Effect of complementation of cattle cooling systems with feedline soakers on lactating dairy cows in a desert environment

Two experiments were conducted on a commercial dairy farm in eastern Saudi Arabia to investigate the effects of Korral Kool (KK; Korral Kool Inc., Mesa, AZ) cattle cooling systems complemented with feedline soakers on core body temperature (CBT) of dairy cows. In both experiments, cows had access to KK 24h/d. In the first experiment, 7 primiparous and 6 multiparous lactating Holstein dairy cows were assigned to 1 of 2 pens, which were assigned randomly to treatment sequence over 4 d in a switchback design. Soakers were on (ON24) or off (OFF24) for 24h/d. For the second experiment, 20 multiparous lactating Holstein cows were assigned randomly to 1 of 2 pens, which were assigned randomly to treatment sequence in a switchback design. This experiment lasted 4 d and feedline soakers alternately remained off or were on (ON12) for 12h/d. In experiment 1, average ambient temperature was 30±0.9°C and average relative humidity was 44±14% (mean ± SD). Feedline soakers complementing KK systems for 24 h/d decreased the mean CBT of lactating dairy cows compared with KK systems alone (38.80 vs. 38.98±0.061°C, respectively). A significant treatment by time interaction was found. The greatest treatment effects occurred at 2100h; treatment means at this time were 39.26 and 38.85±0.085°C for OFF24 and ON24 treatments, respectively. In experiment 2, average ambient temperature was 35±1.5°C and average relative humidity was 33±16%. Feedline soakers running for 12 h/d significantly decreased the mean 24-h CBT from 39.16 to 38.99±0.084°C. Treatment by time interaction was also significant; the greatest treatment effects occurred at 1500h, when ON12 reduced CBT from 39.38 to 38.81±0.088°C. These results demonstrate that complementing the KK system with feedline soakers decreased the CBT of dairy cows housed in desert environments. However, the combined systems were not sufficient to lower CBT to normal temperatures in this extreme environment.