Sprinkler flow rate affects dairy cattle physiological and behavioral responses

Thursday, July 24, 2014: 8:30 AM
3501B (Kansas City Convention Center)
Jennifer M Chen , University of California, Davis, CA
Karin E Schütz , AgResearch, Hamilton, New Zealand
Cassandra B Tucker , University of California, Davis, CA
Abstract Text:

The accumulation of heat load can be problematic for dairy cow welfare and productivity. Sprinklers effectively reduce heat load, but little is known about the optimal amount of water needed for cooling, or about cattle behavioral responses to this resource. Two studies assessed how flow rate affected 1) the effectiveness of sprinklers and 2) cattle preferences. In Exp 1, 19 lactating cows were restrained at the feed bunk for 1 h/d and received 1 of 4 treatments in a crossover design: Control (0 L/min; 3x total) or sprinkler (0.4, 1.3, and ≥ 4.5 L/min, 6x each). Spray was delivered in 4 cycles (3-min on, 12-min off). Cooling effectiveness was evaluated using body temperature (BT) and respiratory rate (RR), by taking the differences between measurements recorded before the first spray cycle (-2 min) and after the final cycle (49 min). In Exp 2, 18 lactating cows were tested in a shaded Y-maze, with 3 pairwise comparisons between either the Control (0 L/min) and/or 0.4 or 4.5 L/min sprinklers. For each pairing, cows chose once daily (12 min/d) for 8 consecutive d. In Exp 1, BT and RR differed among all 4 treatments: as flow rate increased, so did cooling effectiveness (P < 0.01, GLMM). However, for BT there was an interaction with weather [volume*air temperature (AirT), P < 0.004]. At AirT < 28°C, both sprinklers ≥ 1.3 L/min kept BT from rising (P ≤ 0.003), whereas at AirT ≥ 32°C, only the ≥ 4.5 L/min sprinkler did (P ≤ 0.001). In Exp 2, cows tended to choose 0.4 L/min over Control 69% of the time (SE: 9.3%, P = 0.096, Wilcoxon signed-rank test), and showed no preferences in the other comparisons (4.5 L/min: 58% vs. Control, SE: 9.4%; 42% vs. 0.4 L/min, SE: 9.6%; P ≥ 0.552). However, preferences for 4.5 L/min over Control tended to depend on weather (P = 0.065, GLMM): at AirT ≤ 24.9°C, the probability of choosing 4.5 L/min was 0.40, whereas at AirT ≥ 30.0°C, this increased to 0.74. In conclusion, sprinkler flow rate influenced both cooling effectiveness and cattle preferences. In warmer weather, sprinklers ≥ 4.5 L/min were most effective, and were preferred over shade alone. However, more work is needed to fully understand how cattle choose to use cooling resources throughout the day.

Keywords: heat load, preference, sprinklers