Photo credit: Coleen Jones
The safety and quality of feed and forages are critical to avoid losses in production, herd health issues, and even potential loss of cattle. On the commercial side, the Food Safety Modernization Act (FSMA) has increased awareness and placed greater emphasis on providing safe feed and foods through the entire production system encompassing both humans and animals. Animal feed production is undergoing a shift in approach to food safety, with preventive measures to address possible hazards before they occur. The hazards addressed in the animal feed industry can be categorized as biological, chemical, and physical. One hazard that requires attention from dairy producers and the animal feed industry in order to provide a safe product for animals and consumers is mycotoxins, potentially toxic compounds produced by molds in feeds. Mycotoxins are considered a chemical hazard.
Many sources compile annual data on the incidence of mycotoxins in various crops and animal feeds. Mycotoxins include zearalenone, deoxynivalenol (DON), fumonisin, T-2, HT-2, ochratoxin, aflatoxin, and many others. While this article will focus on aflatoxin, it is important to note that multiple mycotoxins may be present in a contaminated sample, which may result in greater effects. Aflatoxins are produced by the molds Apergillus flavus and Aspergillus parasiticus when conditions are hot and humid. Other types of mycotoxins favor cool, damp weather. Some mycotoxins are formed by molds on damaged plants in the field while others are generated under storage conditions. Insect, storm, or drought damage to the plant can promote increased risk for mycotoxin production. Noting the weather patterns and monitoring crop reports alerts feed manufacturers when more vigilant testing may be required. Reports indicate this past year’s wet conditions, drought, and serial storms increased mycotoxin alerts in feeds.
Aflatoxin justifiably garners more attention than some of the other mycotoxins due to the possible effects on livestock and humans when amounts in excess of the recommendations are ingested. The human health risks associated with aflatoxin arise because a metabolite of aflatoxin, M1, is passed through milk and is classified as a carcinogen. In the United States, the Food & Drug Administration (FDA) limits the amount of aflatoxin in milk to 0.5 parts per billion (ppb) and to 20 ppb in other foods for human consumption. No reports of aflatoxin in dairy products in the United States were listed in recently compiled review articles including worldwide data on aflatoxin in milk and milk products (Campagnollo et al., 2016; Ketney et al., 2017).
Cattle can be exposed to aflatoxin through corn grain, corn silage, and corn processing by-products. The effects of aflatoxin in animals vary based on the species, age of the animal, and amount of aflatoxin ingested. In general, younger stock are more susceptible and can ingest aflatoxin as it is passed in milk. The effects include reduced feed efficiency and growth and even death with excess amounts in young cattle. For lactating cattle, the contaminant level of aflatoxin in feed becomes unacceptable at 100 ppb (FDA, 2016). Health effects observed in these animals include decreased milk production and feed intake. Previous research indicated that higher producing cows and cows with mastitis excreted more aflatoxin in milk.
A variety of products and strategies are available to mitigate the effects of aflatoxin in dairy cattle. With increased emphasis being placed on prevention, practices to curb aflatoxin begin with choices made in the field including hybrid selection, tillage, rotation, and harvest practices. Contact an agronomist or your local Extension office for recommended practices. Take note if weather conditions during the growing season favor the production of aflatoxin. Store grain and finished feed in a clean, dry space where there is adequate ventilation as well as protection from moisture and microbial contamination.
Many studies have focused on additives, inhibitors, and other products to reduce aflatoxin M1 in milk. The addition of bacteria used as silage inoculants under experimentally varied conditions reduced aflatoxin B1 (Ma et al., 2017). In another study, a reduction in aflatoxin in the milk and feces of cows that had been treated with clay capsules added to the rumen was observed; however, milk yield and efficiency were not maintained when this treatment was applied (Sulzberger et al., 2017). No significant differences in production, composition, or dry matter intake were observed by researchers who noted a reduction in aflatoxin in milk when adding a calcium montmorillonite clay to rations (Maki et al., 2016). In an earlier study, the effectiveness of several products was tested as lactating dairy cattle were fed diets containing aflatoxin-contaminated corn (Kissell et al., 2013). A significant difference in milk aflatoxin levels was observed only with the product containing sodium bentonite, but the concentration of aflatoxin was still above the action level set by the FDA. While these studies present a few examples, many other studies demonstrating various results have been conducted on products.
To effectively minimize and control aflatoxin levels, preventive practices are needed throughout the production of an animal feed or forage. A little cooperation from Mother Nature helps as well. Consumers are depending on the dairy industry to provide a safe product through the implementation of good crop production, harvesting, and storage practices along with vigilant monitoring from dairy producers and processors for the presence of contaminants.
Additional information on mycotoxins and strategies to prevent or reduce them in livestock feeds.
Adams, R. S., K. B. Kephart, V. A. Ishler, L. J. Hutchinson, and G. W. Roth. 2017. Mold and mycotoxin problems in livestock feeding. Penn State Extension Publication DAS93-21.
Campagnollo, F. B., K. C. Ganev, A. M. Khaneghah, J. B. Portela, A. G. Cruz, D. Granato, C. H. Corassin, C. A. F. Oliveira, and A. S. Sant’Ana. 2016. The occurrence and effect of unit operations for dairy products processing on the fate of aflatoxin M1: A review. Food Control. 68:310-329.
Chase, L.E., D. L. Brown, G. C. Bergstrom, and S. C. Murphy. 2013. Aflatoxin M1 in milk. Cornell University Cooperative Extension Fact Sheet.
Food & Drug Administration. 2016. Guidance for Industry #203: Ensuring safety of animal feed maintained and fed on-farm.
Ketney, O., A. Santini, and S. Oancea. 2017. Recent aflatoxin survey data in milk and milk products: A review. Int. J. Dairy Technol. 70:320-330.
Kissell, L., S. Davidson, B. A. Hopkins, G. W. Smith, and L. W. Whitlow. 2013. Effect of experimental feed additives on aflatoxin in milk of dairy cows fed aflatoxin-contaminated diets. J. Anim. Physiol. Anim. Nutr. 97:694-700.
Ma, Z. X., F. X. Amaro, J. J. Romero, O. G. Pereira, K. C. Jeong, and A. T. Adesogan. 2017. The capacity of silage inoculant bacteria to bind aflatoxin B1 in vitro and in artificially contaminated corn silage. J. Dairy Sci. 100:7198-7210.
Maki, C. R., A. D. Thomas, S. E. Elmore, A. A. Romoser, R. B. Harvey, H. A. Ramirez-Ramirez, and T. D. Phillips. 2016. Effects of calcium montmorillonite clay and aflatoxin exposure on dry matter intake, milk production, and milk composition. J. Dairy Sci. 99:1039-1046.
Sulzberger, S. A., S. Melnichenko, and F. C. Cardoso. 2017. Effects of clay after an aflatoxin challenge on aflatoxin clearance, milk production, and metabolism of Holstein cows. J. Dairy Sci. 100:1856-1869.