The present study was carried out to evaluate the effect of dietary supplemental vitamin D₃ on fibroblast growth factor 23 (FGF23) signals as well as phosphorus homeostasis and metabolism in laying hens. Fourteen 40-week-old Hy-Line Brown layers were randomly assigned into 2 treatments: 1) vitamin D₃ restriction group (n = 7) fed 0 IU/kg vitamin D₃ diet, and 2) regular vitamin D₃ group (n = 7) fed 1,600 IU/kg vitamin D₃ diet. The study lasted for 21 d. Serum parameters, phosphorus and calcium excretion status, and tissue expressions of type II sodium-phosphate co-transporters (NPt2), FGF23 signals and vitamin D₃ metabolic regulators were determined. Hens fed the vitamin D₃ restricted diet had decreased serum phosphorus levels (by 31.3%, P = 0.028) when compared to those fed regular vitamin D₃ diet. In response to the decreased serum phosphorus, the vitamin D₃ restricted laying hens exhibited: 1) suppressed kidney expressions of 25-hydroxyvitamin D 1-α-hydroxylase (CYP27B1, by 52.8%, P = 0.036) and 1,25-dihydroxyvitamin D 24-hydroxylase (CYP24A1, by 99.4%, P = 0.032); 2) suppressed serum levels of FGF23 (by 14.6%, P = 0.048) and increased serum alkaline phosphatase level (by 414.1%, P = 0.012); 3) decreased calvaria mRNA expressions of fibroblast growth factor receptors (FGFR1, by 85.2%, P = 0.003, FGFR2, by 89.4%, P = 0.014, FGFR3, by 88.8%, P = 0.017, FGFR4, by 89.6%, P = 0.030); 4) decreased kidney mRNA expressions of FGFR1 (by 65.5%, P = 0.021), FGFR4 (by 66.0%, P = 0.050) and KLOTHO (by 68.8%, P = 0.038); 5) decreased kidney protein expression of type 2a sodium-phosphorus co-transporters (by 54.3%, P = 0.039); and 6) increased percent excreta calcium (by 26.9%, P = 0.002). In conclusion, the deprivation of dietary vitamin D₃ decreased FGF23 signals in laying hens by reducing serum FGF23 level and suppressing calvaria and kidney mRNA expressions of FGF23 receptors.

本研究旨在评估日粮补充维生素 D ₃对蛋鸡成纤维细胞生长因子 23 (FGF23) 信号以及磷稳态和代谢的影响。14 只 40 周龄 Hy-Line Brown 蛋鸡被随机分配到 2 个处理组：1）维生素 D ₃限制组（n =  7）喂食 0 IU/kg 维生素 D ₃饮食，2）常规维生素 D ₃组（n =  7) 喂食 1,600 IU/kg 维生素 D ₃饮食。研究持续了 21 天。II型磷酸钠协同转运蛋白（NPt2）、FGF23信号和维生素D _{3的血清参数、磷和钙排泄状态和组织表达}代谢调节剂被确定。_{与喂食常规维生素 D 3}饮食的母鸡相比，喂食维生素 D ₃限制饮食的母鸡血清磷水平降低了 31.3%，P  = 0.028 。为应对血清磷的降低，维生素 D ₃限制性蛋鸡表现出：1) 抑制 25-羟基维生素 D 1-α-羟化酶 ( CYP27B1 , 52.8%, P  = 0.036) 和 1,25-二羟基维生素 D 的肾脏表达24-羟化酶 ( CYP24A1 , 99.4%, P  = 0.032); 2) 抑制血清 FGF23 水平（14.6%，P  = 0.048）和增加血清碱性磷酸酶水平（414.1%，P = 0.012); 3) 成纤维细胞生长因子受体 ( FGFR1 , 85.2%, P  = 0.003, FGFR2 , 89.4%, P  = 0.014, FGFR3 , 88.8%, P  = 0.017, FGFR4 , 89.6%, P  = 0.030); 4) 降低肾脏FGFR1 (65.5%, P  = 0.021)、FGFR4 (66.0%, P  = 0.050)和KLOTHO (68.8%, P  = 0.038)的mRNA表达；5) 降低 2a 型钠磷协同转运蛋白的肾蛋白表达（降低 54.3%，P = 0.039); 和 6) 增加排泄物中钙的百分比（增加 26.9%，P  = 0.002）。总之，日粮维生素 D ₃的缺乏通过降低血清 FGF23 水平和抑制颅盖和肾脏 FGF23 受体的 mRNA 表达来降低蛋鸡的 FGF23 信号。