抄録
The objective of this research was to evaluate effects of partial replacement of trace mineral (Cu, Mn, Zn) sulfate by methionine hydroxy analog (MHA) chelates on laying performance, egg quality, enzyme activity and mineral retention in layers. Laying hens (Hyline Brown) of 37 weeks old were fed with 4 different diets with organic or inorganic trace mineral supplementations at equal levels. Treatments are: 1) Control (CON): a basal diet was supplemented with inorganic trace minerals (sulfate source, i.e. Cu 10, Zn 30 and Mn 30 mg/kg of diet); 2) Cu-MHA: Cu in control diet was replaced with 10 mg/kg as Cu-MHA; 3) Zn-MHA: Zn in control diet was replaced with 20 mg/kg as Zn-MHA; 4) Mn-MHA: Mn in control diet was replaced with 20 mg/kg as Mn-MHA. Experiment lasted for 14 weeks from 39 to 52 wk of age. Results showed that eggshell thickness was increased (P ≤ 0.05) by Mn-MHA and Zn-MHA supplementation. The supplementation of organic minerals increased (P ≤ 0.05) Haugh unit after 10 d storage. Ceruloplasmin (CP, P = 0.051), carbonic anhydrase (CA, P ≤ 0.05) and Mn-superoxide dismutase (SOD, P ≤ 0.05) activities were increased in animals treated with organic minerals. Compared with control group, Cu-MHA significantly increased (P ≤ 0.01) Cu concentration in liver, and Zn-MHA increased (P ≤ 0.05) Zn concentration in yolk. No difference was found in Mn concentration between the two Mn sources. Interactions between mineral sources and feeding length were observed in yolk Cu (P ≤ 0.01), tibia Zn (P ≤ 0.05), liver (P ≤ 0.05) and yolk (P = 0.063) Mn retention. In conclusion, MHA chelates of trace minerals (Cu, Zn and Mn) showed higher bioavailability compared with the sulfates when fed to laying hens.
