Dairy Focus: Water - It’s What You Don’t See That Counts

Routine water analyses can help monitor dairy cattle’s mineral intake.

Rain or shine, flood or drought, water is critical to life. Then why is water the last place you look for problems when balancing dairy diets?

That water is the most critical component of any diet goes without saying. This never has been so true as it is for lactating dairy cattle. Water is vital for milk production. You take steps for cows to receive adequate amounts of water, but do you keep an eye on the mineral content in the water? Fine-tuning today’s diets, which incorporate large proportions of byproducts, may mean now is the time for you to check it out.

A few years ago, a massive water analysis project examined the mineral content of water samples from around the nation. The results showed the mineral content of water varies significantly within a region and even on the same farm. This variation should influence your cows’ acceptance of water, their water intake and the way you balance rations - three good reasons to monitor mineral levels in your water on a routine basis. Here’s a look at the research and its implications for your dairy.

Several nutrition consultants and feed companies contributed 3,618 water samples that had been analyzed for several minerals - calcium, iron, magnesium, manganese, sodium and zinc, as well as pH (acidity) and total solids content. After summarizing the results, research nutritionists with Zinpro Corp., Agri-King Inc. and the University of Minnesota found water mineral levels varied significantly within a region with similar ZIP codes.

Perhaps what is most eye-opening about this project is the fact that mineral levels varied significantly within the water supply of individual dairies. For example, on dairies where at least four samples were collected, the average iron content of the water ranged from a minimum of 0.13 parts per million (ppm) to a maximum of 1.39 ppm. Keep in mind, the researchers do not know the location from which samples were collected.

Interestingly enough, all of the minerals examined in this project, except zinc, exceeded the upper desired level for livestock in at least one or more of the 3,618 water samples. And, some minerals were present in surprisingly high amounts. For example, of the 2,423 samples analyzed for iron, 969 (roughly 40 percent) contained excess iron. The average water sample analyzed for iron contained about 0.79 ppm iron. That’s 0.59 ppm more than recommended levels.

Although this research clearly shows the mineral level of water varies and even can be excessive, very little research shows the impact of this variation on animal health and performance.

The amount of minerals a cow consumes from water, even at the very high end of desired levels, probably isn’t going to pose a health risk, except for sulfur. For most of the trace minerals found in water, we’re not looking at toxic effects.

However, while the levels of minerals in water probably aren’t detrimental to your cows’ health, they could be high enough to reduce palatability. Again, the well of research that examines the effect of mineral variability on palatability is shallow. In fact, researchers have borrowed from human drinking water guidelines to help them determine if mineral variability affects palatability and, consequently, water intake.

Like people, animals simply might not like the taste of water that contains variable mineral levels, particularly when those levels exceed desired values. That, in turn, could cause your cows to drink less water, impacting their milk production.

Excess minerals in water could contribute to your cows’ total mineral intake. Water with 56 ppm of chloride can increase a cow’s total chloride intake by 7.9 percent, compared with water containing no chloride. And, some of the water samples found in the nationwide analysis were as high as 727 ppm chloride. At those levels, a cow’s total chloride intake would increase by roughly 48.5 percent. That most certainly can have a direct impact on ration balancing.

Most nutritionists test forages on the farm and make adjustments based on the forage nutrient contribution to the diet. The only thing not routinely accounted for is the nutrients supplied by a cow’s water intake.

Having a lab analyze the level of minerals in your water on a routine basis (about twice a year) can help you and your nutritionist monitor the level of minerals in your water. That can be helpful for diagnosing water intake problems and even balancing your ration.

Dana Tomlinson, research nutritionist with Zinpro Corp., offers these suggestions to help you collect and submit water samples for a mineral analysis:

* Prior to sampling water for the first time, obtain sample bottles from a reputable water-testing laboratory. Using sample bottles from the laboratory helps minimize contamination during sampling.
* At the first sampling, ask the laboratory to analyze the water samples for a broad range of minerals so you can establish a baseline for your dairy.
* Before taking a sample, let the water run for several minutes.
* Always sample water where the cows drink.
* Don’t collect samples from a dirty waterer.
* At each subsequent sampling, ask the laboratory to analyze for pH, calcium, magnesium, iron, sulfates, nitrates, potassium, sodium, chloride, manganese and total dissolved solids.

By J.W. Schroeder, Dairy Specialist - North Dakota State University Extension Service