Managing Nutrients for Profit and Stewardship

This paper will describe how environmental quality is interrelated with feed management and whole farm nutrient management by using the nutrients of N and P to demonstrate the concepts and connections between feed management and whole farm nutrient management. In addition, this paper will focus on aspects of manure management related to the fate and transport of pharmaceuticals to the environment. The intent of this summary is to bring awareness of the potential impact of manure on the environment, and practices which can minimize that risk.

Society has placed an expectation on dairy operations to manage nutrients to limit their loss to the environment (Harrison et al., 2007). This emphasis on environmental stewardship comes at a time when profitability and financial sustainability for the dairy sector has much uncertainty. There are real opportunities to manage feed and manure to the dual goals of increasing profitability and embracing environmental stewardship.

The emphasis of contemporary integrated nutrient management should be placed on three areas: reducing imports, enhancing within farm efficiencies (both cropping and cow efficiencies), and seeking export opportunities for excess nutrients not utilized for crop production on the farm (see figure 1). Long term sustainability should focus on an integrated approach to nutrient management. This will require an intentional effort to reconnect the nutrient cycle and link the movement of nutrients between sites of feed production and feed utilization. 

Figure 1 Three areas of primary importance for integrated nutrient management: nutrient import, within farm efficiencies, and nutrient export.

The ability to produce synthetic nitrogen fertilizer after the Second World War created the opportunity for nitrogen use in agriculture to increase dramatically. The use of nitrogen fertilizer in the USA increased from approximately 0.5 million tonnes/yr in 1940 to 11 million tonnes/ yr in 1980 (Lanyon, 1995). This allowed for the development of specialized regions for production of animals and crops, or animals since animal manure was no longer a requisite for crop production (Lanyon, 1995). Availability of synthetic nitrogen fertilizers has been beneficial for human health by providing increased availability of food with high nutritive value (Galloway et al., 2002). However, unintended consequences of increased use of fertilizers has been human health concerns, such as respiratory and cardiac diseases (Galloway et al., 2002) and environmental concerns such as increased saturation of terrestrial and aquatic ecosystems with reactive nitrogen (Galloway et al., 2003). The association of P with eutrophication of surface waters has resulted in a significant focus on the role of P in animal agriculture. P-related research in recent years has concentrated on two main areas: reducing P excretion from livestock and application and transport of P on agricultural fields.

As agriculture began to organize into specialized regions, the areas of crop production have not necessarily been in close proximity to areas of animal production (Friedmann et al., 1979). This has resulted in nutrient sinks developing in areas of animal production, since transport of nutrients in manure to areas of crop production is expensive and complicated. Lanyon (2000) described the components of an animal production system that relies on geologic phosphorus to sustain crop production and to supplement animal rations (see Figure 2). To reconnect this “broken” nutrient cycle, society should aim to become involved and assist with development of a system that will link the movement of nutrients between sites of feed production and feed utilization. 

Figure 2.The components of an animal production system that relies on geologic phosphorus to sustain crop production and to supplement animal rations. Source: Lanyon, 2000. 

Recent information suggests that the availability of P reserves maybe as short as a few decades. "Our supply of mined phosphorus is running out. Some initial analyses from scientists with the Global Phosphorus Research Initiative estimate that there will not be sufficient phosphorus supplies from mining to meet agricultural demand within 30 to 40 years. The geographic concentration of phosphate mines also threatens to usher in an era of intense resource competition. Nearly 90 percent of the world's estimated phosphorus reserves are found in five countries: Morocco, China, South Africa, Jordan, and the United States."(quote from “Peak Phosphorus” - http://www.foreignpolicy.com/articles/2010/04/20/peak_phosphorus. 

The National Feed Management Outreach team has developed a system and supporting decision aid computer-based tools which integrate management considerations related to feed management, manure management, and nutrient management. Detailed information on the Feed Management Education Program can be located at http://www.puyallup.wsu.edu/dairy/nutrient-management/publications.asp

The key steps involved in the systematic approach include: 1) determining if a detailed feed management plan has the opportunity to impact whole farm nutrient management, 2) evaluating the economics of making a ration change vs transporting manure away from the farm, 3) completing a written feed management plan, and 4) implementing and monitoring the plan. Assessment tools, checklists, templates, and example plans can all be found at the website noted above.

Evaluating the interrelationships between feed management and nutrient management is difficult without the use of tools to account for the fate and transformation of nutrients that occur between the point of feed acquisition and land application of manure for crop production. A decision aid tool has been developed which considers the fate and transport with outcomes of nutrient accounting and profitability http://www.puyallup.wsu.edu/dairy/nutrient-management/software.asp.

There are a number of feed management practices that have proven to reduce the amount of nutrients imported to the farm and excreted in manure. These include: controlling feed wastage, monitoring the mineral content of water, feed processing to increase digestibility, balancing for protein fractions and use of amino acid supplementation, grouping of cattle, and bovine somatotropin (bST) (Harrison, 2004; Harrison and White, 2006; Jonker, Kohn, and High, 2002; Kohn et a., 1997; St-Pierre and Tharaen, 1999). Focusing on the diet formulation component of feed management has been described as precision feed management (Cerosaletti, Dewing, and Lucas, 2006). 

Manure is a biologically active material which hosts and supports many microorganisms, and thus can seldom be considered “pathogen free”. Certain manure handling techniques and methods however can limit the production and multiplication of such pathogens. In addition, common antibiotics and hormones have also been documented in animal manures. Awareness and risk assessments must be considered in developing best management practices and policy related to manure handling.

Antibiotics - The fate of antibiotics used at concentrated animal feeding operations (CAFOs) has gained recent attention by the regulatory community. Watanabe et al. (2010) reported the occurrence of antibiotics in the environment on two dairies. Samples were collected at the points of use of antibiotics and subsequent points of manure handling. They observed that although antibiotics had been used for decades on these two dairy farms, the antibiotics seemed to be detected within farm boundaries. Antibiotics were most frequently detected at lagoons, hospital pens, and calf hutches. Some evidence of sulfonamides was found in shallow ground water, while tetracyclines were identified in soils. Each of these antibiotics has distinct physiochemical properties. Sulfonamides are known to weakly sorb to soils, while tetracyclines have a higher sorption, thus explaining the difference in location of detection. Lincomycin was found in ground water at one dairy, but not in the lagoon water at that same dairy. The authors suggest that due to Lincomycin’s environmental persistence could explain the observation since it is has photochemical and microbial stability. Evaluation of field surface samples demonstrated the presence of antibiotics on fields where manure had been applied, but not in the sandy subsoil.

Davis et al. (2006) studied the potential of seven antibiotics (tetracycline, chlortetracycline, sulfathiazole, sulfamethazine, and erythromycin, tylosin, and monensin) to appear in runoff water and sediment. The seven antibiotics were applied to land that had been prepared for corn production and then exposed to simulated rainfall. They observed that monensin had the highest concentration in runoff, while erythromycin had the highest concentration in sediment. Tetracycline and chlortetracycline had the lowest aqueous concentrations, and lowest absolute losses. The results suggest that erosion control practices would minimize the loss of tetracycline, erythromycin, and tylosin; while other methods would be needed to reduce off-site transport of the other four antibiotics.

The environmental occurrence and shallow ground water detection of monensin was studied by Watanabe et al. (2008). Monensin is expected to persist in the environment since hydrolysis and photolysis is limited (cited by Watanabe et al., 2008). In addition, monensin is expected to be more mobile than tetracyclines and of similar mobility to sulfamethazine (cited by Watanabe et al., 2008). Monenesin was detected in one of eight shallow ground water wells at dairy I and three of eight wells (2 – 5 meters) at dairy II. The wells affected were associated with the lagoons, but not fields where manure was applied. The lagoons at both dairies were > 30 years old, were lined with 10% clay, but had previously been identified as leaking. The authors suggest that anoxic conditions near the lagoons (lack of oxygen) may promote the stability of monensin, while aerobic field conditions would promote degradation of monensin.

Antibiotic Resistance - Resistance of bacteria to antibiotics continues to be a concern of medical health professionals and veterinarians alike. Reducing the effectiveness of proven antibiotics would be costly for meat, milk, and egg production; and, potentially increasing the risk for bacterial infections insensitive to common antibiotics in humans. West et al., (2010) documented the presence of antibiotic resistant bacteria in samples from waterways in close proximity to waste-water treatment plants and CAFOs. From 830 environmental bacterial isolates, 77.1% were resistant to only ampicillin, while 21.2% were resistant to combinations of antibiotics including ampicillin (A), kanamycin (K), chlorotetracycline (C), oxytetracycline (O), and streptomycin (S). Multi-drug-resistant bacteria were significantly more common at sites close to CAFO farms.

There has been uncertainty as to when and therefore what location that bacteria gain their ability to be antibiotic resistant? Does it occur in the animal’s gut or in the environment? Two recent publications (Subbiah et al., 2012; and Subbiah et al., 2011) have provided some insight. Subbiah et al. (2011) evaluated 10 different antibiotics for their ability to be bioactive in soil. When ampicillin, cephalothin, cefoxitin, ceftiofur, florfenicol, neomycin, tetracycline, and ciproflaxin were tested in soil-water slurries. It was observed that supernatants from soil-water slurries of ampicillin, cephalothin, cefoxitin, ceftiofur, florfenicol inhibited bacterial growth. In contrast, supernatants of soil-water slurries from neomycin, tetracycline, and ciproflaxin soil-water slurries did not inhibit bacterial growth. This study suggests that some antibiotics are not bioactive after contact with soil.

A more recent report by Subbiah et al. (2012) suggests that urine containing ceftiofur metabolites is degraded more readily in warm soil (23 degrees C) but persists at 4 degrees C. The persistence under cool temperatures could provide a > 1 log₁₀ advantage to cef^R resistant E.coli populations.

Hormones - Numerous studies have documented the presence of hormones in manure and their subsequent fate when manure is stored in manure lagoons or applied to crop land (Dutta et a., 2010; Khanal et al., 2006: Lorenzen et al., 2004; Raman, et al., 2004; Hansleman et al., 2003; Arnon et al., 2008; and Zhao et al., 2008). The general concern is the endocrine disrupting effects on wildlife and aquatic life when these hormones or conjugates are transported to ground and surface water. Endogenously (naturally) produced hormones excreted by humans and livestock, along with a host of compounds in human personal care products (ibuprofen, pigments, soaps), can disrupt endocrine system and have been linked with developmental, reproductive, neural, immune, and other problems in wildlife and laboratory animals.

Zheng et al. (2008) characterized the concentration of three endogenous hormones (17 alpha-estradiol, 17 beta-estradiol, and estrone) in dairy waste water and lagoon water. The concentration of total steroid hormones in the sequential lagoons was ~ 1 – 3 orders of magnitude less than in fresh dairy wastewaters. The same relationship was observed for steroid hormones in manure soilds.

Bartlet-Hunt at al. (2011) studied the occurrence of thirteen steroid hormones and seventeen veterinary pharmaceuticals at operating swine and beef cattle facilities. The facilities had lagoons that were known from prior studies to have direct infiltration of waste water into shallow ground water and represent a worst case scenario. Steroid hormones were detected less frequently than pharmaceuticals.

Treatment of manure via anaerobic digestion or composting can decrease the amount of estrogens detected in manure (Zhao et al., 2008). While there is still much to be learned, it is apparent that hormones or their conjugates to have an ability to persist in the environment. This persistence can in part be explained by the lipophilic nature of hormones as they are poorly soluble in water and therefore would be absorbed onto sediment particles (Arnon, et al., 2008). 

A number of currently used management practices serve to ameliorate the movement of pharmaceuticals from the point of excretion by the cow to the intersect of surface and ground water.

Grass Filter Strips – Nichols et al (1997) demonstrated that grass filter strips were effective in reducing the concentration of estradiol originating from poultry litter by 58%, 81%, and 94% after transport through filters of 6.1 meters, 12.2 meters, and 18.3 meters.

Composting – Windrow composting of poultry manure for 139 days resulted in a 84% decrease in 17beta-estradiol content and a 90% decrease in testosterone content (Haak et al., 2005).

Identify Readily Available Alternatives – One of the standard practices when producing ethanol from grain has been the use of antibiotics to control the fermentation. When antibiotics are added to fermentation vessels it allows for more efficient conversion of starch to ethanol. The ethanol industry has shifted toward use of non-antibiotic antimicrobial products to avoid the issue of antibiotic residues in distillers grains (Olmstead, 2012).

Anaerobic Digestion - anaerobic digestion of manure (Zhao et al., 2008) and sewage sludge has been shown to result in reductions in pharmaceuticals. 

The following webcasts and websites are recommended for further understanding of the factors related to pathogens and pharmaceuticals in manure.

Arnon, S., O. Dahan, S, Elhanay, K. Cohen, I. Pankratov, A. Gross, Z. Ronen, S. Baram, L. Shores. 2008. Transport of Testosterone and Estrogen from Dairy-Farm Waste Lagoons to Groundwater. Environ. Sci. Technol. 42: 5521–5526.

Bartlet-Hunt, S., Snow, D. D., Damon-Powell, T., and Miesbach, D. Occurrence of steroid hormones and antibiotics in shallow groundwater impacted by livestock waste control facilities. Journal of Contaminant Hydrology. 123(94-103).

Carballa, M., F. Omil, T. Ternes, and J. M. Lema. 2007. Fate of pharmaceutical and personal cre products (PPCPs) during anaerobic digestion of sewage sludge. Water Research. 41:2139-2150.

Cerosaletti PE, Dewing DR, Lucas AW. Managing nutrients through precision feed management. Silage for Dairy Farms: Growing, Harvesting, and Feeding Conference. NRAES-181, 23–25 January 2006. p. 26–36.

Davis, J. G., C. C. Truman, S. C. Kim, J. C. Ascough II, and K. Carlson. 2006. Antibiotic transport via runoff and soil losses. J. Environ. Qual. 35:2250-2260.

Dutta, S., S Inamdar, J Tso, D. Aga, and J. T. Sims. 2010. Free and Conjugated Estrogen Exports in Surface-Runoff from Poultry Litter–Amended Soil J. Environ. Qual. 39:1688–1698.

Haak, H. P., P. Milner, and G. Larsen. 2005. Decrease in water soluble 17 beta-estradiol and testosterone in composted poultry manure with time. J Environ Qual. 34:943-950.

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Harrison JH, White RA. Development of a national feed management education program and assessment tools into a comprehensive nutrient management plan. Future of Agriculture: Science, Stewardship, and Sustainability Conference, Sacramento, CA, August 2006.

Harrison, J.H., Nennich, T., & White, R. (2007, May). Nutrient Management and Dairy Cattle production - Invited Review. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 2(020). http://www.cababstractsplus.org/cabreviews/reviews.asp

Hanselman, T., D. Graetz, and A. Wilkie. 2003. Manure-Borne Estrogens as Potential Environmental Contaminants: A Review. Environ. Sci. Technol. 37:(24)5471-5478.

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Lorenzen, A., J. G. Hendel, K. L. Conn, S. Bittman, A. B. Kwabiah, G. Lazarovitz, D. Masse, T, McAllister, and E. Topp. 2004. Survey of Hormone Activities in Municipal Biosolids and Animal Manures. Environ. Toxicol. 19: 216–225.

Nichols, D. J., T. C. Daniel, P. A. Moore, D. R. Edwards, D. H. Pote. 1997. Runoff of estrogen 17beta-estradiol from poultry litter applied to pasture. J Environ Qual 26:1002-1006.

Olmstead, J. 2012. Bugs in the system: how the FDA fails to regulate antibiotics in ethanol production. Institute for Agriculture and Trade Policy. http://www.iatp.org/files/2012_05_02_AntibioticsinEthanol_JO_0.

Raman, D., E. Williams, A. Layton, R. Burns, J. Easter, A. Daugherty, M. Mullen, and G. Sayler. 2004. Estrogen Content of Dairy and Swine Wastes. Environ. Sci. Technol. 2004: (38) 3567-3573.

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Subbiah, M., D. H. Shah, T. E. Besser, J. E. Ullman, and D. R. Call. 2012. Urine from treated cattle drives selection of cephalosporin resistant Eschercia coli in soil. Plosone. November. 7(11):e48919

Subbiah, M., S. M. Mitchell, J. E. Ullman, and D. R. Call. 2011. Beta-lactams and florfenicol antibiotics remain bioactive in soils while ciprofloxacin, neomycin, and tetracycline are neutralized. Applied and Envir Micro. 77:7255-7260.

Watanabe, N., B. Bergamaschi, K. Loftin, M. Meyer, and T Harter. 2010. Use and Environmental Occurrence of Antibiotics in Freestall Dairy Farms with Manured Forage Fields. Environ. Sci. Technol. 44: 6591–6600.

Watanabe, N., Hater, T., and Bergmaschi, B. 2008. Environmental occurrence and shallow groundwater detection of the antibiotic monensin from dairy farms. J Environ. Qual. 37 (S78-85).

West, B. M., P Liggit, D. L. Clemans, and S. N. Francoeur. 2010. Antibiotic Resistance, Gene Transfer, and Water Quality Patterns Observed in Waterways near CAFO Farms and Wastewater Treatment Facilities. Water, Air, & Soil Pollution. Published online: 28 August, 2010.

Zhao Z ., K . F . Knowlton, and N . G . Love. 2008. Chapter 13. Hormones in Waste from Concentrated Animal Feeding Operations in Fate of Pharmaceuticals in the Environment and in Water Treatment Systems. Edited by Diana S . Aga .CRC Press.

Zheng, W., Yates, S.R., and Bradford, S.S. 2008. Analysis of steroid hormones in a typical dairy waste disposal system. Environ. Sci. Technol. 42(2), 530