Fumonisins: A Neglected Problem in Silage for Cattle


In Brief
 
  • Fumonisins (FUM) are a commonly detected mycotoxin in corn silages.
  • Rumen microbes allow FUM to bypass the rumen mostly unmetabolized.
  • FUM can cause hepatic damage in calves, dairy cows and beef cattle as well as impair the immune system.
  • FUM can lead to decreased milk production and milk quality in dairy cattle and lower weight gain in beef cattle, especially when co-occurring with other mycotoxins.

Fumonisins are often detected in corn silage, and can cause productivity losses and health problems in both beef and dairy cattle.
Recently published research indicates that even low to medium concentrations of dietary fumonisins (FUM), especially in combination with other Fusarium mycotoxins, can lead to impaired health and production losses in both dairy cows and beef cattle.

Is FUM actually a problem in ruminant’s diets?


Several surveys conducted in different parts of the world have confirmed that corn silages can be a significant source of FUM contamination in both dairy rations (Reisinger et al., 2019, Gallo et al., 2021, and Vandicke et al. 2021) as well as beef cattle diets (Custódio et al., 2019).

Figure 1. Fumonisins increase veterinary and treatment costs and decrease milk and meat production.

What happens to FUM once ingested?


Unlike other mycotoxins, FUM is metabolized or detoxified only to a small degree in the rumen. In an in vitro study conducted by Caloni et al. (2000), the vast majority of FUM remained intact, even after 72 hours of incubation in rumen fluid. Other authors have confirmed in their studies (see Figure 2) that FUM can bypass the rumen mostly undegraded (Gurung et al., 1999, Smith & Thakur et al., 1996, Fink-Gremmels 2008, and Gallo et al., 2020). Once it reaches the small intestines, there is evidence from Reisinger et al. (2019) that FUM can be cytotoxic thus negatively impacting the intestinal health of the animals. The authors conclude from their in vitro work that the intestine of ruminants can be just as sensitive to FUM as the small intestine of swine.

Figure 2. FUM degradation patterns from different studies in vivo or after incubation in vitro (adapted from Smith & Thakur 1996, Gurung et al. 1999, Caloni et al. 2000 and Gallo et al., 2020)

Hepatic lesions, increased liver enzymes and impaired immune system


Even though ruminants are still considered less sensitive to FUM, there is evidence that FUM, alone or in combination with other Fusarium mycotoxins, have a hepatotoxic effect as well as impair immune functions in ruminants.

  • Hepatic lesions: Hepatic injury and mild morphologic alterations was induced in Holstein calves that were fed corn containing 440 ppm FUM (Baker & Rottinghaus 1999). Beef calves that received 148 ppm for 31 days showed similar symptoms (Osweiler et al., 1993).
  • Increased liver enzymes: In several studies, diets contaminated with FUM led to an increase in the liver enzymes aspartate amino transferase (AST) as well as gamma-glutamyl transpeptidase (GGT).  AST and GGT levels in the blood can be used to detect chronic, subacute or acute liver diseases and an elevation of these two liver enzymes can be associated with fatty liver syndrome in ruminants. The increase of these liver enzymes was detected in the calves in the aforementioned study (Baker & Rottinghaus 1999) but also in dairy cows receiving 100 ppm dietary FUM (Diaz et al., 2000), dairy cows receiving a combination of 994 ppb FUM and 733 ppb deoxynivalenol (DON) (Gallo et al., 2020) as well as beef cattle receiving 3.5 ppm FUM and 1.7 ppm DON in combination (Duringer et al., 2020). The elevated levels of these liver enzymes are a sign of liver damage caused by FUM ingestion.
  • Immune system:  In the aforementioned study from Gallo et al. (2020) the combination of FUM and DON led to a decrease in ceruloplasmin, hinting at a weaker immune function. Furthermore, specific genes that are responsible for immune activation were downregulated in animals that received the FUM plus DON treatment. With these set of conditions, the animal is more sensitive and defenseless to latent or environmental infections.

Impaired milk production, milk quality in dairy cows, decreased weight gain in beef cattle


Besides the possible hepatotoxicity and immune function impairment, FUM can become a significant risk factor for productivity loss.

  • Milk production: In the study from Diaz et al. (2000) the animals ingesting 100 ppm dietary FUM produced  significantly  less milk (FUM cows 24.2 kg/cow/day vs. control cows 31.2 kg/cow/day). Even lower concentrations, like those used in the study from Gallo et al. (2020), caused a 1.34 kg loss of milk production per day in the treated animals.
  • Milk quality: Besides the loss of milk quantity, milk quality parameters such as the milk coagulation properties were significantly reduced in the animals that received FUM plus DON (Gallo et al, 2020).
  • Weight gain: Angus beef steers on a high grain diet received a total mixed ration contaminated with 3.5 ppm FUM and 1.7 ppm DON for 21 days (Duringer et al., 2020). Control animals received a diet free of mycotoxin contamination. The animals that received FUM in combination with DON showed a significantly worse daily weight gain in comparison to the control animals. Despite being 2 kg heavier on average at the start of the 21 period, the treated animals ended up 14 kg lighter on average than the control animals.

Conclusion
Fumonisins can’t be overlooked and pose a risk that requires testing and assessment in efficient beef and dairy farming.

References

Baker, D. C. & G. E. Rottinghaus (1999) Chronic experimental fumonisin intoxication of calves. Journal of Veterinary Diagnostic Investigation: Official Publication of The American Association Of Veterinary Laboratory Diagnosticians, Inc, 11, 289-292.

Caloni, F., Spotti, M., Auerbach, H., den Camp, H. O., Gremmels, J. F., & Pompa, G. (2000). In vitro metabolism of fumonisin B1 by ruminal microflora. Veterinary Research Communications, 24(6), 379-387.

Custódio, L., Prados, L. F., Yiannikouris, A., Holder, V., Pettigrew, J., Kuritza, L., ... & Siqueira, G. R. (2019). Mycotoxin contamination of diets for beef cattle finishing in feedlot. Revista Brasileira de Zootecnia, 48.

Diaz, D. E., B. A. Hopkins, L. M. Leonard, W. M. Hagler, Jr. & L. W. Whitlow (2000) Effect of Fumonisin on lactating dairy cattle. Journal Of Dairy Science, 83, 1171.

Published on

20 April 2021

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