This study was carried out to determine the effect of different 
forms of Zn and Mn on mineral concentrations and some 
parameters of tibia and liver in laying hens. 162 LSL laying hens 
30-weeks old were randomly allocated to nine dietary treatments, 
each of six replicates (3 birds each). Birds were distributed in a 
factorial design of (3 zinc forms × 3 manganese forms: inorganic, 
organic, and nanoparticles), birds were fed until the age of 46 
weeks. Inorganic forms of Zn and Mn were supplemented at 60 
mg/kg and 100 mg/kg, respectively, while, organic and nano 
forms were supplemented at 50% of the inorganic level. The 
results indicated that the main effect of dietary Zn-NPs reduced 
tibia weight (P< 0.01), and tibia Zn concentration (P< 0.01), 
while Zn concentration was higher (P< 0.05) in the liver when 
birds were fed Zn-NPs. The main effect of Mn forms had no 
effect on all tibia and liver parameters. However, the interaction 
between Zn and Mn forms showed that feeding Zn-Met with MnNPs significantly reduced (P< 0.01) tibia Zn content. Also, 
feeding Zn-NPs with Mn-oxide or Zn-NPs with Mn-Met led to a 
significant increase (P< 0.05) in liver Zn content. The 
interactions had no effect on tibia length or tibia ash percent. 
However, the interaction had a significant effect on tibia weight 
(P< 0.05). In conclusion, replacing the inorganic form of dietary 
Zn and Mn with Nano forms at 50% of the inorganic form can 
highly increase Zn concentration in the liver.