Calcium (Ca) and phosphorus (P) are essential mineral elements in pigs, which play an important role in bone development, energy utilization and signal transduction. Inadequate or inappropriate ratio of Ca to P in diets may affect the normal growth and development of pigs (Gonzalo et al., 2018). Vitamin D, as an important nutrient in the body, acts a pivotal part in regulating Ca and P homeostasis, maintaining growth and development of bone (Plum & Deluca, 2010). It is stated that age, sex, dietary vitamin D intake and sunlight exposure were associated with circulating 25(OH)D 3 concentration (Livingstone et al., 2017). Vitamin D is mainly produced in the skin or ingested from the diet (Holick, 2011). At ultraviolet B-type (UVB) exposure, vitamin D synthesis occurs in the skin and is affected by the duration and the intensity of the light (Judistiani et al., 2019). Vitamin D supplementation is more effective than sunlight exposure in increasing circulating