Pasteurization Procedures for Donor Human Milk Affect Body Growth, Intestinal Structure, and Resistance against Bacterial Infections in Preterm Pigs.

Holder pasteurization (HP) destroys multiple bioactive factors in donor human milk (DM), and UV-C irradiation (UVC) is potentially a gentler method for pasteurizing DM for preterm infants. We investigated whether UVC-treated DM improves gut maturation and resistance toward bacterial infections relative to HP-treated DM. Bacteria, selected bioactive components, and markers of antioxidant capacity were measured in unpasteurized donor milk (UP), HP-treated milk, and UVC-treated milk (all from the same DM pool). Fifty-seven cesarean-delivered preterm pigs (91% gestation; ratio of males to females, 30:27) received decreasing volumes of parental nutrition (average 69 mL · kg · d) and increasing volumes of the 3 DM diets ( = 19 each, average 89 mL · kg · d) for 8-9 d. Body growth, gut structure and function, and systemic bacterial infection were evaluated. A high bacterial load in the UP (6×10 colony forming units/mL) was eliminated similarly by HP and UVC treatments. Relative to HP-treated milk, both UVC-treated milk and UP showed greater activities of lipase and alkaline phosphatase and concentrations of lactoferrin, secretory immunoglobulin A, xanthine dehydrogenase, and some antioxidant markers (all < 0.05). The pigs fed UVC-treated milk and pigs fed UP showed higher relative weight gain than pigs fed HP-treated milk (5.4% and 3.5%), and fewer pigs fed UVC-treated milk had positive bacterial cultures in the bone marrow (28%) than pigs fed HP-treated milk (68%) ( < 0.05). Intestinal health was also improved in pigs fed UVC-treated milk compared with those fed HP-treated milk as indicated by a higher plasma citrulline concentration (36%) and villus height (38%) ( < 0.05) and a tendency for higher aminopeptidase N (48%) and claudin-4 (26%) concentrations in the distal intestine ( < 0.08). The gut microbiota composition was similar among groups except for greater proportions of in pigs fed UVC-treated milk than in pigs fed UP and those fed HP-treated milk in both cecum contents (20% and 10%) and distal intestinal mucosa (24% and 20%) (all < 0.05). UVC is better than HP treatment in preserving bioactive factors in DM. UVC-treated milk may induce better weight gain, intestinal health, and resistance against bacterial infections as shown in preterm pigs as a model for DM-fed preterm infants.