The Effect Of Supplementing Zn, Mn, Cu, And Fe On Production Performance, Nutrient Utilization, And Biochemical Status In Layers

The experiment was conducted to evaluate the effect of dietary contents and combinations of Zn, Mn, Cu and Fe on production performance, apparent availability of these elements, egg quality and some hormones of laying hens. The experiment comprised 525 19-wk-old Lohmann Brown laying hens in 5 groups. The basal diet contained Zn, Mn, Cu and Fe at 76, 90, 14 and 869 mg/kg, respectively. The experimental diets were supplemented with trace minerals (inorganic forms) at different level. A) the control group without trace mineral supplementation, B) supplementation 29 mg/kg of Zn, C) supplementation 64 mg/kg of Zn, 30 mg/kg of Mn and 3 mg/kg of Cu, D) supplementation 99 mg/kg of Zn, 60 mg/kg of Mn and 7 mg/kg of Cu, E) supplementation 17 mg/kg of Zn, 15 mg/kg of Mn, 2 mg/kg of Cu and 30 mg/kg of Fe.At the end of experiment, egg samples were collected and stored at–4℃for determination of yolk color, concentration of yolk cholesterol, and egg mineral contents. Blood samples were collected at , 2h, 4h and 12h after feeding. The plasma were stored at–76℃for determination of the level of plasma cholesterol, AST, ALP, growth hormone (GH), 3,5,3`-triiodothyronine (T₃), thyroxine (T₄), extrogen (E₂) and insulin.In conclusion, egg production of group A was significantly lower than other groups (P<0.01). Daily egg yield of group B was significantly increased (P<0.05). The contents of Zn, Mn, Cu and Fe in excreta were related to their dietary content (P<0.05). The apparent availability of Zn, Cu, Fe were not affected by dietary contents of Zn, Cu, Fe (P>0.05). The apparent availability of Mn was significantly affected by dietary content of Mn (P<0.05). A significant reduction was found in the egg yolk cholesterol concentration with group B (56.78%, P<0.01), group C (45.71%, P<0.01), group D (48.82%, P<0.01) and group E (18.44%, P<0.05). The content of Zn in egg was declined while it was increased in the diet, the content of Mn in egg was increased with the increasing of dietary content of Mn, the content of Cu in egg was increased, and then declined with the increasing of dietary content of Cu. The yolk color of group B and group D were better than others (P>0.05).