Donor milk has become a standard of care for feeding preterm infants, particularly those with gestational ages of 34 weeks or less, whose mothers are not lactating or not producing sufficient milk quantities. However, prior to distribution, donor milk is required to undergo pasteurization, typically using the Holder method, which is believed to destroy immune proteins in the milk and denature many other proteins. Donor milk has been found to contain concentrations of chemokines, cytokines, and growth factors, evidencing the value of donor milk over formula. In light of the findings, donor milk is supplemented with chemokines, cytokines, and growth factors that are found to be lower in the donor milk as compared to mother's own milk.