Agriculture Reference
In-Depth Information
70
60
50
40
30
59%
20
37%
35%
24%
23%
21%
10
10%
0
Animals*
Feed*
Water*
Land*
Manure*
GHG*
Total
industry
GHG
2007
*per unit of milk
Fig. 11.2.
Comparative resource use and greenhouse gas (GHG) emissions for US dairy production in
1944 and 2007.
associated with maintenance from 53% to 45%
and the total days from birth to slaughter from
609 to 485 (Fig. 11.3), thus reducing the life-
time maintenance requirement. The combina-
tion of improved beef yield and growth rate
conferred decreases in feed use, water use and
land use per unit of beef of 19%, 12% and 33%,
respectively. Manure output per unit of beef was
reduced by 18%, with a 16% decrease in the car-
bon footprint per unit of beef (Capper, 2011a).
Anecdotal evidence from the beef processing
industry suggests that average slaughter weights
have plateaued and that further increases in
slaughter weight are undesirable given the cur-
rent processing infrastructure and consumer
portion size demands. Therefore improvements
in growth rate may offer a greater opportunity
for future beef industry sustainability than
further yield increases.
2007 was 24% of that in 1944 and the total car-
bon footprint per unit of milk was reduced by
63%. Despite the increase in total milk produc-
tion between 1944 and 2007, the total carbon
footprint for the entire dairy industry was
reduced by 41%.
Similar yield trends have been exhibited by
the US beef industry, which, as a result of
improved genetic selection, ration formulation
and growth-enhancing technology use, has
increased slaughter weight and thus beef yield
per animal over time. Between 1977 and 2007,
average beef-carcass yield per animal increased
from 274 to 351 kg (USDA, 1978; USDA/NASS,
2008). This allowed beef production in 2007 to
be maintained from a population containing
30% fewer animals (cows, calves, heifers, bulls,
stocker and feedlot animals) than the equivalent
population in 1977 (Capper, 2011a). As per the
previous dairy example, this diluted the popula-
tion maintenance requirement over greater
units of production. As maintenance require-
ments are primarily dictated by bodyweight, the
increased slaughter weights in 2007 meant that
the average daily maintenance requirement per
animal was increased; yet this was overcome by
improvements in growth rate, which reduced
the proportion of daily energy requirements
The Role of a Reduced Maintenance
Requirement in Improving
Environmental Sustainability
Improved productivity has a demonstrable impact
on beef 's environmental sustainability; however,
