Cow cooling on commercial drylot dairies: a description of 10 farms in California.

California summers are hot, compromising the welfare and productivity of dairy cows. To minimize negative effects, producers use shade, fans and sprayed water. However, little is known about how those heat abatement strategies are provided in commercial conditions, nor their effectiveness. Ten dairies with drylots, a common housing system in California, were assessed for strategies provided, and the cows' responses to heat load were observed for 3 days in the afternoon. Dairies were diverse in all aspects. Shade varied in terms of placement (at corral and feed bunk or at corral only) and amount (28 to 74 square feet, or 2.6 to 6.9 square meters, per cow). The quantity of water used to spray cows ranged from 0 to 6.8 gallons (0 to 25.6 liters) per hour per cow. Across dairies, there was a range in the cows' shade use (47% to 98% of herd) and feeding activity (7% to 33% of herd). Respiration rates ranged from 65 (normal) to 95 breaths per minute (very hot) and were positively related to inactivity. Our results indicate that there are opportunities to improve cooling, and consequently dairy cattle welfare, in drylots.