Effects of duration and supplementation dose with astaxanthin on egg fortification

Abstract

Long-term and graded dose of astaxanthin supplementation in laying hen's diet was assessed for egg fortification. Five groups of laying hens with 8 replications each were fed for 24 wk with diet supplemented astaxanthin at 0 mg/kg (control), 7.1 mg/kg, 14.2 mg/kg, 21.3 mg/kg, and 42.6 mg/kg (Basal, A7, A14, A21, and A42, respectively). The performance of laying hens, egg quality, astaxanthin concentration as well as conversion efficiency and geometric isomers proportion in yolks were assessed on wk 8 and 24. One-way analysis of variance (ANOVA) and linear and quadratic regression analyses were used to evaluate the dose effect. In parallel, the Student's t test compared the values between wk 8 and wk 24 of test within a group. Overall, the results revealed that neither production performance nor egg physical quality was affected by astaxanthin dose level and feeding duration. Following the supplementation dose, the redness of yolks (a*) increased (P < 0.001). But, the a* score in A42 (23.48) was just 3-folds the a* score in A7 (8.89). Concentration of astaxanthin in eggs was dose-level dependent showing a linear relationship (P < 0.001) with a slight declination observed in all groups on wk 24 compared to wk 8. The deposition rate of astaxanthin into egg yolk was higher in A21 and A42. The proportion of geometric isomers in egg yolk were not affected by the feeding duration. As the supplementation dose increased, all-trans isomer proportion gradually decreased in the egg yolk, while 13-cis isomer proportion rose. It was concluded that astaxanthin is an efficient carotenoid for egg fortification, which can be supplemented in diet up to 42.6 mg/kg for 24 wk without compromising the performance of laying hens or physical quality of eggs. This appreciably affects the egg yolk color and confers a better accumulation of total astaxanthin and cis isomers into eggs as the supplementation dose increases.

Keywords: astaxanthin; fortification; geometric isomer; laying hen; long-term supplementation.

Figure 1

Color test values of egg yolks analyzed on wk 8 and wk 24. Data are presented as means ± SEM (n = 8). a–e: different letters within a time of test indicate significant difference between groups (P < 0.05). ns: no significant difference with t test between wk 8 and wk 24. L*: lightness, a*: redness, b*: yellowness. Basal, A7, A14, A21, and A42 correspond to the different groups of laying hens fed diet supplemented with astaxanthin at 0 mg/kg (control), 7.1 mg/kg, 14.2 mg/kg, 21.3 mg/kg, and 42.6 mg/kg respectively.

Figure 2

Linear regression plotting of astaxanthin concentration in egg yolk according to the dose supplementation in feed analyzed on wk 8 (A) and wk 24 (B) and deposition rate of astaxanthin into eggs from different groups calculated on wk 8 and 24 (C). Data in (C) are presented as means ± SEM. n = 7. a–b: different superscript letters within a time of test indicate significant difference between groups (P < 0.05). Astaxanthin feed: astaxanthin supplementation dose in feed (mg/kg). Astaxanthin yolk: astaxanthin concentration in egg yolk (µg/g). Astaxanthin yolk rate: deposition rate of astaxanthin into egg (%). A7, A14, A21, and A42 correspond to the different groups of laying hens fed diet supplemented with astaxanthin at 7.1 mg/kg, 14.2 mg/kg, 21.3 mg/kg, and 42.6 mg/kg respectively.

Figure 3

Astaxanthin isomers proportion in total astaxanthin analyzed in egg yolks on wk 8 (wk8) and wk 24 (wk24). n = 7. A7, A14, A21, and A42 correspond to the different groups of laying hens fed diet supplemented with astaxanthin at 7.1 mg/kg, 14.2 mg/kg, 21.3 mg/kg, and 42.6 mg/kg respectively. Bars correspond to SEM. Different letters show significant differences between groups for same isomer (P < 0.05).