Bovine Colostrum Before or After Formula Feeding Improves Systemic Immune Protection and Gut Function in Newborn Preterm Pigs.

Objectives: Maternal milk is often absent or in limited supply just after preterm birth. Many preterm infants are therefore fed infant formula as their first enteral feed despite an increased risk of feeding intolerance, necrotizing enterocolitis (NEC), and infection. Using preterm pigs as a model for preterm infants, we hypothesized that bovine colostrum given before or after formula feeding would alleviate formula-induced detrimental effects during the first days after preterm birth. Methods: A total of 74 preterm pigs received gradually increasing volumes of formula (F) or bovine colostrum (C) until day 5, when they were euthanized or transitioned to either C or F for another 4 days, resulting in six groups: C or F until day 5 (C5, F5, n = 11 each), C or F until day 9 (CC, FF n = 12-13 each), C followed by F (CF, n = 14), and F followed by C (FC, n = 13). Results: Systemically, colostrum feeding stimulated circulating neutrophil recruitment on day 5 (C5 vs. F5, P < 0.05). Relative to initial formula feeding, initial colostrum feeding promoted the development of systemic immune protection as indicated by a decreased T-helper cell population and an increased regulatory T-cell population (CC + CF vs. FC + FF, P < 0.01). In the gut, colostrum feeding improved intestinal parameters such as villus heights, enzymes, hexose absorption, colonic goblet cell density, and decreased the incidence of severe NEC (27 vs. 64%), diarrhea (16 vs. 49%), and gut permeability on day 5, coupled with lowered expression of LBP, MYD88, IL8, HIF1A, and CASP3 (C5 vs. F5, all P < 0.05). On day 9, the incidence of severe NEC was similarly low across groups (15-21%), but diarrhea resistance and intestinal parameters were further improved by colostrum feeding, relative to exclusive formula feeding (CC, CF, or FC vs. FF, respectively, all P < 0.05). The expression of MYD88 and CASP3 remained downregulated by exclusive colostrum feeding (CC vs. FF, P < 0.01) and colostrum before or after formula feeding down regulated HIF1A and CASP3 expression marginally. Conclusion: Colostrum feeding ameliorated detrimental effects of formula feeding on systemic immunity and gut health in preterm newborns, especially when given immediately after birth.