Galaxis® Microbes Restructure Rumen Genetics to Boost Milk-to-Feed Efficiency

In 2024, research out of the University of Florida (Nehme Marinho et al. (2024)) showed that rumen-native microbes help cows make more milk (+3-4 lbs. ECM), more efficiently (+0.04-0.08 pts ECM/DMI). But how? The latest research from the University of Florida, recently published by Journal of Dairy Science, builds on this original Holstein cow dataset and dives into the changes in rumen genetics, rumen fermentation metabolites, host metabolic markers, and total tract digestibility that help shed light on mechanism of action. Galaxis and Galaxis Frontier were studied in this trial.

Key Performance Results

Daily per-head yields of milk and milk components increased without expected increases in dry matter intake, driving a significant improvement in feed efficiency (lbs. ECM / lbs. DMI):

• Milk yield increased: 3.1 lbs. with Galaxis; 3.5 lbs. with Galaxis Frontier. 

• ECM yield increased: 3.0 lbs. with Galaxis; 4.4 lbs. with Galaxis Frontier. 

• Milk protein yield increased: 0.09 lbs. with Galaxis; 0.09 lbs. with Galaxis Frontier.

• Milk fat yield increased: 0.13 lbs. with Galaxis; 0.20 lbs. with Galaxis Frontier.  

• Feed efficiency (ECM/DMI) improved: 0.04-pts with Galaxis; 0.08-pts with Galaxis Frontier

Table of key results adapted from Nehme Marino et al 2024: 

NEW FINDINGS FROM 2025 STUDY: 

Rumen Microbiome and Fermentation

• Galaxis products optimize rumen diversity. Cows receiving either Galaxis or Galaxis Frontier were found to have a significantly lower bacterial diversity in the rumen, with some microbial taxa becoming more dominant. This aligns with previous findings that more feed efficient animals have lower diversity. Trade-offs were observed among groups of Prevotellaceae, with some groups increasing in abundance and other groups decreasing in abundance. This kind of trade-off could indicate a functional rebalancing of different microbial metabolisms, though further work is needed to better understand this shift.

• Galaxis Frontier microbe correlates with increases in milk and component yields. The abundance of Ruminococcus bovis, present in Galaxis Frontier, was positively associated with higher milk, total milk solids, and preformed and PUFA milk fats. The importance of this microbe in high-producing, efficient dairy cows has been corroborated by independent research groups and highlights the value of treatments that increase R. bovis in the rumen. 

• Increases in SCFAs, including propionate and isovalerate. Galaxis Frontier increased ruminal concentrations of isovalerate, a branched-chain fatty acid linked to microbial protein synthesis and productive metabolism. Early sampling also showed increased total short-chain fatty acids, driven largely by acetate and propionate, in cows receiving both Galaxis treatments. Both acetate, an essential precursor for milk fat synthesis, and propionate, the main substrate for gluconeogenesis, are key to supporting lactation suggesting that the observed microbial changes may directly enhance energy supply to the mammary gland.

Host Biomarkers and Digestibility

• Galaxis Frontier cows tended to have slightly lower blood glucose. This reflects increased peripheral uptake or altered hepatic glucose dynamics. Host metabolic biomarkers were otherwise largely stable according to indicators of lipid and protein mobilization, such as serum NEFA and urea nitrogen, and urinary nitrogen excretion.

• Changes in digestibility may be site-specific. Total tract digestibility showed some parity-dependent differences between treatments but no overall consistent change, suggesting benefits are more likely linked to changes in site of nutrient absorption, nutrient partitioning, or metabolic routing than to overall changes to bulk feed digestibility.

Conclusion

These findings show that native rumen microbes provided by Galaxis products can restructure the microbial community in the rumen and alter fermentation pathways, leading to a more efficient flow of nutrients from feed to milk. The combination of greater milk yields, improved efficiency, bacterial community shifts, and subtle changes in host energy metabolism show how Galaxis and Galaxis Frontier target genetics in the rumen to support dairy herds. Future studies will focus on mapping these nutrient flows from the digestive tract to the mammary to better understand how shifts in rumen biochemistry propagate into improved milk production. 

To read the full study publication, click here.