Finally, βAA are also a feed additive, but are restricted
to the final 20-40 days of finishing. β-adrenergic
agonists increase lean muscle mass while decreasing fat
deposition, which means for every pound of body weight
an animal gains when fed βAA, a higher proportion of
the body weight gain will be protein than a similar animal
not fed βAA
1. Each GP works individually to improve feed
efficiency but combining the three GPs can dramatically
improve production efficiency, especially during the
finishing phase, and can decrease GHG emissions per
pound of body weight gain by 28% when compared to
beef production systems not using GPs.
2
While ionophores can directly reduce methane emissions
produced by individual beef cattle, in general, GPs reduce
both GHG emissions produced and natural resources
required per unit of beef (Figure 1) by decreasing
the length of time required for an individual animal to
reach harvest and the number of animals required to
produce a given amount of beef.2,3 For example, research
has shown that in beef production systems using GP
technologies, each animal will produce enough beef to
feed approximately 1.66 more U.S. citizens as compared
to animals in beef production systems that do not use
those technologies (Figure 2).4 Research utilizing both
live animals1,2,4 and computer models3,5 has consistently
shown a decrease in the environmental impact of beef
production with the use of GP technologies. Some
consumers prefer to purchase beef not produced in systems that use GP technologies (i.e., “natural” beef),
which is a recognized food choice; however, there are
negative environmental sustainability consequences for
not using GP technologies in U.S. beef production.