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Maize Versus Wheat/Barley DDGS

Dr Ioannis Mavromichalis
Maize and wheat/barley DDGS are quite often used interchangeably in pig formulations, with disappointing results leading to the misleading conclusion that DDGS should be reserved only for ruminants. Let me explain the basic differences between these two ingredients.

It is no secret that the advent of bioethanol's main by-product, distiller's grains with solubles or DDGS, has reshaped the formulation of pig feeds in the Americas, where the main fermentation raw material is maize. Not insignificant quantities of maize DDGS reach Europe each year, and with some hesitation, they have found their way into pig feeds, mainly for gestating sows and finishing pigs.
Lately, Europe has started to produce her own DDGS, basically from home grown wheat, and sometimes from wheat/barley mixtures. Although the fermentation process is similar, the end products are not! Yet, maize and wheat/barley DDGS are quite often used interchangeably in pig formulations, with disappointing results leading to the misleading conclusion that DDGS should be reserved only for ruminants.
Let me explain the basic differences between these two ingredients.
Composition
Basically, DDGS are the whole cereal kernel, be it maize or wheat/barley, minus almost all its starch content. With current fermentation processes, the end product is around 1/3 DDGS, 1/3 CO2, and 1/3 ethanol (by weight). It is thus logical to assume that the nutrient composition of DDGS would be that of its corresponding cereal concentrated three times. Indeed, the chemical profile of DDGS verifies this assumption. Therefore, maize and wheat/barley DDGS are as similar as are maize and wheat!
Mycotoxins
One of the main problems of DDGS is the concentration of mycotoxins (again, three times the level found in raw material). In maize the major problem is aflatoxins, but in wheat/barley aflatoxins seldom become a major issue as deoxynivalenol, nivalenol, and zearalenone are more prevalent. Thus, a totally different anti-mycotoxin agent should be used in diets formulated with wheat/barley DDGS.
Non-Starch Polysaccharides
Maize contains few, if any, anti-nutritional factors, with non-starch polysaccharides (NSP) being an insignificant fraction. In contrast, wheat and barley contain relatively high levels on NSP, with arabinoxylans and beta-glucans being most prevalent in wheat and barley, accordingly. Diets based on wheat and/or barley are usually supplemented with an appropriate enzyme (or a cocktail of enzymes) to enhance their nutritive value, especially when the cereals are of low quality (high in NSP). It is logical to assume, therefore, that diets based on wheat/barley DDGS would also benefit from such nutritional intervention, especially when the main cereal (energy) in the diet is also wheat/barley. This is pending verification!
Amino acids
Most maize and maize DDGS diets are limiting first in lysine and second in tryptophan, requiring thus supplementation with crystalline amino acids. In contrast, wheat and barley, and consequently their derived DDGS, are limiting first in lysine and second in threonine. As crystalline threonine is quite cheaper than tryptophan, it is apparent that wheat/barley DDGS can enter the formulation at a rather higher price than maize DDGS. Also, the difference in the second limiting amino acid between maize and wheat/barley DDGS, excludes the use of amino acid-containing premixes to be used interchangeably.

3 comments

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    A reader

    Thanks for your time and effort to write on this topic. I want to raise a couple of points here about mycotoxins in your blog:
    You have mentioned that " in maize the major problem is aflatoxins". This is a very strong statement which needs to be supported by research data. Mycotoxins' distribution in cereals varies in different geographic locations.
    You have also mentioned that
    " a totally different anti-mycotoxin agent should be used....". What do you mean by this? Companies, making anti-mycotoxins at commercial levels, claim that their products are effective against a wide range of mycotoxins regardless of nature of raw materials.

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    Ioannis Mavromichalis

    To A Reader...You´re correct. When writing a blog for such a wide audience one has to be generic. So, let me explain in detail. Any textbook on nutrition or mycotoxins will mention that maize is most sensitive to aflatoxins. Not that other mycotoxins don´t affect this cereal, but aflatoxins are the major problem. So, if I were buying maize without being able to test for specific mycotoxins, I would be worried for aflatoxins, especially if it arrived from Americas. Naturally, this also applies to DDGS coming from similar sources. Now, there are some commercial products that might be effective against a wide range of mycotoxins, but they do so at a variable degree of efficiency. If my batch of maize was found to contain specifically aflatoxins at high levels, I would like an anti-aflatoxin-specific agent. On the othe other hand, if I could not test my maize and/or the source was unknown, I would definitely go for a wide-spectrum, generic anti-mycotoxin agent. So, it is all a balance of what information is available!

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    pixietaiwhati

    WE GET OUR MEAL ALREADY MADE,EXAMPLE IN PELLETS HOW WOULD WE KNOW ABOUT THE MICROTOXINS ETC.. IF NOT MADE ON THE FARM? THANKYOU

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