Is the Grass Always Greener? Comparing the Environmental Impact of Conventional, Natural and Grass-Fed Beef Production Systems

SIMPLE SUMMARY: The environmental impact of three beef production systems was assessed using a deterministic model. Conventional beef production (finished in feedlots with growth-enhancing technology) required the fewest animals, and least land, water and fossil fuels to produce a set quantity of beef. The carbon footprint of conventional beef production was lower than that of either natural (feedlot finished with no growth-enhancing technology) or grass-fed (forage-fed, no growth-enhancing technology) systems. All beef production systems are potentially sustainable; yet the environmental impacts of differing systems should be communicated to consumers to allow a scientific basis for dietary choices. ABSTRACT: This study compared the environmental impact of conventional, natural and grass-fed beef production systems. A deterministic model based on the metabolism and nutrient requirements of the beef population was used to quantify resource inputs and waste outputs per 1.0 × 10(9) kg of hot carcass weight beef in conventional (CON), natural (NAT) and grass-fed (GFD) production systems. Production systems were modeled using characteristic management practices, population dynamics and production data from U.S. beef production systems. Increased productivity (slaughter weight and growth rate) in the CON system reduced the cattle population size required to produce 1.0 × 10(9) kg of beef compared to the NAT or GFD system. The CON system required 56.3% of the animals, 24.8% of the water, 55.3% of the land and 71.4% of the fossil fuel energy required to produce 1.0 × 10(9) kg of beef compared to the GFD system. The carbon footprint per 1.0 × 10(9) kg of beef was lowest in the CON system (15,989 × 10(3) t), intermediate in the NAT system (18,772 × 10(3) t) and highest in the GFD system (26,785 × 10(3) t). The challenge to the U.S beef industry is to communicate differences in system environmental impacts to facilitate informed dietary choice.