If you feed dairy cows, at some point, in some way, you will deal with the negative effects of mycotoxins on animal health and performance. The challenge often lies with the degree, since symptoms of mycotoxin contamination are wide-ranging, often nonspecific and may be seemingly unrelated.
Yet the health and performance impacts are real – and expensive. According to a recent Purdue University meta-analysis, three mycotoxins (aflatoxins, fumonisins and deoxynivalenol) cost U.S. livestock producers an estimated $900 million per year.
It’s well documented that mycotoxins may suppress a cow’s immunity, reduce nutrient utilization, alter reproductive performance, reduce feed consumption, irritate tissues – especially in the gastrointestinal tract – and cause cellular death.
When it comes to dairy reproduction, mycotoxins have been associated with a number of factors that reduce performance, including irregular estrus cycles, embryonic mortalities, pregnant cows showing estrus and decreased conception rates.
Complicated scenario
The solution, then, is straightforward. Reduce exposure to mycotoxins and focus on positive ways to manage nutrition programs to support your farm’s health and reproductive goals.
If only it were that easy. Mycotoxin management is seldom an open-and-shut case; it’s not as simple as whether feed ingredients contain these secondary metabolites of fungi or they don’t – or which levels are “safe” for dairy cows to consume.
The fact is: Mycotoxins are common, perhaps even more so than you might realize. Globally, roughly 75 percent or greater of ration ingredients are contaminated by one or more mycotoxin. Most fungi are able to produce several mycotoxins simultaneously, and the mycotoxins produced depend on the feedstuff and crop growing conditions.
Mycotoxins are prevalent among 2016 crops – whether growing conditions were favorable or stressful. Further, mycotoxins can be formed anywhere along the feed chain where molds may exist – in the field, at harvest, throughout storage, at some point in processing or even during feeding.
In other words, mycotoxins always need to be on your radar regardless of the growing year, location or how well you manage your dairy’s feeding program.
Inconclusive results
Complicating the situation is that feed analyses, while valuable, do not find every mycotoxin species present – nor is every species identified or its effects documented. Granted, not all mycotoxins are harmful to animal health and performance, but much remains unknown about these secondary metabolites.
For instance, not enough is understood about the long-term subclinical effects of mycotoxins on cow health and performance. Prolonged exposure, even at levels considered “safe,” may negatively affect performance, and effects may be cumulative.
While a single, large dose of a mycotoxin can cause acute toxicity, it is more likely that the effects are chronic, caused by low-level consumption over time.
Nor does testing account for lags that occur between feeding and sampling, meaning the contaminated feed may have been ingested long before results are known. Or the mycotoxin may have developed after the sample was taken, rendering results ineffectual.
Lastly, feed analyses of mycotoxins are hindered by the difficulty in gathering representative feed samples. Obtaining representative feed samples is difficult because mold growth is inconsistent and mycotoxins are not uniformly distributed within a feedstuff.
As a result, it can be difficult to pinpoint which mycotoxins are the root cause of a dairy’s health challenge or where contamination occurred. Or if a traditional binder material will be effective against the species present.
The reality is: Dairies and nutritionists often cannot be certain exactly how mycotoxins impact a specific dairy herd. But they can be confident that toxins do play a role in animal health and performance. As a result, the industry is more keen than ever to discover how fine-tuning a dairy’s nutrition program can overcome the challenges presented by mycotoxins.
Immune function and gut health
Researchers are learning a great deal more about the ties between gut health and overall immune function, especially as it relates to mycotoxins. This is of key interest because immune suppression is one of the ways mycotoxins exert their effects.
Intestinal cells are the first cells to be exposed to mycotoxins – and often at higher concentrations than other tissues. Maintenance of a healthy gastrointestinal tract is crucial, as it ensures nutrients are absorbed at an optimum rate and provides efficient protection against pathogens through its own immune system.
The result affects the animal on two levels – locally (at the point of attack) and systemically if the release of inflammatory compounds reduces immunity in other parts of the body. That ripple effect begins when gut health is compromised and tissues are irritated.
This often opens the door for opportunistic diseases that also reduce immune function, negatively impacting reproductive performance and productivity.
In the end, if animals are fighting off a health challenge – whether locally or systemically – it affects the energy available for other biological processes, including cyclicity and pregnancy retention.
A better approach
It’s time to approach mycotoxins in the same way dairies have successfully addressed subclinical milk fever and subclinical ketosis. Assume it is present and take steps to proactively manage your herd to reduce negative effects.
Research shows that certain types of carbohydrates can bind mycotoxins and prevent them from being absorbed through the gut and into the blood circulation. The toxins then pass harmlessly through the digestive system and are excreted without negatively affecting animal performance.
This level of protection enables animals to devote energy to all functions – especially reproduction – instead of staving off infections or struggling to maintain nutrient uptake. 
Neil Michael is global tech services manager with Arm & Hammer Animal Nutrition.
References omitted but are available upon request. Click here to email an editor.
PHOTO: Staff photo.
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Joel Pankowski
- Manager Technical Services - Eastern Region
- Arm & Hammer Animal Nutrition
- Email Joel Pankowski
