Comparative Evaluation of the Functional and Immunomodulatory Properties of Raw and Spray-Dried Donkey Milk

Donkey milk contains bioactive components with immunomodulatory potential, but preservation technologies must retain these effects to support its use as a functional food ingredient. This study investigated whether spray drying preserves the in vivo biological functionality of donkey milk. Forty-five female Pannon White rabbits subjected to a standardized vaccine-induced immune challenge were randomly allocated to three groups: one Control group and two groups receiving raw or reconstituted spray-dried donkey milk (2 mL/day; n = 15/group) for four weeks. Serum lysozyme and total immunoglobulins were monitored longitudinally, while biochemical, hematological, and integrated multivariate profiles were assessed. Lysozyme increased progressively in both supplemented groups, reaching 29.4% and 33.1% above baseline with raw and spray-dried milk, respectively; cumulative responses were statistically equivalent. Total immunoglobulins recovered earlier after both treatments, reaching 31.31 and 28.92 mg/mL, respectively, versus 23.04 mg/mL in Control; their mean response profiles were closely aligned, although inter-individual variability reduced the precision of the equivalence assessment. Biochemical and hematological assessments revealed no coordinated adverse response to either milk preparation. Moreover, the integrated immune, biochemical, and hematological profiles showed strong concordance between Raw and Spray. Overall, spray-dried donkey milk retained the principal biological responses elicited by raw milk, supporting its potential development as a stable bioactive dairy ingredient.