Native rumen microbes boost milk and feed efficiency while lowering methane intensity in Jersey cows

Most prior work on native rumen microbial supplements has focused on Holsteins. However, the four microbial strains in Galaxis Frontier were originally identified because they’re consistently more abundant in highly efficient and productive dairy cows, regardless of breed, region, or management system. 

 In a recently published controlled trial with a randomized block design, Valldecabres and colleagues tested Galaxis Frontier in early-lactation Jersey cows on a California dairy ration. Building on six peer-reviewed Holstein studies (Bulnes 2025, Dickerson 2022, Goldsmith 2023, Marinho 2024, Tabor 2025, Valldecabres 2022), this controlled trial shows that rumen-native microbes can shift cow energetics in Jersey cows as well. The results showed consistent improvements in milk and ECM, higher feed efficiency, and lower methane intensity, along with reduced somatic cell counts.

Study design: 

In this 16-week trial, all animals were housed together in a single pen containing Biocontrol CRFI feed intake managers. These managers permit entrance only to animals assigned that experimental diet and they electronically record intakes at each feeding event. This setup allowed researchers to control for environmental variables and isolate the impact of 5 g/hd/day Galaxis Frontier when supplemented to the baseline total mixed ration. In total, 46 mature Jersey animals (2^nd-4^th lactation) were enrolled at 38-68 DIM, blocked according to baseline milk yield and randomly assigned to either treatment (Galaxis Frontier) or control groups. AfiMilk electronic milk meters, equipped with in-line optical analyzers, provided AM and PM measurements of milk yield and fat and protein composition. Dual GreenFeed systems were used to track methane production, yield, and intensity. 

Results summary:

• More milk and milk solids. Compared to control cows, those fed native microbes produced on average +4.85 lbs more ECM across the 16-week trial. This was driven both by increased milk yield (+3.62 lbs), increased fat yield (+0.16 lbs), and a trend towards increased protein yield (+0.06 lbs).

• Improved feed efficiency. Importantly, this increase in production was achieved without a corresponding increase in DMI or difference in body weight, so cows essentially converted the same amount of feed into more energy-corrected milk. Feed efficiency (lbs ECM per lb of DMI) was +0.09 units higher in cows fed Galaxis Frontier, which corresponds to about a 5.5% improvement. This reinforces findings from six other peer-reviewed academic trials in Holstein cows showing that Galaxis Frontier consistently drives better feed efficiency (+0.05 in a random-effects meta-analysis across all trials).

• Lower somatic cell counts. SCC (log₁₀) was 0.13 units lower in supplemented cows, a statistically significant reduction (p = 0.04) equivalent to roughly 20,000–30,000 fewer cells per mL of milk. Although this trial did not evaluate mastitis or immune outcomes directly, the result is directionally consistent with two recent peer-reviewed studies using the same native microbial consortium. Those studies reported enhanced innate immune responsiveness, including increased neutrophil oxidative burst during the transition period (Tabor 2025) and increases in acute-phase proteins such as haptoglobin and ceruloplasmin (Bulnes 2025).

• Decreased methane intensity. The study found no evidence of a treatment effect on methane production (g/d) or methane yield (g CH₄/kg DMI). Because ECM increased while methane production remained essentially unchanged, methane per pound of ECM decreased. This metric, known as methane intensity (g CH₄/kg ECM), tended to be lower in supplemented cows (p = 0.09 when estimated from monthly averages; p = 0.13 from weekly averages). 

---

This study confirms that Galaxis Frontier improves performance in Holsteins as well as in Jerseys. The four live organisms in Galaxis Frontier are part of the core rumen microbiome, meaning that they are naturally present in most dairy cows. Recent research showed that daily supplementation of these keystone microorganisms reduces the diversity of the rumen microbiome and promotes increased concentrations of volatile fatty acids (VFAs) (Marinho 2025). VFAs are key fuel sources for dairy cattle that support their immune system and milk production, and they can also influence how the animal responds to hormonal signals. By supporting the core microbial genetics inside of the rumen, Galaxis Frontier promotes a more efficient conversion of feed into functional energy for both Holstein and Jersey cows. This study adds further confirmation of how specifically selected rumen-native microorganisms can induce systemic changes in dairy cattle, leading to improved animal production and efficiency.

To read the full paper, click here.