Heat stress is intensifying, subacute ruminal acidosis remains widespread and dairy producers are under increasing pressure to maintain performance while reducing reliance on medications. Many of these challenges share a common thread: the gut.
From microbial imbalance to compromised intestinal barrier function, disruptions in gut health can trigger inflammation, reduced production and poorer welfare outcomes. Herd health is increasingly approached through the lens of gut integrity and systemic inflammation, and interest in nutritional tools that support digestive stability is growing.
Nicole Reisinger, senior scientist with dsm-Firmenich Animal Health and Nutrition in Austria, studies how feed additives influence gut biology, biomarkers and animal health. In a recent conversation on the “Dairy Podcast Show”, she described emerging evidence that plant-derived compounds may help cows cope with physiological stress affecting the digestive tract. Phytogenic feed additives may support gut health by stabilizing rumen microbial populations, strengthening intestinal barrier function and reducing inflammatory responses.
What Are Phytogenic Feed Additives for Cattle?
Phytogenic feed additives are gaining attention as part of this shift toward preventative herd health. Derived from plants, they include essential oils, herbs, spices and plant extracts, often combined into blends designed to produce complementary biological effects.
Reisinger notes part of their appeal lies in the biological roles these compounds already play in nature.
“The nice thing is that they’re kind of designed by nature. Those compounds all have a purpose in nature, so it’s quite logical that they would also have an impact on animals,” Reisinger says.
Rather than relying on a single compound, many phytogenic products combine multiple ingredients designed to influence several physiological pathways.
“It might be that one substance is not enough. You need to combine them in the right way so that you really have the effect you are interested in,” she explains.
These combinations may influence microbial activity, inflammatory pathways and digestive processes simultaneously — an approach that may be useful when addressing multifactorial health challenges in cattle.
Can Phytogenic Feed Additives Improve Rumen Health During Acidosis?
Subacute ruminal acidosis (SARA) remains one of the most common nutritional disorders in high-producing dairy herds. While ration formulation and feed management remain central to prevention, a growing body of research is beginning to show how phytogenic blends may influence rumen function during acidosis challenges.
This includes controlled work from the University of Veterinary Medicine Vienna, where phytogenic blends containing compounds such as menthol, thymol and eugenol have been shown to improve rumen pH, stabilize fermentation patterns and reduce inflammatory markers during SARA challenges.
“For acidosis, there were quite a few positive effects we could see. It really started with feed intake and then also saliva production and buffering the rumen pH. We had an influence on the pH of the saliva, but then also on the microbiome, which is very essential,” Reisinger says.
What recent research suggests:
A recent meta-analysis of essential oils in ruminants found these compounds can shift fermentation pathways, reduce ammonia production and improve efficiency without compromising animal health.
These effects are consistent with observed changes in rumen stability and feed utilization during acidosis challenges, where microbial modulation appears to play a central role in maintaining digestive function.
How Does Heat Stress Affect Gut Health in Cattle?
Beyond rumen acidosis, heat stress presents another major physiological challenge for cattle, particularly as extreme temperatures become more frequent and severe.
Heat stress can affect the digestive system in several ways, including:
- Reduced blood flow to the intestinal tract
- Increased gut permeability (leaky gut)
- Movement of endotoxins into circulation
- Activation of systemic inflammatory responses
“Phytogenics are essential for this kind of challenge because they can really impact gut permeability. They can really help to strengthen the gut barrier, and this is one of the major things we see with heat stress,” Reisinger says.
What recent research suggests:
Phytogenic blends can improve feed efficiency and nutrient utilization in lactating dairy cows under summer conditions without negatively affecting milk yield, even when dry matter intake is reduced.
By helping maintain intestinal integrity, phytogenics may improve the animal’s ability to cope with environmental stress.
Where Do Phytogenic Feed Additives Fit in Herd Health Management?
Despite the potential benefits, feed additives alone cannot solve complex herd health problems.
“It’s always a combination of nutrition as well as management. We also need to be honest that it’s not the feed additive alone,” Reisinger says.
Sound ration formulation, transition cow management and environmental controls such as ventilation and cooling remain essential. Phytogenic additives may serve as another tool to help cows remain resilient when stressors arise.
What recent research suggests:
In grazing dairy cows, phytogenic blends can lead to improvements in rumen fermentation and milk production comparable to monensin, supporting their role as a viable alternative.
What Is the Future of Phytogenic Feed Additives in Cattle?
Interest in phytogenic feed additives continues to grow as the dairy industry looks for preventative approaches that support productivity and animal welfare.
“I think phytogenics are a good choice for the future, especially thinking about staying a bit more into the natural support,” Reisinger says. “Consumers are probably interested in us looking more into biological support than giving medication.”
Many of the dairy cow’s most significant health challenges begin in the digestive tract. Supporting gut stability may be central to helping cows remain healthy and resilient in the face of both nutritional and environmental stress.
