Abstract
This study was conducted to determine the effect of 25-hydroxyvitamin D (HDV) and essential oils (EO) on the uterus antioxidant capacity, egg quality, and eggshell ultrastructure in laying hens. A total of 400 48-wk-old Lohmann laying hens were randomly allocated into 2 groups and fed a basal diet (control) or a basal diet supplemented with a combination of 69 μg/kg HDV and EO (including 200 mg/kg thymol and 50 mg/kg carvacrol) for 12 wk. There are 10 replicates of 20 hens each. Compared with the control, dietary HDV+EO supplementation improved (P < 0.05) egg production rate, feed efficiency, eggshell thickness and strength, and decreased (P < 0.05) the translucent egg score. Ultrastructural changes indicated that dietary HDV+EO supplementation decreased (P < 0.05) mammillary knob width, mammillary thickness and the proportion of mammillary thickness, and increased (P < 0.05) the proportion of effective thickness and total thickness of the eggshells compared with the control. Supplementation with HDV+EO complex led to higher serum HDV concentration and increased antioxidant capacity in the uterus, indicated by higher (P < 0.05) antioxidant enzyme activities (catalase [CAT], total antioxidant capacity [T-AOC], and glutathione S-transferases [GST]) and lower malondialdehyde (MDA) content. Therefore, dietary HDV and EO complex (including thymol and carvacrol) supplementation can improve the productive performance and the eggshell quality in laying hens, and the improving effect on eggshell quality may through enhancing eggshell ultrastructure and antioxidant capacity of uterus.