Comparison of cooling methods for gestating sows in different climate conditions

The Staldvent software was used to investigate the potential to avoid undesired high Effective Temperatures in a gestating sow unit. Used data for outdoor climate originated from Denmark, Slovakia, Iowa, China, Mexico, and The Philippines. Seven configurations of combinations of maximum ventilation rate (150 or 300 m³ h^-1 sow^-1) and cooling method were investigated at each location. An Effective Temperature of 25 ⁰C was used as threshold for when pregnant sows were expected to begin to experience undesired high heat load. Furthermore, it was anticipated that an increase in the air velocity from 0.2 to 2.4 ms^-1 could correspond to an air temperature increase from 25 to 31 ⁰C. The calculation showed that both included maximum ventilation rates in combination with evaporative cooling (high pressure cooling or pad cooling) was largely sufficient to avoid Effective Temperatures above 25 ⁰C in Denmark even at the low air velocity (0.2 ms^-1). The equivalent could be achieved in Slovakia and Iowa if the air velocity was increased to 2.4 ms^-1. Even the combination og high ventilation rate, evaporative cooling and the high air velocity was insufficient to avoid Effective Temperatures of above 25 ⁰C in warmest 5, 4 og 11 % of the yearly hours in China, Mexico, and The Philippines, respectively. Air conditioning was assumed dimensioned, so it could ensure Effective Temperatures below 25 ⁰C at all conditions, but at the low air velocity, it caused a very high electricity consumption when it was used in the warmest locations.