The effects of desalted duck egg white peptides (DPs), phosphorylated DPs (PDPs) and DPs–calcium complexes (DPs-Ca) on calcium absorption in vivo were investigated. Ninety fast-growing male rats were divided into 10 groups and treated with different dosages of CaCO 3 , calcium gluconate, DPs-Ca as well as CPPs, DPs and PDPs supplemented with CaCO 3 . Eight-week oral administration results indicated that the high dosage PDPs+CaCO 3 group was significantly higher than the high dosage DPs+CaCO 3 group in calcium absorption, bone calcium content, BMD and maximum stress, but lower in ALP activity (P < 0.05). Additionally, the high dosage DPs-Ca group showed higher bone indices than the high dosage DPs+CaCO 3 , calcium gluconate and CaCO 3 groups (P < 0.05). These results suggest that in vivo, phosphorylated DPs are more effective than DPs in improving calcium absorption and bone strength, and DPs–calcium complexes are more beneficial to bone tissues than the DPs and CaCO 3 mixture.