Figure 3: Percentage of the overall national environmental burdens exerted by the individual animal categories. [Bar graph shows that over 60% of the national GHG burden is attributable to beef.]
"Beef is consistently the least resource-efficient of the five animal categories in all four considered metrics. The resource requirements of the remaining four livestock categories are mutually similar."
Eshel et al., “Land, irrigation water, greenhouse gas, and reactive nitrogen burdens of meat, eggs, and dairy production in the United States,” PNAS Early edition, June, 2014., 3, Figure 3, http://www.pnas.org/content/early/2014/07/17/1402183111.full.pdf.