title: Thermoregulatory responses of Holstein and Brown Swiss heat-stressed dairy cows to two different cooling systems.
abstract: Thirty-seven Holstein and 26 Brown Swiss dairy cows were used to evaluate the effect of two different cooling systems on physiological and hormonal responses during the summer. A control group of cows had access only to shade (C). A second group was cooled with spray and fans (S/F) and the third group was under an evaporative cooling system called Korral Kool (KK). The maximum temperature humidity index during the trial was from 73 to 85. Rectal temperatures and respiration rates of the C group were higher (P<0.05) than those of the S/F and KK groups in both Holstein and Brown Swiss cows. Triiodothyronine levels in milk were higher (P<0.05) in the KK group than in the S/F and C groups, while cortisol levels were lower (P<0.05) in the C group than in S/F and KK. There was no significant difference in the hormonal response of the two breeds. These results demonstrate that both cooling systems may be used increase the comfort of Holstein and Brown Swiss cows during summer in hot, dry climates.
authors: Department of Animal Sciences, University of Arizona, Tucson, Arizona, USA. acorrea@uabc.mx
authors: Abelardo
authors: A
authors: Correa-Calderon
authors: Dennis
authors: D
authors: Armstrong
authors: Donald
authors: D
authors: Ray
authors: Sue
authors: S
authors: DeNise
authors: Mark
authors: M
authors: Enns
authors: Christine
authors: C
authors: Howison
mesh_terms: D000222:Adaptation, Physiological; D000822:Animal Husbandry; D000818:Animals; D001833:Body Temperature Regulation; D002417:Cattle / Q000502:physiology*; D005260:Female; D018882:Heat Stress Disorders / Q000517:prevention & control / Q000662:veterinary*; D006854:Hydrocortisone / Q000032:analysis; D008892:Milk / Q000737:chemistry; D012621:Seasons; D013472:Sunlight; D013696:Temperature; D014284:Triiodothyronine / Q000032:analysis
chemical_list: D014284:Triiodothyronine; D006854:Hydrocortisone