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Meat and Animal Products

Consumption Trends

Meat consumption, as a share of total diet, has been increasing worldwide and varies considerably by country and region.

Source: FAOSTAT [13].

Historically, increased wealth has been associated with a "nutrition transition", or a move to diets heavier in meat and dairy [8]. The evidence is that humans have an innate preference for energy-dense foods, particularly those heavy in fats and sugar [9].

Figures are derived from the Food Balances data from FAOSTAT [13].

Environmental and Welfare Impacts

Animal products, especially beef, tend to have much greater land use, greenhouse gas, and water impacts than plant-based products.

The feed conversion efficiency of an animal (or substitute) is the ratio of input feed to edible output product, measured by mass. Feed conversion efficiency is highly correlated with lifecycle land use and greenhouse gases [2].

Data sources: Alexander et al. (2016) [2] for poultry, pork, beef, lamb and mutton, eggs, and milk; Alexander et al. (2017) [1] for mealworm, crickets, tilapia, Chinese carp, cultured meat, and imitation meat; Froehlich et al. [15] for crustaceans. Values vary depending on the choice of feed, method of raising animals, and other factors.

Following is an estimate of the number of animals that are slaughtered, or that are required to produce over their lifetimes, to provide 5% of a human's lifetime nutritional needs.

Sources: FAOSTAT [13], FAO [11][12], Compassion in World Farming [6].

In the United States, the trend has been toward more efficient beef production, though not at a rate that is sufficient to fundamentally change beef's high impacts relative to other foods.

Source: Capper [4].

On metrics such as yield per animal [13], meat production tends to perform better in wealthier countries than in poorer countries.

Animal Feed

Following is a comparison of estimated impacts of grass-fed beef, relative to feedlot beef.

Sources: Clapper [4], Lupo et al. [19], Tichenor et al. [26].

Grass-fed cattle may play a role in sequestering carbon in the soil, though the magnitude of this effect is of considerable controversy. Even with the sequestration effect, the lifecycle emissions of grass-fed beef is likely to be only marginally lower than those of feedlot beef [19].

As an additive to animal feed, seaweed has the potential to reduce enteric fermentation by 50-95% [18][23].

Insects [28] and algae [20] are of interest as a partial replacement for fishmeal in feed for cattle, poultry, and aquaculture.


The world is trending toward aquaculture production of seafood, though primarily as an augmentation, rather than a replacement, to wild catch.

Source: FAO [14].

Farmed fish require protein, which in turn comes in part from wild fish as follows.

World fish-in-fish-out (FIFO) in aquaculture as of 2015. FIFO is the ratio of wild fish into an aquaculture system to fish produced, measured by mass. FIFO is typically higher for carnivorous fish such as salmon, and it has generally been decreasing as aquaculture becomes more efficient and fishmeal is partially replaced by terresterial feed sources. Source: The Marine Ingredients Organization [25].

A fish-in-fish-out value of 4.9 for farmed salmon has been commonly cited [24], but this value has been rebutted [17].

Following are estimates of greenhouse gas emissions from four methods of seafood production.

Figures are determined through a literature review of lifecycle assessments. Source: Clark and Tilman [5].

The high impact of recirculating aquaculture systems (RAS) is driven primarily by electricity consumption. On other metrics, RAS tends to perform better than other forms of aquaculture due to recycling of nutrients. If electricity is produced from a low-carbon source, RAS may also have lower greenhouse gas emissions.

Source: d’Orbcastel et al. [10].

Integrated multitrophic aquaculture--or the mixing of species at different levels in the food chain [21]--is of interest as a means of conserving feed [17] and reducing overall environmental impacts [22].

Potential for Dietary Shift

Price is not necessarily a barrier in shifting to established meat alternatives.

Sources: Bashi et al. [3], Diet & Fitness Today [7], FAO [11], IndexMundi [16].

It is unclear if emerging meat alternatives, such as cultured meat, will be better able to gain consumer acceptance than established alternatives. Such acceptance depends on politics and culture, in addition to cost, taste, and nutrition [27]. Furthermore, in wealthier countries, protein and fat intake already exceed healthy levels [27].

For Further Reading

National Geographic goes into greater detail on the outlook for aquaculture.

Modern Farmer explains how animal products generally have greater environmental impacts than plant products and circumstances under which the reverse can be true.

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[1] Alexander, P., Brown, C., Arneth, A., Dias, C., Finnigan, J., Moran, D., Rounsevell, M. "Could consumption of insects, cultured meat or imitation meat reduce global agricultural land use?". Global Food Security 15, pp. 22-32. December 2017.

[2] Alexander, P., Brown, C., Arneth, A., Finnigan, J., Rounsevell, M. "Human appropriation of land for food: The role of diet". Global Environmental Change 41, pp. 88-98. November 2016.

[3] Bashi, Z., McCullough, R., Ong, L., Ramirez, M. "Alternative proteins: The race for market share is on". McKinsey & Company. August 2019.

[4] Capper, J. "Is the Grass Always Greener? Comparing the Environmental Impact of Conventional, Natural and Grass-Fed Beef Production Systems". Animals 2, pp. 127-143.

[5] Clark, M., Tilman, D. "Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice". Environmental Research Letters 12(6). June 2017.

[6] Compassion in World Farming. "The life of: dairy cows". September 2012.

[7] Diet & Fitness Today. "Protein in salmon, per 100g". Accessed January 27, 2020.

[8] Drewnowski, A., Popkin, B. "The nutrition transition: new trends in the global diet". Nutrition Reviews 55(2), pp. 31-43. February 1997.

[9] Drewnowski, A., Rock, C. "The influence of genetic taste markers on food acceptance". The American Journal of Clinical Nutrition 62(3), pp. 506-511. September 1995.

[10] d’Orbcastel, E., Blancheton, J., Aubin, J. "Towards environmentally sustainable aquaculture: Comparison between two trout farming systems using Life Cycle Assessment". Aquacultural Engineering 40(3), pp. 113-119. May 2009.

[11] Food and Agriculture Organization. "Nutritive Factors". Accessed January 7, 2020.

[12] Food and Agriculture Organization of the United Nations. Egg Marketing - A Guide for the Production and Sale of Eggs. ISSN 1010-1365, FAO Agricultural Services Bulletin 150, Chapter 1. 2003.

[13] Food and Agriculture Organization of the United Nations. "FAOSTAT".

[14] Food and Agriculture Organization of the United Nations. "Global Aquaculture Production". Accessed January 25, 2020.

[15] Froehlich, H., Runge, C., Gentry, R., Gaines, S., Halpern, B. "Comparative terrestrial feed and land use of an aquaculture-dominant world". Proceedings of the National Academy of Sciences of the United States of America 115(20), pp. 5295-5300. May 2018.

[16] IndexMundi. "IndexMundi". Accessed January 27, 2020.

[17] Jackson, A. "Fish In - Fish Out (FIFO) Ratios explained". International Fishmeal and Fish Oil Organization. January 2010.

[18] Kinley, R., de Nys, R., Vucko, M., Machado, L., Tomkins, N. "The red macroalgae Asparagopsis taxiformis is a potent natural antimethanogenic that reduces methane production during in vitro fermentation with rumen fluid". Animal Production Science 56(3), pp. 282-289. March 2016.

[19] Lupo, C., Clay, D., Benning, J., Stone, J. "Life-cycle assessment of the beef cattle production system for the northern great plains, USA". Journal of Environmental Quality 42(5), pp. 1386-94. September 2013.

[20] Madeira, M., Cardoso, C., Lopes, P., Coelho, D., Afonso, C., Bandarra, N., Prates, J. "Microalgae as feed ingredients for livestock production and meat quality: A review". Livestock Science 205, pp. 111-121. November 2017.

[21] Martinez-Porchas, M., Martinez-Cordova, L. "World Aquaculture: Environmental Impacts and Troubleshooting Alternatives". The Scientific World Journal. Article ID 389623, 9 pages. 2012.

[22] Prescott, S. "Exploring the Sustainability of Open-Water Marine, Integrated Multi-Trophic Aquaculture, Using Life-Cycle Assessment". University of Stirling, Aquaculture eTheses. October 2017.

[23] Roque, B. et al. "Effect of the macroalgae Asparagopsis taxiformis on methane production and rumen microbiome assemblage". Animal Microbiome 1(3). February 2019.

[24] Tacon, A., Metian, M. "Global overview on the use of fish meal and fish oil in industrially compounded aquafeeds: Trends and future prospects". Aquaculture 285, pp. 146-158. 2008.

[25] The Marine Ingredients Organization. "Fish in: Fish Out (FIFO) ratios for the conversion of wild feed to farmed fish, including salmon". Accessed January 25, 2020.

[26] Tichenor, N., Peters, C., Norris, G., Thoma, G., Griffin, T. "Life cycle environmental consequences of grass-fed and dairy beef production systems in the Northeastern United States". Journal of Cleaner Production 142(4), pp. 1619-1628. January 2017.

[27] van der Weele, C., Feindt, P., van der Goot, A., van Mierlo, B., van Boekel, M. "Meat alternatives: an integrative comparison". Trends in Food Science & Technology 88, pp. 505-512. June 2019.

[28] van Huis, A., Oonincx, D. "The environmental sustainability of insects as food and feed. A review". Agronomy for Sustainable Development 37:43. October 2017.