Welfare of lactating Holstein cows under outdoor grazing and indoor housing in relation to temperature and humidity in summer in Japan.

摘要

Aim: The aim of this study was to investigate the differences in the physiological responses of lactating Holstein cows between outdoor grazing and indoor housing in summer in Japan. Method: The cows (n=16) were grazed outside from indoor housing and returned indoors 3 weeks later, with a 1-week transition phase to mitigate each environmental change. Grazing cows remained in pasture except for milking twice per day and concentrate feeding before milking. Indoors, the cows were tethered except for milking twice per day and about 5.5 h of exercise in an open-air paddock. Results: When the Temperature-Humidity Index (THI) threshold was above 72, urinary cortisol levels were higher only in the grazing phase. The indoor cows took a longer time to prepare to lie down compared with grazing cows. Conclusions: This study suggests that forcing cows outside during hot weather can induce certain physiological stress responses in lactating Holstein cows. Cows exhibit more fluid lying-down movements on pasture, suggesting that the comfort of lying conditions of indoor housing was not ideal.