). Compared with MHA group, concentration of lysine and phenylalanine in plasma of Industrial standard and NRC proportion was decreased significantly(P < 0.05). Concentration of plasma proline was higher in NRC standard as compared with Industrial standard, NRC proportion and Relative bioavailability group(P < 0.05). No significant difference was observed in small intestinal morphology and liver nutrient metabolism among all treatments(P > 0.05). MHA pattern could improve nutrition status of plasma amino acid through increase activity of trypsin.Above all, different supplemental patterns of trace minerals could affect absorption, accumulation and excretion of trace minerals in broilers. MHA pattern increased absorption of Cu, Fe and Mn in duodenum, and improved antioxidant capacity and activity of trypsin in later broiler. However, pattern of industrial standard enhanced Mn accumulation in broiler liver and gene expression of metal contained anti-oxidative proteins.