Dietary stevioside supplementation improves laying performance and eggshell quality through increasing estrogen synthesis, calcium level and antioxidant capacity of reproductive organs in aged breeder hens

Aged breeder hens often exhibit a significantly decreased reproductive performance in the late laying period. The objective of this study was to investigate the effects of dietary stevioside (STE) supplementation on the laying performance and egg quality of aged breeder hens. A total of 120 aged Jinmao breeder hens (54-week-old) were randomly divided into 2 treatments: (1) basic cornsoybean diet (CON); (2) basic corn-soybean diet supplemented with 0.25 g/kg stevioside (STE). The results showed that dietary STE supplementation improved the daily egg production, daily egg mass, feed conversion rate, eggshell strength and eggshell thickness of aged breeder hens (P < 0.05). The serum triglyceride and uric acid levels were reduced, and the antioxidant capacity of the ovary and shell gland was enhanced by dietary supplementation with STE (P < 0.05). In addition, dietary STE supplementation increased the serum estrogen level via enhancing the transcription level of follicular cytochrome P450 family 19 subfamily A member 1 (CYP19A1) and hypothalamic gonadotropin releasing hormone 1 (GNRH1) (P < 0.05). Dietary STE supplementation also increased the calcium concentration in both serum and shell gland (P < 0.05). The activity of Ca2+-ATPase and mRNA expression of calcium-binding-related genes in the shell gland were increased after STE supplementation (P < 0.05). Moreover, aging-induced apoptosis and morphological damage in the shell gland were reversed by dietary supplementation with STE. In summary, dietary supplementation with STE could improve the laying performance and eggshell quality through increasing estrogen synthesis, calcium level and antioxidant capacity of reproductive organs in aged breeder hens. Our data provide an evidence that STE could be used as an anti-aging feed supplement in the production of aged breeder hens.