“…The most studied environmental variable is temperature with a few studies focusing on humidity and air velocity. Poultry response variables that have been examined include deep body temperature (Kettlewell et al, 1997;Hamrita et al, 1998;Lacey et al, 2000aLacey et al, , 2000bMitchell et al, 2001, as cited in Silva et al, 2005;Brown-Brandl et al, 2001, as cited in Wang et al, 2006;Blanchard et al, 2002;Yanagi et al, 2002aYanagi et al, , 2002bBrown-Brandl et al, 2003;Tao & Xin, 2003a, 2003bCrowther et al, 2003;Khalil et al, 2004;van den Brand & van de Belt, 2006;Hamrita & Hoffacker, 2008;Leterrier et al, 2009); brain and heart activity (Blanchard et al, 2002;Crowther et al, 2003;Aubert et al, 2004;Khalil et al, 2004;Lowe et al, 2007;von Borell et al, 2007;Coenen et al, 2009); and physical activity (Khalil et al, 2004;Quwaider et al, 2010). The majority of studies were concerned with deep body temperature responses to heat stress.…”