4763 views 12 commentsupdate:Sep 26, 2012

Green Eggs

Ioannis Mavromichalis
Recently, I had a call from Mexico regarding a quite rare occurrence. Eggs started being green (slightly so, but definitely greenish!) The owner was alarmed because the eggs were for the fresh market. The attending veterianarian had rulled out any disease problems and it was left to the feed. So, they contacted me!


As it happened, after some questions back and forth, this producer had recently been offered a cheap load of imported cottonseed meal and he had started using it at 5% in  all his laying hen formulas (it appears, the 5% rule of thumb is a universal one!) This was not the only ‘alternative’ ingredient added to the formulas at the same time (we are in a global crisis after all) and so it was not obvious what had happened.

Now, cottonseeds contain a yellow pigment called gossypol. There are some varieties without this pigment, but it is generally safe to assume any cottonseed meal will contain gossypol. Concentration varies, but it is about 1% with only 0.1% being free gossypol.

Free gossypol is not that harmful for birds, but even at low concentrations it can cause  egg yolk discoloration starting from green, to brown, even to black! This intensifies with intake and egg cold storage. It is fortunate that free gossypol is easily bound by iron and this is the only remedy, indeed. In our case above, we added 1 kg of ferrous sulphate per tonne of feed and things returned back to normal.

Of course, if cottonseed meal contains more than 0.5-1.0% residual oil, eggs will start appearing with a ‘rose’ tinted albumen, but that’s another’s blog story!

Did you ever happen to encounter this problem and what was the story there?


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    waseem Al-shible

    Thank you
    But can I ask question about the green egg (gossybol) if it is affected pregnant.
    Best Regards
    MVD.Waseem Amer Al-shible

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    nadim Amarin, Technical manager Boehringer Ingelhe

    The article is interesting. I saw this type of greenish yolk in Jordan and we refer it to Cotton seed as well.

    It is good to know the % of ferrus to be used in the feed


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    Vet Abdulkader

    thank you very much for this valuable information

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    Prof.Dr.essa almashhadani

    Intersting article. i have done work in iraq and used ferrus . but it is good to know % of ferrus. Thanks for valuable information.

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    Wael Omar

    Very interesting. can these eggs if consumed, harm human health?

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    thank you for this article.i have a question:is dangerous green yolk for human and birds?

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    Muhammad Imran Haider

    Very good. Being a Student I have learnt vey much from your article.
    Muhammad Imran Haider
    FVS,University of Agriculture Faisalabad,PAKISTAN

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    Nice article, thanks!
    I have an extra question: Could this problem may be encountered in dairy too (greenish milk)?

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    Ioannis Mavromichalis

    Many thanks for the interesting feedback. I have no accurate knowledge regarding the questions you're asking (regarding humans, reproduction, and ruminants) as these are outside my field of expertise. Perhaps someone with more knowledge on these topics could help us!

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    The info is most valuable in terms of quality of feed

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    muhammad ahmad

    i have never seen not even listen about this. This is new and interesting for me

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