REDUCTION OF NUTRIENT LOSSES AND AERIAL EMISSIONS FROM LIVESTOCK PRODUCTION FACILITIES
Location: Agroecosystems Management Research Unit
Title: Impact of United States biofuels co-products on the feed industry
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: July 5, 2012
Publication Date: September 11, 2012
Citation: Shurson, J.C., Tilstra, H., Kerr, B.J. 2012. Impact of United States biofuels co-products on the feed industry. In: Makkar, H.P.S., editor. Biofuel Co-products as Livestock Feed—Opportunities and Challenges. Rome, Italy: FAO Publishers. pp. 35-60.
Although 140 biodiesel plants produced 1.2 billion liters of biodiesel in 2010, very little crude glycerol has been used in animal feeds in the U.S. due to relatively low volume produced compared to ethanol industry co-products, and its higher value for consumer products and industrial manufacturing. Distillers grains co-products have been fed to livestock for more than a century and the feed industry acceptance over time coincided with the evolution of our nutritional knowledge and growing supply of these ingredients. Distillers grains serve primarily as an energy source in animal feeds, but also contribute a significant amount of amino acids, and are high in digestible phosphorus compared to other grains and grain by-products used in animal feeds. Because of the abundant supply, excellent feeding value, and low cost relative to corn and soybean meal, distillers grains have become the most popular alternative ingredient used in beef, dairy, swine, and poultry diets in the United States and in over 50 countries worldwide. Dietary inclusion rates have been increasing in recent years because of the increasing price of corn and the high energy value DDGS provides to animal feeds at a lower cost. Relative value of distillers grains varies by species, the price differential between corn and soybean meal, and geographic region. The widespread acceptance of distillers grains by the international feed industry is a result of several key factors including: 1) extensive research defining the benefits and limitations of using distillers grains at various levels in ruminant and non-ruminant diets, 2) media attention and use of a variety of information dissemination technologies and programs, 3) economical value relative to record high prices of competing ingredients, and 4) extensive promotion and export market development efforts. The most significant barrier for domestic and international feed industry acceptance has been the variability of nutrient content and digestibility among distillers grains sources. Because color has been historically used as a qualitative indicator of nutrient digestibility, particularly for amino acids, dried distillers grains with solubles (DDGS) with a light, golden color has become the preferred physical quality characteristic in the market. Currently, there are no grading systems or quality standards to differentiate quality, and efforts to develop such systems have not been successful. As a result, various feed industry companies have recently developed and commercialized “nutritional tools” to provide more accurate nutrient loading values for diet formulation and approaches to compare value among distillers grains sources. Other concerns impeding the acceptance of distillers grains in the feed industry include: mycotoxins, antibiotic residues, sulfur content, and risk of introducing bacterial pathogens. An emerging concern about the extent of lipid oxidation in DDGS and its effects on health and performance of monogastrics requires further research. As ethanol production technology continues to evolve, so does the composition and diversity of co-products resulting from these processes. Significant research was conducted to develop, evaluate, and implement front-end fractionation technologies, but because of a number of challenges, there are only a few ethanol plants using these technologies and producing fractionated corn co-products for use in the feed industry. Therefore, front-end fractionation and its associated co-products have had minimal impact on the U.S. feed industry. In contrast, back-end oil extraction technologies are being widely implemented in several dry-grind ethanol plants resulting in reduced oil distillers grains co-products becoming available in significant quantities. However, the impact of oil extraction on energy value of these co-products for livestock and poultry has not been determined, but it will likely result in lower value and reduced dietary inclusion rates in animal feeds. Use of alternative ethanol feedstocks such as other grains, sources of cellulose, and algae, along with the possibility of phytate phosphorus extraction and other technologies, will dramatically change the availability and nutritional composition of co-products. Emerging new markets for distillers grains include aquaculture, horses and companion animals, and human foods, but research to support these market applications is needed.