219not be valued in isolation but on the basis of its impact to the profitability, productiv-
ity or risk management within the whole management system.
Supplementation strategies not only have the capacity to boost livestock produc-
tivity by reducing feed shortages, but also offer strategic support during periods of
high energy demand during the reproductive cycle, from puberty to ovulation and
lactation (Blache et al. 2008 ). Such strategies have great merit because relatively
short periods of supplementation (‘focus feeding’ for a few days; Martin et al. 2008 )
can have long-term benefits for productivity. However, relying on externally-
sourced supplements can add another level of risk to production systems, because of
potential uncertainties in availability or price. Therefore, growing and using plants
that are suited to the local environment as ‘standing supplements’ to other feed
resources (i.e., plants that nutritionally complement each other) is an attractive
proposition, and will be discussed below (Section 4). Moreover, because supple-
mentary feeding can be labour intensive and costly, there is an added advantage in
allowing grazing animals to source their own supplements from a mixture of plants
on offer. Finally, plant resources used as supplements can also address the sustain-
ability of livestock production in dryland systems (Masters et al. 2006 ).
3.2 Managing Water
The consumption of an adequate amount of water is essential for productivity and
welfare of livestock. Water is essential to life and, even if species from semi-arid
environments have evolved to be more water-efficient than species living in temper-
ate climates, they still need regular access to quality water. The percentage of water
in the body can vary but is kept within a narrow window in which osmolarity (salt
water balance) can be tightly regulated. The needs for water repletion depend on the
environmental conditions, the physiological status of the animals, and the metabolic
activity of the animal (Willmer et al. 2009 , Revell 2016 ). When ambient tempera-
ture increases, homeotherms limit a rise in body temperature by using thermoregu-
latory mechanisms such as sweating or panting, a mechanism that is effective when
ambient humidity is not too high. Both mechanisms are based on evaporative water
loss and are efficient at maintaining core body temperature within comfortable lim-
its (the ‘thermocomfort zone’; Willmer et al. 2009 ). Consequently, when the tem-
perature rises, animals will necessarily increase their water intake to compensate for
their losses (Silanikove 1994 ). Water needs also depend on the physiological status
of the animals. For example, genotype, live weight, sex and reproductive status
(pregnancy, lactation), as well as ambient temperature, affect the water require-
ments of cattle (Winchester and Morris 1956 ). Livestock will get water from drink-
ing water points (about 10 % of their water need), from the plants they consume
(estimated globally at 90 % of consumptive water use), but forage plants contain
variable amounts of water and salt, both of which affect their osmoregulation
(Hoekstra and Mekonnen 2012 ; Ran et al. 2016 ).
Integrated and Innovative Livestock Production in Drylands