The ingredients in the milk replacer we select to feed preweaned calves receive a lot of attention. But Tom Earleywine, PhD, Director of Nutritional Services for Land O’Lakes Animal Milk Products, says the contents of the water used to reconstitute it are just as important.

          “Young calves do not tolerate poor water quality well,” says Earleywine. “Water quality can affect mixed milk-replacer quality; mixed electrolyte solution quality; calf water consumption and starter intake; calf health; rumen development; and the effectiveness of cleaners and disinfectants.”

          One often-overlooked error in water management is using sodium-chloride-softened water to reconstitute milk replacer. Don’t do it, says Earleywine. “In typical softeners, sodium replaces the hardness minerals to soften the water and this can lead to sodium toxicity for calves,” he says.

          While some testing guidelines indicate that 2,000 ppm of sodium in water is safe for cattle, those numbers do not apply to young calves. “Calves only can tolerate 50 ppm of sodium,” Earleywine advises. “Soft water often exceeds that threshold, not even considering the additional sodium in milk replacer.”

          He adds that calves also are sensitive to excessive levels of iron, manganese, magnesium, sulfur and microbial contamination. His advice: get a “calf suitability test” of the water delivered to preweaned calves, including the water source used to mix milk replacer.


When submitting water samples for analysis, ask for an assessment of:

  • Total soluble salts or total dissolved solids, which measure the salinity or amount of soluble salts in water, including calcium, magnesium, sodium, chloride and sulfate salts.
  • Hardness. Calcium, magnesium, iron, zinc and manganese all affect water hardness.
  • All of the individual minerals listed in Total Dissolved Solids & Hardness
  • pH
  • Nitrates
  • Copper
  • Phosphorus
  • Microbial contaminants, such as coliforms, E. coli and salmonella.

At a minimum, water should be tested annually.