Maternal Milk Composition in Eutherian and Marsupial Mammals

Maternal milk is a complex, dynamic fluid tailored to the developmental needs of mammalian young. In eutherian (placental) mammals, milk composition often shifts rapidly from colostrum to mature milk, supplying antibodies, signalling molecules and energy substrates in distinct temporal phases. Marsupials, by contrast, exhibit prolonged lactation phases with highly regulated delivery of macronutrients and bioactives as their altricial young develop externally. Proteins, lipids, oligosaccharides and micronutrients vary both among and within species, reflecting evolutionary adaptations to neonatal immaturity, environmental pressures and maternal metabolic constraints. Comparative studies reveal conserved mechanisms—such as early provision of immune factors and later energy‐rich lipids—while also highlighting lineage-specific innovations in milk protein genes, regulatory pathways and bioactive profiles. Understanding these patterns informs neonatal nutrition, mammary gland biology and the evolution of reproductive strategies across the mammalian clade.

Research from Nature Portfolio

Recent studies have identified a key molecular regulator of milk production efficiency across mammals. Investigation of the RNA-binding protein FUS revealed its role as a negative regulator of mammary epithelial differentiation via cell cycle pathways, linking high FUS levels to reduced lactation performance in both a marsupial model and human subjects. This work illuminates an evolutionary transition in milk output from marsupials to eutherians and suggests interventions to enhance lactation in clinical contexts. Complementing this, lipidomic analyses in a large altricial placental species demonstrated a staged shift from developmental signalling lipids—such as docosahexaenoic acid and lysophosphatidic acid—present in early colostrum to triglyceride-rich mature milk. This transition underpins central nervous system maturation initially, then sustained energy provision, and exemplifies how temporal lipid dynamics support neonatal growth trajectories in eutherian mammals.

Maternal Milk Composition in Eutherian and Marsupial Mammals publication trend

The graph below shows the total number of articles in maternal milk composition in eutherian and marsupial mammals across all publications each year (not limited to Nature Index journals).

Technical terms

Colostrum: The first milk produced postpartum, rich in immunoglobulins, growth factors and other bioactives essential for neonatal immunity and development.

Oligosaccharide: Complex carbohydrates in milk that resist digestion, promote beneficial gut microbiota and inhibit pathogen attachment.

Bioactive: A molecule in milk (e.g., peptide, lipid, growth factor) that exerts specific biological effects beyond basic nutrition.

FUS (Fused in Sarcoma): An RNA-binding protein that negatively regulates mammary epithelial differentiation and influences lactation efficiency.

Lipidomic analysis: Comprehensive profiling of lipid species in milk to characterise shifts between signalling lipids and energy-providing triglycerides.

References

1. Fused in sarcoma (FUS) inhibits milk production efficiency in mammals. Nature Communications (2024).
2. The importance of colostrum in maternal care and its formation in mammalian species. Animal Frontiers (2023).
3. Buffalo milk: an essential natural adjuvant. Discover Food (2024).
4. Changeover from signalling to energy-provisioning lipids during transition from colostrum to mature milk in the giant panda (Ailuropoda melanoleuca). Scientific Reports (2016).
5. The tammar wallaby: A marsupial model to examine the timed delivery and role of bioactives in milk. General and Comparative Endocrinology (2016).