Eggshell Quality Comparison between Blue-Shelled and White-Shelled Eggs of Brown Tsaiya Ducks

ABSTRACT

This study aimed to compare the egg quality between the bluish-shelled (BSh) and whitish-shelled (WSh) eggs of Taiwanese Tsaiya ducks. Experiments were conducted to determine eggshell thickness and strength, heat absorption capability, and egg yolk lipid peroxidation. Our results showed that the eggshell thickness and strength of BSh eggs were higher than that of WSh eggs during both the autumn and winter seasons (p<0.05). The egg surface temperature in either indoors and outdoors conditions was higher in the BSh group than in the WSh group. The extent of lipid peroxidation was determined to analyze the anti-oxidative ability of egg yolk. When eggs were stored at room temperature in autumn for 0 day and 7 days, the levels of thiobarbituric acid reactive substances (TBARS) in BSh eggs (1.21±1.04 and 1.49±0.69, respectively) were lower than those of WSh eggs (3.42±1.32 and 3.74±1.86, respectively) (p<0.05). Moreover, TBARs in the BSh group stored at 4°C for 14 days were also lower than those of the WSh group, indicating that despite the heat absorption capability of BSh eggs being higher, the anti-oxidative ability remained sound. Then, we determined serum red blood cells, which are the original source of the anti-oxidant component biliverdin in the egg shell. The results showed that the levels of red blood cells and packed cell volume in the BSh group were higher than those of the WSh group (p<0.05). All in all, we suggest that BSh eggs with higher eggshell thickness and strength and antioxidant capacity may possess greater quality and shelf life.

Keywords:
Blue-shelled eggs; white-shelled (WSh) eggs; eggshell thickness; eggshell strength; Lipid peroxidation