effect of different levels of manganese and zinc on shells with translucent areas, haugh unit, mortality, percentage of ash in eggshell and composition of eggshell in laying hens

this experiment was carried out to study the effect of manganese in four levels (30, 60, 90 and 120 mg/kg) and zinc in four levels (50, 100, 150 and 200 mg/kg) on shells with translucent areas, haugh unit, mortality, percentage of ash in eggshell and composition of eggshell in laying hens, in a completely randomized design and in a 4×4 (16 treatment) factorial arrangement, three hundred and twenty (320) white leghorn laying hens, strain hy-line w36 and 28 weeks old were divided in to 64 replicate, five hens per replicate. the experimental period lasted 90 day until hens were 40 weeks of age. the result indicated that manganese and zinc in combination and alone had not a significant effect on mortality and haugh unit but had a significant effect on percentage of ash in eggshell and shells with translucent areas (p<0.01).