US Dairy Industry Faces Environmental Challenges

The dairy industry faces increasing environmental challenges particularly with regard to air and water quality.
calendar icon 19 September 2009
clock icon 8 minute read
While efforts to improve management of dairy farms has reduced the environmental impact of milk production, regulatory and social pressures mandate that further improvements be made to reduce the pollution potential even more says Wendy Powers from the Department of Animal Science and Biosystems Engineering at Michigan State University.

Air quality challenges

Concerns over air emissions from dairy operations range from nuisance conditions to human health impacts to ecological impacts. The varying scales of concerns, alone, pose a challenge to producers. Local concerns of neighbors include nuisance events such as odours (NRC, 2003) and attraction of flies. While odour nuisance is likely the underlying cause of local concerns, odour regulation is difficult. Several states have odour standards, such as Colorado and Pennsylvania, while other states, such as Iowa, have considered an odour standard but not adopted one. Reports of psychological as well as physiological impacts of exposures to mal odours exist but variability from one individual to the next coupled with the challenges of measuring transient odours and isolating health effects from emotional effects has made regulation and effective mitigation of livestock odours a formidable task.

Human health
Research has implied that doubling animal numbers increases infant mortality by 7.4 per cent, these deaths are likely caused by respiratory diseases from air pollution, however the research does not take into changes in population densities, traffic patterns and additional ancillary consequences of a growth in livestock production. Much research is based on worker exposure rather than data from community exposures.

Ms Powers says that livestock industries have been proactive in addressing concerns by funding the National Air Emissions Monitoring Study. The study which is due to conclude by the end of 2009, is intended to provide information regarding the range of emissions in ammonia, hydrogen sulfide and particulates that occurs from livestock operations. Emissions are measured at the exhaust air from housing and from some outdoor manure storages. While the number of operations monitored over the 2-year period is not a statistically representative sample of the industry, nor are the measurements made beyond facility property lines, the data that results will make an important contribution to the limited data that currently exist.

Recent Regulatory Activity
In 2008, a ruling was signed that required a Concentrated Animal Feeding Operation (CAFO) to report emissions under the Emergency Planning, Community Right-to-Know Act.

The US Environmental Protection Agency (EPA) ruled that agricultural sources could be considered and regulated for both coarse and fine particulate matter. It is now up to individual states to determine if they will restrict particulate emissions from agricultural sources of coarse particular matter as part of a State Implementation Plan, which must address areas within a state that are in a non-attainment for the current standard. With regard to fine particulate matter the US Court of Appeals remanded the standards back to the US EPA for further review.

Greenhouse Gases (GHG)
Greenhouse gas emissions are one example of how dairy operations contribute to concerns that are of global scale. Research has suggested that feed and pasture fertilisation in 11 countries, account for 20 per cent of global fertilser nitrogen consumption. Livestock production is attributable to other sources of carbon release as well, i.e. deforestation in Argentina, desertification in arid regions, soil cultivation for feed production, methane production in rice cultivation where animal manures are present, releases from burning of pastures as a management practice. Ms Powers says it is indisputable that methane production is a result of enteric fermentation. The US EPA estimated in 2004 that methane production by domestic ruminants accounts for 19 per cent of the national production. 12 per cent of the worldwide anthropogenic methane production is estimated by US EPA to come from manure storage. Other research suggests double this amount. 40 per cent of all anthropogenic GHG emissions are a result of livestock production research suggests.

The US EPA announced a plan to mandate reporting GHG, however a final ruling has not been decided. Ms Powers believes it will be likely that future decisions will require remediation or mitigation of emissions.

Reactive nitrogen (Nr)
Nr refers to all forms of biologically active, chemically reactive and radiatively active forms of nitrogen, including ammonia, nitrous oxide, and nitrogen oxides. The US EPA Science Advisory Board has convened a panel of scientists to:

1. Identify and analyse, from a scientific perspective, the problems nitrogen presents in the environment and the links among them;

2. Evaluate the contribution an integrated nitrogen management strategy could make to environmental protection;

3. Identify additional risk management options for EPA’s consideration; and

4. Make recommendations to EPA concerning improvements in nitrogen research to support risk reduction.

In a draft reports, the Intergrated Nitrogen Committee (INC) recommend research and management recommendations to assist EPA in developing an intergrated nitrogen management strategy and recommendations to decrease the amount of Nr lost to the US environment by 25 per cent.

One recommendation is to maximise the N efficiency of both crop and livestock production systems and to develop strategies for avoiding increased Nr load in the environment. A second recommendation promotes a policy, regulatory, and incentive framework to improve manure management to reduce Nr load and ammonia losses.

Water quality challenges

Ms Powers believes that nutrients into water supplies, conveyed through either direct discharge or following land application of manures continues to be an important area of management for dairy operations. Many states have adopted standards addressing applications of nutrients, others have faced different challenges.

Research is underway to identify if sources of pathogens in water supplies are of human or animal origin. Some research suggests that current manure storage, handling and land application practices do not adequately or effectively protect water resources from pathogen contamination. Not surprising is that pathogenic microorganisms have been documented at high densities in receiving surface waters following manure spills.

In the future, Ms Powers says, more emphasis may be placed on controlling the release of pathogens by using treatment technologies to trap or destroy pathogens. Pathogen destruction may be required in some situations prior to land application of excreta and/or litter.

The public is very much aware of the use of antibiotics in food production, says Ms Powers. The use of antibiotic use as a growth promotant has reduced considerable, however, there is further pressure for a complete phase out of antimicrobial growth promotants. Studies have suggested the need for mitigation strategies to further reduce the need for anitbiotic use.

Endocrine disrupting compounds
Endocrine disrupting compounds are a class of compounds either synthesised or present naturally in nature that are suspected to have adverse effects in animals and humans. The primary source of EDCs in manure is the animal itself. Natural hormones produced by animals are shed in manure and may persist in ecosystems.

They affect organisms primarily by binding to hormone receptors and disrupting the endocrine system by either mimicking natural hormones or by interfering with their binding. Monitoring for the presence, concentration, and distribution of these compounds in the environment and in food is becoming an important issue because of the potential negative consequences these compounds can have when present at relatively low levels. Testing for these compounds in food products, litter, and water is still a developing science. As defined, EDCs include pesticides, herbicides, plant phytoestrogens, and other chemicals that interact with endocrine systems.

Resource utlisation

Research found that optimising feed composition to incorporate highest yield feed crops and regional sources for feed will reduce land area requirements, however it was noted that the world's optimal feed production regions are insufficient to meet the world's meat demand when land use intensity is reduced.

Crops generally require greater inputs of fossil fuel-based fertiliser, pesticides, and irrigation water to achieve high yields, which Ms Powers accepts will contribute negatively to the environmental, human-health, and ecological impacts of an animal-based production system.

Energy use has received considerable attention as supplies and sources of fossil fuels are questioned, energy prices are increasing, and environmental issues are increasing. Energy use in food production will likely face greater scrutiny in the future as consumer awareness of energy use issues continues to increase. Calculation of the carbon footprint of an industry allows one to tally the energy use from farm to table.

Climate change has effects on water availability. Research proposed that land areas classified as 'dry' have doubled since 1970 and will continue to increase in some areas of the world while rising oceans will make other areas less able to support food production due to saltwater. Population growth, industrialisation, and increased standards of living all contribute to an increasing demand on a finite supply of freshwater.

Ms Powers says that irrigation is an important mechanism to meet food demands of a growing population, research suggests that 80 per cent of the additional food supplies required to feed the world will depend on irrigation. However, studies how shown that 60 per cent of the water diverted or pumped for irrigation is wasted, which could lead consumers to question agricultural use of water supplies.

Conflicting Objectives

Ms Powers says that one of the greatest challenges in meeting environmental objectives is that the breadth of the regulation are increasing beyond what has been customary water quality and air quality regulations. Much of the research addresses only one or two issues and does not take into account outside effects.

As retailers and consumers continue to push livestock and poultry production to change common production systems, recognise and address our current limited understanding about the environmental costs of ethical animal production, says Ms Powers. Often consumers may inherently associate livestock-intensive systems with environmental degradation while considering non-confined systems, such as those often promoted as animal-friendly, better for the environment. While efforts to improve animal well-being are well-intended, the consequences of mandated production practices may not be thoroughly thought through nor studied. Data are limited documenting the environmental impact of production systems designed to improve animal well-being.

In conclusion, the challenges facing the dairy industry are vast and while not all of the current and pending challenges have an environmental component, it is often difficult to distinguish where environmental issues start and stop. Arguments made critics of the dairy industry often incorporate the environmental impact of livestock production even in discussions regarding animal care. As society proceeds to adopt greater regulation of the dairy industry in order to achieve less impact on the environment a system-wide approach is needed to evaluate policy implications in order to avoid unintended and undesirable consequences.

September 2009
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