FROM THE FARM REPORT: USING RUMEN-NATIVE MICROBES TO SUPPORT COWS THROUGH THE TRANSITION PERIOD

The transition period is a crucial time for dairy cows, as they experience many concurrent changes during a time that already has the highest occurrence of metabolic disorders and infectious disease. With changes in hormones, metabolic stress, and nutritional challenges, most cows decrease their dry matter intake (DMI), thus entering a negative energy and protein balance. This most often results in the increased mobilization of fat, which can lead to metabolic disorders such as ketosis. Therefore, it’s vital to provide adequate energy and nutrients during this time.

Supplementation of feed additives, such as microbial-based supplements (MFS), has been shown to help enhance rumen function, improve digestion, and boost productivity. Extensive research has been done on MFS; however, the organisms chosen are usually picked because they are relatively inexpensive and easy to grow and are neither isolated from nor native to the rumen environment. Additionally, not much research has been done on prepartum supplementation.

A recent study done at the University of Wisconsin Dairy Cattle Research Center (Tabor et al., 2025; https://doi.org/10.3168/jds.2025-26677) looked at whether supplementation using microbes from the dairy cow rumen during the final weeks before calving, and continuing post-calving, would have additional benefits compared to post-calving-only strategies.

The MFS for this study were chosen by looking at a network-based analysis of sequenced rumen microbiome samples, which identified ruminal bacteria and fungi with strong positive associations with milk yield, milk component yield, and gross feed efficiency. This resulted in 4 microbes being isolated and formulated into a live-microbe feed supplement, which was marketed under the name Galaxis Frontier (GF).

In the study, 60 dry, pregnant multiparous Holstein dairy cows enrolled 35 days before calving were used. There were 3 different treatments (20 cows per treatment): (1) GF supplementation for 4 weeks prepartum and 16 weeks postpartum, (2) GF supplementation for 16 weeks postpartum, (3) no supplementation of GF. All cows were fed the same diet, with dry cows fed a prepartum TMR diet and lactating cows fed a postpartum TMR diet. The only difference was the microbial feed supplement that was top-dressed daily at 5 g per cow in a carrier of 100 g of dried sugarcane molasses.

The results showed supplementation before calving (27±2 d) improved colostrum yield, protein content, and increased calf birth weight . This suggests that GF supplementation may have increased the ability of the dam to digest and absorb nutrients from her feed, therefore improving energy utilization, which would support fetal growth. Additionally, this reinforces the possibility of prepartum nutrition having an effect on colostrum production and composition.

Cows receiving GF supplementation also had reduced BHB and NEFA levels and higher glucose levels . This indicates increased gluconeogenesis without any increase in fat mobilization. Reducing BHB and NEFA levels while maintaining DMI and BCS may help lower the risk of metabolic disorders and negative EBAL during the transition period. Although the study reported that GF-supplemented cows appeared to have a more negative energy balance, especially after week 5 of lactation, those cows still maintained DMI and milk yield and exhibited lower NEFA and BHB levels, suggesting a reduced risk of metabolic disorders and disease.

Post-calving supplementation showed increased feed efficiency and increases in fat and protein content, which were more pronounced compared to the Pre+PostGF group. This study saw no improvements in milk yield, but previous studies using the same or similar rumen-native MFS have reported increases in milk production (Bulnes et al., 2025). Through mammary gland biopsies it was observed that cows supplemented with GF had more alveoli and mammary epithelial cells compared to nonsupplemented cows, which may be a result of increased nutrient availability. Although no improvements in milk yield were observed, increased alveoli indicate expanded milk producing tissue, suggesting the potential for increasing milk yield.

Another potential benefit of MFS supplementation is its support of glucose utilization and liver function. In this study, cows supplemented with GF during the pre- and postpartum periods showed increased neutrophil oxidative burst activity during the first week after calving compared with nonsupplemented cows, indicating enhanced immune cell function.

These findings suggest that the use of rumen-native microbes can provide benefits when supplemented both pre- and postpartum and solely postpartum. GF supplementation helps cows better manage the physiological challenges associated with the transition period. Although further research is needed to expand on the underlying mechanisms of these effects in dairy cows.

— Corina Warren

cwarren@whminer.com