Adoption of feeding technology reduces ammonia emissions from swine grow/finish facilities

The combined impact of high feed costs and increased use of synthetic amino acids in swine grow/finish diets is reducing ammonia emissions from pig farms.

Pork producers have adopted feeding strategies that reduce ammonia emissions from swine grow/finish facilities. A research group led by Wendy Powers, director of Environmental Stewardship for Animal Agriculture at Michigan State University, reported a 22 percent reduction in average daily ammonia emissions when grow/finish pigs were fed diets formulated using three synthetic amino acids (lysine, methionine and threonine; 29,123 mg/pig) compared with emissions when pigs were provided diets formulated using lysine only (37,136 mg/pig).

The U.S. Department of Agriculture (USDA) reports that 2 million hogs are marketed from Michigan farms annually. Because farms turn over their inventory about 2.6 times each year, Michigan’s inventory of pigs in the grow/finish phase of production was estimated at 795,000 head. During October, feed company sales representatives who supply feed ingredients to growers of approximately 90 percent of the pigs raised in Michigan were polled. These knowledgeable industry resources estimate that 80 percent, or 636,000 head, of the grow/finish pigs in Michigan are currently fed diets formulated with at least three synthetic amino acids compared to just 6 years ago when most farms fed diets containing only lysine. On the basis of the state’s inventory of grow/finish pigs and the ammonia emission reduction reported by Powers, it’s estimated that the adoption of this feeding strategy in Michigan has resulted in an annual reduction of approximately 2,000 tons of ammonia emissions. The impact of this feeding strategy in Michigan provides an indication of what is occurring nationwide, assuming other producers are adopting this practice as well.

The adoption of this technology is a result of a number of factors. One factor is the research at both public universities and private feed companies along with outreach efforts by Extension specialists and educators, such as those at Michigan State University Extension, that provide nutrition programming throughout the hog industry. Another important factor encouraging the feeding strategy is current feed prices compared with synthetic amino acid prices, and the availability of these products.

Two computer software programs released in 2012 are providing swine nutritionists the tools to estimate the pig’s nutrient utilization and develop diets that limit nutrient losses and air emissions. The National Swine Nutrition Guide ( formulates diets to meet the daily requirements of the pig and provides estimates of the pig’s nutrient retention and excretion. Using this program, nutritionists can formulate multiple diets and compare which diet most closely meets the needs of the pig while maximizing nutrient utilization, minimizing nutrient losses and reducing diet costs.

A supplemental Excel spreadsheet to the National Research Council’s 11th revised edition of The Nutrient Requirements of Swine will evaluate already formulated swine diets. The spreadsheet report advises users whether the diet meets the nutrient requirements of the pig and reports the estimated daily excretion of nitrogen, phosphorus and carbon. The spreadsheet can be found at

Jerry May is a Michigan State University Extension senior educator. He can be contacted at Wendy Powers is a professor and director of agriculture and agribusiness for MSU Extension. She can be contacted at

This article was originally published in the December 2012 issue of the Michigan Farmer.

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