Location: Dairy Forage ResearchTitle: Relationship among methane emission, ammonia emission and selected animal performance measurements Author
Submitted to: International Conference on Greenhouse Gasses and Animal Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 3/4/2013
Publication Date: 6/23/2013
Citation: Aguerre, M.J., Wattiaux, M.A., Powell, J.M., Arndt, C. 2013. Relationship among methane emission, ammonia emission and selected animal performance measurements. International Conference on Greenhouse Gasses and Animal Agriculture. 7(2):535. Interpretive Summary:
Technical Abstract: Enteric methane (CH4) emission and subsequent CH4 emission from manure of ruminant livestock are major contributors to anthropogenic greenhouse gases (GHG) emission in many countries. Similarly, livestock manure is an important source of undesirable atmospheric ammonia (NH3). Identifying and quantifying relationships between animal performance and emission of CH4 and NH3 are critical first steps in the development of emission models that may be used to evaluate GHG mitigation strategies. Thus, our objective was to summarize a series of trials conducted in our laboratory to explore responses associated to CH4 and manure NH3 emission from high-producing lactating dairy cows fed typical diets of the Midwestern United States. Data were obtained from three experiments comprising 12 dietary treatment means with data of diet composition, animal performance and CH4 and NH3 emission. Animal performance and gas emission measurements were conducted in four air-flow controlled chambers, each constructed to house four cows in a modified tie-stall barn. Forage-to-concentrate ratio of dietary treatments, fed as total mixed rations, ranged from 47:53 to 68:32 (dry matter (DM) basis). Alfalfa silage to corn silage (the only forages fed) ratio ranged from 20:80 to 80:20 (DM basis). Range values for dietary chemical composition was 157 to 181 g/kg for crude protein, 271 to 383 g/kg for neutral detergent fiber (NDF) and 200 to 290 g/kg for starch. Average dry matter intake (DMI) ranged from 20.0 to 29.5 kg/day, energy correct milk yield (ECM) ranged from 36.1 to 45.6 kg/day, feed efficiency (ECM/DMI) ranged from 1.53 to 1.82, intake nitrogen (N) ranged from 498 to 757 g/day, CH4 emission ranged from 538 to 764 g/day, and NH3 emission ranged from 13 to 57 g/day. Methane emission was most highly correlated with ECM/DMI (r = -0.78) but was also significantly correlated with neutral detergent fiber intake (r=0.68). Furthermore, the relationship between ECM/DMI and CH4 emission was quadratic (y=-5907x2 + 19386x +15153, R2 = 0.87) with a maximum emission at an ECM/DMI of 1.64, suggesting a reduction in DM digestibility at higher efficiencies due to faster feed passage rate. A quadratic relationship was also observed between DMI, NDFI and CH4 emission (R2 = 0.75 and 0.66, respectively). Ammonia emission was highly correlated with milk N/N intake (r = -0.85, P<0.01), but was also correlated with N intake (r = 0.80, P<0.01). Milk urea nitrogen was weakly correlated with intake N (r = 0.13) and NH3 emission (r = 0.39). Also, there was a correlation (r=0.68) between CH4 and NH3 emission. Results from this study suggested that animal selection based on feed and N utilization efficiencies are important tools to mitigate CH4 and NH3 emission. However, the relationships reported in this study capture only a fraction of the important factors determining CH4 and NH3 emission. Future research should address the impact of the rumen environment and manure chemical composition on enteric CH4 production and NH3 emission.