The complex story of mycotoxins in ruminants

Author: Nick Adams, Alltech Mycotoxin Management, Global Director

Mycotoxins within the ruminant setting, particularly dairy, offer a fascinating complexity that is not seen within the monogastric setting. When thinking about a monogastric diet, the emphasis is purely on understanding mycotoxin contamination from key grains and coproducts, such as corn, wheat, soya bean, DDGs, etc. Because of better understanding and improvements in storage practices, the principle challenge seen from these grains comes from the pre-harvest setting. Therefore, it is largely based around the Fusarium mycotoxins, with Aspergillus mycotoxins becoming more prevalent in warmer climates. While, for the ruminant sector, this picture is also true, there is an additional consideration around the mycotoxin contamination of forage.

Research into mycotoxins in ruminants over the years

While there is published research outlining the prevalence of Penicillium mold and mycotoxins in silage in the 1990s, Penicillium mycotoxins such as Roquefortine C, Penicillic Acid, Mycophenolic Acid and Patulin have not routinely been measured in forages until recently. Does this matter? Yes, because typical mycotoxin analyses — historically and even in today’s environment — focus heavily on the mycotoxins produced by molds pre-harvest. Therefore, when we look at silage, we do not always consider the potential contamination of mycotoxins that have developed post-harvest. These primarily come from a different mold set, such as Penicillium, than we would see pre-harvest. When silages are not optimally stored, for a variety of reasons, Penicillium molds can flourish, and their mycotoxins can become a significant contaminant.

During the 2000s, many people worked with mold count and identification to understand the potential challenge within silage. These tests often showed silage contamination with higher levels of Penicillium mold. However, given the lack of mycotoxin analysis methods, it was impossible to quantify any mycotoxin contamination that may result from this mold infestation. Alltech first started testing for Penicillium mycotoxins directly in 2013 with the Alltech 37+® mycotoxin analysis assay that utilizes UPLC-MS/MS technology. This method has since been expanded and now tests for patulin, mycophenolic acid, roquefortine C, penicillic acid, citreoviridin and wortmannin.

Why is this important?

Of 764 samples of maize silage and grass silage analyzed by the Alltech 37+® mycotoxin analytical services laboratory from October 1, 2019, through to now, nearly 20% of samples have contained Penicillium mycotoxins, with the maximum level found being just over 3,900 ppb. To put these numbers in context, Santos and Fink-Gremmels (2014) identified significant performance improvements in cows when Mycosorb® was fed to three herds consuming diets containing Penicillium mycotoxins ranging from approximately 700–7,500 ppb.

Not a huge amount has been published around the impact of Penicillium mycotoxins and animal health and performance. Work by Tapia et al. (2005) showed that increasing levels of patulin added to an in-vitro fermentation model reduced the production of volatile fatty acids. However, these levels were not ones that would typically be found in a commercial environment. Oh et al. (2012) looked at the impact of five Penicillium mycotoxins within a bovine macrophage cell proliferation model. The study showed that individual mycotoxins could reduce BoMac cells’ proliferation, while certain combinations of those Penicillium mycotoxins increased the negative impact. Perhaps the effect of Penicillium mycotoxins on immune function should not be a surprise. Mycophenolic acid is used within the health industry as a drug given to organ transplant recipients to suppress the immune system and aid in the body’s acceptance of the new organ. More recently, Debevere et al. looked at the disappearance of mycotoxins within the rumen, demonstrating that mycophenolic acid had no relevant degradation. This is opposed to Deoxynivalenol (DON), which entirely degraded to DOM 1 over a 24-hour period.

When considering Santos and Fink-Gremmels (2014), it was noted that the antioxidant capacity of cows consuming silage with higher levels of Penicillium mycotoxins was decreased, alongside an increased somatic cell count and reduced milk production. This, alongside the seeming rumen stability of these toxins, highlights the importance of considering Penicillium mycotoxins within silage as a contributor to poor performance on-farm.

For more information or to find out how to have silage or TMR tested for Penicillium mycotoxins, please email mycosorb@alltech.com.