A recent study by the SDSU Dairy and Food Science Department investigated the effects of water quality on heifer preference and drinking behavior. Providing good quality water to livestock is a major challenge in the Midwest. Eastern South Dakota groundwater, which is used for drinking, industry, and agricultural purposes is hard, with high mineral content. Calcium and magnesium concentration affects this hardness. Total dissolved solids (TDS) are used to assess how much total inorganic matter is dissolved in water, which is also a concern in this area. High concentration of TDS and greater hardness in drinking water used for dairy cattle may influence drinking behavior, which in turn affects health and performance. Low intake of water can lead to reduced: body weight, rumen contractions, respiratory rate, milk yield, and dry matter intake (DMI).

Reverse osmosis systems are a means of water purification that uses a semi-permeable membrane to remove excess ions, molecules, and some bacteria from water and may be an option to improve drinking water quality for dairy animals. It was hypothesized that improving water quality with reverse osmosis would lead heifers to drink that water preferentially.

Experiment

To determine water quality effects on heifer drinking preference a study was conducted at the SDSU Dairy Research and Training Facility. Water types tested were: 1) water from a reverse osmosis system (ROW) (Culligan Inc. Brookings, SD), 2) water from the municipal city water treatment plant (MCW), and 3) local untreated well water (UWW). Six Holstein heifers (98 days of age; 299 lbs of body weight were used in a sequential elimination study, meaning the most favored water was removed after each phase so that preference ranking could be established. Heifers were kept in individual pens and fed similar rations of pellets and grass hay (see picture). Three containers (4 gallons) of water were provided for each heifer and refreshed three times per day. The location of the container for each water type was randomized each day and an extra container on each side was left empty to avoid preferential behavior by location. Throughout the eight-day experiment period individual water intakes by heifer and water type were measured. During the adaptation phase of the study, heifers were given MCW for three days to establish baseline intake. During phase 1, all three water types were offered for three days and the most preferred water of each heifer was removed at the end of this period. During phase two, the remaining two water types were offered for two days to establish ranking. Water preference ranking by each heifer was determined based on intake amounts during the two phases.

Findings

Chemical composition was analyzed in the three water types (Table 1). Total dissolved solids were analyzed using two different methods (gravimetric and electrical conductivity) and values varied depending on the method used for analysis. Results showed that UWW and MCW had more sulfates, TDS and hardness compared to the ROW. Total average water intake was 4.20, 4.14 and 3.93 gallons/day for the adaptation, phase 1 and phase 2, respectively. When all three waters were offered at the same time during phase 1, average intake was 1.87, 1.34, and 0.93 gallons/day for ROW, MCW, and UWW, respectively. Three heifers preferred the ROW first and MCW second. Two heifers preferred MCW first and ROW second. One heifer chose UWW first and was a potential outlier in the group for taste preference. Average preference rankings were 1.67, 1.83, and 2.50 for ROW, MCW and UWW with lesser values indicating greater preference. Overall, results showed ROW was slightly preferred over MCW and both were preferred over UWW. In agreement with the hypothesis as water quality improved, so did heifer preference. A reverse osmosis treatment system could be an option, especially when only UWW is available, to encourage more water intake by growing dairy heifers.

Acknowledgements

This research was funded by Culligan Water, Brookings, SD with support by South Dakota Agricultural Experiment Station at SDSU.