# Untargeted metabolomics reveals stage-specific metabolic signatures in yak colostrum, transitional milk and mature milk

## TL;DR

This study identifies unique metabolic profiles in yak colostrum, transitional milk, and mature milk, revealing their roles in immune support, energy metabolism, and neurodevelopment.

## Contribution

The study provides the first comprehensive untargeted metabolomics analysis of yak milk across lactation stages.

## Key findings

- Yak colostrum contains higher levels of essential nutrients and bioactives compared to transitional and mature milk.
- Metabolites in yak colostrum support neonatal immune defense and neurodevelopment, while mature milk supports sustained energy metabolism.
- Yak colostrum and transitional milk are linked to circadian rhythm regulation and cognitive function under high-altitude hypoxia.

## Abstract

Yak milk's stage-specific metabolic profiles remain largely uncharacterized. In this study, yak colostrum (YC) was found to contain higher levels of essential components (e.g., milk fat, lactose, lactoprotein and non-fat solids) than transitional (YT) and mature milk (YM). A comprehensive untargeted profiling was conducted using UHPLC-Q Exactive HF-X to investigate the metabolic signatures of YC, YT and YM. A total of 2005 metabolites were identified. Metabolites enriched in YC were implicated in promoting intestinal microbiota colonization and supporting neonatal immune defense and neurodevelopment. In contrast, YM exhibited a metabolomic profile associated with sustained energy metabolism and the maturation of adaptive immune responses. YT exhibited a hybrid profile containing select bioactives characteristic of both YC and YM stages. Metabolites in YC and YT showed dynamic changes associated with circadian rhythm regulation and cognitive function under high-altitude hypoxia. This study reveals lactation-stage dynamics and supports functional development of yak milk products.

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•2005 stage-specific metabolites were identified in three stages of yak milk.•Yak colostrum has higher level of sialylated oligosaccharides and choline.•Yak colostrum and transitional milk implicate in circadian rhythm regulation.•Yak milk support neurocognitive development in low-oxygen environment.

2005 stage-specific metabolites were identified in three stages of yak milk.

Yak colostrum has higher level of sialylated oligosaccharides and choline.

Yak colostrum and transitional milk implicate in circadian rhythm regulation.

Yak milk support neurocognitive development in low-oxygen environment.