The purpose of this study was to investigate the egg freshness and eggshell characteristics of old laying hens by adding sea urchin shell powder to the feed of such hens to achieve the objectives continuously pursued by environmental management, such as business profitability and waste resource utilization. A total of 90 Hy-Line Brown layers (66 weeks of age) were randomly divided into 2 treatments with 3 replicates, each of which consisted of 15 older layers, for 4 weeks. These treatments included a control (i.e., 0%) and 2% sea urchin shell powder. The 2% supplementation of sea urchin shell powder increased the Haugh unit (HU) at 2 and 4 weeks and eggshell strength at 4 wks compared to the controls (p<0.05). The HU at 0 weeks, eggshell thickness from 0 through 3 weeks, and eggshell strength at 0 and 2 weeks were not different between treatments (p>0.05). These results suggest that the addition of 2% sea urchin powder to the feed of laying hens improves egg freshness and eggshell strength in old laying hens.

The present study aimed to examine the effects of dietary illite as a feed additive on the Haugh unit and fatty acid profiles of eggs. One hundred and twenty laying hens (48-week-old Hy-line Brown) were randomly assigned to one of the following two treatments: control or 2% illite powder. At 2 and 4 weeks, the Haugh unit values between the control and 2% illite powder groups were not significantly different (p>0.05). In addition, individual fatty acid content at 2 and 4 weeks did not differ between the treatments (p>0.05), except for palmitic (C16:0) and palmitoleic acid (C16:1) content. The addition of 2% illite powder caused no difference between the total saturated and total unsaturated fatty acids at 2 and 4 weeks (p>0.05). In conclusion, the addition of dietary illite at a rate of 2% did not improve the Haugh unit values or fatty acid profiles of eggs.