NE1544: Dairy Production systems: C,N, and P management for production, profitability and the environment.

(Multistate Research Project)

Status: Active

NE1544: Dairy Production systems: C,N, and P management for production, profitability and the environment.

Duration: 10/01/2015 to 09/30/2020

Administrative Advisor(s):

NIFA Reps:

Statement of Issues and Justification

1) The need, as indicated by stakeholders.

The dairy industry has defined a sustainable industry as one that can adopt new practices and management approaches that: address the uncertainty of climate change, efficiencies of water and energy use, with an emphasis on nutrient management, and profitability.
At each of our individual stations, representative stakeholders are supportive of the objectives of this project as assessed by formal stakeholder meetings, field days and education events, and presentation of research results at industry meetings.

Objective 1) Reduce GHG emissions and transport of nutrients, pathogens, pharmaceuticals, and VOCs from livestock production systems. This will include management of feed, manure collection, manure storage, and manure application

Objective 2) Characterize the opportunities for selecting dairy cows for feed efficiency and adaptability to different production systems.

Objective 3) Develop science-based tools and educational materials to promote environmental stewardship on US dairy industries.

2) The importance of the work, and what the consequences are if it is not done.

There is increasing evidence and concern that excessive nutrient use and gaseous emissions from agriculture contributes to water and air quality impairment at local, regional, and global scales. The public is demanding accountability of animal agriculture.
Environmental and climate related information is in high demand in the dairy sector, and the dairy industry depends on this public investment in research as a key source of information for a sustainable dairy industry. Producers need to control or reduce leaching of nutrients to ground water, runoff of nutrients in surface water, release of hazardous compounds to the atmosphere and greenhouse gas (GHG) emissions. If additional research is not forthcoming, the dairy industry will be at greater risk of negatively impacting the environment, greater financial risk, and at increased jeopardy of environmental lawsuits.

3) The technical feasibility of the research

This project has a 30+ year history of research productivity and cooperation based on sustained grant funding. Three tenets of this proposal (production, profitability, and the environment) are win-win-win as a result of the systems research approach. Evidence of research productivity is demonstrated by peer-reviewed publications, decision aid tools (e.g. IFSM, FMNP$.net), webcasts, field days, and web content. All research sites are well equipped (e.g. laboratories, land, animals and dairy facilities) to conduct the necessary studies.

4) The advantages for doing the work as a multistate effort.

The diversity of production systems for major dairy regions in the US are represented by location of the participants of this project. This creates a unique opportunity to address regional issues but also address challenges that are of strategic importance on a national basis. The scope of this work requires a multi-state approach because the needed technical expertise is not present at any one location and because livestock production systems vary so much across the country. In addition, the most pressing environmental problems differ by region. The investigators participating in this project represent various disciplines with a broad range of knowledge and skills from field research to modeling, and all regions of the country. Coordinated efforts through this project will advance our understanding of these issues and identify strategies and management practices to mitigate environmental problems while maintaining farm profitability. The products and tools developed by this project will be used by a wide range of audiences including service and supply dealers, producers, nutrient management planners, policy makers, and extension and university educators.

5) What the likely impacts will be from successfully completing the work.
Through our outreach methods (peer-reviewed publications, decision aid tools (e.g. IFSM, FMNP$.net), webcasts, field days, and web content) we will disseminate the outcomes of the project to producers, agri-professionals, researchers, and policy makers.
Adoption of these practices will lead to enhanced economic and environmental sustainability of the US dairy industry. We anticipate 20-30% increase in feed use efficiency and similar reductions in nutrient loss and GHG emissions. Greater resilience to climate change will be realized through enhanced animal genetics, and adoption of management strategies that conserve nutrient, energy, and water resources.

Measurements of impacts will be assessed by enhanced feed efficiency (kg milk/kg feed, and rate of gain) reduced GHG, reduced N losses (air and water), reduced P losses (water), while enhancing C sequestration in soils.

Related, Current and Previous Work

During the 2010 – 2014 term, the NE -1044 project made the following progress in the areas noted below:

Research examining nutrient removal by cover crops.

Cover crops utilize 40-50% more N if the cover crop is planted by Sept 1 vs Sept 15. This can be related to the GDD needed. The Cover Crop Planting tool is currently operational on the web as Cover Crop Planting DSS (Decision Support System) at for Massachusetts. The GDD values are compiled for the New England region and used in calculating optimal cover crop planting date. Thirty years of climate information is used in calculating optimal planting dates for cover crop (Fall Rye). The spatial data points are spline interpolated for spatial coverage in the region. GIS data on climatic variables is being processed for regional and other larger scales. A map of optimal planting dates for Fall Rye for the northeast US is available. The datasets are converted to shape files for use in the DSS. The Web-based DSS is extended to mobile platforms so that farmers have easy access to the spatial information. The mobile platform is being developed for IPad and Android operating systems. An implementation of the DSS in Android operating system in Google Nexus is presented at the right. This iOS operating system version is being tested for use in iPad. Testing the tools at farmer fields is being conducted for validating performance of the tools at various spatial locations. Nutrient loss reduction and economic gains from optimal planting regimes is presented along with optimal planting dates.

Research evaluates plant growth on artificial floating islands to improve multi-stage wastewater treatment systems.

The objective of this project was to evaluate and improve primary (anaerobic/facultative lagoon), secondary (aerobic lagoon) and tertiary (constructed wetland) dairy wastewater treatment practices that are appropriate for manure typically collected in grazing dairy farms. This project was initiated in September, 2010 with the intent to 1) promote uptake by plants grown on islands; and 2) stimulate nitrogen volatilization through denitrification at the intersection of floating islands with the wastewater lagoon surface. During 2010-2011, floating islands were used in two densities covering anaerobic lagoons, 2,000 vs. 1,000 sq ft or 8% vs. 14% coverage, respectively. Corn and ryegrass, and anaerobic lagoons were chosen for this study based on a two-year study carried out during the 2009 and 2010 cool and warm seasons. Ryegrass was planted in the fall and was harvested in the spring in both years (2010-2011, and 2011-2012). Corn was planted immediately after June ryegrass harvest. A poor corn crop was harvested in September, 2011.

Research examines the effects of a silage inoculant on rumen microflora and milk production.

Lactobacillus plantarum (Ecosyl MTD/1) alters the rumen microbial community, milk production, and efficiency of nitrogen utilization compared to untreated silage. This inoculant has had a large amount of research conducted on it. Ecosyl MTD/1 results in increased milk production even when no observed effect in the silage was present. When fed directly to the cows no effect was observed. Think the effect is occurring in the silo, resulting in an improvement in microbial biomass production. Monitoring the in vivo effects by sampling fluid at the omasum and by using PCR techniques to observe changes in the rumen microbial populations. Significant changes have been observed in ARISA populations, MUN, protein %, lactose. No effect on milk fat.

Research to evaluate the comparative attributes of grazing, organic, and conventional management systems focused on profitability and stewardship.

Meadow fescue or tall fescue silage was fed in combination with alfalfa and corn silage to evaluate the effects on milk production and the potential to reduce sub-acute ruminal acidosis (SARA) in lactating dairy cows. This data indicates that high quality meadow and tall fescue silages can be fed to high producing dairy cows without a decrease in fat corrected milk production.

Another study examined the impact of grazing experiences early in life on grazing behavior and performance of lactating dairy heifers in a 3-year study. GPS units were utilized to monitor cow movement. Those with no previous grazing experience tended to move around very little when grazing. Milk production was lowest initially for cows with no previous grazing experience. Results indicate that previous grazing experience can impact behavior and milk production during the first 3 days on pasture. After this time, experienced and inexperienced cattle presented a similar grazing behaviors and performance

We evaluated partially replacing alfalfa (Medicago sativa L.) silage and corn (Zea mays L.) silage with tall fescue (Festuca arundinacea Schreb) silage, meadow fescue (Festuca pratensis Huds) silage, or wheat straw (Triticum aestivum) to test the hypothesis that the energy from non-fibrous carbohydrates can be partially replaced by the energy from digestible fiber without reducing DMI or milk production in total mixed rations (TMR) for dairy cows. Forty eight lactating dairy were fed one of four treatment diets in a 98 d study. The four treatment rations consisted of an alfalfa silage and corn silage-based TMR formulated for a low neutral detergent fiber (NDF) content 25%, and three TMRs formulated for 28% NDF where tall fescue silage, meadow fescue silage, or wheat straw partially replaced alfalfa and corn silages. The in vitro and in situ NDF digestibility of tall and meadow fescue silages were equal to or greater than the alfalfa silage and greater than the corn silage and wheat straw. The total tract NDF digestibility was highest for cows consuming the grass diets. Organic matter digestibility was higher when cows ate tall fescue than wheat straw or did not receive supplemental fiber. No differences in DMI (26.0 kg/d) or 3.5% fat-corrected milk production (41.9 kg/d) were found between treatment diets, although higher milk yield and lower milk fat (% and yield) were observed for cows that did not have supplemental fiber in their diets. These results indicate that highly digestible fiber from grass silages can partially replace non-fibrous carbohydrates without reducing DMI and FCM production.

Dairy Gas Emission Model (DairyGEM) calculates ammonia and hydrogen sulfide volatilization, GHG emissions, and carbon footprint. There are 100-150 types of VOCs from silage. Modeling of VOC Emissions, silage and manure are important sources of VOC emissions in dairy and beef production. A model for predicting silage emissions was revised and a new component model was developed to predict emissions from manure sources. Together these components estimate the major VOC emissions from farms. Emissions from manure are determined using a two-stage, steady-state emission model for five groups of compounds (two groups of acids, alcohols, and two groups of aromatics). Limited measurements of VOCs in manure show that VOCs may be produced or destroyed during manure storage; however, there is not enough information known about these processes to develop a model that predicts their development. Instead bulk concentrations of compounds are set at an initial value, and cumulative emissions are calculated over fixed times, allowing for a decrease in VOC concentrations within manure. Emissions are estimated from manure during three stages: on the barn floor, during storage, and after field application. Emissions are adjusted according to their reactivity to determine the ozone formation potential of the emitted compounds. These new components were incorporated and tested in our Integrated Farm System Model (IFSM) and Dairy Gas Emission Model (DairyGEM) where they will be used to evaluate strategies for mitigating VOC production.

Environmental Footprints of Beef Production Systems: The environmental footprints of the beef produced at the U.S. Meat Animal Research Center in Clay Center, Nebraska were determined through a simulation study. Relevant information for their operation was gathered and used to establish parameters to represent their beef production system with IFSM. Model simulated predictions agreed well with actual records for feed production and use, energy use and production costs in 2011. A preliminary analysis of the current production system of the Meat Animal Research Center shows that the carbon footprint of the beef produced is 11 lb of carbon dioxide equivalent units per lb of live weight sold. This carbon footprint is a little lower than most previously published values. The energy required to produce that beef (energy footprint) is 11,150 Btu/lb of live weight sold. The total water required (water footprint) is 2,550 gallon/lb of live weight, and the water footprint excluding that obtained through precipitation is 340 gallon/lb of live weight sold. The simulated total cost of producing their beef was about $1.00/lb of live weight sold, which agrees with their production records. Simulations are being developed for 2005 and 1970 to determine if the environmental footprints have improved over time.

A methodology was developed and used to determine environmental footprints of beef cattle produced at the U.S. Meat Animal Research Center (MARC) in Clay Center, Nebraska with the goal of quantifying improvements achieved over the past 40 years. Information for MARC operations was gathered and used to establish parameters representing their production system with the Integrated Farm System Model. The MARC farm, cow calf, and feedlot operations were each simulated over recent historical weather to evaluate performance, environmental impact, and economics. The current farm operation included 841 ha of alfalfa and 1,160 ha of corn to produce feed predominately for the beef herd of 5,500 cows, 1,180 replacement cattle, and 3,724 cattle finished per year. Spring and fall cow calf herds were fed on 9,713 ha of pastureland supplemented through the winter with hay and silage produced by the farm operation. Feedlot cattle were backgrounded for 3 mo on hay and silage with some grain and finished over 7 mo on a diet high in corn and wet distillers grain. For weather year 2011, simulated feed production and use, energy use, and production costs were within 1% of actual records. A 25-year simulation of their current production system gave an average annual carbon footprint of 10.9±0.6 kg of CO2 equivalent units per kg BW sold, and the energy required to produce that beef (energy footprint) was 26.5±4.5 MJ/kg BW. The annual water required (water footprint) was 21,300±5,600 liter/kg BW sold, and the water footprint excluding precipitation was 2,790±910 liter/kg BW. The simulated annual cost of producing their beef was $2.11±0.05/kg BW. Simulation of the production practices of 2005 indicated that the inclusion of distiller’s grain in animal diets has had a relatively small effect on environmental footprints except that reactive nitrogen loss has increased 10%. Compared to 1970, the carbon footprint of the beef produced has decreased 6% with no change in the energy footprint, a 3% reduction in the reactive nitrogen footprint, and a 6% reduction in the real cost of production. The water footprint, excluding precipitation, has increased 42% due to greater use of irrigated corn production. This proven methodology provides a means for developing the production data needed to support regional and national full life cycle assessments of the sustainability of beef.

Nutrient transformation in manure was evaluated with anaerobic digestion and method of application of dairy manure. A three year agronomic plot study was completed that evaluated the nitrogen use efficiency of undigested and anaerobically digested dairy manure. AD and non-AD manure support equal grass production when applied at equal amounts of total N. Anaerobically digested dairy slurry was shown to provide adequate soil fertility and N availability for crop uptake and forage production over the three field seasons. There was no indication of differences between sources of manure for pounds of uptake of P by the grass crop. However, more P was applied with non-AD manure vs AD manure which complicates the interpretation. When the P uptake data was expressed as a ratio (P uptake/P applied) the AD manured forage showed a higher ratio. Further investigation of P availability from AD manure is warranted. Subsurface deposition of manure did not increase forage yield or N uptake compared with surface broadcast application, possibly because the slurries were low enough in solids to infiltrate readily into the soil, and because the subsurface injectors may have disrupted plant growth. An additional goal was to evaluate if AD manure had any negative impacts in the soil microbial communities. Source of manure had little effect on soil enzymes or microbial communities. Greatest treatment differences were seen between the manure and urea treatments. Flooding of the plot area had a dramatic yet fleeting impact on the enzymes and communities. Application of anaerobically digested slurry did increase nitrifier and denitrifier gene copies that correlated with N2O production. AD and non-AD manure, as well as the solids content was evaluated for their effect in NH3 emission on day of application to grass plots. AD manure was shown to have the least amount of NH3 emission, non-AD with large particle solids removed to be intermediate, and non-AD manure to have the greatest NH3 emission on day of application.

A three-year study was conducted to study the interactive effect of anaerobic digestion (AD), large particle solids, and a manure additive MTMTM on ammonia (NH3) and greenhouse gas (GHG; carbon dioxide, nitrous oxide, and methane) emissions when manure/manure effluent was surface applied. The presence of large particle solids resulted in greater NH3 emissions due to the reduced infiltration of liquid manure into soil (P < 0.05). Anaerobic digestion did not have a consistent effect on NH3 emission. Manure effluent with greater ammoniacal nitrogen (AN) concentrations achieved significantly greater NH3 loss after manure application (P < 0.05). Anaerobic digestion of manure effluent did not have a significant effect on GHG flux (P > 0.05). Treatment with large particle solids in raw manure had significant greater CO2 flux than the other raw manure treatments on the day of manure application (P < 0.05). There was no significant manure treatment effects (P > 0.2) on methane flux over the three-day period after manure application. The manure additive MTMTM did not have a significant effect (P > 0.05) on NH3 and GHG fluxes. The results of this study suggest that solids and AN concentrations in manure/manure effluent are the most important factors affecting NH3 emissions after surface application.

The effect of anaerobic digestion (AD), large particle solids, and a manure additive MTMTM on ammonia (NH3) emission from dairy manure/manure effluent were studied during 110 d of storage. The study consisted of eight treatments in duplicate: AD manure effluent and Non AD manure, with and without large particle solids, and with and without MTMTM. This study was conducted in a naturally ventilated barn. The nitrogen content of manure, especially the ammonical nitrogen played an important role in NH3 emission. During the first 11 weeks of the storage, AD manure effluent emitted significantly greater average (26 to 22 ppm) and peak (38 to 33 ppm) concentrations of NH3 and NH3 fluxes (130 to 94 ?g•min-1•m-2 ) when compared to raw manure treatments (11 to 9 ppm, 25 to 14 ppm, 81 to 55 ?g•min-1•m-2 , respectively). From the 11th week until the end of storage, there was no significant difference in NH3 emissions across the manure treatments. The presence of large particle solids on manure surface resulted in significantly lower NH3 emissions when data was evaluated for the whole storage period. The manure additive MTMTM, crust formation and temperature did not have a significant effect on NH3 emissions during storage. Total ammonical nitrogen and solids concentration in manure were the most important factors affecting NH3 emissions during storage.

Data collected on nutrient partitioning after liquid-solids separation indicates a range: in solids separation of 13 to 25 %, in N separation of 4.3 to 12.9 %, and in P separation of 9.2 to 21.5 %. The EYS screw system resulted in greater removal of solids, N and P, but was observed to require greater maintenance and had a lower liquid throughput rate. The overall observation of significance is that the majority (>75%) of solids and nutrients reside with the liquid fraction.

The Feed Nutrient Management Planning Economics Tool (FNMP$) was refined to include the following: a) addition of dairy manure handling systems that include liquid-solids separation, sand bedding and sand separation; b) more accurate estimates of nutrient and solids flows and transformations in beef feedlot systems; c) feed management factors into tool function that can affect nutrient losses; d) added additional crops, nutrients, and revised nutrient estimates; e) updated equipment prices; and f) providing a version of the tool on-line for remote use.

Feeding tannin extract and less crude protein (CP) to dairy cows may have synergistic impacts on reducing urinary N excretion and NH3 emissions from dairy barns and land applied manure. Holstein dairy cows were fed four levels (g kg-1) of dietary tannin extract (mixture from red quebracho and chestnut trees): 0 (0T), 4.5 (LT), 9.0 (MT) and 18.0 (HT); each fed at two levels (g kg-1) of dietary CP: 155 (LCP) and 168 (HCP). The addition of tannin extracts to the diets did not significantly impact animal performance but increased feed N use efficiency and decreased N excretion in urine. Reductions in NH3 emission from simulated barn floors due to tannin feeding were greatest when tannin was fed at LCP: the LCP-LT and LCP-HT treatments emitted 30.6% less NH3 than LCP-0T; and the HCP-LT and HCP-HT treatments emitted 16.3% less NH3 than HCP-0T. Feeding tannin extract decreased urease activity in feces resulting in 11.5% reduction in NH3 loss. The application of tannin directly to simulated barn floor also reduced NH3 emissions by 19.0%. Tannin did not significantly impact NH3 emissions from soils. But emissions from the HCP slurry were 1.53 to 2.57 times greater than from the LCP slurry. At trial’s end concentrations of soil inorganic N were greater in HCP slurry-amended soils than in LCP slurry-amended soils. Emissions from the sandy loam soil were 1.07 to 1.15 times greater than from silt loam soil, a result which decreased soil inorganic N in the sandy loam compared to the silt loam soil.

Whereas much is known about relationships between dairy cow rations, milk production, manure excretion and environmental risks of confinement dairy production, much less is known about these relationships on grazing- based farms. Seasonal snap-shots of feed-milk-manure relationships on grazing-based dairy farms were taken to determine relationships (1) between feed N intake (NI), milk production, milk urea N (MUN), feed N use efficiency (FNUE), and excreted manure N (ExN), and (2) between feed P intake (PI), fecal P (FP) concentrations, and excreted manure P (ExP). An additional objective was to assess correspondence between feed, milk and manure relationships established on confinement dairy farms to those on grazing-based dairy farms. Four dairy farms located south eastern Australia were visited during autumn and spring. Information was gathered on feed practices for six cows selected randomly from each of high, medium and low producing cow groups on each farm. Samples of each ration component, and milk and feces from each cow were taken. Total ration dry matter intake (DMI) was calculated as the sum of feed supplements (silage, hay, by-products, grain, concentrates) offered manually plus the amount of pasture estimated indirectly using a bio-energetic approach. Each farm offered a similar basal ration with varying levels of barley grain (0.5 to 8.8 kg cow-1 d-1) or concentrate (0.8 to 9.4 kg cow-1 d-1). Although milk production was greater during spring than autumn, milk response (2.23 L kg-1 DMI) was similar during both seasons. Milk responses to NI were greater during spring (63 mL g-1) than during autumn (55 mL g-1), and milk response to supplemental grain or concentrate were variable. Ration CP concentrations during spring ranged from 183 to 248 g kg-1, or 11% to 50% greater than recommendations for high producing cows on confinement farms. As ration CP increased FNUE declined. In contrast to findings on confinement farms, no significant relationships were found between ration CP and MUN, or between MUN, parity, or milking frequency. NI and DMI provided the best predictors of ExN, and PI provided the most accurate prediction of ExP. Unlike findings on confinement farms, no relationships were found between ration P and fecal P. A significant positive relationship between total P in feces and HCl-extractable P in feces indicates that ration P (range of 4.4 to 6.4 g kg-1) on the study farms exceeded cow requirements.

We evaluated relationships between feed nitrogen (N) intake, milk urea N (MUN), urinary urea N (UUN) and ammonia (NH3) emissions from dairy farms. Regression relationships between MUN (within the range of 10 to 25 mg/dL), UUN, and relative NH3 emissions from barns were developed from studies conducted in Wisconsin, California, and The Netherlands. Relative reductions in NH3 emission were calculated as percent decreases in NH3 emissions associated with a baseline MUN level of 14 mg/dL (prevailing industry average). The two studies with cows in stanchion chambers provided relative linear reductions in NH3 emission of 14.1 to 25.6% when MUN levels decreased from 14 to 10 mg/dL. Similarly, analyses of 4 free-stall studies provided relative linear reductions in NH3 emissions of 10.3 to 33.7% when MUN levels declined from 14 to 10 mg/dL. Wide-spread, effective use of MUN as a management tool to assess the impact of farm practices on NH3 emissions under a variety of commercial dairy farm conditions requires reliable and repeatable methods of both MUN and NH3 measurements.

Experiments were conducted to evaluate possible mitigation strategies to reduce gaseous emissions from dairy farms. In trial 1 (Aguerre et al. 2010c; Aguerre et al. 2011a), increasing the proportion of forage in the diet from 47 to 68% while maintaining dietary CP, increased CH4 emission per unit of milk by 25% but did not alter NH3 emission or milk production. In a follow-up study (Trial 2; Aguerre et al. 2012a), the pattern of change in volatile C loss (CO2 and CH4,) and volatile N loss (NH3 and N2O) during a 77-day storage period was determined using the manure collected from cows in the companion study (Trial 1). Dietary treatments had no effect on emission rates. However when a crust formed after 28 days of storage, NH3 emission became negligible. In addition to its physical effects, the crust may have provided a growth environment for bacterial species that use NH3 and CH4 as substrate, reducing emission of these compounds, but promoting the production and emission of N2O and CO2, respectively. In trial 3 (Arndt et al. 2010ab), alfalfa silage (AS) and corn silage (CS) were fed at 20:80, 40:60, 60:40 and 80:20 ratio, in a 55:45 forage to concentrate ratio diet. Varying the AS:CS ratio had no effect on NH3 emission. Although greatest CH4 emission was observed at ratio of 40:60, primary forage did not affect CH4 emission per unit of milk. Feeding tannins at a level that does not compromise animal performance might be used to reduce urinary N and therefore NH3 emissions. Data from a lactation study (Trial 4; Aguerre et al., 2010ab) suggested that incorporating tannin in the diet at 1.8% DM at two dietary CP levels (15.5 vs. 16.8 %DM), did not alter manure N but increased fecal N and reduced urine N, with limited impact on animal performance. Manure from cows fed 1.8% tannin and 15.5 or 16.8% dietary CP, emitted 30.5 and 16.3% less NH3 than no tannin diet, respectively (Powell et al. 2011). On a follow up study (Trial 5; Aguerre et al., 2011b), our objective was to determine the effects of a tannin extract on lactating cow performance and emission of CH4 and NH3, and whether any responses were affected by dietary forage to concentrate ratio. Adding tannin to the diet at a 0.45% inclusion rate (DM basis) had negative effects on performance and increased CH4 emission per unit of ECM by 8% but had no effect on manure NH3 emission, regardless of the dietary content of forage. The objective of Trial 6 (Arndt et al., 2011) was to determine whether CH4 emission is lower for high feed efficient (kilograms of milk/kilograms of dry matter intake; HE) compared with low feed efficient (LE) lactating dairy cows. High compared to low feed efficiency was associated with lower CH4 emission (grams) per kilogram of milk (16.0 vs. 23.7 g/kg). Future research should assess the additive effect of combining different mitigation strategies and the potential trade-offs between NH3, N2O and CH4 emission reduction in large scale and long-term field trials. A Markov chain model was used to simulate a herd dynamics based on productive and reproductive input parameters and estimate the impact of reproductive performance on CH4 emission, and N and P excretion of dairy cows (Aguerre et al., 2012b). Under the simulation conditions of this study, changes in herd structure associated with improved reproductive performance reduced predicted environmental impact while improving profitability.

Grass-legume mixtures and tannin-containing forages can improve livestock and pasture productivity and economic and environmental sustainability. High costs of nitrogen fertilizer and potential negative environmental effects of N application have created a critical need to maintain or increase pasture production while reducing N fertilizer inputs. Research compared the forage production, livestock performance, and economics of grazing pastures of tall fescue (Festuca arundinacea Schreb.) monoculture with and without nitrogen fertilizer, tall fescue-alfalfa (Medicago sativa), and tall fescue-birdsfoot trefoil (Lotus corniculatus). Results showed that a pasture mixture of tall fescue and the condensed-tannin-containing legume, birdsfoot trefoil, improved nitrogen utilization and steer weights, as compared to using commercial fertilizer on tall fescue. While, yearly forage yields of grass-legume mixtures were slightly lower than fertilized tall fescue, small-plot studies determined that certain grass-legume mixtures and ratios were more productive than fertilized grass monocultures. Analyses of leachate samples indicated that grass-legume mixtures result in lower nitrate concentrations in leachate, compared to N fertilizer; and thus reduce groundwater contamination. Finally, the tall fescue-legume mixtures doubled the economic return when compared to fertilized tall fescue monocultures.


  1. Characterize and develop management practices to reduce GHG emissions and transport of nutrients, pathogens, pharmaceuticals, and VOCs from livestock production systems. This will include management of feed, manure collection, manure storage, and manure application. (Miller, Harrison, Herbert, Moriera, Miller, Powell, Rotz, Wattiaux, Hashemi)
  2. Characterize the opportunities for selecting for feed efficiency (Utsumi, Wattiaux)
  3. Develop science-based tools and educational materials to promote environmental stewardship on US dairy and beef industries. (Harrison, Herbert, Powell, Rotz, Westendorf, Westra)


General Approach - Data from field and university studies (project collaborators will conduct lactation and growth trials, on farm research, field plot work, and laboratory experiments in major dairy regions of the US) will provide the basis for site-specific (state) recommendations. Results of the research from individual states become critical input to the development of dairy system models. The models are valuable to understand and apply information and technology that will enhance the productivity, economic viability, and environmental performance of the US dairy and beef industries.

Studies will be conducted with standardized methods and data expression to allow for comparison of results across regions.

Objective 1 - Characterize and develop management practices to reduce GHG emissions and transport of nutrients, pathogens, pharmaceuticals, and VOCs from livestock production systems. This will include management of feed, manure collection, manure storage, and manure application. (Harrison, Herbert, Moriera, Miller, Powell, Rotz, Wattiaux, Hashemi)

Subobjective 1. Examine the impact of tannins (birdsfoot trefoil) on nitrogen cycling.

Subobjective 2. Determine the impact of increased soluble carbohydrates (plant sugars) and total digestible nutrients (total energy) on nitrogen cycling.

This study will examine the impact of grazing dairy heifers on grasses as monocultures versus grass-legume mixtures with birdsfoot trefoil on ADG, carrying capacity, and nutrient cycling. The predominant soil type is a Lewiston Fine Sandy Loam. Four treatments: 1) tall fescue (TF) [Festuca arundinacea Schreb.]; 2) meadow brome (MB) [Bromus bieberrsteinii]; 3) orchard grass (OG) [Dactylis glomerata]; and 4) a high carbohydrate perennial ryegrass (PR) [Lolium perenne] as monocultures and as grass legume mixtures with birdsfoot trefoil (BFT) [Lotus corniculatus] for a total of eight treatments. Rotational grazing practices will be utilized. The number of animals will be determined by the amount of forage available. Plots will be grazed for seven days and then allowed to regrow before grazing again. Ammonium sulfate fertilizer (35 kg ha-1) will be applied approximately every 30 days during the growing season. Plots will be watered every two weeks applying an average of 10 cm (4”) per set. Weather data will be recorded from a weather station located just outside of the treatment area.

To document the effects of tannins on nutrient cycling, determination of the nutrients in each phase (plant, soil, and soil water) will be made. Plant samples will be collected before and after each grazing event. Soil samples will be collected in the spring, prior to grazing, and in the fall after the growing season using a Giddings® soil extraction instrument to a depth of 1.524 meters. Soil samples will also be collected in the fall at the beginning of the study for a baseline reading and in the spring of the third year to monitor nutrient movement. Four soil cores will be taken in each plot and divided into three subsamples; 0-30.48 cm, 30.48-60.96 cm, 60.96-152.40 cm. Composite soil subsamples will be analyzed for available nitrogen (ammonia and nitrate) and for total N.

Soil water (leachate) nitrogen will be monitored by means of zero-tension lysimeters that were previously installed at this location. Leachate will be collected every two weeks during the growing season, and as close as possible to every two weeks during the winter months. Samples will be analyzed for nitrate-nitrite.

A mass balance approach comparing total nitrogen outputs against total nitrogen inputs for each treatment will be utilized to estimate losses due to volatilization. Data will be analyzed using SAS PROC Mixed with Repeated Measures.

Subobjective 3. Examine the impact of tannins in the forage (BFT) on greenhouse gas (GHG) emissions from urine and feces collected from grazing cows. Feces and urine will be collected from five heifers grazing tall fescue and five grazing tall fescue-birdsfoot trefoil. Manure will be composited by treatment and added to laboratory chambers with a soil substrate. The laboratory chambers will be constructed according to Misselbrook et al. (2005) but modified for CH4 and NOx emissions analysis rather than ammonia analysis. Soil will be placed in each chamber to form a base. Composited manure will be applied at rates similar to those found in a manure pile in a grazing system. A lid will be fitted to the top with silicone grease to ensure an air-tight seal. Each chamber will be exposed to a constant gas flow of 4 L/min by means of a vacuum pump. Gas samples will be taken at 1, 3, 6, 12, 24, 36, and 48 hours after application. Gas samples will be analyzed for CH4 and NOx. The effects of tannin on CH4 and NOx emissions will be determined. Data will be analyzed using SAS PROC Mixed with Repeated Measures.

Subobjective 4. Validate and refine a novel method of indexing NDF digestibility across grasses, legumes and alfalfa

In vitro methods are widely used to indirectly estimate ruminal NDF digestibility. In vitro NDF digestibility estimates have not been quantitatively validated to in vivo measurements across forage types. This project will include three intensive feeding studies with lactating dairy cows.

In each study, ruminal and total tract fiber digestion and passage kinetics will be measured in vivo, and compared to estimates of ruminal and total tract fiber digestion that have been derived from mathematical models that use in vitro estimates of fiber digestibility and an assumed rate of fiber passage. Two in vitro methods for measuring rates of fiber degradation will be compared.

The traditional in vitro method (Goering and Van Soest, 1970) that is widely used in research in commercial forage testing will be compared to the in vitro method developed in our laboratory in which fermentative activity of rumen fluid inoculum has been standardized (Goeser and Combs, 2009). We expect that the estimated rates of fiber digestion from the standardized method will be 30 to 50% lower than the rates estimated by the traditional method (unpublished data). The objective of this project will be to determine if either in vitro method reflects the rate of fiber digestion measured in vivo. In vivo fiber digestion kinetics will be determined in each study by the rumen evacuation technique. This technique has been used by several labs to measure ruminal NDF digestion and passage (Taylor and Allen, 2005, Huhtanen et al., 2007, Ivan et al., 2005). This method is carried out with ruminally cannulated animals. Rumen pools of digestible and indigestible fiber are measured by total rumen evacuation and fiber flow from rumen is estimated using external markers and spot-sampling digesta from the omasal orifice (Huhtanen et al., 1997). Reliable estimates of ruminal digestion and passage require that the animals be in steady state so that rumen fill varies minimally throughout the course of the day. This can be achieved by feeding cows frequently and monitoring daily feed intake to ensure that day-to-day variation in feed intake is minimal (Huhtanen et al., 2007). We will disseminate findings and new tools (i.e., our fiber digestibility model) to producers, extension agents, and private consultants working with dairy farm systems. Programs will involve training in how to utilize iv NDFD to index forages, how to utilize in vivo estimates of fiber digestibility in ration formulation and how to optimize dairy forage cropping systems for best utilization of forage and optimal milk production.

Subobjective 5 – Quantify and reduce the emission of greenhouse gases and pollutants from animal production systems

Micro-met methods will be used to measure greenhouse gas emissions as part of the permanent LTAR monitoring system.

In a cropping rotation study supported by a NESARE long-term sustaining cropping system study at Rocksprings, PA, nitrous oxide emissions will be measured using flux chambers. Emissions from corn phases of dairy rotations following alfalfa/orchard grass mixture, winter rye, and red clover and will be compared to emissions from corn following soybean without a winter cover crop.

The DayCent model will also be used to evaluate the impact of additional cropping systems options.

Long-term monitoring of carbon dioxide and nitrous oxide emissions will be conducted in support of Long Term Agro-ecosystem Research (LTAR) utilizing and comparing micro-met technology and chamber systems in annual and perennial crop rotations.

A process-based model for predicting VOC emissions from cattle facilities will be evaluated by comparing predicted and measured data. This model is incorporated as a component of the IFSM and DairyGEM farm models. Emission data measured on dairy farms in California will be compared to that predicted by the VOC component model for the same weather and management conditions. Model parameters will be set to represent the actual conditions, and internally set parameters will be adjusted as needed to assure proper representation. Through this analysis, the model will be calibrated and hopefully found to appropriately represent the actual VOC emissions. When the model is found to work satisfactorily, it will be used to simulate different management conditions to evaluate the potential benefits of strategies for mitigating emissions. Mitigation strategies may include changes in the dimensions of silage storage, use of bags for silage storage and changes in silage feeding methods.

Subobjective 6 - Effect of the substitution between dietary forage fiber and starch in the diet of late lactating dairy cow on performance, manure composition and gaseous emissions.

For this experiment, an animal-size chamber study will be conducted with 48 lactating cows (16 rumen fistulated) allocated to 12 blocks in a randomized complete block design with equally spaced arrangement of treatments. Each diet will be formulated to meet the nutritional guidelines of NRC (2001), see Table

1. All cows will be fed the experimental diet for a 6-wks period. After 5-wks of experimental diet, animal performance parameters (body weight, intake, and milk yield) and milk composition (fat, protein lactose and MUN), CH4 and NH3 emission and rumen variable will be measured. Nitrogen partitioning in feces and urine will be measured by total collection. Animal performance and gaseous emission will be conducted in four tie-stall emission chambers. Powell et al. (2008 ), Aguerre et al. (2011) and Arndt et al. (2015) described the technical aspects of chamber design, operation, and calibration.

Table 1: Dietary and chemical composition of the experimental diets.

FNDF1/Starch (% diet DM) 20/30 23/27 25/23 28/20
Alfalfa silage (AS) 27.5 31.0 34.5 38.0
Corn silage (CS) 27.5 31.0 34.5 38.0
Forage (AS + CS) 55.0 62.0 69.0 76.0
High moisture corn 26.8 20.0 13.3 6.5
Soybean meal (48CP) 8.3 7.3 6.3 5.3
Soy Hulls 8.0 8.75 9.5 10.3
Vit. & Min. 2.0 2.0 2.0 2.0
Chem. Composition (% of dietary DM) Crude Protein (CP) 15.6 15.6 15.6 15.7
Total NDF 27.1 29.7 32.2 34.8
Non-Forage NDF 7.0 7.0 7.0 7.0
FNDF1 20.1 22.7 25.3 27.8
Starch 30.4 26.9 23.4 19.9
Ether Extract 3.3 3.3 3.2 3.1
Predicted decline in CH4 due to change in NDF alone2 Delta CH4 Mj/d -0.32 -0.32 -0.32 0

The CH4 prediction equation of Moraes et al., (2014) will be used to estimate the effect of reducing dietary NDF from 34.8 to 27.1% of dietary DM. With every stepwise decrease in NDF concentration, the reduction in energy loss in the form of CH4 was 0.32 MJ/d, which correspond to 16.2 g/d of CH4. Under standard conditions, 1 gr CH4 = 19.9 KJ, there is thus an expected reduction in CH4 emission of 48.5 g/d as dietary NDF decline from the high to the low NDF. This value is approximately 8-10% of the expected daily emission. Data will be analyzed for treatment effects with the mixed procedure in SAS (2004) including test for linear and quadratic effects.

Subobjective 7 - Effect of the substitution between dietary forage fiber and starch in the diet of late lactating dairy cow on gas emission and changes in manure composition during storage.

This experiment will be conducted as a complete randomized block design. Thirty-two 180-L barrels will we used to store manure collected from each of the dietary treatment at the end of experiment 1. Manure from each dietary treatment will be stored with or without the addition of a cover. Enough wheat straw will be added to obtain a 5-cm cover on top of the manure surface. This process will lead to a total 8 barrels (replicates) for each dietary treatment (4 with cover and 4 without cover). Manure will be mixed and diluted with wash water from the milking parlor to mimic washing waters typically added to manure storage on commercial farm. Manure will be stored for a period that may vary from 3 to 6 months.

Manure samples for chemical analysis and emission measurements will be conducted either weekly or every other week. Emissions will be recorded over a 6 hour period, following a procedure that we (Aguerre et al., 2012) developed after Misselbrook et al. (2005) and Xue et al. (1998). Data will be analyzed for treatment effects with the mixed procedure in SAS (2004) including test for linear and quadratic effects, and repeated measurements will be used to test changes in composition and rate of emission over time. Pearson correlation coefficient will be used to study the association among gaseous emissions.

Subobjective 8 – Characterize the potential for improved nitrogen use efficiency in first lactation dairy cows.

First lactation dairy cows will be fed diets formulated to be targeted for reduced intake of CP, but formulated to meet predicted needs of MP, lysine, and methionine. Measures of nitrogen use efficiency will be: DMI, N intake, milk production, MUN, and production of milk fat, milk protein, and milk lactose. Manure (feces and urine) will be collected from cows on various diets and incubated in the laboratory for measurement of ammonia emission.

Objective 2. Characterize the opportunities for selecting for feed efficiency (Utsumi, Wattiaux)

Subobjective 1 – Measurement of feed efficiency of grazing cows Two farmlets differing in number of lactating animals during the grazing season (65 vs. 85 cows), stocking rate (4.1 vs. 2.5 cow/ha), feeding system and combination of dairy breeds (US and NZ Holstein-Friesians). In both farmlets, cows will be managed on a voluntary milking system using AMS combined with same pasture allocation management. The primary goal of grazing management will be the efficient utilization of grazed pasture focused on maximizing pasture productivity. The dairy farm comprises a grazing platform (east and west sections) for lactating cows of 48 ha of perennial pasture, subdivided into 1 ha paddocks for rotational grazing management of cows. Paddocks are connected via split laneways to a central milking barn with capacity to milk two separate herds. The milking barn layout includes two freestall pens (58 stalls/pen), each equipped with a single-stall Automatic Milking System (AMS; Astronaut A3, Lely Industries, NV, Maassluis, Netherlands), a two-way drafting gate for the exit of cows to pasture (Grazeway gate, Lely Industries, NV, Maassluis, Netherlands) and an automatic feeding station (Cosmix, Lely Industries, NV, Maassluis, Netherlands). On a normal year, cows are housed on a partial mixed ration (PMR; 65% forage) during winter (usually from December to April), and are rotationally grazed on adjacent pasture the rest of the year. Pasture utilization is approximately 10 t DM/ha or between 3 to 3.5 t DM/cow. Grazing management will consist in the rotational grazing of the 2 farmlets' herds across 2 grazing platforms. Each day, herds will be receiving 2 breaks of fresh pasture on alternating locations of the farm (north and south); this two-way pasture allocation system (i.e. A-B grazing schedule) was decided for improved traffic of cows on a voluntary milking system (Lyons et al., 2013). Pasture allocations will be made available from 1000 h to 2200 h and from 2200 h to 1000 h, respectively. A same average distance to grazing paddocks of 275 ± 7 m (one-way) will be maintained throughout the study. The approximate daily herbage allowance will be 35 kg DM/cow, divided evenly between the two pasture allocations offered per day. The criteria to define pasture allocations will consider the following rules: a) maintenance of pre-grazing herbage mass of 2400 kg DM/ha, b) maintenance of post-grazing residual of 1200 kg DM/ha, c) maintenance of an average herbage mass of 1700 kg/DM across the site, and, d) an average consumption of 38 Mcal/d of metabolizable energy (ME) or the equivalent of 16-17 kg DM/cow. Therefore, the major objective of supplementary feeding, in particular in HSR will be to minimize herbage deficits that resulted from increasing stocking rates, but without sacrificing pasture growth rate, pasture utilization/ha, or modifying dry matter intake (Fariña et al., 2011). The supplementation of pasture deficits will be conducted with PMR based on conserved pasture, but corrected with concentrates according to NRC (2001) guidelines to achieve similar ME energy of pasture, as needed. The amount of PMR will be determined weekly according to changes in pasture growth rate and herbage mass. The inventory of PMR in the HSR and LSR farming systems is maintained by farm staff. The concentrate offered to LSR and HSR (Table 1) will include 1 kg of pellet concentrate per 6 kg of milk, fed during milkings in the AMS, and a flat amount of 1.36 kg/d of ground corn made available in the automatic feeding stations. Cows will have free access to mineral and vitamin supplements formulated for lactating cows (Crystallyx®, Ridley Block Operations, Eden Prairie, MN).

Objective 3 - Develop science-based tools and educational materials to promote environmental stewardship on US dairy and beef industries. (Miller, Harrison, Herbert, Powell, Rotz, Westendorf, Westra)

Subobjective 1 - As new process information becomes available, models used to predict emissions in IFSM and DairyGEM will be revised and evaluated to improve prediction accuracy.

Subobjective 2 - As new mitigation strategies are developed, process models for predicting emissions will be developed or refined for implementation in IFSM and DairyGEM for assessing the interactions within and overall impacts on farm production systems.

Subobjective 3 - The Anaerobic Digester OPtimization Tool will be placed on a public web platform to be readily available for users. Tool enhancements will include: accepting multiple feedstocks, nutrient mass balance, electricity production, renewable energy credits, carbon credits, and nutrient redistribution to contributing dairies accounting for any land application constraints.

Subobjective 4 – Whole farm and global climate models will be used to evaluate the sustainability of U.S. dairy and beef production systems under current and projected future climate variability. Downscaled projected climate data for this century will be prepared by collaborating climate scientists at Texas Tech University for important dairy and beef cattle production regions of the U.S. Projected daily climate data will be provided for each location using an ensemble of climate models representing two greenhouse gas emission pathways (business as usual and stabilization). Representative dairy and beef cattle production systems will be developed for the various climatic regions of the country and simulated with the Integrated Farm System Model (IFSM). Simulations with current and projected future weather patterns and atmospheric carbon dioxide levels will quantify effects on the performance, economics and environmental impacts of farming systems in each region. Model parameters will then be tested to represent management changes such as planting and harvest dates, crop varieties, crop species, double cropping, and strategies to reduce heat stress on cattle to explore ways of maintaining or improving the sustainability of farms. In dry western regions, potential impacts on water availability and water shortage will be addressed.

This work will lead to a series of research journal articles that document projected climate change effects on dairy and beef production in various climatic regions of the U.S. and strategies that help adapt farms to the changing climate. The Integrated Farm System Model will be revised as needed to properly assess climate effects on crop and animal production. The IFSM software and associated data files used to evaluate production systems will be made available to others through internet download for further analyses. Models and information generated will benefit ongoing efforts by USDA’s Northeast Climate Hub to provide timely information to farmers on adapting to climate variability and projected changes in variability.

Measurement of Progress and Results


  • Systems models, IFSM, publications (peer reviewed, fact sheets, case studies, newsletters, field days), feeding and management recommendations
  • Education programs/models, tools, promoting environmental stewardship on farms, publications, webcasts

Outcomes or Projected Impacts

  • Reduce gaseous emissions and transport of nutrients, pathogens, pharmaceuticals
  • More effective N & P use as determined by nutritionists, reduced environmental loss of
  • Informed management decisions, Informed policy decisions, more economically viable and sustainable operations


(2018): Complete initial research for gaseous model development

(2020): Complete model refinement

(2019): Complete animal feeding trials on N use efficiency

(2020): Model validation and refinement, Conduct workshops, field demonstrations, and webcasts

Projected Participation

View Appendix E: Participation

Outreach Plan

The proposed research will help integrate current research in agricultural science so that farms can be managed in a cost effective way to reduce negative environmental effects. Software will be developed from this research allowing widespread and rapid use of findings in the field. The software developed in one or more states could also be refined for use in other states. In addition, the research will assist with development of technology transfer and incentive programs that target the most effective programs. It potentially will be used by agricultural scientists to focus their research efforts on priority areas.

In essence, the proposed research will identify low cost and effective methods for reducing nutrient losses from farms in addition to current management strategies. The software and other publications generated in the proposed work will be useful to farmers, educators, policy makers, regulators, commodity groups, politicians, and other researchers. The information will aid farmers as they make strategic plans for crop production and manure management.

Extension specialists will obtain useful information for extension workshops and other forms of teaching or consulting with farmers on issues related to grazing, manure management and cropping systems. The results will provide a better understanding of the costs, benefits and potential impact of legislation on the dairy and beef industries. The process of developing these tools will also help direct other research by pointing out information gaps and critical areas of need for further research. The completed software tools may also provide an aid for teaching the principles of crop and manure management and their interaction with crop harvest, storage and use on dairy farms.


The voting membership of the technical committee consists of a technical representative from each participating USDA lab or state agricultural experiment station (SAES) as designated by the SAES director. Non-voting members include the regional administrative adviser, the NIFA representative, and additional representatives from participating SAES and USDA labs. All voting members are eligible to hold an office on the technical committee. These officers are the chair and the secretary. The chair, in consultation with the administrative advisor, notifies the technical committee members of the time and place of meetings, prepares the agenda, and presides at the annual meeting of the technical committee. The chair also prepares the annual report of the regional project. The secretary records and distributes the minutes of the technical committee meeting. A new secretary is elected at the annual meeting of the technical committee and succeeds the chair at the time the annual report is filed with the administrative advisor.

Literature Cited

Arndt, C., J.M. Powell, M.J. Aguerre, and M. A. Wattiaux. 2015. Performance, digestion, nitrogen balance, and emission of manure ammonia, enteric methane, and carbon dioxide in lactating cows fed diets with varying alfalfa silage-to-corn silage ratios. J. Dairy Sc. 98:418-430

Aguerre, M. J., M. A. Wattiaux, and J. M. Powell. 2012. Emission of ammonia, nitrous oxide, methane, and carbon dioxide during storage of dairy cow manure as affected by dietary forage to concentrate ratio and crust formation. J. Dairy Sci 95:7409-7416

Aguerre, M. J., M. A. Wattiaux, J. M. Powell, G. A. Broderick, and C. Arndt. 2011. Effect of forage to concentrate ratio in dairy cow diets on emission of methane, carbon dioxide and ammonia, lactation performance and manure excretion. J. Dairy Sci. 94:3081-3093.

Fariña SR, Garcia SC, Fulkerson WJ and Barchia IM 2011. Pasture-based dairy farm systems increasing milk production through stocking rate or milk yield per cow: pasture and animal responses. Grass and Forage Science 66, 316–332.

Misselbrook, T.H., J.M. Powell, G.A. Broderick, and J.H. Grabber. 2005. Dietary manipulation in dairy cattle: laboratory experiments to assess the influence on ammonia emissions. Journal of Dairy Science 88: 1765-1777.

Mores, L. E., A. B. Strathe, J. G. Fadel, D. P. Casper, and E. Kebreab. 2014. Prediction of enteric methane emissions from cattle. Global Change Biology. 2014 (doi: 10.1111/gcb.12471 in press).

Powell J.M., Broderick G.A., Misselbrook T.H. (2008) Seasonal diet impacts on ammonia emissions from tie-stall dairy barns. J. Dairy Sci. 91:857-869.
NRC (National Research Council). 2001. Nutrient Requirements of Dairy Cattle. 6th rev. ed. Natl. Acad. Sci., Washington, DC.

Xue, S. K., S. Chen, and R. E. Hermanson. 1998. Measuring ammonia and hydrogen sulfide emitted from manure storage facilities. Transactions of ASAE 41(4): 1125-1130.


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Non Land Grant Participating States/Institutions

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