How mycotoxins predispose poultry for health & nutrition challenges and their risk management

Health and nutrition: inherently intertwined

Although awareness of mycotoxins and their clinical affects has increased, the ability to source materials with low levels or are free of mycotoxins is limited. When birds consume mycotoxins, even at relatively low levels, there can still be sub-clinical challenges related to nutrition and health.

The challenges with nutrition and health are intertwined, when there is damage to organs, there is compromised nutrition. Liver, kidney, gizzard and intestine can be main sites of mycotoxin damage; compromising their function and digestion and absorption of nutrients and energy, culminate into a loss of productivity. Below is a compilation of the main mycotoxins affecting poultry (Table 1).

When health and nutrition are compromised even sub-clinically, there is a loss of production efficiency. On farm, producers may not always see the classic clinical signs with mycotoxins but could be seeing a drop in performance or reproduction due to sub-clinical mycotoxin challenges.

Location, location, location: how clinical signs can help identify mycotoxins

Classic clinical signs associated with mycotoxin contamination have been well documented.

• Mouth ulcers, caused by toxicity in the mouth is usually the result of T2 exposure. Buccal ulcers will also cause reduction in feed consumption. Often when sub-par performance in longer living birds such as layers or breeders is identified, the mouth is a great place to begin an investigation.
• Black vomit and gizzard erosion can be associated with T2. When gut health is compromised, often by protein sources such as rapeseed or sunflower meal, T2 is implicated again.
• Fatty degeneration of the liver can be affected by aflatoxins, as the organ fails to effectively detoxify.
• Subcapsular hematoma – blood clots – in the liver can also result with zearalenone, Fatty liver specifically in laying flocks results in higher mortality, reduced egg production and even prolapse.

As clear cut as clinical signs appear to be, it is often not the case as multiple mycotoxins can have overlapping outcomes (Table 2). Additionally, mycotoxins can lead to other challenges that are not often thought of when it comes to mycotoxin challenges.

Poor immune response is common as mycotoxins affect the gut which is critical for immune function. In turn, mycotoxins reduce immune response to viral diseases. This will have a direct affect on the producer’s vaccine program, where vaccines will not work as effectively leading to increased disease costs and susceptibility as well as welfare issues. When disease is observed either during a necropsy or outbreak, mycotoxins should be considered as they exacerbate the clinical signs.

Necrotic enteritis and coccidiosis, often subclinical, can be related to a low dose of DON, at 3 to 4mg per kg in the diet. Tight junction proteins are closely related to the function of the intestinal barrier in birds. DON could reduce the gene expression related to the tight junction constituent claudin – resulting in leaky gut. Tibial dyschondroplasia could be induced by the presence of Fusarium mycotoxins (DON, ZEN, FUM).

Did you know that mycotoxins also compromise eggshell quality? While perhaps not visible to the naked eye, when using lights, poor eggshell quality can be associated with Aflatoxin B1 and cyclopiazonic acid.

When mycotoxins work synergistically together, their effect is more harmful. Think 1+1=3. This is important in management, where measurement of mycotoxins may show an acceptable level; however, when combined, even at low levels, multiple mycotoxins can reduce performance.

Active decision making: risk management

So how are mycotoxins, individually considered at ‘safe’ levels, managed together? Amino acids are required in excess, to counteract aflatoxicosis’ ability to reduce absorption of amino acids, and to digest protein. Expecting the liver to detoxify, even with liver protectant support, is unlikely to lead to the elimination of the mycotoxin risk, and can even mask subclinical effects.

The power of multiple, combined, mycotoxins eliminate the safety limit figures typically considered for standard risk assessment. Different mycotoxins can contaminate raw commodities and finished feed at various levels depending on harvesting location, climate, commodity type, and time of year. Testing these materials give the producer an indication of what mycotoxin risk management feed additive is the best value for their needs. Understanding the contamination of both major mycotoxins and masked mycotoxins in ingredients and feed gives the producer a full picture of the flock’s risk. It is important also to consider mycotoxins during a necropsy or a change in health status of a flock, as mycotoxicosis can have clinical signs or be exacerbating another challenge. Management’s focus on feed quality, bird monitoring, and consideration of reputable mycotoxin deactivators to counteract toxic effects are all essential.