Improving air quality and dairy profitability through reduced protein feeding

View the project final report

• 2007 annual report
• 2008 annual report

Commodities

• Animal Products: dairy

Practices

• Animal Production: feed formulation, feed rations

In 2005, dairy producers were asked by the U.S. Environmental Protection Agency (EPA) to consider signing a voluntary consent agreement that would help fund research to determine the level of air pollution that is being produced by dairy farms. The major pollutant of concern for dairy operations is ammonia. Ammonia is released on dairy farms from manure application to crop land and pastures, from animal housing, manure storage systems, and open feedlots. The major areas of concern as stated by EPA were ammonia emissions from animal housing, manure storage systems, and open feedlots. Until recently, agriculture has escaped the regulations of the Federal Clean Air Act. However, the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Emergency Planning and Community Right–To–Know Act (EPCRA) laws now require anyone to notify the National Response Center if more than 100 pounds of ammonia are released into the atmosphere with a 24 hour period. Failure to comply can lead to large penalties. U.S. agriculture can no longer bury its head in the sand on air quality issues. In a recent investigation of air emissions from concentrated animal feeding operations, the National Research Council identified ammonia emissions as the major air quality concern at the regional, national, and global level. Atmospheric ammonia can negatively impact the environment through several pathways. Ammonia deposition contributes an estimated 35% to 60% of the total nitrogen load to coastal waters. Ammonia deposition can result in excessive buildup of nitrogen in soil, leading to crop damage in sensitive plants and soil acidification as ammonia is converted to nitrate. Finally, ammonia contributes to the formation of fine airborne particles or liquid droplets, called particulate matter. Ammonia contributes significantly to the formation of particles with a diameter of 2.5 μm or less (PM2.5). Particulate matter of this size can penetrate deep into the lungs, contributing to respiratory disease and contributes to haze formation that reduces visibility. Recent lawsuits have prompted EPA to begin monitoring emissions from animal operations as they have been enforced with industrial sources. In 1997 the EPA established regulatory standards for PM2.5 and began monitoring non-attainment areas, where levels of PM2.5 persistently exceed the standards. Currently several counties in southwestern Pennsylvania exceed the thresholds for PM2.5 and are considered non-attainment areas. Best management practices will be needed to bring these counties into compliance. Because of the feeding practices, housing, and manure handling/storage systems used on dairy farms today, dairy producers need to be aware of the potential impact they have on air quality and be prepared to make changes to comply. Excessive feeding of protein is unnecessary and can be very expensive. Overfeeding protein can have a negative effect on profitability and sustainability of the dairy operation. In addition, excess protein feeding can have a direct effect on animal performance. With overfeeding of protein, excess nitrogen is converted to ammonia in the liver and excreted in the urine. Both processes result in an energy expense to the dairy cow. A final result could be a reduction in milk yield and milk protein content. Also, excess nitrogen in the blood can have a detrimental affect on reproductive performance. Excess blood urea nitrogen can be toxic to the developing fetus. Nitrogen quantity and form in the urine determine ammonia volatilization from dairy cattle manure. Dietary manipulation via reduced protein intake has reduced nitrogen excretion and the potential for ammonia emissions.

Research on the amount of ammonia produced daily by dairy cattle has been very limited, however, numerous studies are now being conducted to help answer this question. We do know that the level of protein (crude and soluble) can have an effect on potential ammonia production. It is highly likely that many dairy producers are feeding excess protein in the diet of their lactating cows. In the past, this was a common recommendation by many dairy nutritionists as an insurance measure. However, excessive protein feeding is expensive in addition to the potential for causing ammonia production and air quality issues. Dairy producers along with their dairy nutritionists need to look closer at protein quality and solubility and formulate rations that are more nitrogen efficient. Adding energy sources that capture excess nitrogen produced in the rumen may help. Rations need to be formulated using metabolizable protein (MP) instead of crude protein (CP). Using ration balancing programs such as the Cornell Net Carbohydrate and Protein System model (CNCPS) or the Cornell University, University of Pennsylvania, and Minor Agricultural Research Institute (CPM-Dairy) dairy ration formulation software program by a dairy nutritionist may help to improve nitrogen utilization. This could improve economic returns to the dairy producer to make their operations more sustainable and reduce potential ammonia production in the urine and limit what can volatize into the atmosphere.