Estimating Corn Use by Iowa Livestock and Poultry
Iowa is a historic leader in production of corn (Zea mays), livestock and poultry. Feeding corn to livestock has been a proven strategy for Iowa farmers to add value to their crop, and livestock feed has been the primary use of Iowa corn for most of its history. More recently, Iowa has taken a leading role in biofuel production, particularly ethanol from corn grain. The rise in ethanol production from corn grain has contributed to an ongoing and lively discourse regarding the uses of corn. The “feed vs. fuel” debate is complicated by the fact that corn used for ethanol production is not entirely lost as feed for livestock. To better examine the use of corn by livestock and poultry within Iowa, a corn-use calculator was developed. This tool combines Iowa livestock and poultry population statistics with livestock production budgets to calculate feed use under several pre-determined scenarios. The tool also allows users to adjust model assumptions regarding feed use to examine corn use by Iowa livestock under conditions of interest to the individual user.
Livestock and poultry population
Livestock and poultry population statistics for the state of Iowa for the years 2006–2010 were collected from USDA summaries (USDA, 2011). Five major categories of livestock were considered: swine, poultry, beef cattle, dairy cattle, and sheep. Within each category several subcategories were identiﬁed in order to account for both maintenance of the population supporting production and the animal products produced - meat, eggs and dairy products. Table 1 summarizes livestock population by subcategory for the state of Iowa for the years 2006–2010.
Corn use as livestock and poultry feed
Livestock enterprise budgets for Iowa (Ellis et al., 2010) were combined with Iowa agricultural statistics (USDA, 2011) to generate simpliﬁed estimates of corn use by Iowa cattle, swine and sheep (Ellis et al., 2010). Corn use estimates by Iowa poultry - layers and turkeys - were developed in consultation with Dr. Mike Persia, Assistant Professor of Animal Science and Iowa State Poultry Specialist (Persia, personal communication).
Corn use scenarios
Three scenarios for feed corn use by Iowa livestock and poultry were developed and are presented in table 2. The ﬁrst (Current) assumes that the mix of corn grain and biofuel co-products presented by Iowa State livestock enterprise budgets mirrors current production conditions in Iowa. The second (None) assumes that no bio-fuel co-products are fed to livestock. The third scenario (Max Co-products) assumes that biofuel co-products are fed at levels approaching the maximum practical limit - amounts of co-products that have been demonstrated to support typical growth and performance without adverse impacts on product quality, animal health or feed management for each class of livestock. The maximum practical limit of co-product inclusion for each class of livestock was determined based on peer reviewed experiments, ﬁeld studies and extension recommendations (USGC, 2007) and are summarized in table 3.
Corn grown and product fed
The corn use calculator summarizes total corn use in two ways. The ﬁrst reports bushels of corn grain needed to feed livestock and poultry and to generate adequate biofuel co-products for feeding livestock. It is assumed that one 56 lb bushel of corn grain will produce 2.8 gallons of ethanol and 17 lbs of co-products (RFA, 2011). This total is an estimate of the corn that must actually be grown in order to meet the demand by various corn grain users. For example each market pig is assumed to consume 9.8 bushels of corn and 32 lbs of co-products. Thus, the total corn grain demand for one market pig is 11.7 bushels (equation 1).
The second method for summarizing corn use is based on mass of feedstuffs directly fed to livestock. For example each market pig is assumed to consume a total of 580.8 lbs of corn grain and co-products (equation 2).
These totals are then compared to the actual corn grain production for the state of Iowa during the modeled year (USDA, 2011) and the estimated corn used by Iowa biofuel reﬁneries in 2010 (RFA, 2011).
Results and discussion
The Iowa livestock and poultry corn use calculator was used to model corn grain use during 2010 and results are summarized in table 4. In 2010, approximately 620,488,000 bushels of corn grain were fed to livestock directly. Another 199,389,000 bushels of corn grain were ﬁrst processed into ethanol and co-products before being fed to livestock. Actual corn production by the state of Iowa totaled 2,153,250,000 bushels (USDA, 2011) with a little more than 50 percent (1,136,785,714 bushels) reﬁned into biofuels (RFA, 2011). Swine was by far the largest single animal user of corn in the state of Iowa. Beef cattle was the largest user of biofuel co-products under typical use assumptions. If the use of biofuel co-products was maximized in livestock diets, swine would be the largest user of both corn grain and biofuel co-products. Feeding the maximum amount of co-products to livestock and poultry would require harvesting 1,174,687,000 bushels of corn grain. This is 3 percent more corn grain than was processed into biofuel in 2010, but still less than 55 percent of the total Iowa corn crop in 2010. The model results demonstrate that Iowa grows adequate corn grain for current feed and fuel uses within the state boundaries under current conditions.
This project was supported by the Iowa Grain Quality Initiative, Charles Hurburgh Professor-in-Charge.
Ellis, S., W. Edwards, J. Lawrence, and A. Johanns. 2010. Livestock enterprise budgets for Iowa - 2010. FM 1815. Iowa State University Extension, Ames, IA.
RFA. 2011. Feeding the world: The role of the U.S. Ethanol industry in food and feed production. Renewable Fuels Association, Washington, D.C.
USDA. 2011. 2011 Iowa agricultural statistics. USDA-National Agricultural Statistics Service, Iowa Field Ofﬁce, Des Moines, IA.
USGC. 2007. DDGS user handbook. U.S. Grains Council, Washington, D.C. Available online.. Accessed: January 23, 2012.