Comparison of Urinary Cortisol Levels in Holstein and Japanese Shorthorn Cows in Response to Breeding System and Heat Stress

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This study was performed to compare the stress hormone levels of Holstein and Japanese Shorthorn cows in response to the breeding system and heat stress. A total of 50 Holstein and 17 Japanese Shorthorn cows were used. The breeding system and heat stress were classified into grazing and indoor housing groups, and into the Temperature-Humidity Index (THI) ≥72 and THI <72, respectively. For Holstein cows, the urinary cortisol levels were higher in the grazing group than in the indoor housing group. In contrast, for Japanese Shorthorn cows, the urinary cortisol levels were higher in the indoor housing group than in the grazing group. In the grazing group, the urinary cortisol levels were higher in Holstein cows than in Japanese Shorthorn cows. In the grazing group of Holstein cows, the urinary cortisol levels were higher in the THI ≥72 group than in the THI <72 group. On the other hand, in Japanese Shorthorn cows, the urinary cortisol levels did not differ between the 2 THI groups, regardless of the breeding system. This study suggested that Holstein and Japanese Shorthorn show differing stress responses to breeding system and (or) heat stress.