For preterm neonates, the quality of the first milk is crucial for intestinal maturation and resistance to necrotizing enterocolitis (NEC). Among other factors, milk quality is determined by the stage of lactation and processing. We hypothesized that unprocessed mature bovine milk (BM, raw bovine milk) would have less bioactivity than corresponding bovine colostrum (BC) in a preterm pig model, but have improved bioactivity relative to its homogenized, pasteurized, spray-dried equivalent, whole milk powder (WMP), or a bovine milk protein based infant formula (IF). For five days, newborn preterm pigs received parenteral and enteral nutrition consisting of IF (n = 13), BM (n = 13), or BC (n = 14). In a second study, WMP (n = 15) was compared with the above-mentioned IF (n = 10) and BM (n = 9). Compared with IF pigs, BM pigs had significantly improved intestinal structure (mucosal weight, villus height) and function (increased nutrient absorption and enzyme activities, decreased gut permeability, nutrient fermentation and NEC severity). BC further improved these effects, relative to BM (lactase activity, lactose absorption, plasma citrulline, and tissue IL-8). WMP induced similar effects as BM, except for lactase activity and lactose absorption. In conclusion, the maturational and protective effects on the immature intestine decreased in the order BC>BM>WMP, but all three intact bovine milk diets were markedly better than IF. The stage of lactation (colostrum versus mature milk) and milk processing (e.g. homogenization, fractionation, pasteurization, spray-drying) are important factors determining milk quality during the early postnatal period of preterm neonates.
American Journal of Physiology: Gastrointestinal and Liver Physiology, 2014, Vol 306, Issue 1