摘要This study explored the effects of uterine inflammation on eggshell mineralization,ultrastructure and mechanical properties in laying hens modified by a lipopolysaccharide(LPS)challenge or dietary essential oil(EO)addition.In trial 1,a total of 72 Hy-line Brown layers at 36 wk of age were randomly assigned to 3 treatment groups(n=8),where they were intravenously injected with phosphate buffered saline,LPS at 1 mg/kg body weight,or LPS 3 times at 24-h intervals.In trial 2,a total of 288 Hy-line Brown layers at 60 wk of age were randomly divided into 4 groups(n=8),where they were fed basal diets supplemented with EO at 0,50,100 and 200 mg/kg for 12 wk.A uterine inflammation model was constructed with LPS treatment,indicated by the elevated expression of IL-1β and TNF-α(P＜0.05)and lymphocyte infiltration.Uterine inflammation caused remarkable decreases in eggshell thickness and mechanical properties with structure deteriorations(P＜0.05).Uterine inflammation stimulated the expression of matrix proteins ovotransferrin(TF)and ovalbumin(OVAL),while depressing the mRNA levels of calbindin-1(CALB1)and osteopontin in uterine mucosa(P＜0.05).In contrast,EO addition alleviated uterine inflammation,evidenced by depressed levels of IL-1 β and IL-6(P＜0.05).There was a significant elevation in shell thickness and breaking strength following EO intervention(P＜0.05),and these effects were maximized at addition of 100 mg/kg.Further,EO improved shell ultrastructure including more early fusion,less type B mammillae,and increased effective thickness(P＜0.05).The alleviated inflammation decreased the expression of OVAL and TF,whereas ion transport genes like CALB1 and solute carrier family 26 member 9 were upregulated(P＜0.05).Our findings suggest that inflam-matory status can impact uterine functions in calcium transport and the synthesis of matrix proteins especially such as OVAL and TF,which in turn modulates calcium precipitation and ultrastructure for-mation,thereby determining eggshell mechanical properties.These findings provide a novel insight into the uterine inflammation-mediated modifications of eggshell quality.