DIETARY ORGANIC TRACE MINERALS LEVEL INFLUENCES EGGSHELL QUALITY AND MINERALS RETENTION IN HENS

The objective of this study was to investigate the effect of reduced levels of Cu, Zn, Mn in combination from organic mineral source on eggshell quality and mineral retention in hens. After feeding the basal diet (8.82 mg/kg Cu, 24.94 mg/kg Zn, and 16.38 mg/kg Mn) without Cu, Zn, and Mn addition for 4 weeks, hens (39-week-old) were assigned to 5 treatments according to the equal body weight and egg production for 12-week experimental trial. The 5 treatments included the basal diet without Cu, Zn, and Mn (NCON), and NCON added with 16-80-60 mg/kg Cu-Zn-Mn from sulfates (ITM100%), or 4-20-15, 8-40-30 or 16-80-60 mg/kg Cu-Zn-Mn from 2-hydroxy-4-(methylthio) butanoic acid (HMTBA) mineral chelates (OTM25%, OTM50% or OTM100%). Supplementation of Cu, Zn, and Mn had no significant influences on the performance of hens. After 12 weeks feeding, eggshell breaking strength (EBS) decreased in the following order: OTM25% and ITM100% > OTM50% > NCON and OTM100%. The eggshell weight and thickness in OTM25% were greater than that in NCON, while not differing from that in ITM100%. The EBS and eggshell weight linearly decreased with increasing level of OTM. After 12 weeks feeding, supplementation of Cu, Zn, and Mn increased the concentrations of liver Zn, tibia Zn and Mn, and Zn and Mn retention in eggs as compared with NCON. No significant difference was observed in the concentrations of Cu, Zn, and Mn in liver and plasma, and Zn and Mn in eggs between any OTM treatment and ITM100% groups. Addition of OTM at increasing level had quadratic effect on tibia Cu, Zn, Mn concentrations, with the greater retention of Cu, Zn, and Mn in OTM50%. In conclusion, the OTM25% from HMTBA mineral chelates can substitute for ITM100% evaluated by the eggshell quality in the diet of laying hens.