Mycotoxins: Menace in Animal Farm

Mycotoxins are toxic secondary metabolites synthesized by organisms of the kingdom fungi such as Aspergillus, Penicillium, Fusarium etc. that can cause illness and death in humans and animals. Mycotoxins may be produced in crops, cereals or feed either in field or during storage when moisture content and temperatures are favourably high for growth. Animals and birds can be intoxicated by ingestion, inhalation or direct contact with skin however ingestion of contaminated feed is primarily responsible for it. Mycotoxicosis may cause huge economic losses to poultry and cattle farmers by affecting production, growth rate and reproduction. Moreover, treatment with antibiotics has minimal effect on the course of disease.

Toxic effect produced by various mycotoxins:

• Hepatotoxins- Aflatoxins, Cyclochlorotine, Luteoskyrin, Sporidesmin, Luteoskyrin, Rubratoxins
• Nephrotoxins: Ochratoxin, Citrinin, Oosporeine
• Neurotoxins: Penitrema, Patulin, Citreoviridin
• Cytotoxins: Trichothecenes, T-2 Toxin, Diacetoxyscripenal, Nivalenol, Diacetylnivalenol, Deoxynivalenol (Don, Vomitoxin), Fusarenon X
• Estrogenic Mycotoxins: F-2 Toxin (Zearalenone)
• Carinogenic: Aflatoxin B₁, Ochratoxin A, Fumonisin B₁.
• Immunosuppressive: Aflatoxin B₁, Ochratoxin A and T-2 toxin.

Commonly encountered mycotoxicosis in animals and poultry 

• Aflatoxicosis

Aflatoxins produced by Aspergillus flavus, A. parasiticus are potent hepatotoxins and also have carcinogenic, teratogenic and mutagenic activity. The four major aflatoxins are B1, B2, G1 and G2 of which aflatoxin B1 is most potent. Inappetence, weight loss, decreased milk production and decreased feed efficiency are predominantly seen in chronic cases. Aflatoxins M1, M2 are excreted in the milk of lactating cattle and is therefore an issue of public health concern.

• Ochratoxicosis

Ochratoxins are potent nephrotoxins produced by Penicillium viridicatum and Aspergillus ochraceus in grains and feed. Affected birds show diarrhoea, paralysis, low weight gain and decline in egg production.

• Ergot poisoning

Ergotism occurs due to ingestion of sclerotia of the parasitic fungus Claviceps purpurea containing ergot alkaloids. Vasoconstrictive effect of alkaloid results in necrosis and gangrene of extremities. Besides this, ergot alkaloids are also responsible for agalactia, dyspnoea and heat intolerance in dairy cattle.

• Fusarium toxicity

Fumonisins are mycotoxins produced by Fusarium sp. on moldy corn grain. Pigs and horses are more vulnerable to the poisoning. Equine leukoencephalomalacia and porcine pulmonary oedema are associated with ingestion of fumonisins.

Prevention and Control

• Removal of source of toxins and detoxification of contaminated feed
• In feed storage areas, implement effective rodent and insect control programmes.
• Antifungal feed preservatives and binding agents (activated carbons, bentonite, hydrated sodium calcium aluminosilicate, zeolites, and lactic acid bacteria) can be added in feed.
• Administration of soluble vitamins, mineral additives capable of binding mycotoxins and acid treatment and pelleting of feed is also beneficial.
• Raw material and feed should be stored hygienically at low temperature and low moisture.
• Biological control methods, as well as targeted plant breeding strategies and increasing host plant resistance reduces the risk.