Leaky epithelium at the centre of transition cow disorders
How metabolic stress, oxidative imbalance, and dietary shifts disrupt the rumen and lower gut barrier.
15 September 2025
6 minute read
By: During the transition period, dairy cows experience several physiological, metabolic, and environmental stressors that affect the intestinal barrier integrity, leading to the development of a ‘leaky’ epithelium that stimulates inflammation.
The transition period in dairy cows is marked by significant changes in nutrient intake and metabolism; the cow's nutrient intake is usually insufficient to meet the increasing demands of the developing calf and the initiation of milk production, which can lead to a negative energy balance (NEB). During the NEB state, the cow is using more energy than it is taking in through its diet. As a result, it starts mobilizing body fat reserves to make up for the energy deficit; this mobilization can lead to an increased risk of metabolic disorders such as ketosis. The increased metabolic demand, along with the demands of the developing calf, can lead to an elevated production of reactive oxygen species (ROS) as byproducts of metabolism. A disruption in the balance between ROS and antioxidants can cause oxidative stress, which can also contribute to inflammation and immune dysregulation. Stress activates the hypothalamic pituitary-adrenal axis, leading to the release of corticotropin-releasing factor (CRF), which can disrupt the intestinal barrier and cause systemic inflammation.
Why focusing on the rumen and lower gut matters during the transition period?
As emphasized by Professor Mike Steele, a specialist in physiology and metabolism of dairy calves and transition cows, at the University of Guelph, the gastrointestinal tract is important for digesting and absorbing nutrients, and it's a barrier to diffusion from the gut into circulation, which causes inflammation resulting in cow disorders. During an expert talk interview, focusing on the management of gut health in high-producing cows, he underscored the importance of minimising inflammation during the transition period. “So, it's really critical to have a very healthy gut, not just the rumen in the fore stomach, but also the lower gut, as well as the small and large intestine, so that we can get more nutrients absorbed as well.” Get more insight on “Managing gut health in high-producing dairy cows, by Mike Steele”.
A ‘leaky’ gut or epithelium triggers inflammation
A shift to lactating rations (higher energy and protein) during the transition period changes the microbiota balance in the rumen; there is a decrease in fibrolytic microbiota (bacteria and fungi) and an increase in rapidly fermentable carbohydrate degraders; this switch decreases rumen pH and can lead to a higher risk for subacute ruminal acidosis (SARA) that damages the rumen wall epithelium. On the other hand, tight junctions, which are a key component of the rumen epithelial barrier, are also disrupted, leading to increased permeability of the rumen epithelium and subsequent inflammation.
A compromised epithelial barrier (leaky gut) of the rumen and lower gut results in excessive immune activation; this increased energy demand of the immune system causes the animal to shift its metabolic priorities, negatively affecting growth, reproduction and productivity (Fig. 1).
Inflammation impacts feed intake and milk production
Peripartum cows are particularly susceptible to oxidative stress and inflammation due to the increased metabolic activity associated with late pregnancy, parturition, and the onset of lactation.
Inflammation can significantly affect dry matter intake (DMI) as pro-inflammatory cytokines have been shown to negatively influence feeding behavior and appetite regulation. Cytokines can act on the hypothalamus, reducing the sensation of hunger and consequently decreasing feed intake. The reduced DMI exacerbates the negative energy balance and may lead to a limited supply of nutrients and natural antioxidants from the feed. Inflammation stimulates the immune system, which requires energy; this results in nutrients being partitioned towards the immune system at the expense of milk production. Recent studies show that the energy to fight against inflammation (modelized by LPS-induced infection) costs the equivalent of 1 kg of sugar every half day and approximately 26 kg of milk loss.
Inflammation can lead to post-partum disorders
Inflammation can also cause post-partum disorders in dairy cows, such as ketosis, milk fever (hypocalcemia), reproductive tract infections such as retained fetal membranes, metritis, and endometritis, all of which can negatively impact the cow's health, fertility, and milk production. For example, ketosis, which occurs when the cow mobilizes excessive fat for energy, leads to an accumulation of ketone bodies, resulting in a decrease in milk quality and fertility. Research shows that inflammation during the transition period negatively impacts cow reproductive performance as it decreases ovarian activity.
Mitigating the effects of “leaky epitheliums”
Supporting optimal microbiota balance is essential to prevent leaky epitheliums as gut barrier disruption leads to increased permeability and inflammation. Reducing leaky gut by maintaining a balanced microflora can be achieved by supplementing a probiotic live yeast, the rumen-specific yeast strain S. cerevisiae CNCM I-1077 (LEVUCELL SC). LEVUCELL SC limits inflammation at the epithelium level (strengthens rumen post-calving), boosting DMI post-calving and milk production. When supplemented before calving, LEVUCELL SC helps the rumen wall better prepare for the stress encountered around calving by improving rumen wall integrity (tight junctions) and resistance to rumen wall inflammation through its effects on cytokines.
In a recent trial performed during early lactation, LEVUCELL SC fed cows were shown to produce
6 litres of extra milk, partly explained by a higher DMI of 2.5 kg/head/day. This higher DMI was equivalent to a higher non-fibre carbohydrate (NFC) intake in the LEVUCELL SC group of 1.21 kg, equivalent to an extra 20%, corresponding to a higher energy supply. The overall benefits of supplementing LEVUCELL SC are summarized in Figure 2.
In another commercial trial with Holstein transition cows, Poland (2015), the same rumen-specific live yeast combined with specific yeast product from Lallemand, reduced the number of ketotic cows by 26.4% compared to the unsupplemented cows. This unique pro-postbiotic combination has the following benefits:
- Improves energy balance after parturition
- Improves rumen function and optimises rumen pH
- Stimulates rumen microbiota to increase fibre digestion
- Enhances oxygen scavenging, preventing harmful oxidative reactions
In an interesting study conducted in multiple commercial farms in Europe, the combination of the probiotic yeast S. cerevisiae CNCM I-1077 with MELOFEED and Alkosel antioxidants (fed 3 weeks before to 3 weeks after calving), increased milk production, body condition, colostrum quality, fertility parameters and improved rumen pH (Figure 3; key findings during early lactation).
Concluding remarks
Yeast-based nutritional additives can help maintain epithelial integrity during the transition period; this helps maintain cow health and high performance under such challenging conditions, yielding high economic outcomes. Nutritional live feed additives that target the rumen and take care of lower gut integrity are key management solutions that can help, among other management actions, to ensure a smooth transition period in dairy cows.
Leaky epitheliums are the central cause of inflammation and immune activation during the transition period; nutritional additives that help mitigate the negative consequences on cow productivity are important during the cow’s transition period. Lallemand Animal Nutrition’s yeast-based nutritional solutions ensure a successful transition and help to limit inflammation and oxidative stress while increasing energy extraction from the diet for lactational performance.
