Effects of supplementing natural astaxanthin from Haematococcus pluvialis to laying hens on egg quality during storage at 4 degrees C and 25 degrees C

The objective of this study was to evaluate the effects of different levels of dietary natural astaxanthin (ASTA) (from the microalga Haematococcus pluvialis) and storage at 4 degrees C and 25 degrees C on the quality of eggs from laying hens. Nongda No. 3 laying hens (n = 450) were randomly allocated to 1 of 5 dietary treatments. Each treatment had 6 replicates of 15 hens each. All birds were assigned to a corn-soybean meal- based diet containing 0, 20, 40, 80, or 160 mg/kg natural ASTA for 4 wk. A total of 540 eggs were collected at the end of the 4-week feeding trial. Sixty fresh eggs were collected and measured for egg quality within 24 h after collection. The other 480 eggs were used in a factorial arrangement with 5 dietary ASTA levels, 4 storage times, and 2 storage temperatures. During the 8-week storage period at 4 degrees C and 25 degrees C, egg quality measurements were performed every 2 wk on 12 eggs per treatment. No significant effects (P 0.05) on yolk index, yolk pH, Haugh units, weight loss, or eggshell strength were observed with increasing concentrations of dietary ASTA. Yolk color darkened linearly with increasing dose of ASTA (P < 0.05). During storage of eggs, yolk index and Haugh units decreased significantly (P < 0.05), whereas yolk pH and weight loss increased (P < 0.05). An interaction was observed between dietary ASTA level and storage time on yolk index, yolk color, and Haugh units (P < 0.05). These results demonstrated that dietary ASTA from H. pluvialis delayed the decrease in yolk index and yolk color during storage at 4 degrees C and 25 degrees C. Therefore, we speculate that there may be a combined effect of dietary ASTA level and storage time on egg internal quality; this information may provide additional options by which to extend the storage time of eggs.