Agriculture Reference
In-Depth Information
antibiotics, probiotics and propionate precur-
sors like fumarate or malate, or other nutrients)
that would alter the ruminal ecosystem to
reduce methane production (Smith et al ., 2007;
Gill et al ., 2010). However, methanogensis is a
fundamental disposal sink for excess electrons
resulting from normal ruminal fermentation.
Finding alternative electron acceptors, app-
roaches or pathways to rid the ruminal ecosys-
tem of excess electrons, yet maintaining
near-normal ruminal fermentation, will prove a
very formidable task.
disease situations are not very predictable
when influenced by: changes in overall climate
in different regions, variability in climate,
demographic changes in the relationships
among animal and human populations, and
deployment of effective technologies to survey
and combat infectious diseases (Thornton et al .,
2006). Future changes are uncertain, at best.
Back to the Future
Holistic integrated mixed
plant-animal systems
Animal health
Animal agriculture in its early evolution in
now developed countries was a crucial compo-
nent of mixed plant-animal systems. Effective
management of agricultural land in mixed
plant-animal systems can be quite sustainable
and efficient if done appropriately in well-
coordinated nutrient cycles. In the past, having
animals as key components of mixed plant-
animal systems was advocated widely to main-
tain soil fertility (Shaw, 1911 and Shutt, 1913,
as cited by Janzen, 2011). Shutt (1913) wrote,
'How, then are soils to be maintained in a pro-
ductive state and at the same time yield a profit
for their working? First in the keeping of live-
stock; in the manure so obtained we have the
opportunity of restoring to the soil eight-
tenths of the plant food taken from it in crops
they consume … We do not keep sufficient live-
stock on our farms.' In developing countries
and most areas of the world where synthetic
fertilizers are very expensive and (or) not avail-
able, recycling of nutrients through animals
continues to be an indispensable practice,
especially with use of N 2 -fixing forage leg-
umes (Wilkins, 2008). In the future, as high
energy costs limit the production and use of
synthetic fertilizers even for developed coun-
tries, having animal agriculture tightly linked
with crop production in nutrient cycles can
provide a natural way of using, recycling and
re-using nutrients and organic residues
(energy) effectively and efficiently. Also,
beyond direct on-farm nutrient cycling from
livestock feed to plant nutrients, animals
(especially ruminants) have an additional
advantage of being able to extract valuable
nutrients and energy for by-product feeds
Overall, in the last several decades there has
been a general reduction in the severity and
prevalence of animal diseases, attributed
mainly to more effective vaccines and pharma-
ceuticals and advancements in diagnostic strat-
egies (Perry and Sones, 2009). Even so there
were serious outbreaks of foot-and-mouth dis-
ease in the UK (Bio-Era, 2008), and of avian
influenza H5N1. Each caused considerable
global concern with the potential risk for shift in
host from poultry to man, and emergence of a
new human influenza, which did not occur. In
developing countries over the last few decades,
fortunately, there were few changes in the dis-
tribution, prevalence or severity of many epi-
demic or endemic diseases in animal agriculture
(Perry and Sones, 2009).
In the future, occurrence and transmis-
sion of infectious diseases likely will be influ-
enced by travel, migration and trade - all part
of ongoing and accelerating globalization -
that will increase risk of introduction of infec-
tious agents into naïve animal populations.
Confined animal management in large-scale
systems and transport over greater distances
can increase risk of disease transmission
among animals (Otte et al ., 2007). Confounding
in the longer time frame, disease trends could
be modified significantly by changes in global
climate. Geographical incidences of diseases
may shift depending on the climate and suita-
ble vectors. The nature and degree of impact
of climate change likely will be different on
future disease situations with livestock com-
pared with known situations (Woolhouse,
2006). However, characteristics of future
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