mportance of Cooling Holstein Cows During the Dry Period in Summer Months

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 [3]. 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 [4]. Therefore, cooling since the dry period of the cow must be identified as part of the total cooling period of a lactating cow.