Check Water Sources For Mineral Levels That May Affect Intake

By Crystal McNett, Assistant Editor
Thursday, August 2, 2007 8:31 AM CDT

It’s no secret that cows need a lot of water to produce high levels of milk.

A cow producing 80 pounds per day will be loosing nearly 70 pounds of water in her milk alone. Water availability and quality can be issues on some dairy farms, said Charles Elrod of Springfield Farm Enterprises, Newfield, N.Y.

“All too often we fail to provide this crucial nutrient in adequate quantities or in acceptable quality for our cows,” he said during Alltech’s 23rd International Feed Industry Symposium, held May 21-23, in Lexington, Ky. The conference featured presentations from 65 of the world’s most distinguished scientists to over 1,500 attendees from 78 different countries.

As a very general rule of thumb, Elrod explained, free water intake (excluding water in feeds) in liters per day, averages two times milk production in kilograms.

“Leaving aside the issues of water quality, optimal water intake assumes that water is available in sufficient locations, free of obstructions and at adequate rates of flow to meet the needs of groups of cows at peak drinking times,” Elrod explained.

Linear space per cow and waterer location should be considered. Given the opportunity, a cow will alternate drinking and feeding, therefore a cow should never be more than 50 feet from water. There should also be enough space at a waterer to allow 7 to 10 percent of the group to drink at one time, Elrod explained. Be sure that flow rate of the water is adequate to accommodate this level of water consumption.

“The source of water has a large impact on its quality,” explained Elrod. Look at the underlying geology and bedrock in your area. It will give good clues as to water quality, he said.

The depth of your well should reflect the depth and type of bedrock. “The ability of water to dissolve minerals depends on the type of rock through which water flows, such that limestone or dolomite ability is greater than shale or sandstone, which is greater than granite or basalt,” he explained. “Concentration of dissolved solids increases with the depth of the water source.”

Total mineral content as measured by total dissolved solids can affect water intake. Water sampling done on a certain schedule can identify what minerals may be curbing consumption. This will identify mineral levels in the water and the potential mineral interactions which, indicate some levels that may be formulated into the diet and also indicate levels that may be toxic, Elrod explained.

Sulfur is a frequent culprit of reduced water intake. Most often recognized by its odor similar to rotten eggs, this mineral, depending on its form, presents several challenges. “Levels as low as 0.1 parts per million (ppm) can reduce water intake, though this is probably more an aesthetic effect of taste or odor,” Elrod said. Increasing dietary sulfur decreases both copper and selenium absorption. Levels in water above 1,000 ppm can have a laxative effect on dairy cows.

High levels of iron in water (above 500 mg per Kg) reduce the dairy cow’s ability to absorb calcium, zinc and magnesium.

Typically resulting from some sort of surface water contamination, high levels of nitrites in water reduces oxygen carrying capacity of the cow’s blood. “Water nitrate levels in excess of 133 ppm may lead to poor growth, infertility, abortions or general ill thrift,” Elrod noted.

“Knowing only the concentration of a mineral in water is an incomplete description as to the toxicity and availability of the mineral,” explained Elrod. Mineral complexes will dissociate and re-form into different complexes when those minerals hit the rumen. It is important to know what levels of minerals are being taken in, in order to understand how they will interact in the rumen.

Elevated mineral levels tend to result in more subtle, chronic conditions of poor performance or increased health issues, rather than a sudden, severe illness. Water supplies with a negative strong ion difference (SID) (derived from mineral levels) that are introduced to the rumen of a dairy cow consuming high quantities of rapidly fermentable carbohydrate and fiber resulting in the production of lactate, volatile fatty acids and non-esterified fatty acids, may be enough to cause sub-acute rumen acidosis, Elrod explained. “The rumen does not care whether the source of ions is from water or feed,” he said. “It responds to an excess of anions, a negative cation-anion difference or SID, with perturbations in fermentation and hence its efficiency.”

In order to overcome water issues, Elrod suggested testing water sources twice per year using strong ion difference to evaluate results. “Water treatment options exist for most problems,” he said. In addition feeding organic trace minerals that are more available can help.

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