NEWS
Perspective on environmental
issues and livestock production
Michiel Scholtz
Current Address: Agricultural Research Council
E-mail Address: [email protected]
Reprinted From: http://bit.ly/2tM7mwg
P
rof Michiel Scholtz, specialist re-
searcher in applied animal genetics
at the Agricultural Research Coun-
cil, shares a South African perspective
on livestock production and how it re-
lates to greenhouse gases and water
usage.
“Quoting percentages does not always
make sense. In industrialised countries
the Greenhouse Gas (GHG) emissions
for agriculture are less than 6%, simply
because the contribution of their en-
ergy sectors, mines, etc. to GHG emis-
sions is very large. In non-industrialised
countries the relative contribution by
agriculture can be 40% to 50%, but the
actual contribution can be considerably
less than the 6% of the industrialised
countries.
When considering mitigation options, it
is obvious that a 10% reduction in GHG
emissions by the energy and mining
sectors would be far more effective than
a 10% reduction in the 5% to 10% contri-
bution of agriculture. So, the proposed
“meat free once a week” argument will
not do much to rectify the problem, as
other sources of protein for human con-
sumption are required, and they may
have an even higher carbon footprint.
Livestock has been accused of using
large quantities of water to produce
beef and milk. Some of the assumptions
used to calculate the water footprint, or
the amount of water required to pro-
duce livestock products, are question-
able. In studies with more realistic and
justifiable assumptions, the water re-
quirement for red meat production and
for the production of total milk solids in
whole milk and in skim milk powder, is
much lower.
It must be realised that ruminant live-
stock are important to mankind since
most of the world’s vegetation bio-
mass is rich in fibre. Only ruminants
can convert this high fibre vegetation
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into high quality protein sources (i.e.
meat and milk) for human consumption.
This needs to be balanced against the
concomitant production of methane.
Despite this important role ruminants
play, they are specifically targeted and
singled out as producers of large quan-
tities of GHG that contribute to climate
change.
Livestock production and greenhouse
gases
Livestock agriculture is the world’s larg-
est user of land resources and Sub-Sa-
haran Africa is no different to the rest
of the world. In South Africa, approxi-
mately 84% of the surface area is avail-
able for farming, but only 13% of this
area is arable. The greater part of South
Africa (71%) is only suitable for exten-
sive livestock farming. In Africa, subsist-
ence farmers farm livestock for multiple
purposes. Rural households depend on
livestock for milk, meat, hides, horns,
fertiliser and income, making it central
to the livelihoods and wellbeing of rural
communities.
Although primary beef cattle farming
(cow-calf production cycle) is largely ex-
tensive in South Africa, more than 75%
of cattle slaughtered in the formal sec-
tor are finished in feedlots on maize and
maize by-products. The cow-calf por-
tion of the production cycle (the exten-
sive part in South Africa) accounts for
72% of the nutrient requirements from
conception to harvest. Under natural
rangeland conditions, decomposition
of manure is aerobic, leading to the
production of carbon dioxide (CO 2 ))
and water (H 2 O) as end products. Part
of the CO 2 released from the aerobic
digestion of manure is absorbed during
the regrowth of the surrounding veg-
etation, rather than released into the
atmosphere. The carbon sequestration
measurement of this has been neglect-
ed and therefore the quantitative effect
is not known.
March 2019
This is in sharp contrast to intensive
systems in large parts of Europe and
North America, where great quantities
of manure are stockpiled, often for long
periods. These manure piles undergo
anaerobic decomposition. Anaerobic
decomposition of manure, as found
in intensive cow-calf systems, feedlots
and intensive dairy systems, produces
methane (CH 4 ) as one of the major end
products.
It is also relevant to consider calf finish-
ing systems, or the post weaning phase.
Cattle in South Africa are fattened in
feedlots for approximately 110 days,
which means that they produce GHG for
only 110 days before being slaughtered.
Cattle on rangeland/pasture need more
than 200 days to finish to the same car-
cass classification, because of the lower
quality feed [they take in] compared to a
feedlot diet. Furthermore, there is sub-
stantial evidence indicating that organic
production systems consume more en-
ergy and have a bigger carbon footprint
than conventional production systems.
For example, grass-fed cattle require
roughly three times more energy per
kilogram of weight gain and release
more than double the quantity of GHG
per kilogram of weight gain than con-
ventional feedlot cattle. Most consum-
ers purchasing organic products do
not know that such systems may have
a higher carbon footprint [than that of
conventional systems].
The effect of methane from livestock on
global warming is totally overplayed by
groups with their own agendas. They
frequently quote values and figures that
are based on questionable assumptions
or they are just wrong.
The most important greenhouse gases
are:
• Carbon dioxide – 49%
• Methane – 18%
• Nitrate gases – 6%
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