NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

September 3, 1998

When Evaluating Dairy Performance, Check Water Quantity and Quality

When evaluating dairy performance and diagnosing dairy production problems, don't forget water, warns a North Dakota State University dairy specialist.

"Dairy cows are large consumers of water," notes J.W. Schroeder of NDSU's Extension Service. "We often think about how important water is during the hot summer months, but we need to realize that it is a key nutrient 365 days of the year."

A cow producing 80 pounds of milk daily may consume more than 300 pounds of water per day from both drinking water and from moisture in the ration. Drinking water generally provides 80 to 90 percent of the dairy cow's water needs.

"If a herd is experiencing less than optimum production and health problems persist, even after all obvious nutrition and management areas have been evaluated, there may be a water-related problem involved," Schroeder says. "Low water intake may depress milk production by 5 to 15 percent or more."

Inadequate or malfunctioning watering devices and lack of pressure in the system are the most frequent causes of low water intake, Schroeder notes. Transient or other voltage on water lines or around the base of water tanks will make cows hesitant to drink.

Clean water is also important, Schroeder says. Iron bacteria may produce a residue that restricts flow in lines and drinking devices and imparts an off-taste to the water. Microbial contamination of water supplies, drinking cups, or tanks can alter rumen microflora and metabolism by competing with normal rumen bacteria. The result is depressed production and health problems. Depending on the specific organism contaminating the water, diarrhea, reproductive problems, and mastitis infections can result. Calf morbidity and mortality rates may be related to a contaminated water supply.

Schroeder advises having water supplies tested periodically. Request a total bacteria standard plate count, fecal coliform, fecal strep and a total coliform count. There are some minerals in water that can create problems for the dairy cow. An induced copper deficiency in cattle may sometimes involve a high concentration of iron, manganese, molybdenum and sulfur in the water. This could potentially be a concern in areas with high iron levels in forages. High sodium, potassium, and possibly, calcium levels in water may contribute to more milk-fever cases if not considered in formulating dietary needs for pregnant dry cows. Watch for high magnesium content (greater than 100 to 125 ppm) in water, which may result in chronic diarrhea and adversely effect performance. The problem is more likely to occur when dietary and water-sulfur levels are relatively high, or when cows are fed buffers containing relatively high levels of magnesium oxide.

The quality of wash water can also influence milk quality and flavor. For example, oxidized or cardboard-like flavor in milk may result when water containing iron, copper, and manganese is used to wash milking equipment. If the water leaves a mineral residue of more than 0.1 to 0.3 ppm on surfaces with which milk comes into contact, off-flavors may result.

In North Dakota, no single water-related problem is common, Schroeder says. Water intake problems occur more frequently than water quality problems and microbial contamination from unclean waters appears more prevalent than chemical or mineral problems.

For more information on available water-testing laboratories, contact your local office of the NDSU Extension Service.

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Source: J.W. Schroeder (701) 231-7663

Editor: Tom Jirik (701) 231-9629