QI understand GM maize is grown in the US for cattle feed. Is any of this sold to the UK agricultural sector for cattle feed? And if so, it is known that maize has a deficit of certain nutrients [which necessitate cattle fed on maize being also fed supplem

I understand GM maize is grown in the US for cattle feed. Is any of this sold to the UK agricultural sector for cattle feed? And if so, it is known that maize has a deficit of certain nutrients [which necessitate cattle fed on maize being also fed supplements], is there a similar deficit in GM maize or are there any different nutrient deficits with GM maize?

AExpert Answer

Thanks for your question.  I’m going to break down my response to make sure I answer all of your points. 

  • First, contrary to some Internet rumors, GM maize is not just used for animal feed in the United States. GM maize is grown for the same uses as non-GM maize, and they are no different in their nutrient composition.  According to USDA, approximately 45 percent of corn grown in the United States is used as feed for animals.  In animal nutrition, individual feeds that make up the total diet are selected for specific reasons. The nutritional reason animals are fed maize is that it is a good source of energy (i.e., calories), both as a result of digestible energy per pound of feed and because animals readily consume it.

    According to USDA-ERS, corn processed for human consumption and industrial uses accounts for about one-third of U.S. corn utilization. Dry millers process corn into flakes for cereal, corn flour, corn grits, corn meal and brewers' grits for beer production.  It also can be wet-processed into high-fructose corn syrup (HFCS), glucose and dextrose, starch, corn oil, beverage alcohol, industrial alcohol and fuel ethanol. Approximately one-third of the corn used for ethanol production comes back as animal feed in the form of distillers' grains.


  • Second, regarding your question about the U.K., the U.K. imports most of the maize it uses, but less than 5 percent of it is used as feed. In the U.K., wheat and barley are more commonly used as energy sources in diets of animals. 

  • And last, regarding the nutritional composition of GM maize and maize in animal feed, diets for animals need to be balanced for many nutrients.  For example, here are the numbers for protein, which often is the most expensive nutrient in their diet.  Compared with other feeds, maize is relatively low in protein (9.4 percent) compared with the nutritional requirements of many animals (e.g., 18 percent for a high-producing dairy cow).  Adding soybean meal (53.4 percent protein) to diets is a good way of achieving nutritional goals for protein.  In fact, it stands to reason that prices of commodity feeds are related to their protein content.

    As has been discussed in previous answers on this site, and contrary to Internet myths, all GM products go through comprehensive composition testing. Regardless of whether derived from GM or non-GM, the maize grain is nutritionally equivalent.  This manuscript has data on the nutritional composition of SmartStax corn, which has eight genes added by GM technology, compared with near-isogenic conventional corn.


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