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increases to generate heat associated with digestion and metabolism (the heat incre-
ment of eating) and, at high temperatures, feed intake declines to avoid adding to the
body’s heat load. Managers of grazing livestock cannot influence climatic conditions
but they can modify the microclimate in which animals graze through the provision
of shade and shelter, and the benefits to production can be significant. For example,
the combination of 30 km/hour wind and an overnight temperature of 0°C can dou-
ble the maintenance requirement of a recently shorn sheep. Even a sheep with a
30 mm long fleece on a calm night that drops to 5°C will have a maintenance
requirement about one-third higher than if it had remained in its zone of thermal
comfort. At high temperatures, animals exhibiting rapid, shallow breathing with
have an elevated maintenance requirement of about 7 % and, with open-mouthed
panting, their maintenance requirement will be elevated by about 25 % at that time.
Maintaining animals in their thermal comfort zone is analogous to meeting their
nutrient requirements. Either side of meeting requirements, there is a subclinical
cost to production and, if the deviations increase further, clinical signs will be appar-
ent. In tropical regions, milk production and profit margin are increased when shade
is available (Yamamoto et al. 2007 ; Murgueitio et al. 2011 ) and, in semi-arid regions,
lamb survival should be improved if shelter were offered since shorn ewes are
known to actively seeking shelter at lambing time (Lynch et al. 1980 ; Mottershead
et al. 1982 ).
In addition, native plants, shrubs and trees benefit natural resource management
by reducing the environmental risks of land degradation, ecosystem degradation
and carbon emissions that are often a consequence of inappropriate systems and
management of grazing livestock. Shrubs can i) protect the companion pasture
species from excessive exposure to solar radiation as a secondary mitigation of risk
of feed availability and ii) improve soil fertility (Power et al. 2003 ). The extensive
root system of shrubs coupled with their perenniality give them the ability to reduce
the risk of dryland salinity by stabilizing the level of the water table and decreasing
the risk of desertification, land erosion and salinization of the land (Bienes et al.
2016 ). Shrubs, especially legume shrubs, also reduce the risk of damage to the eco-
system caused by grazing livestock and can even help the restoration of degraded
ecosystems (Emms et al. 2005 ; Smith et al. 2013 ). By protecting the topsoil from
erosion and compaction (Bienes et al. 2016 ), as seen in simpler annual pasture sys-
tems, shrubs increase the diversity of arthropods, reptiles and birds (Collard and
Fisher 2010 ; Brown et al. 2011 ; Liu et al. 2016 ). In addition, forage shrub species
host beneficial predatory insects offering potential advantages for integrated pest
management in nearby crops and pastures (Taverner et al. 2006 ).
Shrubs and trees can also improve atmospheric carbon sequestration
(Schoeneberger 2009 ) and mitigate greenhouse gas emissions (Monjardino et al.
2010 ). For example, E. glabra (R. Br.) Ostenf. can decrease the population of meth-
anogens in the rumen and thus reduce methane emissions from grazing livestock (Li
et al. 2014 ). Incorporating shrubs with antimethanogenic effects, such as E. glabra
(R. Br.) Ostenf., into the pastoral landscape, could have the dual benefits of improv-
ing production efficiency and reducing methane emissions, reducing the risk of pro-
duction of livestock in dryland regions.
D. Blache et al.