Ammonia and Methane Emission Factors from Cattle Operations Expressed as Losses of Dietary Nutrients or Energy

Abstract

Abstract:The objective of this study was to conduct a systematic review of published literature on ammonia (NH 3 ) and enteric methane (CH 4 ) emissions from beef and dairy cattle operations to obtain statistically representative emission factors based on dietary intakes of nutrients or energy, and to identify major causes of emission variations. NH 3 emissions from lagoon or other manure storage facilities were not included in this review. The NH 3 and CH 4 emission rates, expressed as a percentage losses of dietary nutrients or energy, demonstrated much less variation compared with emission rates expressed in g/animal/day. Air temperature and dietary crude protein (CP) content were identified as two major factors that can affect NH 3 emission rates in addition to farm type. Feed digestibility and energy intake were identified as two major factors that can affect CH 4 emission rates expressed as a percentage losses of dietary energy. Generally, increasing productivity and feed efficiency represented the greatest opportunity for mitigating NH 3 or CH 4 emissions per unit of livestock product. Expressing CH 4 loss on a digestible energy basis rather than a gross energy intake basis can better represent the large variation among diets and the effects of varying dietary emission mitigation strategies.

Oscillating and static dietary crude protein supply. I. Impacts on intake, digestibility, performance, and nitrogen balance in young Nellore bulls1

“…There are growing concerns about the effects of feedlot operations on air and water quality. Ammonia (NH 3 ) is the main gas emitted into the atmosphere from manure decomposition that affects environmental ecosystems and represents an unproductive loss of dietary nutrients ( Liu et al, 2017 ). Several factors can affect the excretion of nitrogen such as feed intake, chemical composition of the diet, and efficiency of nutrient utilization ( Muñoz et al, 2015 ).…”

Key Components and Contrasts in the Nitrogen Budget Across a U.S.‐Canadian Transboundary Watershed

“…Moreover, multiple mitigation strategies can be combined at different stages (housing, storage, and application) to reduce overall whole‐farm emission; for example, frequent removal of manure, anaerobic digestion, and manure acidification were all found effective in reducing emissions (Sajeev et al, 2018). Adjusting cattle diet such as lowering dietary crude protein was also associated with decreases in ammonia emissions rates and emission as a percentage of N intake (Liu et al, 2017). Subsurface application of dairy slurry can also decrease ammonia volatilization compared to surface application (Saunders et al, 2012).…”

Dependence on policy revenue poses risks for investments in dairy digesters

“…Methane emissions from enteric fermentation can be reduced by altering ruminants' diets. However, the biological relationships among emissions, health and nutrition in the context of alternative diets are complex (Liu et al 2017;Moraes et al 2014;Veneman et al 2015). Research in this area is under way, but the potential to effectively and feasibly reduce methane emissions associated with enteric fermentation is currently limited.…”

“…Unless handled carefully, new methane regulations could erode the economic position of dairy farms and processors in California. If that were to happen, we would expect additional exits from the industry or relocation out of California, resulting in reduced dairy-related economic activity, especially in the San Joaquin Valley (Medellín-Azuara et al 2018;Sumner et al 2015). The potential for such a downward spiral deserves careful consideration.…”