Milk microbiomes: implications for neonatal nutrition and development

Citation

Bornbusch SL, Muletz-Wolz C, and Power M. 2025. Milk microbiomes: implications for neonatal nutrition and development. In Treiber K, Brooks M, D’amato-Anderson J, Nylander J, Eds. Proceedings of the Sixteenth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Oklahoma City, OK.

Abstract

Milk has long been studied as a source of vital nutrients for mammalian neonates. Although milk has, historically, been considered sterile, recent research has identified distinct communities of microbes in milk, known as milk microbiomes. These milk communities are (a) sourced from maternal and neonatal communities, (b) shaped by stochastic and deterministic factors such as evolutionary history, diet, and milk nutrients, and (c) vary across species and lactation phase. Increasing research in human and model systems indicates that milk microbiomes play key roles in neonatal health and development, particularly through interactions with milk macronutrients and the neonatal immune system. In this presentation, we review studies on the variation in milk microbiomes across host species and consider their interactions with milk nutrients. We focus, when possible, on data from non-model species (e.g., wildlife) while also drawing on the more extensive literature in humans and domestic animals. We summarize our group’s collective research on milk microbiomes in over 50 mammalian species, stemming from studies with the Smithsonian Milk Repository (Bornbusch et al., 2024; Bornbusch et al., 2022; Keady et al., 2023; Muletz?Wolz et al., 2019; Power et al., 2024). We additionally suggest future research avenues that can provide practical applications of milk microbiomes to improve neonatal health and development. In particular, we discuss the potential – and limitations – of milk microbes as biotherapeutic additions to milk replacers, focusing on recent research on supplemented formulas for human neonates.

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