| The supplementation of trace minerals were often blindly carried out in the process of poultry production. A common practice is to supplement 1~3 times of trace mineral as NRC recommendations without considering the concentrations contained in basal diets, which leaded excessive concentrations in the complete diet and impaired the balance among minerals. Plenty of minerals were excreted from poultry manure, and the environmental pollution by trace mineral has increasingly attracted public attention. Thus, the objective of the present study was to investigate the interaction and optimal supplementation of the copper, iron, zinc and manganese for pullets and laying hens.1. Study on the optimal supplementation of zinc and manganese for layers. As many scientists reported, iron was often found to be with excessive concentrations in laying hen diets, which may cause great antagonistic interactions with other minerals. This study was conducted to investigate how to supplement zinc and manganese in the diets without iron added. In experiment one, four hundred and sixty 18-week Lohman Brown layers were fed a basal diet or a basal diet supplemented with 30-0, 65-30, and 100-60 mg/kg of zinc and manganese, respectively. In experiment two, three hundreds and sixty 40-week Lohman Brown layers were fed a basal or a basal diet supplemented with 15-0, 35-0, and 55-15 mg/kg of manganese and zinc, respectively. Both zinc and manganese in this study were supplemented in the form of sulfate. Egg production was improved by 30Zn or 65Zn30Mn treatments in experiment one. In experiment two, a significant reduction of egg performance occurred by 35 mg/kg manganese supplementation. Manganese and/or zinc supplementation increased eggshell thickness for aged layers, and decreased yolk cholesterol in both experiments. Serum growth hormone (GH), thyroxine (T4), and insulin levels, or alkaline phoshpatase (AKP) activity was not affected by treatments, serum estrogen, and triiodothyroninie (T3) were different but there was no consistency by dietary treatments. This study demonstrates that 30.00 mg/kg zinc seems most necessary to be added to obtain the maximal egg production, and there seems no need to supply manganese if iron supplementation is canceled. 2. Study on the optimal supplementation of copper, iron, zinc, and manganese for pullets and layers. One throunds and five hundreds females of an egg-laying strain (60-d old, Lohmann Brown) were used by the quadratic general rotary unitized design (four factors, half done). Copper, iron, zinc and manganese were all supplied in the form of sulfate, and the experiment was conducted till the end of 35 week of age. If significances were established at P﹤0.05,trace mineral supplementation did not affect the weight gain, feed intake and F:G (Feed: Gain) for pullets, and also did not affect hen-d egg production, egg mass, feed intake, and F:E (Feed:Egg) for layers. RBC and Hct of pullets did not response with the various supplementations of the four minerals, but Hb concentration was affected by the supplemental amount of copper and manganese; RBC and Hct of layers were also not affected but Hb responded to dietary supplemental zinc. Activities of total serum SOD for pullets or Mn-SOD for layers was affected by iron and copper supplementation and iron and zinc supplementation, respectively. If significances were established at P﹤0.2, growing performance for pullets, laying performance for laying hens, indices of hematological, and SOD activities were responded to the supplementation of the four minerals.Based on results of the present research, it is concluded that mineral concentrations of basal diets seems to be with great variability, of which iron varied the most and followed by zinc and manganese, however, copper showed a relatively consistent concentrations. Thus it is difficult to make suitable schemes for trace minerals supplementation due to the great variable concentrations of the basal diets. Copper, iron, zinc and manganese supplied by natural ingredients seemed to be adequate enough and not affected the growth performance for pullets, but copper seemed to be a potential element adversely affected the daily weight gain (P=0.1288), thus, we suggested approximately 15.00 mg/kg copper should be added to be with a total of 35.00 mg/kg dietary copper for pullets. In the laying period, minerals should be supplemented according the concentrations of iron contained in basal diet and it seems no need to supplement manganese due to the contribution by limstone. In those diets with high iron concentrations (500~800 mg/kg), approximately 30 mg/kg zinc should be considered for necessary supplementation; In diets those with moderate iron contents (150~250 mg/kg), the four minerals seems to be adequate to support laying productivity, but iron shortage potential affected hen-d egg production (P=0.1799), thus, we suggested approximately 100.00 mg/kg iron should be supplemented, with a total iron concentration of 300.00 mg/kg.
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