by Brian Tomasik
First written: 9 May 2016; last update: 30 Oct. 2017
Other pieces on this site survey the impacts of cattle grazing on pasture invertebrate populations and primary productivity. This piece is a grab bag of other miscellaneous wild-animal impacts of beef production: eutrophication, climate change, and crop cultivation. The net effect of these considerations on wild-animal suffering is very unclear.
How eutrophication affects wild-animal suffering is discussed here.
This report explains:
The livestock sector [...] is probably the largest sectoral source of water pollution, contributing to eutrophication, “dead” zones in coastal areas, degradation of coral reefs [...]. in the United States, with the world’s fourth largest land area, livestock are responsible for [...] a third of the loads of nitrogen and phosphorus into freshwater resources.
This page reports: "The other main source of agricultural eutrophication is livestock farming. The amount of phosphorous excreted by British livestock each year is four times that excreted by its human population."
This page says:
Although the ECE (1992) regarded livestock wastes as a point source and excluded it from calculations of the contribution of agriculture to eutrophication in Europe, their statistics indicated that livestock wastes accounted "on average" for 30% of the total phosphorus load to European inland waters, with the rest of agriculture accounting for a further 17%. The situation for nitrogen, as for phosphorus, was quite variable from country to country. Danish statistics indicated that manure contributes at least 50% of the leaching of inorganic N (Joly, 1993). [...]
[while] direct runoff from intensive cattle, pig and poultry farms [...] is controlled in many western countries, it constitutes a serious problem for water quality in much of the rest of the world. For example, Appelgren (FAO, 1994b) reports that discharge of pig wastes from intensive pig raising in Lithuania is a major source of surface water pollution in that country. The FAO/ECE reports similar problems in the Po River of Italy. The Canadian Department of Agriculture calculated in 1978, on the basis of detailed study of several feedlot operations, that cattle feedlots and manure storage facilities contributed 0.5-13% of the total loading of total phosphorus at that time to the Canadian portion of the Lower (agricultural portion) Great Lakes (Coote and Hore, 1978).
This page reports:
In the Western United States many stream and riparian habitats have been negatively affected by livestock grazing. This has resulted in increased phosphates, nitrates, decreased dissolved oxygen, increased temperature, turbidity, and eutrophication events, and reduced species diversity. [...] In the Eastern United States waste release from pork farms have also been shown to cause large-scale eutrophication of bodies of water, including the Mississippi River and Atlantic Ocean (Palmquist, et al., 1997). However, in North Carolina, where Palmquist's study was done, measures have since been taken to reduce risk of accidental discharges from manure lagoons; also, since then there is evidence of improved environmental management in US hog production.
Despite Allan Savory's claims, cattle grazing of any type is often a net greenhouse-gas source because of the methane emitted by ruminants. Methane emissions probably outweigh possible increases in soil carbon. Soils have a limited capacity to store carbon, whereas methane emissions continue year after year. This post says: "While there may be circumstances under which grazing could increase carbon in soil, most rangeland soils have a limited ability to store additional carbon, and under most conditions livestock grazing will reduce carbon storage, rather than increase it."
This source argues: "Ruminants generate methane, but all ruminants are not domesticated. There are millions of head of ruminant wildlife and their numbers in the past, in some situations, were greater than the current number of domestic ruminants. The American bison existed in greater numbers than the current number of cattle in the Great Plains of the United States." But this is beside the point. The relevant comparison is between grazing cattle or not grazing cattle. If we don't graze cattle, tons of bison probably won't return to the American West. Plausibly the elimination of wild bison reduced greenhouse-gas emissions.
Climate change has an unclear net impact on wild-animal suffering and far-future suffering, but since cattle grazing is a leading contributor to climate change, exploring this topic further would be valuable.
Cattle grazing vs. feedlots
Cattle raised in the US spend the majority of their lives grazing (or drinking mother's milk). The final 4-6 months are spent on feedlots where cattle eat cultivated grain, as well as hay and other materials.
This document says of US beef production:
virtually all beef production systems continue to use significant quantities of forages or other roughages as the primary feed source. [...]
While practices vary widely across specific beef production systems, most cattle are typically born and raised on range or pasture land for the majority of their lives. Cattle in the United States, whether finished with grain or forages, spend at least half of their lives on pasture of some sort [...].
This anti-meat report suggests that many pre-feedlot ranches are pretty small:
feedlots buy from small or mid-sized ranches that raise young cattle and then “finish” cattle to market weight. Even in 2012, nearly half (46 percent) of all beef cattle were raised on 665,000 farms and ranches with fewer than 100 head of cows.23
And a pro-beef fact sheet concurs: "When it comes to beef cattle production, most operations are smaller than you might think; according to USDA, the majority of beef cattle operations (79%) have less than 50 head of cattle."
Crop cultivation to feed cattle
US beef cows spend 6-12 months on the farm/ranch where they're born, may further graze until they're 12-16 months old, and then are fed grain in a feedlot for the last 4-6 months. So in general, at least as much time is spent eating grass or forage materials as is spent eating grain. Although later-stage cows probably eat more per day due to being bigger, it seems plausible that cows eat at least as much grass/forage on average as grain. If we assume that feeding a cow M kg via grazing requires at least as many hectares as feeding it M kg of grain, then it's plausible that the impacts of grazing and crop cultivation for US/European cows are of comparable magnitudes. So, for example, even if corn cultivation increases suffering by an amount A on a given hectare, if grazing reduces invertebrate suffering by, say, 1.5 * A on a given hectare, then -- given roughly equal hectares used for corn vs. grazing -- the result would be net good.
This paper reports (p. 230, Table 1) that pasturing one hectare can produce 152 kg of beef per year, while wheat can produce 2600 kg. Given that cows have feed-conversion ratios (FCRs) of 5 to 20, it seems that using land to grow grains to feed cattle would require not much more land than grazing and probably somewhat less, since even using an FCR of 20, 2600 kg of grain could produce 2600/20 = 130 kg of meat, which is close to the 152 kg number for grazing.
This paper suggests that permanent pasture in the EU27 yields 1.6 ton dry matter per hectare per year, while growing beef-cattle feed yields 6.3 tons/hectare-year (p. 24, Table 8). The marginal beef cow is estimated to eat 55% crop-grown feed ("cereal grains, hay, silage, etc") and 45% pasture grass (p. 23, Table 7). Therefore, a beef cow requires 45/1.6 hectares of pasture for every 55/6.3 hectares of cropland, which is a ratio of ~3/1 for area of pasture vs. cropland required.a
If cropland produces more biomass per hectare, does this mean it may produce more invertebrate suffering per hectare? If insecticides are used and much of the grown biomass is fed to cattle, then probably not, but the higher biomass on cropland is at least worrisome. Here's a sample calculation. Suppose cattle require 3 times as much pasture land as cultivated land on average. Let invertebrate suffering on ungrazed pasture be S per hectare. Suppose that, due to higher yields, invertebrate suffering on grain crops is 2 * S per hectare. Then, in order for grazing to be net beneficial, pasture grazing would have to reduce suffering on pasture fields by at least 1/3 per hectare, because (1 - 1/3) * S * 3/4 + 2 * S * 1/4 = S, i.e., the weighted-average suffering on pasture and cropland comes the same as if the land had been left undisturbed. Reducing invertebrate suffering by at least 1/3 on grazed pasture land seems possible, but it's not obviously true.
This page suggests that the ratio of grazed to grain-growing land for cattle is more than 3/1: "More than 302 million hectares of land are devoted to producing feed for the U.S. livestock population -- about 272 million hectares in pasture and about 30 million hectares for cultivated feed grains." Of course, some of those grazed hectares are probably only lightly grazed(?), so the impact on invertebrate populations may sometimes be small per hectare.
Pimentel et al. (1997) say (p. 100): "Producing 1 kg of beef requires approximately 100 kg of hay-forage and 4 kg of grain (Pimentel et al. 1980)." Fairlie (2010) claims (p. 64, footnote 5) that the Pimentel et al. (1997) figure is probably too high and that actual hay consumption per kg of beef is 40-50 kg, not 100 kg.
It seems likely that fully grass-fed beef is net good for wild animals, since it doesn't involve much grain feeding, which has uncertain sign. That grass-fed beef seems best is a happy confluence between wild-animal welfare and (at least sometimes) farm-animal welfare, consumer health, and (maybe) environmentalism (depending on methane production and other factors for grass-fed vs. grain-fed cows).
Note that grass-fed cattle take longer to mature: "Because they don’t receive the same amount of calories every day as their grain-fed counterparts, they are often closer to three years old before they reach their finished weight." Thus, if grazing is net good for wild animals, the fact that grass-fed cattle graze longer per kg of beef produced is an added bonus.
Unfortunately, there may be some instances in which even pasture grazing increases total invertebrate suffering, such as when cattle graze irrigated pastures. Irrigation in dry regions creates lots of stored plant energy that wouldn't have existed otherwise because without irrigation, plants would grow more slowly. As with crop irrigation, I think pasture irrigation is fairly common in the Western USA, suggesting that beef from the Western USA may be worse from a wild-animal-suffering standpoint than beef from other parts of the USA.
Dairy vs. beef cattle
My impression is that in general, dairy cattle often eat somewhat more grain than beef cattle do. If you're less certain about the net impact of crop cultivation than about the net impact of grass feed, then you may be somewhat more uncertain about the net impact of dairy compared with the net impact of beef.
This page says: "In the United States, most grass-fed cattle are raised for beef production. Dairy cattle may be supplemented with grain to increase the efficiency of production and reduce the area needed to support the energy requirements of the herd."
Mekonnen and Hoekstra (2010, Vol. 2) include the following table (p. 11), where I've drawn boxes around the numbers that are most relevant to consumers in wealthy Western countries:
These numbers confirm the general trend that beef cattle eat a smaller fraction of concentratesb (and hence a larger fraction of roughage) than dairy cattle, though even dairy cattle on average consume more roughage than concentrates, except in some industrial production systems.
Frontier Economics (2008), p. 9:
dairying in Australia is not like the Northern Hemisphere because it is grazing-based all year round [...]. Grain feeding also takes place but in varying proportions[...].
The claim seems to be validated by the fact that Oceania has a lower fraction of concentrate feed for dairy cattle than the USA and Europe do in the Mekonnen and Hoekstra (2010, Vol. 2) table.
One additional consideration that's relevant to the choice between grass-fed vs. confined cattle operations is what happens to cattle poop. On pastures, cowpats tend to be heavily infested by invertebrate animals. What about waste produced by feedlot cattle? I don't know much about this topic, but I can imagine that such poop might create fewer total invertebrates, especially if it's composted at high temperatures or decomposed anaerobically. Are there cases in which the waste generated by cattle concentrated animal feeding operations actually gives rise to more invertebrates than if it were decomposed on pasture?
- This same ratio can be calculated based on the numbers in the paper's Table 3 on p. 10: 11.3/3.5. (back)
- Mekonnen and Hoekstra (2010, Vol. 1) explain (p. 14) that concentrates "include cereals, roots and tubers, oil crops, oil meals, bran, molasses, pulses, sugar crops, fruits and vegetables." (back)