# Rumen-Protected Glucose Supplementation Enhances Yak Calf Growth Through Gut Microbiota–Metabolic Interactions

## TL;DR

Adding rumen-protected glucose to yak mothers' diets improves calf growth by enhancing milk quality and gut microbiota.

## Contribution

This study reveals transgenerational benefits of low-dose rumen-protected glucose supplementation in yaks through microbiota-metabolite interactions.

## Key findings

- Low-dose RPG supplementation increased milk nutrients and calf weight gain by 21.74%.
- Calves showed improved antioxidant and immune functions with higher SOD, CAT, and lower IL-6, TNF-α.
- RPG enriched beneficial gut bacteria like Akkermansia muciniphila and upregulated key metabolites.

## Abstract

This study investigated the effects of rumen-protected glucose (RPG) supplementation on calf health in periparturient yaks. The findings revealed that daily supplementation with 150 g of low-dose RPG (L-RPG) significantly increased protein, fat, lactose, and total energy content in dam milk, while concurrently promoting calf body weight gain and activating growth axis-related hormones. Furthermore, calves in the L-RPG group exhibited enhanced antioxidant capacity and improved immunomodulatory function. Multi-omics analysis further revealed that L-RPG could optimize the hindgut microbiota structure of calves, enrich beneficial bacteria such as Akkermansia muciniphila, and upregulate serum levels of metabolites associated with microbial metabolism. In summary, maternal supplementation with low-dose RPG synergistically promotes offspring growth and development by improving milk quality, modulating calf gut microbiota and host metabolism, thereby providing theoretical basis and practical guidance for integrated dam–calf health management in yak farming.

Alleviating negative energy balance in perinatal yaks is a critical challenge for safeguarding the health of both dams and calves and achieving sustainable development of yak husbandry. While RPG supplementation represents an effective nutritional strategy, its transgenerational benefits, particularly the long-term effects on offspring calf development through maternal intervention, remain largely unexplored. In the present study, low-dose RPG (150 g d−1, L-RPG, n = 6) markedly improved milk composition, elevating protein, fat, lactose, and gross energy contents (p < 0.05), and enhance calf weight gain (21.74%) with activation of the somatotropic axis (increased GH, IGF-1, etc.). Calves in this group also exhibited enhanced antioxidant capacity (higher SOD, CAT, and T-AOC) and improved immune regulation (lower IL-6, TNF-α). Multi-omics analyses revealed that L-RPG enriched beneficial taxa such as Solbacillus, Citricoccus, and Akkermansia muciniphila, optimized the hindgut microbiome, and upregulated serum metabolites including di-O-methylfraxetin and phenylalanyl-histidine. Integrated microbiota–metabolite profiling demonstrated significant cross-talk between the altered bacteria and metabolites. Collectively, supplementing dams with 150 g d−1 RPG improves milk quality, modulates the calf gut microbiota, and reshapes host metabolism, thereby synergistically promoting offspring growth. Our findings provide a comprehensive “maternal nutrition–microbiota–metabolism” framework for understanding RPG’s mode of action and furnish both theoretical insights and practical guidance for dam–calf health management in yak production systems.