In dairy cattle production, the effects of endotoxins on performance parameters are gaining attention and importance. It’s clear that endotoxins contribute to infectious and metabolic diseases, affecting the health, performance, and ultimately, the profit of dairy operations.

Endotoxins and gut health

Endotoxins, also known as lipopolysaccharides (LPS), are components found in the outer cell wall of gram-negative bacteria. These toxins are released during bacterial growth. Normally, the epithelium acts as a barrier, limiting the entry of LPS into the bloodstream. However, various factors such as stress, dietary changes, and lactation stage can compromise this barrier, leading to increased permeability and LPS uptake.

Translocation process

LPS translocation, the movement of these toxins across the epithelium, can occur through the cell membrane (transcellular) or between cells (paracellular). Transcellular transport is mainly active, involving receptors on the cell membrane that trigger endocytosis.

Impact on the system

Endotoxins in the gastrointestinal tract (GIT) can enter the system through the lymphatic system, portal vein, or systemic circulation. This can lead to increased concentrations of pro-inflammatory cytokines (IL-1, IL-6, TNF-α) in the bloodstream, originating from damaged gastrointestinal epithelium, liver macrophages, lymph nodes, or adipose tissue. These cytokines cause metabolic, clinical, and immunologic effects.

Understanding the role of endotoxins in dairy cattle production is crucial for maintaining herd health and optimizing profitability. By addressing factors that influence endotoxin levels and gut health, producers can improve performance and reduce the incidence of diseases, ultimately leading to greater profitability.

Translocation of endotoxins through the gastrointestinal tract

Figure 1: Endotoxin Pathway in Livestock: When endotoxins enter the lymphatic system or portal vein, local macrophages work to remove them. This process triggers the release of pro-inflammatory cytokines like IL-1, IL-6, and TNF-α. These cytokines enter the bloodstream, prompting the liver to produce acute phase proteins such as SAA, LBP, Hp, and CRP. If endotoxins evade the local macrophages, they enter the systemic circulation, where they bind to lipoproteins with the help of LBP and sCD14. Bound to lipoproteins, endotoxins are absorbed by liver hepatocytes, deactivated in bile, or stored in white adipose tissue (WAT). Adipose macrophages then release additional cytokines into the bloodstream. (Eckel and Ametaj, 2016)

Endotoxins and etiopathology

There is growing knowledge about the role of endotoxins in the etiopathology of multiple periparturient diseases of dairy cows. These include laminitis, retained placenta, metritis/endometritis, fatty liver, displaced abomasum, and milk fever. It’s important to note that these diseases have multiple causes, not solely attributable to endotoxins.

Endotoxins can contribute to disease directly by triggering inflammation or indirectly by exacerbating the natural protective mechanisms of the host (Eckel and Ametaj, 2016). Not only the concentration of endotoxins but also the toxicity of the bacterial species plays a role in the induction of in¬flammation. Additionally, the toxicity of the bacterial species producing endotoxins also influences the severity of inflammation. For instance, E. coli endotoxin is particularly toxic compared to other gram-negative bacteria commonly found in cattle rumen (Hurley, 1995). This means that when the LPS of E. coli predominates the rumen, the negative effect is expected to be greater.

Figure 2: Negative energy balance and an activated immune response reduces the dairy cow’s resilience in early lactation

Endotoxins and Subacute Rumen Acidosis (SARA)

Transition periods in dairy cows, especially early lactation, put significant stress on their systems (Figure 2). Dietary changes from a low-energy, high-fiber diet pre-calving to high-grain, low-fiber post-calving can increase the load of ruminal and intestinal endotoxins, affecting production.

Subacute rumen acidosis (SARA) is a prevalent feeding disorder in dairy cows, affecting around 11–26% of herds (Plaizier et al., 2018). The term SARA is often used as a synonym for poor rumen health and it is characterized by a low rumen pH (<5.6 for at least 180 minutes/day), leading to changes in bacterial composition and increased populations of gram-negative bacteria (Plaizier et al., 2017). This acidic environment releases more LPS into the rumen fluid, potentially exacerbating SARA by promoting the growth of acidosis-related bacteria, creating a harmful cycle (Figure 3).

Figure 3: The endotoxin-SARA cycle

How to break the cycle

Given the strong link between Subacute Rumen Acidosis (SARA) and endotoxicosis, preventing SARA and promoting rumen health is crucial. Practices such as ensuring adequate dietary fiber, selecting the right type of concentrate and starch, and managing feeding schedules are essential.

However, in intensive dairy farming, avoiding SARA entirely can be challenging. Therefore, it’s vital to mitigate the negative effects of endotoxins and maintain cow health through comprehensive support measures.

Reducing endotoxin impact

Endotoxins affect productivity through their concentration and toxicity, the integrity of the epithelium, changes in rumen fermentation profiles, translocation of endotoxins, immune response, changes in nutrients partitioning, and shifts in behavior. The use of the toxin binder is an excellent first step in preventing them from entering the bloodstream and causing inflammation.

  • Vitafix® Spectrum helps reduce the concentration of endotoxins and mycotoxins in the GIT. This dual benefit is a cost-effective method to decrease the chance of toxins interacting with the epithelium, preventing them from entering the systemic circulation and causing an inflammatory response. In addition, the gastrointestinal epithelial wall forms a barrier that can be compromised due to different factors, like LPS.
  • With Vitanox, the harmful effects of endotoxins can be prevented by inducing a positive effect on the integrity of epithelial cells in the small intestine.
  • Finally, stabilizing the rumen microflora with medium-chain fatty acids (Aromabiotic® Cattle) helps to create a healthy rumen environment. This leads to fewer endotoxins being released, reducing the activation of the immune system, and sparing energy to improve milk production.

Promoting longevity and profitability

By bolstering overall health and immune function, cows can enjoy multiple healthy lactations. Implementing preventative measures not only increases cow longevity but also ensures sustainable profitability for dairy farms, maximizing income for farmers.

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Kobe Lannoo
Global Lead Category Management