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Effect of water treatment on drinking preferences of dairy heifers
As ground water is hard with high mineral content in eastern South Dakota there is concern about its effects on dairy cattle drinking behavior, which may consequentially affect health and performance. Our objective was to determine drinking preference of dairy heifers offered water treated with a reverse osmosis system (RO) or by a municipal water treatment plant (MW), compared to local untreated well water (WW). Six Holstein heifers (100 ± 6.5 d of age; 137 ± 5.9 kg BW) were used in a sequential elimination study. Heifers were kept in individual pens (1.5 × 3 m) and fed similar rations of pellets and grass hay. Three containers (14 L) of water were provided for each heifer and refreshed 3× per day. An extra container on each side was left empty to avoid preferential behavior by location. Throughout the 8 d experiment period individual water intakes by heifer and water type were measured. During the adaptation phase of the study heifers were given MW for 3 d to establish baseline intake. During phase 1, all 3 water types were offered for 3 d and the most preferred water of each heifer was removed at the end. During phase 2, the remaining 2 water types were offered for 2 d. Water preference ranking by heifer was determined based on intake amounts. Kendall’s coefficient of concordance (W) was calculated to evaluate agreement of preference among heifers. Total average water intake was 16.0 ± 2.14, 15.8 ± 1.95, and 14.9 ± 2.21 kg/d for the adaptation, phase 1, and phase 2, respectively. During phase 1 average intake was 7.10 ± 3.97, 5.10 ± 3.59, and 3.55 ± 4.89 kg/d for RO, MW, and WW, respectively. Three heifers preferred the RO first and MW second. Two heifers preferred MW first and RO second. One heifer chose WW first and was a potential outlier in the group for taste preference. Average preference rankings were 1.67, 1.83, and 2.50 for RO, MW, and WW with lesser numbers indicating greater preference. Overall, W = 0.19 for agreement of preference among heifers with P = 0.31. When the outlying heifer was removed W = 0.53 with P = 0.07. Results showed RO was slightly preferred over MW and both were preferred over WW with more consumption when all three water types were offered.
Keywords: water treatment, palatability, dairy heifer