Sheep grazing on New Zealand Landscape

Note: This webpage is for instructional purposes only and the scenario described below is fictional.

Comparing GHG emissions from Beef and Lamb production systems in New Zealand

UW-Madison Task Force Members:
   Bailey Fritsch, Department of Dairy Science
   Pablo Silva, Department of Dairy Science

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Scenario | Abstract | Introduction | Literature Review | Methods | Results | Limitations | Conclusions | Citations | Acknowledgements | About the Authors

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Scenario

      Pablo and Bailey were put on the task force to collect data on greenhouse gas emissions in New Zealand supported by the Ministry of Agriculture and Forestry. Every country will be presenting their agriculture environmental impact, and ways that their scientists have develop to reduce greenhouse gas emissions on their livestock species in a meeting presented by the Bill and Melinda Gates Foundation, as an organization dedicated to the use of technology in the agriculture field. The goal of the meeting is to spend time on the subject so different counties can learn new ways to reduce greenhouse gas emissions in the agriculture field.

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Abstract

Greenhouse gas emissions and their impact in global warming, have become a very important topic for world economies as many are looking for ways to reduce them. Agriculture leads to one of the higher proportions of greenhouse gas emissions specifically with human related nitrous oxide and methane emissions. For the particular country of New Zealand, agriculture is the major driving force of GHG emissions, and there have been efforts made to reduce the emissions from this source. Therefore, the goal of this website was to evaluate GHG emissions from NZ beef and lamb production systems, explore several mitigation practices, and estimate whether a shift towards one of the two production systems would result in a reduction of GHG emissions. Conversion factors for calculation of emissions for these production systems were from the Food and Agriculture Organization from the United Nations (FAO) and the Intergovenmental Panel on Climate Change (IPCC). Results show that GHG emissions in agriculture are mainly due to enteric fermentaiton the produces large amounts of methane and that the majority comes from dairy cows, followed by sheep, and then beef for New Zealand. Some mitigations practices have been researched, such as using high quality forages, legumes, and oils. Further results show that by creating a scenario of a 60 hectare farm, similar total amounts of enteric methane are produced by both species, but due to higher stocking rates achievable by the sheep system, more kg of live weight can be produced with the same amount of emissions.

A shift in the production proportion from one species to the other could prove an effective strategy to reduce GHG emissions from livestock; however, there are other factors such as economical, social, and consumer based issues that would have to be evaluated to properly assess this topic.

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Introduction

Agriculture accounts for roughly 10 to 12% of greenhouse gas emissions (GHG), and are the major sources of human related Nitrous Oxide and methane emissions. These values have a variation from country to country depending on how important the agricultural and other sectors are in their economies (Garnett, 2009 ; Browne, et al., 2011). The need for a reduction in greenhouse gas emissions is something scientists estimate needs to be somewhere between 50% to 85% less than year 2000 levels to avoid permanent impact (Garnett, 2009). However, protein demand is increasing globally (FAO, 2006).

Many countries have stated goals and plans for reduction in GHG emissions. The UK has set a target of 80% reduction in GHG emissions by 2050, but researchers have found that if no changes are made the to the proportion of production systems, the only way to have only a 20% reduction in GHG emissions would be to reduce livestock number by 20% (Webb et al. 2014). For the case of the UK, the highest sub sector in agriculture that would contribute to a reduction in GHG emissions was estimated to be a reduction of 54% of the current number of suckler beef herds. However, beef and sheep systems are usually thought as being the only means of oconverting roughages and using low nutritional value land into meat products (Dyer, et al., 2013). In the case of New Zealand, the goal is to achieve an 11% less GHG emissions that what was produced in 1990 by the year 2030 (Ministry for the Environment, n.d.). Until the year 2015, agriculture in New Zealand was responsible for the highest levels of GHG emissions, and from the agricultural sub-sector, livestock represented the highest emissions levels of GHG, with nearly 30,000 kt of carbon dioxide - e.

The purpose of this website is to look at the emissions from beef and lamb production system, explore possible mitigation strategies, and how livestock emissions can be reduced in a fictional 60 hectare farm.

Shown above is the emissions from agriculture specifically for the country of New Zealand. The purpose of their webpage that this figure came from is to summarize review literature on GHG emissions from beef and lamb production systems and estimate if it is possible to reduce overall GHG emissions by shifting partially the production matrix towards a lamb meat market.

Why Ruminants and why not monogastrics?

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Methods

In this fictional scenario, we created the calculation below. The research team wanted to look at what type of production systems would produce the lowest amount of methane in a particular amount of land available. To expand on the previous idea, we wanted to calculate the effect of replacing part of the meat market with lamb over beef to see the effect on the overall greenhouse gas emissions. This study will draw on the calculations on consumptions of livestock products, specifically in beef and lamb. This data will be used to cross to the emissions per kilogram of product calculations and overall emissions to evaluate their impact.

For estimating how many animals a 60 hectare farm can support, we needed to look at the average production of a well managed ryegrass pasture, the estimated dry matter intake a year for each animal. With this data we could calculate how many animals per hectare and total we could have in this pretend scenario. This way we can estimate the population of animals to estimate their methane emissions.

As described in the infographic, we used the equation of Emissions = Emission Factor multiplied by the number of livestock species. It is divided by the 10^6 to get the units of tons. Emission factor for each species vary depending on the liveweight of the animals and the species. For the case of sheep, the emission factor is between 5 to 8, with the last one asasociated with a sheep with a mature weight of 65 Kg. For beef cattle, the emission factor for animals in pasture based setting is 60.

Interviews

Dr. Daniel Schaefer

BS, Meat & Animal Science, University of Wisconsin - Madison, 1973

MS, Meat & Animal Science, University of Wisconsin - Madison, 1975

PhD, Nutritional Sciences, University of Illinois-Urbana , 1979

The questions that the research team drafted in the infographic shown below. The interview was conducted on April 12, 2018 at 2:30 pm.

Literature Review for Mitigation Strategies

The research team conducted a Literature Review using the database of Google Scholar and Science Direct to find articles pertaining to mitigation strategies for lamb and beef production system. Some of the keywords included "lamb," "beef," and "methane emissions."

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Results

When calculating the emission of cow calf and lamb production systems, we used a a formula detailed by the Intergovernmental panel for climate change (IPCC) that uses an emissions factor depending on the species to estimate the amount of methane produced. The emission factor for beef cattle was 60 and the emissions factor for sheep was between 5 and 8. Then, a next step was to calculate how many animals we could have in our pretend farm scenario of 60 hectares. To do this, we estimated the annual dry matter intake of these two species, that is how much feed they can consume based on the content of the feed without the water that naturally is in the feed. We estimated that a cow with its calf would consume roughly 5,800 kg of dry matter per year and a sheep with the lamb would consume is 650 kg of dry matter per year. The average yield for a ryegrass pasture, which is a high quality grass, is 14 tons of dry matter per year in New Zealand. This means that a hectare of this land can support 21 sheep with their lambs or 2.4 cows with their calves per hectare. The whole farm could be able to support close to 1290 sheep and 145 cows in total. The weight of a calf when it is weaned is roughly 230 kg, while the weight of a lamb is close to 40 kg. We expect that close to 65,000 kg of live weight to be produced by the all lamb system and 30,000 kg of live weight by the all breed systems. This would mean the whole sheep scenario could have greater emissions if the emissions factor is used as 8, but also would have more product which would mean it is more efficient in the use of land to produce meat.

Overall, total methane emissions from livestock in New Zealand have remained constant, with about 30,000 Kt of CO2 -e per year. This amount is produced mainly due to enteric fermentation, roughly 25,000 (83%) Kt of CO2 -e per year in the year 2015. This was mainly attributed to cattle. There was an overall increase in greenhouse gas emissions from cattle to approximately 18,000 Kt of CO2 -e, however most of these emissions correspond to dairy cattle. Beef cattle accounted for roughly 5,000 Kt of CO2 -e in 2015. Emissions from sheep corresponded to 8,700 Kt of CO2 -e methane emissions in 2015 (Table 1), however there has been a sustained decrease in total emissions from this source from 1990, from close to 14,000 Kt of CO2 -e to the levels mentioned for 2015. We found that New Zealand farmed roughly 29 million sheep and 3.5 million beef cattle in 2015. In the case of sheep this accounts for both breeding sheep and for wool production.

Table 1. Estimate stocking rate and methane emissions for a 60 hectare farm scenario.

Systems	Pasture Production (kg/ha)	Intake/year	Stocking rate (hd/ha)	Total Animals	Total Emissions	Total Liveweight
Sheep	14000	650	21	1292	0.006-0.01	65000
Beef	14000	5800	2.4	145	0.087	30130

Mitigation Stratgies: Literature Review

1. Addition of Nitrate in the Diet: Nitrate can raise the redox potential. Methane in the rumen is produced by hydrogenotrophic reaction, meaning the substrates in the reaction is hydrogen and carbon dioxide. Nitrate has efficiency of inhibiting methane production in this form due to the toxicity of the nitrite that could accumulate. If producers wanted to increase the level of nitrite in the diet through their dry matter intake, it would take the inclusion of 80 to 100 grams of nitrate/kg dietary dry matter (Yang, et al., 2016).
2. Certain forages can reduce the production of methane: As shown below, this study used this variety of forages in the diet to test the emissions and performance of lambs. The study showed a two-fold range in methane emissions from the diets in the study which is a good sign for opportunity in feeding our animals certain forages as mitigation strategies. Condensed tannin forage on methanogenesis shows a reduction of 16 percent. The effects exactly on how condensed tannin reduces methane production is unknown, but the theory is changes that in microbial degradation specifically directs and indirect effects on bacteria and methanogenic organisms which are archaea. Legumes over grasses have shown to reduce methane, and maturity of grasses does have effect on the methane production (Waghorn, G. C., et al. 2002).

	Fresh Ryegrass
	Fresh white clover
	Fresh Unpelleted lucerne
	Fresh Sulla
	Fresh Chicory
	Red Clover

3. Additions of the supplements of Monensin, Sunflower Oil, Enzymes, Yeast, and Fumaric Acid: Sunflower oil reduced methane emissions by 22 percent compared with the control, although it droped dietary energy by 21 percent. Monensin, proteolytic enzyme, yeast, and fumaric acid treatments had no effect on the methane emissions. The limitation of this study was that the supplementation of this products was short term, and the feed costs were expensive (McGinnn, S.M., et al. 2004).
4. Vaccines a possible answer in lamb production?: One vaccination protocol was a vaccine with 3 methanogen mix followed by another shot of the 3 methanogen mix at day 153. The second vaccination protocol was a vaccine with a 7 methanogen mix followewd on day 153 with a 3 methanogen mix vaccination. Through this immunization process, the researchers saw a 7.7 percent reduction in methane emission (Wright, A.D. G., et al., 2004).

Interview Results

"Farmers have dropped greenhouse gas emissions over the last few years, and farmers have not intentionally dropped these emissions on purpose."

1. How has beef producers in the United States tried to lower methane emissions?
   

   Grain based diets have lower methane emissions than forage based diets. High forage diets in cows and sheep with a relatively higher methane emissions. What proportion of gross energy is loss to methane? In high forage diets, 8-10% gross energy loss as methane. Farmers are not doing anything intentionally because there is no reward for doing that criterium. Changes have been correlated and not intentional. Over the years, there is a push to characterize methane emission and less effort to reduce methane emissions. There are no ruminants to his knowledge that do not produce methane. By the addition to nitrite to the diet in the purpose of reducing methane emissions. From a commerical sense, biggest way producers can reduce methane is through anaerobic digesters. Although, in a digester sense they need higher methanogenesis and the residence time is 20 days. In a rumen, the residence time is 30 to 36 hours.

2. Do you think there will be a push for regulations on how much beef production can contribute to methane emissions in the future?
   

   He does not see the regulations to methane emissions being separated from its political concept. He studied the redirection of methane formation to a more desirable to acetic acid, and everyone criticized him for it. Researchers are focused on to refine the estimates for methane emissions, and there is some support for mitigating methane emissions.

3. In this project, we will be comparing beef to sheep in terms of methane. In the U.S., beef is a major meat to eat. Do you see people wanting to change their eating habits to eat more lamb if it leads to lower methane emissions?
   

   The people that he sees changing are the ones that already have dedicated themselves to being vegan, organic, or their other dietary plans.

4. Do you have an estimate of cow-calf operations in terms of methane emissions?
   

   He did not know the exact number off hand. He did say the biggest contributors on a cow-calf operation in terms of animals for methane emissions is the mature beef cow and bull.

5. What strategies have proven useful in reducing methane production in beef cattle?
   

   The addition of different supplements such as Rumensin and feed additives. He specifically looked at an anaerobic bacteria that increased production of acetic acid over methane. Also, the diet being grain based over forage based (Schaefer, 2018).

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Limitations

No emissions in lambs and baby calves.

They actually start eating grass soon after birth and also start to produce methane, but since their intake changes so rapidly during this period it was very difficult to estimate. So this study is slightly underestimating the emissions from both these systems although assuming they would be proportional.

Study does not focus on the consumer's preference.

The study is solely in the estimation of methane produced by both these systems and not looking into if it is possible to actually transition from one type of meat to the other. Also, the study left out if the two meats could actually be nutritionaly equivalent.

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Conclusions

Nitrates can be one potential way to reduce methane production due to its capability to bond to hydrogen. Although, the response can be questionable on how much to feed to animals as accumulation and absorption of nitrite in the diet. Legumes and the stage of maturity have shown to reduce methane production in the rumen of the animal. Sunflower oil can be an effective way with the ability to compete for hydrogen atoms, but the feed costs can increase for the producer. As we mentioned above, researchers have looked into ways to reduce the methane production, although the hunt is still on for an economic and practical applications and solutions.

New Zealand shows a decrease in methane production for sheep and beef cattle industries, although over the years they have shown a decline in the number of animals. Our results show that for a 60 hectare farm with perennial ryegrass for pasture, overall methane emissions can be similar between the sheep and the beef production system. More lamb can be stock in this type of farm, and so when evaluated by the total live weight produced in a year. The lamb production system seems more efficient in the production of methane. Also, beef calves need more time to continue the process of growth for a longer time than lamb, which needs to be accounted for in the estimation of methane emissions. This could indicate that moving towards a lamb poduction base could have a positive impact on a reduction in methane from enteric fermentation; however, on a consumer perspective preference and price need to be considered.

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Citations

Anon, n.d.,, WI beef information center.

Beef and Lamb New Zealand, n.d., , Guide to New Zealand Cattle Farming.

Browne, N.A.,, Eckard R. J., Behrendt R., Kingwell R. S. (2011). A comparative analysis of on farm greenhouse gas emissions from agricultural enterprises in south eastern Australia. Animal feed science and technology 166-167: 641-652. http://dx.doi.org/10.1016/j.anifeedsci.2011.04.045.

[Link for topic is unavailable at this time.] Bryan, K. A., , Kime L.F., Barkley M. E., Hartman D.W., Knoll K., Harper J.K. Spring Lamb Production. .

Buddle,B.M A. D. G., , Denis M., Attwood G. T., Altermann E., Janssen P., Ronimus R. S., Pinares-Patiño C., Muetzel S., Wedlock N. D. (2010). Strategies to reduce methane emissions from farmed ruminants grazing on pasture. The veterinary journal 188: 11-17. https://doi.org/10.1016/j.tvjl.2010.02.019

Dairy New Zealand, n.d. , Ryegrass. https://www.dairynz.co.nz/feed/pasture-renewal/select-pasture-species/ryegrass/.

Dyer J.A., Vergé X. P., Desjardin R. L., Worth D. E. (2013). A comparison of the greenhouse gas emissions from the sheep industry with beef production in Canada. Sustainable agricultural research. http://dx.doi.org/10.5539/sar.v3n3p65

FAO. , (2006). Livestock’s Long Shadow—Environmental Issues and Options. Food and Agriculture Organisation, Rome, Italy. http://www.fao.org/docrep/010/a0701e/a0701e00.HTM

Foley P. A., , Crosson P., Lovett D. K., Boland T. M., O’Mara F. P., Kenny D. A. (2011). Whole farm systems modeling of greenhouse gas emissions from pastoral suckler beef cow production systems. Agriculture, ecosystems and environment 142: 222-230. https://doi.org/10.1016/j.agee.2011.05.010

Garnett, T. , (2009). Livestock related greenhouse gas emissions: impacts and options for policy makers. Environmental science & policy 12: 491-503. https://doi.org/10.1016/j.envsci.2009.01.006.

Intergovernmental Panel on Climate Change. , (2006). Emissions from livestock and manure Management. Chapter 10, Guidelines for National Greenhouse Gas Inventories. http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/4_Volume4/V4_10_Ch10_Livestock.pdf.

Mackay, A. D. , , Rhodes A. P., Power I., Wedderburn M. E. (2012). Has the eco-efficiency of sheep and beef farms changed in the last 20 years? Proceedings of the New Zealand grassland association 74: 11-16. https://www.grassland.org.nz/publications/nzgrassland_publication_2263.pdf.

McGinn, S.M., , et al. (2004). Methane emissions from Beef Cattle: Effects on Monensin, Sunflower Oil, Enzymes, Yeast, and Fumaric Acid. Journal of Animal Science, 82, (11). 3346-3356. https://doi.org/10.2527/2004.82113346x.
br> National Research Council. (2000). Nutrient Requirements of Beef Cattle: Seventh Revised Edition: Update 2000. Washington, DC: The National Academics Press. https://doi.org/10.17226/9791.

National Research Council. (2007). Nutritent Requirements of Small Ruminants: Sheep, Goats, Cervids, adn New World Camelids. Washington, DC: The National Academics Press. https://doi.org/10.17226/11654.

Schaefer, D. (2018, April 11). Personal interview.

New Zealand's Interactive Emissions Tracker (n.d). Ministry for the Environment. https://emissionstracker.mfe.govt.nz/#NrAMBoDYA4F12ARnAIgHIFMAuL7AEzj6iICse0qusQA.

Stackhouse-Lawson, K. R., Rotz C. A., Oltjen J. W., Mitloehner F. M. (2012). Carbon footprint and ammonia emissions of California beef production systems. Journal of Animal Science 90: 4641-4655. https://www.grassland.org.nz/publications/nzgrassland_publication_2263.pdf

Waghorn, G.C., et al. (2002). MEthanogenesis from Forages Fed to Sheep. Proceedings of the New Zealand Grassland Association 64: 167-171. https://pdfs.semanticscholar.org/3de8/3ee2f4ca51425f94fcd44d170456acb3731f.pdf

Wang T., Teague R. W., Park S. C., Bevers S. (2015). GHG mitigation potential of different grazing strategies in the united states southern great planes. Sustainability 7: 13500-13521.http://dx.doi.org/10.3390/su71013500

Webb J., , Audsley E., Williams A., Pearn K., Chatterton J. (2014). Can UK livestock production be configured to maintain production while meeting targets to reduce emissions of greenhouse gases and ammonia? Journal of cleaner production 83: 204-211.https://doi.org/10.1016/j.jclepro.2014.06.085.

Wright, A. D. G., , Kennedy P., O’Neill C. J., Toovey A. F., Popovsky S., Rea S. M., Pimm C.L., Klein L. (2004). Reducing methane emissions in sheep by immunization against rumen methanogens. Vaccine 22: 3976-3985.http://dx.doi.org/10.1016/j.vaccine.2004.03.053.

Yang, C. et al. (2016). Nitrate and Inhibition of Ruminal Methanogenesis: Microbial Ecology, Obstacles, and Opportunities for Lowering Methane Emissions from Ruminant Livestock. Frontiers in Microbiology 7:1-14. https://doi: 10.3389/fmicb.2016.00132

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Acknowledgements

      This project would not have been successful without the contributions of the outstanding students in our Food Systems, Sustainability, and Climate Change class.  We would particularly like to acknowledge the wonderful and challenging questions, and the specific knowledge that students with different areas of expertise provided.

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