Mycotoxins were first identified in the 1960s, but it is only recently that they are gaining more notice due to increased monitoring, improved analytical technology and continued scientific research. Mycotoxins have now become a regular concern in regard to feed quality and animal safety. With more than 500 mycotoxins discovered, the most significant types that contaminate feed and feedstuffs are aflatoxins, ochratoxins, type B trichothecenes (DON group), type A trichothecenes (T-2/HT-2 group), zearalenones and fumonisins.
Mycotoxins can cause a variety of symptoms from chronic to acute, that result in decreased growth and productivity of animals. This in turn can significantly impact animal production and profitability. As a result, molds and mycotoxins pose a significant threat to livestock productivity and an ongoing risk to feed and food security.
Effects of mycotoxins on animal performance and health
Mycotoxins can exert their effects on animals in many ways, and responses to acute (large single dose) and chronic (a lesser quantity consumed over time) mycotoxin consumption may vary greatly. Animals may show changes to feeding behaviour, altered intestinal structure and function, changes to endocrine system signalling and modification of the immune system responses. These negative effects can impact all stages of animal production for all animal species. Symptoms of mycotoxicosis are often dependent on the type of mycotoxin involved, the concentration consumed and the age, production requirements or health status of the animal.
There have been numerous studies linking mycotoxins to altered animal performance. Arvind et al. (2003) showed that broiler weight gain can be reduced when birds consume a mixture of mycotoxins, while Santos and Fink-Gremmels (2014) showed that the milk production of dairy cows can be reduced when storage-type mycotoxins are consumed. Immunity can also be altered by mycotoxins, which can lead to changes in immune responses. Fumonisins in pig diets are shown to reduce the efficacy of mycoplasma vaccine titer (Toranu et al., 2005). Fumonisins not only affect the efficacy of vaccines, but can also influence the growth of bacteria, such as E.coli, in the gastrointestinal tract (Oswald, 2003).
Managing the mycotoxin risk to keep feed safe
In order to understand the risk of mycotoxins in feedstuffs or finished feeds, analytical procedures must be conducted to determine the levels of these chemical compounds. Historically, there has been limited availability of risk analysis methods for determining multiple mycotoxins simultaneously in feedstuffs. Today, using an improved liquid chromatography/mass spectrometry method, such as Alltech's 37+™ mycotoxin analysis, detailed results on multiple mycotoxin contamination can be gained which then provides valuable information to producers on the total risk of mycotoxins. With the results of mycotoxin analysis, feed producers have the opportunity to segregate highly contaminated grains or to include these in the ration at a lower rate to reduce overall risk.
The Alltech 37+ program reports not only the levels of mycotoxins measured in a given sample, but also provides a risk assessment that calculates the risk equivalent quantity, or REQ (risk factor multiplied by the quantity of mycotoxins), for that particular feedstuff or finished feed sample. Analysis completed by the Alltech 37+® mycotoxin analytical services laboratory can be utilized for individual samples as well as for analysis of yearly crop contamination. This information is valuable, as contamination levels will vary from year to year based on weather condition during growing and harvest.
Storage of feedstuffs and finished feed
Mycotoxin contamination often occurs when crops are still growing in the field. In these cases, the major influence on the growth of molds and production of mycotoxins are weather conditions. Some molds prefer to grow on plants in hot and dry weather conditions, while others prefer cool and damp conditions and other molds prefer somewhere in between. On the other hand, some mycotoxin-producing molds also grow well when the crop is in storage or during the feed processing procedure (Jounay, 2007). In these cases, molds may produce mycotoxins throughout the storage period. Storage molds and mycotoxins are just as harmful to animal performance and health as field-type mycotoxins, often having strong effects on gastrointestinal and immune systems (Santos and Fink-Gremmels, 2014).
Although little can be done to effectively control mold growth and mycotoxin production in the growing crop, producers may have more control over storage conditions. Properly storing grains is important to maintaining long-term quality of feed materials. After harvest, grains should be dried to under 14 percent moisture or have a water activity (aw) of less than 0.65 (Jouany, 2007). Proper drying may be completed by providing sufficient air flow throughout the feedstuff materials, stirring, drying immediately after harvest, using heat to speed the drying process and cooling efficiently after drying. Feedstuffs should be stored in silos that are free of holes or moisture entry, and fans should be started on a regular basis to avoid the accumulation of moisture.
Feed mill maintenance
Cleaning of the feed mill and storage facilities should be completed regularly. Crusts can build up on mill equipment that harbor storage molds and mycotoxins, as well as other contaminants such as yeasts and insects. These crusts may break off at any time to contaminate finished feed with undesirable compounds. However, with regular audits and maintenance programs, control of these feed contaminates may be achieved. Programs such as the Alltech mycotoxin hazard analysis program (MIKO™) can be particularly useful in reducing mold and mycotoxin risk at feed mills. The Alltech MIKO program incorporates risk assessment and evaluation utilizing HACCP principles, which allows the Alltech team to generate customized reports and recommendations for that particular farm and/or feed mill.
A successful mycotoxin management program goes beyond sampling and rejection of specific ingredients. The feed mill manager must also establish an extensive quality assurance program, train employees and execute the program across all feed manufacturing and delivery processes. Feed mill managers must also educate their customers and growers in order to help prevent mold growth and mycotoxin production in the bin on-farm.
Although good agricultural and manufacturing practices are the best methods of controlling mycotoxin contamination, the use of mycotoxin mitigation products is valuable in the case of contamination occurrence. These products can also be beneficial as preventative measures when mycotoxin levels in feedstuffs or feed are unknown.
A variety of mycotoxin mitigating products are available that may help to alleviate some of the detrimental health effects of mycotoxin exposure to animals (Chaytor et al., 2011). Care should be taken to ensure that the underlying nature of the intoxification is properly understood to make sure a suitable product is used. Mycotoxin contamination rarely occurs as a single mycotoxin type, but rather as co-contamination with multiple mycotoxins. These mycotoxins may interact to increase the toxic response within the animal. As a result, the use of a mycotoxin mitigation product that reduces multiple mycotoxin compounds simultaneously is essential. Mitigation products, such as Mycosorb A+, provide a broad adsorption profile with rapid and efficient mycotoxin mitigation.