Managing heat stress and endotoxins:
how to protect your dairy cattle’s health & maximize yield ?
Ensuring consistent production and performance during high temperatures
Combatting heat stress and endotoxin threats in modern dairy farming: safeguarding cattle welfare and milk quality in a warming world
Prolonged hot summers, combined with high productivity in modern livestock production, significantly increase the heat load on dairy cows. Heat stress occurs when cows generate more heat than they can dissipate, causing physiological strain that compromises their welfare and production.
Heat stress negatively impacts milk yield and quality, and heightens dairy cows’ susceptibility to harmful bacterial components called endotoxins. The complicated relationship between heat stress and endotoxins poses a significant threat to both ruminant health and milk production.
Regardless, there is no question that proactive measures are needed to mitigate these negative effects as global temperatures continue to rise and productivity is pushed to its limit.
Heat stress reduces milk yield and quality
During heat stress, cows try to regulate their body temperature by reducing their feed intake to minimize the heat released during digestion. However, this reduced feed intake means they do not meet the energy and protein requirements needed for optimal milk quality and production. In addition, heat-stressed cows have difficulty mobilizing fat tissue, leading to an increased reliance on glucose as an energy source. Consequently, there is reduced availability of glucose for milk production. During heat stress, amino acids, which are crucial for milk protein production, are mainly used for maintenance processes and immune system strengthening instead of for milk protein synthesis. Finally, heat stress also affects the integrity of cell-cell connections in mammary gland cells leading to poor mammary gland development during the dry period. This, in turn, significantly reduces milk production during the subsequent lactation period.
Apart from decreased milk production and quality, heightened somatic cell counts (SCC) are often observed during the summer months. In hot weather, cows undergo more physical stress, leading to decreased productivity as they seek cooler places to rest and spend less time feeding. This behavioral change, coupled with reduced activity, increases the risk of mastitis, as prolonged exposure to bacteria at the teat ends is more prevalent. Research also highlights the impact of increased stress hormone levels during heat stress on the effectiveness of the immune system in fighting bacterial infections and endotoxins.
The effect of endotoxins on dairy cattle during heat stress
Endotoxins
Endotoxins, specifically lipopolysaccharides (LPS), are heat-stable structural components of the outer membrane of bacterial cell walls. These potentially toxic compounds are produced by both beneficial and pathogenic gram-negative bacteria and are released when they multiply or undergo lysis. Endotoxins are ubiquitous, with the main sources being bacteria in the gastrointestinal tract, the rumen, animal feed, water and infections caused by gram-negative bacteria.
⚠️ Once released, endotoxins can trigger a powerful inflammatory response when they enter the bloodstream. This comes at a great cost because this immune response consumes energy and nutrients needed for milk production. In addition, endotoxins can contribute significantly to the development of various metabolic disorders such as fatty liver, milk fever and lameness.
Heat stress increases intestinal permeability, facilitating endotoxin leakage
Under normal conditions in healthy animals, the integrity of the intestinal barrier is maintained by epithelial cells that are tightly interconnected and reinforced by tight junction proteins, which are cell-cell adhesion complexes that regulate the paracellular flow of solutes. This physical barrier acts as a crucial defense that keeps bacteria, endotoxins, enzymes and food particles within the intestinal lumen and prevents them from entering the bloodstream. Besides this physical barrier, an additional biochemical barrier of detoxifying enzymes prevents the leakage of endotoxins from the lumen to the blood circulation.
However, several factors, including heat stress, weaning, mycotoxins, feed transitions and the presence of pathogens in the gut, are known to increase epithelial permeability and thus endotoxin leakage. During periods of heat stress, the body attempts to dissipate as much heat as possible by decreasing blood flow to the organs and increasing that towards peripheral tissues, such as the skin. Lower blood flow to the intestine reduces the supply of oxygen and nutrients to the epithelial cells, compromising the integrity of the tight junction proteins and thus that of the intestinal barrier. This weakening facilitates the leakage of endotoxins into the bloodstream (Figure 1).
In ruminants, leakage of endotoxins can also occur through the epithelium of the rumen. This epithelium is multilayered and cornified and forms a protective barrier against endotoxin leakage under normal conditions. However, disruptions occur in this rumen barrier when a cow experiences acidosis, for example as a result of feeding highly fermentable carbohydrates. These changes increase the risk of endotoxins entering the bloodstream from the rumen.
Elevated risk for endotoxemia
Once endotoxins are absorbed, they will be detected by specific receptors (e.g. TLR-4 receptors) that stimulate the production of pro-inflammatory cytokines. These cytokines initiate inflammation by acting as signaling molecules that trigger other immune cells to move to the inflamed area and release even more pro-inflammatory cytokines, setting off a chain reaction. This process modulates the functioning of various tissues and triggers the liver to produce acute-phase proteins.
The increased immune responses will consume energy and nutrients needed for growth and milk production. In severe cases, elevated endotoxin levels in the blood (endotoxemia) can cause septic shock and even death. Thus, it is critical to minimize the transfer of endotoxins into the bloodstream and tissues. Endotoxemia can be prevented by minimizing damage to the intestinal barrier or by reducing the number of endotoxins in the gastrointestinal tract and rumen, for example by detoxifying the endotoxins.
EndoBan protects gut health & improves production performance
Nutrex developed an innovative feed additive called EndoBan®, which integrates multiple strategies to reduce the translocation of harmful endotoxins into the bloodstream.
- First of all, EndoBan® removes free endotoxins from the rumen and gut lumen by physically binding them and removing them via the faeces.
- Secondly, EndoBan® reduces endotoxin toxicity by stimulating the production of LPS-detoxifying enzyme, intestinal alkaline phosphatase (IAP) (Figure 2).
This double protection shields the animal from the adverse effects of endotoxins. EndoBan® supports dairy cows during heat stress by reducing leakage of endotoxins into the bloodstream, which prevents inflammatory responses that would otherwise drain energy from milk production. Consequently, EndoBan® maintains or even increases milk production despite heat stress due to rising temperatures or high metabolism.
Multiple trial results have shown that EndoBan® improves milk production and quality (fat, protein and lactose content), and significantly reduces somatic cell counts in dairy cows, in normal conditions as well as in challenging situations.
EndoBan® is recommended for use in situations where gut barrier integrity is challenged by various environmental and nutritional factors (heat stress, mycotoxins in the feed, weaning stress, pathogens,…).
Moreover, its use is particularly encouraged in conditions where endotoxins are more prevalent such as during heat stress, in case of high-carbohydrate diets, post-antibiotic treatment or feed transitions.
To conclude
As temperatures rise, heat stress will increase potential endotoxin-related problems in dairy cows by increasing intestinal permeability. This increased permeability facilitates the transfer of endotoxins to the bloodstream, leading to inflammatory reactions, endotoxemia and production losses.
Addressing heat stress is therefore necessary, not only to mitigate its direct effects, but also to minimize the associated endotoxin-related challenges to ensure the overall health and productivity of dairy cattle.
EndoBan® has proven its effectiveness in reducing the adverse effects of endotoxins, resulting in improved milk production and quality. In addition, EndoBan® effectively reduces somatic cell counts, leading to healthier cows and improved performance.
WHAT TO EXPECT FROM ENDOBAN !
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- EndoBan limits the leakage of endotoxins through the rumen and gut barrier
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- EndoBan prevents energy-consuming inflammatory responses
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- EndoBan improves milk production and milk quality
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- EndoBan reduces somatic cell counts
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- EndoBan improves ruminant health
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