Agriculture Reference
In-Depth Information
loss of energy to the animal. In slaughter pigs, the
enteric methane production corresponds to 0.2-
0.5% of the gross energy intake approximating to
3.4 l methane per day, but the loss will be higher
in pigs fed more fibrous feed (Jørgensen et al .,
2011). The enteric production of methane in
monogastric animals is very low compared with
the losses in dairy cows covered in Chapter 2,
this volume. However, the methane emission in
the barn and during storage of pig manure may
contribute markedly to the total emissions from
the agricultural sector (Mikkelsen et al ., 2005).
The calculated contributions from the pigs were
10% from enteric methane production and 70%
from manure storage amounting to 26% of the
total methane emission from the Danish livestock
production (Mikkelsen et al ., 2005). Recently,
experiments have shown that the emission of
GHG could be lowered by acidification of the feed
before feeding (Eriksen et al ., 2010) or by acidifi-
cation of the manure (Petersen, 2012, unpub-
lished results).
Nutrient flow
Ex animal
Ex housing
Ex storage
Fig. 3.11. The energy and nutrient flow on a farm
(Poulsen et al ., 2006).
Summarizing Considerations
and on the other using data from the 25% of
Danish pig herds with the highest technical effi-
ciency in terms of number of piglets per sow
and feed use per kg pork produced (Nguyen
et al ., 2011). The latter group of herds is
expected to be representative for the typical
Danish pig production in a few years. The LCA
showed that by far the major part of the envi-
ronmental impact occurs at the farming stage.
This stage is responsible for more than 95% of
the total impacts except for use of non-renewable
energy, where the slaughtering stage and related
transport accounts for 12-13%. The low impact
related to the slaughtering stage is due to an
efficient use of residues and by-products for
energy production and feed (Nguyen et al .,
2011). Interestingly, the 25% of herds with the
highest technical efficiency produce pork with
a 10% lower environmental impact, indicating
that this will be the case in a few years (Nguyen
et al ., 2011).
The nutrient flowchart (Fig. 3.11) illustrates
that feeding affects all of the following steps
from the feed to the final step where manure is
amended to the soil. Consequently, the applied
practical feeding condition and management
enormously affect the production efficiency and
utilization of energy and nutrients in the pri-
mary livestock production but also quantita-
tively on the losses of ammonia and GHG during
housing and storage of manure.
Therefore, the feeding measures and the
use of efficient pig and poultry breeds have huge
impacts not only on the overall nutrient and
energy efficiency but also on the quality of the
manure used as fertilizer amendments to the
soils used to produce cereal or protein crops.
Table 3.5 summarizes the main factors (dietary
means, feeding strategies, breeding and man-
agement) that affect the production efficiency
and nutrient excretion and utilization.
Life cycle assessment (LCA) is often used to
summarize the overall efficiency of productivity.
Recently, such an approach was used to evaluate
the environmental impact of the Danish pig
production. The environmental assessment was
performed using data representing the typical
Danish pig production in 2010 on the one hand,
In many ways, monogastric animals compete
with humans for feed as they are primarily fed
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