1, no obvious calcium deficiency: during the baby's growth and development, if there is no obvious calcium deficiency, AD and D3 can be eaten alternately for about 6 months, and complementary food can be added later to supplement calcium, such as whitebait and shrimp skin;

2. Mild calcium deficiency: If there is mild calcium deficiency in the baby's growth and development, you can supplement calcium by alternately eating AD and D3, which can generally be eaten for about 12 months, and you need to receive more outdoor sunlight to promote calcium absorption;

3, severe calcium deficiency: If the baby is severely calcium deficient, it may affect the development of bones and even cause rickets. Generally, the time for alternating eating AD and D3 needs to be extended, and it can be 18 months or about 24 months.