The Global Roundtable for Sustainable Beef has identified five global principles for defining sustainable beef and sustainable beef production practices – natural resources, people and the community, animal health and welfare, food and efficiency and innovation. Under each principle is a list of criteria that relate to a specific element of sustainability, and clearly to one of the principles. Efficient use of resources is an issue under natural resources and efficiency and innovation.
Sustainable beef sourcing will occur in a world of increasing demand for animal protein from a growing middle class in middle-income developing countries and a growing consumer interest in sustainable beef. For example, a few months ago Chinese government officials announced they expect to import one million metric tons (MMT) of beef per year, up from virtually nothing a few years ago.
The beef animal is unique in that it has a four stomach digestive system that allows it to consume large volumes of grasses, legumes and other fodders that cannot be used by humans and produce animal protein that can be consumed by humans. That same digestive system can also consume corn in a high energy diet. With an abundance of pasture and corn under normal conditions, it was natural for the U.S. to develop a production system that grows calves to 600-800 mostly on grass and then finishes those animals on a high energy corn diet to slaughter weight of roughly 1,300 pounds.
A common current measure of the environmental sustainability of all types of foods and production practices is the carbon footprint. This allows for comparisons to be made across production systems. Analysis by Judith L. Capper, Washington State University and Sustainability Consultant, Is the Grass Always Greener: Comparing the Environmental Impact of Conventional, Natural and Grass-Fed Beef Production Systems in the April 2012 issue of journal Animals is used in this analysis unless otherwise noted.
A deterministic model based on the metabolism and nutrient requirements of the U.S. beef population was used to quantify resource inputs and waste outputs per 1.0 MMT of hot carcass weight beef in conventional U.S. beef production (finished in feedlots with growth-enhancing technology) (CON), natural (feedlot finished with no growth-enhancing technology) (NAT) or grass-fed (forage-fed, no growth-enhancing technology) (GFD) systems. The carbon footprint of the CON beef production was lower than both the NAT and the GFD systems.
Increased productivity as measured by slaughter weights and growth rates per day in the CON system reduced the size of the national cattle herd required to produce 1.0 MMT of beef and reduced the amount of resources used per 1.0 MMT of beef produced. The carbon footprint per 1.0 MMT of beef was lowest in the CON system at 15.99 MMT, intermediate in the NAT system at 18.77 MMT and highest in the GFD system at 26.79 MMT. The CON system required 56 percent of the animals, 25 percent of the water, 55 percent of the land and 71 percent of the fossil fuel energy required compared in the GFD system.
Productivity is a major driver of environmental impact via the “dilution of maintenance” effect. The fewer days needed to achieve a given weight results in fewer calories used to maintain existing animal weight. Animals within the CON system had an average slaughter weight of 1,254 pounds and took a total of 444 days to grow from birth to slaughter; compared to 1,144 pounds slaughter weight per animal after 464 days in the NAT system; and 1,071pounds after 679 days in the GFD system.
Efficient land use is crucial for agricultural sustainability. The CON system, which required 13.5 million acres (MA) of land per 1.0 MMT of beef, appears to be more sustainable than either the NAT system which required 22 percent more land (16.5 MA) or the GFD system at 81 percent more land (24.4 MA) to produce the same quantity of beef. Beef production systems that utilize range and pastureland (which are generally unsuitable for human food crop production) gain a sustainability advantage over monogastric animals that only rely upon human-edible grains and legumes.
Increased growth rate and slaughter weight in the CON system reduce water consumption to 128.3 million gallons (MG) per 1.0 MMT of beef compared to an 18 percent increase in the NAT system (151.2 MG) or a 302 percent increase in the GFD system (517.1 MG). This assumes that 50 percent of the grassland used to finish cattle is irrigated. That is an assumption since that data is not now collected. But even if only 10 percent of the finishing grasslands are irrigated, the GFD system would still use more water.
Nutrient (N and P) excretion is primarily affected by animal productivity, with minor effects of nutrient supply vs. requirements. The quantities of N and P excreted from the animals per 1.0 MMT of beef produced were reduced in the CON system to 0.40 MMT of N and 0.037 MMT of P compared to the NAT system at 0.49 MMT of and 0.047 MMT of P and the GFD system at 0.81MMT of N and 0.077 MMT of P. Excretions of N and P do not provide a direct measure of nutrient run-off or ammonia emissions, but are simply a comparative measure for the potential for run-off or gaseous emissions to occur.
The pastureland used to finish cattle in the GFD system would need to sequester 2.0 MT CO2 per acre/year, equivalent to 0.55 MT C per acre/year, in order to produce a finishing sub-system with a similar carbon footprint to that of the CON system. This appears to be a lofty target, given that other studies show 0.08-0.22 MT per acre year.
Feed and animal transportation are often considered to be a major factor affecting fossil fuel use in CON or NAT beef production systems, yet within the current study transport accounted for 0.87 percent of the carbon footprint from the CON system, 0.83 percent of the NAT system’s carbon emissions and 0.24 percent of total carbon emitted from the GFD system.
Capper had previously compared the CON system in 2007 production to the beef production characteristics of 1977. The modern beef production in 2007 used 19% less feed, 12% less water, 33% less land and exhibited a 16% decrease in the carbon footprint per unit of beef produced.
Capper’s summary comment on her study was, “Use of technologies that improve animal productivity in combination with intensive feedlot finishing systems demonstrably reduced both resource use and GHG emissions per unit of beef.” Measures of the overall sustainability of beef include more than just GHG emissions from beef production at the farm and ranch level, but these will be key factors in the analysis.