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Toxicity by mycotoxins in laying hens

Contamination by mycotoxins impairs the health of the hen, its productivity and egg qualityContamination by mycotoxins impairs the health of the hen, its productivity and egg quality

Contamination by mycotoxins has a negative impact on the economic return of egg producers, not only due to productivity losses, but also because of their consequences on the health of the layers and on egg quality.

Laying hens are more susceptible to mycotoxins than broilers for three main reasons:

  • A longer life makes laying hens ideal candidates for chronic mycotoxicosis, caused by continuous exposure to low levels of toxins.
  • Layer feeds often include by-products like DDGS, that are usually more contaminated than corn.
  • Layers are subject to frequent stressful practices. The negative consequences of stress, such as immune deficiency, exacerbate the consequences of mycotoxins.

Toxicity of mycotoxins on the health of the hens

1. Gastrointestinal lesions

Cyclopiazonic acid and trichothecenes (T-2 toxin, HT-2 toxin, deoxynivalenol, monoacetoxyscirpenol and diacetoxyscirpenol) are caustic and produce lesions in different parts of the gastrointestinal tract, leading to decreased feed intake, impaired FCR and presence of undigested feed in the intestine.

T-2 toxin diacetoxyscirpenol and are the main mycotoxins responsible for lesions in the beak, tongue and palate.

Lesions in proventriculus and gizzard are mainly caused by T-2 toxin. HT-2 toxin, deoxynivalenol and diacetoxyscirpenol. Fumonisins are associated to enlarged proventriculus.

Ulcers and hemorrhages in the intestinal mucosa are commonly associated to trichothecenes.

Contamination by mycotoxins impairs the health of the hen, its productivity and egg quality

2. Digestive diseases and diarrhea

Ochratoxin, aflatoxins and trichothecenes are possible causes of feed passage.

The negative effect of deoxynivalenol on the intestinal epithelium is a predisposing factor for necrotic enteritis.

Ochratoxin, oosporin and citrinin impair kidney function, which makes the bird drink an excessive amount of water and may lead to wet droppings.

3. Skeletal problems

An adequate supply of calcium and phosphorus in a ratio of 2:1 is key for the health of the skeleton, as well as for the quality of the eggshell. Vitamin D3 is also involved in bone and eggshell formation because it regulates the absorption and metabolism of calcium.

Aflatoxin B1 and T2 toxin interfere with the absorption and metabolism of vitamin D3. Therefore, whenever layer feed is contaminated with mycotoxins, it is advised to increase the dose of vitamin D3.

Other mycotoxins such as ochratoxins, aflatoxins and citrinin impair the renal clearance of urates. Crystals of urate may precipitate in the joints, leading to articular gout.

4. Immunosuppression

Aflatoxins, trichothecenes and ochratoxin, at levels that do not cause signs of mycotoxicosis, suppress immune functions, decreasing the resistance to infectious diseases and causing vaccination failures.

Worsening of productive parameters

It is calculated that contamination by mycotoxins impacts layer farms reducing the amount of eggs produced by 0.08 eggs/hen/week, on average.

  • Aflatoxins, ochratoxins, deoxynivalenol, T-2 toxin and HT-2 toxin have a negative impact on the laying rate.
  • Fumonisins and trichothecenes worsen feed conversion.
  • Ochratoxins delay sexual maturity in pullets.
  • Zearalenone at very high doses causes hormonal disorders, prolapse of the oviduct and enlargement of the cloaca.

Negative effects on egg quality

1. Reduced egg size

Contamination by aflatoxins, ochratoxin and deoxynivalenol results in smaller eggs.

2. Eggshell defects

  • As explained above, aflatoxin B1 and T2 toxin interfere with the absorption and metabolism of vitamin D3 and reduce eggshell weight.
  • Aflatoxin B1 lowers the deposits of vitamin A in the liver of the laying hens. Vitamin A is a key vitamin in the process of eggshell formation.
  • Diacetoxyscirpenol, T-2 toxin and fumonisins increase the percentage of thin-shelled and cracked eggs.
  • Ochratoxins produce yellow-brown stains in the eggshell due to the deposits of urate in the cloaca.
  • Long term exposure to deoxynivalenol results in a higher occurrence of soft eggs.

Contamination by mycotoxins impairs the health of the hen, its productivity and egg quality3. Pale yolks

Ochratoxins, aflatoxins, fumonisins and trichothecenes interfere with the absorption of carotenoids in the intestine and with their metabolism in the liver, resulting in pale yolks.

Additionally, contamination by aflatoxin may result in smaller egg yolks due to the interference of this mycotoxin with the metabolism of fats.

4. Blood spots

Contamination by aflatoxins is linked to a higher occurrence of blood spots in the albumen. Blood spots are the result of a small hemorrhage near the ovarian follicle during the ovulation. Aflatoxins have hemorrhagic effect.

5. Watery whites (poor Haugh unit values)

Long term exposure to aflatoxins and deoxynivalenol impairs the quality of the albumen, that becomes watery.

6. Mycotoxin residues in table eggs

Aflatoxin B1, aflatoxinol, deoxynivalenol and T-2 toxin accumulate in eggs although usually they do not pose a significant risk for human health.

7. Microbiological contamination

Chronic low-level ingestion of mycoxins results in increased digestive infections that can result in egg contamination by E.coli or Salmonella sp.

Conclusions

Laying hens are more sensitive than other poultry to mycotoxins. The health of the layer, its productivity and the quality of the egg can be negatively affected.

Nowadays there is no technology which can fully prevent the mycotoxin contamination before or after harvest. It is necessary to set up a HACCP program to control mycotoxin contamination in layer feeds and to routinely use a suitable mycotoxin binder.

Products of choice

Plusbind©, our line of mycotoxin binders, is the ideal choice to prevent mycotoxicosis in all speciesPlusBind© binders are based on studied cocktails of silicates, providing an excellent and balanced binding capacity, better than binders based only on one silicate.

For more information on this topic and on our products, do not hesitate to contact us through info@plusvet.eu

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Certain health statements may not be applicable in your geographical region. Product claims may differ based upon the requirements of your government.

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Posted in: Mycotoxins, Poultry

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