Drinking water temperature preferred by Holstein calves under different temperature-humidity index conditions

No studies have been performed on calf preference for different drinking water temperatures (DWTs) under different temperature-humidity index (THI) conditions. The present study was conducted to explore the drinking water temperature (DWT: 0, 5, 10, 15, 20, 25, 30, and 35 degrees C) preferred by preweaning and postweaning Holstein calves under different THI conditions (THI: < 38, 38 to < 50, 50 to < 72, and > 72). Preweaning calves (32.8 +/- 5.7 d) were fed via a hutch and were supplied water four times daily, and postweaning calves (139.9 +/- 18.3 d) were reared in groups and were supplied water ad libitum. The duration of each experiment was 10 minutes. Spearman correlation coefficients between the logarithm of the DWT and drinking intake, number of trials, drinking frequency, drinking time, drinking pattern (drinking frequency/number of trials), drinking time/number of trials and average drinking time were estimated. The data showed that the drinking pattern was positively correlated with DWT (preweaning calves: R=0.85, P < 0.05, postweaning calves: R=0.94, P < 0.05). Preweaning calves were more likely to choose warm water (35 degrees C) (P < 0.05), and the choice of drinking water was not affected by the THI (P > 0.05); postweaning calves were more likely to choose warm water (35 degrees C) (P < 0.05), and the choice of drinking water was affected by the THI (P < 0.05). In conclusion, pre- and postweaning calves seemed to prefer warm drinking water at 35 degrees C, and the drinking pattern represents an interesting and novel measure of drinking behavior and reflects water palatability in calves.