ASAS/ADSA Ruminant Nutrition: Water Quality and Minerals

Water is an essential nutrient for feedlot cattle. Drinking water may contain a variety of compounds. The important question is to what degree these substances impact water palatability and cattle health. The NRC in 1974 published limits for some potential problem causing substances in drinking water. Recommended safe upper limits for nitrate, sulfate, and total dissolved solids (TDS) were 440, 300, and 3000 mg/L, respectively. In 1999, the National Animal Health Monitoring System conducted a study monitoring water quality in feedlots with 1000 hd or more capacity in the 12 leading cattle feeding states. A total of 263 feedlots from 10 states supplied a water sample for analyses. Average nitrate, sulfate, and TDS content was 33.6±3.5, 204.9±23.5, and 800±100 mg/L, respectively. No samples exceeded the recommended limit for nitrate. Approximately 23% of the samples had sulfate concentration greater than 300 mg/L. Less than 3% of the samples had more than the recommended level of TDS. In a study conducted at Continental Beef Research, water sulfate concentrations greater than 1000 mg/L caused increases in ruminal gas cap hydrogen sulfide (H2S) concentration and reductions in water intake and feedlot performance. Elevated ruminal H2S was associated with increased incidence of polioencephalomalacia in a Colorado feedlot using well water containing 2500 mg sulfate per liter. Molybdenum appeared to reduce the rate of H2S production in vitro. Molybdenum fed at the rate of 100 mg/kg dry matter intake reduced H2S concentration in the rumen gas cap by 21% (P=0.0337) and reduced the frequency of cattle with greater than 1000 mg/L H2S by 40% (P=0.0019). No effect on feedlot performance was observed. Cattle fed 57g clinoptilolite daily exhibited a 14.5% and a 36.3% reduction in ruminal H2S from d0-10 and from d11-20, respectively. Feeding clinoptilolite reduced performance by feedlot cattle. Efforts to alleviate water quality problems through dietary manipulation have not been successful.