COUNCIL FORFOR AGRICULTURALAGRICULTURAL SCIENCE SCIENCE AND AND TECHNOLOGY—1 TECHNOLOGY NUMBER 33 JULY 2006 ANIMAL AGRICULTURE'S FUTURE THROUGH BIOTECHNOLOGY, PART 4 BIOTECHNOLOGICAL APPROACHES TO MANURE NUTRIENT MANAGEMENT TASK FORCE MEMBERS: Xingen Lei, Chair, Department of Animal Science, Cornell Univer- neering. This type of technol- INTRODUCTION sity, Ithaca, New York; John P. Blake, Depart- Food animals are fed and ogy may be applied to de- produced for the purpose of ment of Poultry Science, Auburn University, crease total manure mass or feeding humans. Manure from Auburn, Alabama; Cecil W. Forsberg, Depart- concentrations of P, N, am- these animals is a valuable ment of Microbiology, University of Guelph, monia (NH3), trace elements, source of fertilizer, but con- Ontario, Canada; Danny G. Fox, Department of and other factors. Targeted modifications centrations of manure nutri- Animal Science, Cornell University, Ithaca, New 1 can be based strategically on ents such as phosphorus (P) , York; Elizabeth Grabau, Department of Plant nitrogen (N), and metals may plants, animals, ruminal and Pathology, Physiology, and Weed Science, Vir- exceed needs for plant growth intestinal microorganisms, and cause environmental pol- ginia Tech, Blacksburg; Zdzislaw Mroz, Ani- and diets. The plant-based lution. Thus, managing live- mal Sciences Group, Division of Nutrition and approaches include genetic stock manure nutrients has Food, Wageningen, The Netherlands; Alan L. and chemical modifications of been a task shared by those Sutton, Department of Animal Sciences, Purdue feeds (e.g., overexpressing hydrolytic enzymes such as interested in animal nutrition, University, West Lafayette, Indiana; William R. agronomy, and environmental phytase in seeds, decreasing Walker, DPI Global, Fort Dodge, Iowa; Ken- protection. Many strategies poorly digestible components can be used to monitor manure neth Webb, Department of Animal and Poultry such as phytate, and enriching nutrient composition, and bio- Sciences, Virginia Tech, Blacksburg; REVIEW- essential nutrients such as technology has emerged as ERS: James C. Matthews, Department of Animal amino acid lysine). Animal- one of the most effective tools and Food Sciences, University of Kentucky, Lex- based approaches feature ge- netically engineering or for this purpose. ington; Stephen B. Shears, Laboratory of Signal modifying key enzymes and Biotechnology, in this Transduction, National Institute of Environmental context, is regarded as meth- pathways in tissues for en- Health, Research Triangle Park, North Carolina; ods and products derived hancing nutrient digestion from genetic material deoxy- Trygve Veum, Animal Science Research Center, and use. One recent success is ribonucleic acid (DNA) and ri- University of Missouri, Columbia; CAST Board the creation of the “Enviro bonucleic acid (RNA) manipu- Liaison: Alan W. Bell, Department of Animal Pig” that can digest feed P lations and/or protein engi- Science, Cornell University, Ithaca, New York from phytate effectively. Microorganism-based ap- proaches aim to modulate the metabolism of the inhabit- This material is based upon work supported by the United States Department of Agriculture under Grant No. 2004-34531-14969\ISU ant microbes or modify the microbial genes for improv- Project No. 416-44-92 and Grant No. 2005-38902-02319. Any opin- ing feed fermentation and adding new digestive ions, findings, conclusions, or recommendations expressed in this pub- capacities. Nutrition- or diet-based approaches are de- lication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or Iowa State University. signed to improve dietary nutrient balance and 1Italicized terms (except species names) are defined in the Glossary. bioavailability for the physiological needs of animals. COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY—2 The primary purpose of this Issue Paper is to review Water Quality the existing biotechnology (including novel technology) More than 56,000 kilometers (km) (35,000 miles) of applied to manage animal manure nutrients. This paper rivers in the United States have been estimated to be dam- differs from two related, previous CAST issue papers (IP aged by runoff manure and excessive nutrient loading to 21, Animal Diet Modification to Decrease the Potential agricultural land from animal feeding operations, with for Nitrogen and Phosphorus Pollution, and IP 23, Bio- 60% of these waterways unfit for fishing or swimming technology in Animal Agriculture: An Overview) in that (USEPA/USDA 1998). Nutrients, especially N and P, the current one serves as a more comprehensive and up- organic matter, and microbial organisms, are the primary dated review of developed biotechnology—the advances concerns from animal manure pollution. Increased ni- in transgenic animals and microorganisms, in particular. trates in water can cause methemoglobinemia, commonly New topics discussed include potential biotechnology called “blue baby syndrome” (Johnson and Kross 1990), derived by genomics approaches, integration of multiple although the occurrence is rare in the United States. The biotechnologies in production conditions, and industrial nitrate molecule is converted to nitrite, which replaces and societal issues related to biotechnology for manure oxygen on hemoglobin and starves the infant for air. nutrient management. Similarly, N, especially in the ammonium form, can stress aquatic life at a very low concentration and is toxic NUTRIENT COMPOSITION OF ANIMAL to fish at excessive levels. Elevated P concentrations in MANURE water cause algal blooms and eutrophication of water, Manure Mass and Composition resulting in decreased oxygen levels and fish kills (Correll 1998). There are approximately 18,000 km2 of a hypoxic Total collectable manure produced in the United “dead zone” in the Gulf of Mexico, the largest water body States amounts to approximately 56 million dry metric adjacent to the United States that is so affected (CAST tons per year (CAST 1996), an amount that could be used 1999). The hypoxic condition is derived from a long-term as a plant nutrient resource. The nutrient value of this nutrient enrichment, primarily from organic matter (sedi- quantity of manure has an economic value of $3.4 bil- ment) and N flow into the Mississippi Basin, and the se- lion per year and would replace 15% of the fertilizer N verity of the condition varies from year to year. Such dead and 42% of the fertilizer P purchased for crop produc- zones occur in water systems around the world, includ- tion, respectively. ing several in the United States: the upper East Coast A recent publication (ASABE 2005) has detailed the shoreline (North Carolina and Chesapeake Bay), upper average composition of freshly excreted manure by dif- Northwest shoreline (Oregon and Washington), and ferent species at different life cycles of typical livestock southern California shoreline. and poultry production. The amount and composition of freshly excreted manure can vary considerably and is influenced primarily by the original composition of the Air Quality diet, species, and feeding management. Factors affecting Odorous and gaseous compounds are emitted from manure composition at the time of removal and applica- manure immediately after excretion because of microbial tion to land include type and time in storage, and amount metabolism in the digestive tract of the animal. Further of added water, bedding, spilled feed, soil, and other con- decomposition occurs in storage, resulting in significant taminants. Climatic conditions such as temperature, hu- gaseous emissions and odors that may impact air quality midity, and air movement can influence the rate of mi- (Le et al. 2005). These emissions include nitrogenous and crobial degradation, volatile losses, and moisture content sulfur compounds, volatile organic compounds, and of the manure. greenhouse gases (methane, carbon dioxide, nitrous ox- ides) that may cause acid rain (nitrous oxides, sulfates) Environmental and Agricultural Impacts on land and surface water. Greenhouse gas emissions can contribute to the reduction of the Earth's ozone layer. Manure is an inevitable by-product of animal pro- High concentrations of NH3 emissions and gases created duction, but excess manure production or nutrient excre- from the digestion of manure slurry in pit systems of tion not only represents inefficiencies but also can cause confinement facilities can lead to nasal and lung irrita- a series of negative environmental impacts. tion in workers caring for livestock in these facilities, if COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY—3 buildings are poorly ventilated (Zhang et al. 1998). gaseous compounds such as NH3, hydrogen sulfide, and volatile organic compounds will alleviate air quality con- Soil Quality cerns associated with animal production. Specific fer- mentable feed ingredients may be used to control manure Excess application of manure to the soil is one of the odor and to balance manure composition for crop use. greatest concerns regarding livestock and poultry produc- Biotechnology potentially can alter or control the biodeg- tion. This practice creates an accumulation of nutrients, radation or retention of nutrients during storage of ma- with the potential impact of enriching water sources dur- nure and after the manure is placed in the soil. ing runoff to surface water or leaching into groundwater supplies. Soil nutrient imbalances also can impair nutri- ent uptake and cause nutrient