| This study was aimed to investigate the relative bioavailability of organic manganese and the effects of dietary Mn levels on the weaned piglets, so as to obtain the suitable Mn level of weaned piglets. The experiment contains two parts.The first part was carried out to determine the bioavailability of organic Mn(Mn-Gly and Mn-AA) relative to inorganic source(Mn SO4.H2O) in the weaned piglets. A total of two hundred and twenty-four post-weaning piglets(Duroc× Landrace × Largewhite,9.67±0.13 kg) were randomly allotted to one of four replicate(eight piglets per replicate)for each of seven treatments in completely randomized design involving a 3×2 factorial arrangement of treatments with three levels of added Mn(0, 20, 40 mg Mn/kg)and three Mn sources(Mn-Gly, Mn-AA and Mn sulfate) plus a control with no added Mn for an experimental phase of 35 d, including 7 days adaption. The result showed that the growth performance, serum Mn, Mn-SOD activity, heart Mn content, kidney Mn content, pancreas Mn content, in different groups of Mn source or source×level interaction were not significantly different(P > 0.05). However, the liver and bone Mn content was affected by Mn source and Mn level(P < 0.05). Based on slope ratios from multiple linear regression of these two items on dietary supplemental Mn intake, the relative bioavailabilities of Mn-Gly and Mn-AA were 125.95% and 112.79% for liver Mn content and 133.08% and 119.25% for metatarsal bone Mn content com ared to 100% of Mn sulfate, respectively. Mn-Gly and Mn-AA were more available(P < 0.05) than Mn sulfate, but there were no significant difference between Mn-Gly and Mn-AA(P > 0.10).The second part was carried out to study the influence of dietary manganese on the weaned piglets. a total of one hundred and sixty post-weaning piglets(Duroc× Landrace × Largewhite,9.84±0.85 kg) were randomly allotted to one of four replicate(eight piglets per replicate)for each of five treatments in a completely randomized design. Dietary treatments included the basal diet(Control, 39.22 mg Mn/kg) supplemented with4, 20, 40, and 80 mg Mn/kg of diet from manganese sulfate, and the piglets received the diets for 28 days after 7 days adaptation. the results showed the serum Mn content, tissue Mn content, liver Mn-SOD activity and Mn-SOD m RNA level were significantly affected by the added Mn in dietary, and increased linearly and quadratically as dietary Mn level increased(P < 0.05). However, the serum Fe content, liver Fe content, metatarsal bone Fe content, hemoglobin, the digestibility of Fe decreased significantly by the added Mn in dietary, and decreased linearly and quadratically as dietary Mn level increased(P < 0.05). Besides, the duodenum DMT1 and FPN1 m RNA level were significantly affected by the added Mn in dietary, and taking all the indicators into consideration, the suitable level of manganese supplementation for weanling piglets is 4~20 mg/kg... |
