Maize Versus Wheat/Barley DDGS

03-08-2007 | |
Mavromichalis
Dr Ioannis Mavromichalis International consulting nutritionist, Ariston Nutrition, Madrid, Spain

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.
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