MYCOTOXINS EFFECTS IN SWINE

In pig nutrition, animals can be highly exposed to mycotoxins as a result of their diet rich in cereals. Furthermore, pigs are considered the most sensitive species to mycotoxins, which can have a wide variety of adverse effect in the health of the pigs (Tkaczyk and Jedziniak, 2021). The level of effects depends on the animal itself as well as on the mycotoxins (type and concentration). In fact, weaned piglets and sows are often more susceptible so the effects of mycotoxins are more visible (Osweiler and Ensley, 2012).  

Besides, it is common to detect the presence of several mycotoxins in feed (multi-contamination). However, it is important to identify the potential adverse effects of each mycotoxin in particular in order to, in turn, identify possible synergies. The most common symptoms are detailed below (Arroyo-Manzanares et al., 2009; Devreese et al., 2013; Khoshal et al., 2019): 

Aflatoxins

Aflatoxins, especially aflatoxin B1, affect liver function and they are also immunosuppressive. At low doses, aflatoxin usually accumulates without producing clinical signs. However, ingestion of aflatoxins over a long period of time can lead to a chronic aflatoxicosis which can worsen growth, feed conversion rate and reduce the feed intake. In addition, immunosuppression predisposes the animal to be more susceptible to secondary diseases.  In general terms, nursery pigs are more susceptible than pigs and sows, and aflatoxins can pass into the piglets through the milk. 

Deoxynivalenol

Pigs are animals characterized by their high sensivity to mycotoxins from trichothecene group (DON and T2). In general, when DON ingestion increases, pigs reduce abruptly their intake and growth. Furthermore, it is important to highlight its cytotoxic effect on the immune system and the intestinal barrier.

Mycotoxin T2

Unlike DON, T2 intoxication can usually develop acute symptoms after the multiple intestinal and hepatic bleeding that it can cause. Besides, this mycotoxin is immunosuppressive and reduce feed consumption to such an extent that it can cause a total rejection of the intake in animals. 

Ochratoxins

Ochratoxin A is the most prevalent mycotoxin of this group. It is characterized by altering renal functions, as kidney is its target organ, although it can also be detected residually in the liver or in the muscles. In general, pig intoxicated by ochratoxin A tend to have altered renal function and increase urination and water intake. Regarding the production parameters, feed conversion rate and growth rate are comprised, although feed intake may not be altered. Furthermore, it is worth noting the possible detection of abnormalities in the kidney at the slaughterhouse: pale, firm and large kidneys 

Fumonisins

Fumonisin B1 is the most prevalent mycotoxin in this group and alters the cellular function in many tissues, particularly in the lungs, hearth and liver. Furthermore, this mycotoxin is immunosuppressive. Acute intoxication presents severe respiratory signs that can lead to a heart failure. However, the ingestion of small amounts of fumonisin over a long period of time leads to a chronic toxicity, affecting production parameters and increasing the susceptibility to secondary diseases. 

Zearalenone

The symptomology of pigs fed with diets contaminated with zearalenone is centered in the reproductive tract because its structure is similar to the hormone estrogen. Alterations in the reproductive parameters are observed generally in sows and young boars. On the one hand, ZEA swells and reddens the vulva, as well as rectal and vaginal prolapses. On the other hand, this mycotoxin suppresses testosterone levels and libido in males. In addition, in sows there are changes in heat behavior, false pregnancies and early pregnancy losses.

Masked and emerging mycotoxins

In addition to the mycotoxins mentioned, there is also possible intoxication by masked mycotoxins (secondary metabolites of mycotoxins) or emerging ones such as enniantins, beauvericin or moniliformin. Individual and multi-contamination intoxications have been described that impact production parameters, alter the intestinal barrier and cause damage to organs. 

Thus, contamination by various mycotoxins in pig production turns out to be a complex scenario that calls for effective solutions to reduce its negative effects on animal health.