Rumen Microbes, Mammary Gains: A New Angle on Transition Cow Support.

The latest Galaxis™ Frontier research out of the University of Wisconsin-Madison suggests that the benefits of rumen-native microbes may reach far beyond digestion. In a study led by Dr. Jimena Laporta (Tabor & Guadagnin et al., 2025 JDS), researchers explored how native rumen microbes influence whole-animal physiology, including the mammary gland, colostrum and milk composition, and energy metabolism.

The transition from the dry period to lactation is one of the most metabolically demanding times in a dairy cow’s life. Her body must rapidly shift gears, mobilizing energy from body reserves to support milk production while minimizing the risk for metabolic diseases like ketosis or milk fever. Ensuring that her rumen microbiome is performing optimally during this window is critical for supporting metabolic balance, immune function, and a strong start to lactation.

Earlier research showed that providing cows with Galaxis Frontier starting in the close-up period increased colostrum (Logan Real, 2022) and milk production during early lactation (Bulnes et al., 2024). This new study builds on those findings and helps explain why. The UW-Madison team found that rumen-native microbes didn’t just affect rumen function, they also appeared to support mammary gland development and colostrogenesis, revealing a potential mechanism behind the previously observed production gains. Researchers evaluated Galaxis Frontier in 60 pregnant multiparous Holstein cows that were blocked by parity and assigned to one of three groups: a control group that received no intervention, a group that received Galaxis Frontier both before and after calving (from 4 weeks prepartum to 100 days in milk), and a group that began receiving it on day one after calving. They tracked changes in body weight and condition, milk production, and blood energy markers throughout the transition period and early lactation. Colostrum and weekly milk samples were collected, and biopsies of mammary tissue were performed at 2 and 8 weeks after calving to track structural changes in early lactation and composition of the fluid. Overall, here’s what the research found in cows receiving Galaxis Frontier:

• The mammary gland was more developed. Treated cows tended to have more milk-producing cells and more alveoli, the tiny cells and structures that make milk, and this was especially visible around peak production. This suggests Galaxis Frontier helped maintain udder development and capacity beyond the immediate post-partum period. Importantly, this response was seen both in cows that started on Galaxis Frontier prepartum and those that started on Galaxis Frontier on day one after calving.

Tabor et al., 2025

KEY

Control = no microbes

PostG = daily Galaxis Frontier supplementation starting fresh (1 DIM)

Pre+PostG = daily Galaxis Frontier supplementation starting close-up (28 days pre-fresh)

Adapted from figure 2 in (Tabor & Guadagnin et al., 2025), cows receiving Galaxis Frontier displayed increased number of mammary alveoli, especially 60 days after calving, and increased numbers of mammary epithelial cells. Mammary biopsies were taken from 8 cows per treatment group at each time point; four representative images from each cow at each time point were used for quantification.

• Colostrum yield improved. Cows that were provided Galaxis Frontier before calving produced 4.4 lbs. more colostrum overall, including 1 lb. more protein with the same concentration of IgGs. Colostrum quantity is notoriously difficult to shift with diet alone, suggesting that these rumen-native microbes are directly or indirectly influencing the cow’s pre-programmed colostral antibody and protein delivery response during the transition to lactation. Additional high-quality colostrum can help support calf growth, health, and early immune development and can potentially ensure year-round quality and volume of colostrum.

COLOSTRUM MEASUREMENT	Control group	Frontier group	p-value (treatment)	Effect of Galaxis Frontier	% change
yield	11.68 lbs.	16.09 lbs.	0.06	+4.41 lbs.	38%
protein	16.5% 1.72 lbs.	17.2% 2.71 lbs.	0.47 0.03	- +0.99 lbs.	- 58%
IgG	100 g/L	108 g/L	0.34	-	-

Adapted from Table 2 in (Tabor & Guadagnin et al., 2025), Colostrum was assessed from 20 “Frontier group” cows that received Galaxis Frontier for 4 weeks pre-partum and 40 “Control groups” cows that did not receive the treatment. Effect sizes were calculated when the effect of treatment had a p-value<0.10, and percent change reports the improvement relative to the Control group.

• Milk fat improved. Even though overall milk yield didn’t significantly increase, milk fat percentage was higher in cows on Galaxis Frontier (+0.24%).

• Calves were bigger at birth. Calves born to cows that were on Galaxis Frontier for 4 weeks before calving had higher birth weights (93 lbs. versus 87 lbs.)—suggesting that changes in maternal metabolism may have benefited fetal growth.

• Cows mobilized more weight without increasing their risk for ketosis. Cows on Galaxis Frontier lost more weight in early lactation but did not exhibit increased plasma NEFA concentrations. Both NEFA and BHB are metabolic indicators associated with ketosis risk and, in alignment with these findings, clinical ketosis incidence did not differ across groups (χ² = 0.93). In fact, cows fed product while pregnant had lesser plasma ketone (BHB) and greater blood glucose concentrations during the close-up period. Altogether, these results suggest that cows fed Galaxis Frontier helped the cow mobilize energy more efficiently to support milk production without increasing the risk of ketosis.

• Immune responsiveness was enhanced. Cows receiving Galaxis Frontier before calving showed moderate signs of increased neutrophil activity, including a stronger oxidative burst in the first week after calving. Signs of increased oxidation while treating transition cows were also observed in (Bulnes et al.,2024). Enhanced responsiveness suggests that Galaxis Frontier may help to prime the immune system to respond more effectively during this high-stress period.

• The benefits extend beyond the rumen. Although Galaxis Frontier was developed for the rumen, its influence was evident in mammary tissue development, energy metabolism, and even the calf. These findings suggest that supporting the rumen microbiome influences the whole-animal physiology, not just rumen function.

While the cows fed Galaxis Frontier showed positive shifts in energy metabolism and mammary development, these changes did not translate into increased milk production in this study. It’s important to note that these were well-managed and high-producing cows that were maintained on a fresh-cow ration throughout the trial, likely limiting their ability to translate the physiological improvements into additional milk yield. This outcome underscores a key takeaway: supporting the microbiome is only part of the equation. To unlock the full benefits, especially in high-performing animals, the nutritional program must match their production potential. We recommend working with a nutritionist to evaluate whether a diet can support higher output, or reach out to us to connect with producers who have seen production responses in their own herds using Galaxis Frontier.

This research is exciting because it highlights that microbiome-based technologies that are derived from the cow may offer a new tool to support transition health benefits for both the cow and her calf. It’s not just about feeding the cow; it’s about optimizing the microbial ecosystem that feeds the cow.

Stay tuned for even more findings. This study opens the door for more research and exploration on how the microbiome can be harnessed to improve cow health, production, and efficiency. To read the full paper, click here.