Arid and semi-arid regions of the world are characterized by
extreme climatic conditions with very low rainfall availability.
Livestock production systems located in these zones are
threatened by very high ambient temperatures as well as feed
scarcity, especially during summer months [1,2]. This scenario
is predicted to be worsened because of Global Warming, which
involves a projection of an annual increased in global surface
temperature of about 3.7 to 4.8 °C by the year 2100 . Holstein
cows in hot environments can be at risk of heat stress, which
affect their productivity and well-being. Feed intake is negatively
affected by heat stress, leading to a reduction in milk production
and quality, as well as depressed reproductive efficiency of Holstein
cows and heifers. A common management practice is to apply
artificial cooling to cows when they are lactating, that is, during the
postpartum. However, the prepartum period is a stage that involves
several important physiological mechanisms that will definitively
impact on productive and reproductive efficiency postpartum.
So, when heat stress is present in the dry period can provoke an
endocrine imbalance, which means alterations of concentrations of
several hormones related to essential metabolic processes which
are associated to postpartum Holstein cow productivity and health
. Therefore, cooling since the dry period of the cow must be
identified as part of the total cooling period of a lactating cow.