Abstract
To determine whether persimmon peel (PP) showing high chitinase activity could alleviate the detrimental dietary effects of chitin-rich shrimp meal (SM), we assessed the laying performance, nitrogen (N) balance, and egg quality of laying hens provided with SM diets containing PP. We also examined the color and antioxidant properties of egg yolk, as we anticipated these would be improved by providing SM and PP. Seventy-two laying hens (45 weeks of age) were allotted to one of the nine dietary treatments (eight hens each), namely three levels of SM (0%, 10%, and 15%)×three levels of PP (0%, 6%, and 8%), and fed with the experimental diets over a period of 6 weeks. Hen-day egg production, feed intake, egg mass, feed conversion ratio, and N balance reduced with increasing levels of SM, whereas the reductions were recovered in a dose-dependent manner in response to increasing levels of PP; however, the SM0% treatment showed that PP exerted little effects. Notably, reductions in the Haugh unit and albumen height of eggs with increasing SM levels, and recovery by provision of increasing levels of dietary PP, were observed. Yolk color was improved by SM, although PP exerted little effect, whereas the antioxidant properties of yolk were enhanced by the inclusion of both SM and PP in diets. Furthermore, eggshell strength, weight, and thickness were enhanced with increasing levels of SM, whereas dietary PP had little effect on these parameters. Thus, we suggest that PP can alleviate the negative effects of dietary SM and improve egg quality, without causing a reduction in laying performance, provided that the level of supplementary PP in diets is less than 8%. These findings accordingly indicate that PP is a promising feed constituent for laying hens fed with SM diets.