Growth performance and health of dairy calves given water treated with a reverse osmosis system compared with municipal city water

Our objective was to determine effects of drinking reverse osmosis water (RW) versus municipal city water (MW) on growth, nutrient utilization, and health scores of calves. Twenty-four Holstein calves (14 females, 10 males; 2 d old; 44.6 ± 6.10 kg of body weight), housed in individual hutches, were used in a 10-wk randomized complete block design study. Calves were blocked by birthdate and sex. Treatments were RW (Culligan Water Filtration System, Brookings, SD) versus MW (Brookings Municipal Utilities, Brookings, SD) that contained 13 and 387 mg/L of total dissolved solids, respectively. Milk replacer (28% crude protein; 18% fat) was fed twice daily during wk 1 through 5 and then once daily during wk 6. At each feeding, 0.45 kg of dry milk replacer was mixed with 2.83 L of the respective water type according to treatment. Calves were fed water, respective to treatment, and calf starter pellets ad libitum throughout the study. All intakes were recorded daily. Daily total respiratory scores (healthy ≤3, sick ≥5) were calculated from the sum of scores for rectal temperature, cough, and ocular and nasal discharges. Fecal consistency scores (0 = firm, 3 = watery) were also recorded daily. Body weights and frame growth were measured 2 d every 2 wk and jugular blood samples were collected 1 d every 2 wk at 3 h after the morning feeding. Fecal grab samples were collected 5 times per day for 3 d during wk 10 for analysis of apparent total-tract digestibility of nutrients. We found treatment by week interactions for dry matter intake and gain-to-feed ratio, and total dry matter intake increased more during the study for RW than MW. Gain-to-feed ratio was greater during the first few weeks of the feeding period for RW compared with MW and then comparable during the rest of study. Water intake was less in RW than MW, potentially indicating more efficient water use by calves. Frame growth, body weight, average daily gain, serum glucose, plasma urea nitrogen, β-hydroxybutyrate, total-tract digestibility of dry matter, and crude protein were similar. Fecal scores tended to be lower (firmer) in calves on RW, with an interaction by time. Respiratory scores decreased during the weaning period when calves drank RW. Results demonstrated calves drinking RW had similar growth and improved health scores with treatment by time interactions compared with MW.