The Effects of Boron (orthoboric acid) Supplementation into Diets of Laying Hens on Egg Shell Quality and Tibia Biomechanic Parameters and Serum, Shell and Tibia Mineral Concentrations During Late Laying Period

This study was carried out to determine the effects of boron (ortoboric acid) addition into the diets of hens in the late laying period on egg shell quality, and tibia biomechanic parameters and mineral concentrations of serum, egg shell and tibia. Lohman commercial laying hens which are 62 weeks old were fed with 0, 50, 75, and 150 mg/kg of B for 12 weeks. Although the addition of B into the diet increased the egg weight (P<0.05) and improved the shell strength (P<0.06), and decreased damaged egg rate (P<0.01), the egg shell weight, shape index and shell thickness were not affected by B addition. The addition of B into the diet increased the egg shell minerals such as B, P, Ca (P<0.01) and Pb (P<0.05); and decreased Fe (P <0.01); Zn, Mg, Mn, Na and S were not affected by additional B (P>0.05). B from serum minerals increased (P <0.01); Cu, Mn, Fe, Na (P<0.01) and Ca decreased (P<0.05); Mg, Zn and P remained unchanged. The effect of B on the biomechanical properties was not significant (P>0.05), while the B mineral concentration of tibia bone increased (P <0.01), Ca, Zn, Mg, P and Mn concentrations decreased (P <0.01). It is concluded that in order to have a positive effect on egg shell quality traits and damaged egg rate of hens in the late laying period, 50 mg/kg B supplementation into the diet is adequate and may be suggested