HOW IMPORTANT IS WATER?

Water is important for transport of nutrients in the body and for removal of waste products. Milk is 86 to 88% water. Poor access to water reduced cows dry matter intake (DMI).

Veterinarians are often asked how much water do cows drink? There are two methods available to predict free water intake (FWI). The first method is quick and simple. It simply states that cows consume about 3 pounds of water for every pound of milk produced. This means that cows milking 80 pounds per day will drink 30 gallons of FWI per day. The second method is based on an equation and includes several variables. The National Research Council recommends the following equation for the prediction of FWI in lactating dairy cows:
FWI (kg/day) = 15.99 + 1.58 x DMI (kg/day) + 0.9 x milk (Kg/day) + 0.05 x sodium intake (g/day) + 1.2 x minimum daily temperature (degree C).

Both methods predict that high producing dairy cows will drink 30 or more gallons per day. It is clear that cows must have access to water and water tanks should be cleaned regularly.

Research at Michigan State University showed that cows housed in free stalls drank an average of 14 times each day. Cows drink between one and four gallons of water per minute. Cow prefer to drink immediately after milking and after eating. Most drinking occurs during daylight hours. Research has shown a 25% increase in water intake as temperatures rise from 63 degrees to 83 degrees F. Veterinarians should know that water bowls or tanks with a flow rate of one gallon or less per minute are restricting water intake. This is a common problem in older barns where heavy mineral deposits build up on water pipes and restrict water flow. We had this problem at Hill Top Dairy and our barns are less than three years old. Many dairy producers report improved milk production when additional water space is provided during warm weather.

Calves offered water separate from their liquid feed consume more starter grain and gain weight faster than calves without access to water. Free choice water for calves is important in the summer during heat stress.

Water is the most important nutrient for dairy cows and it is also the cheapest. We can improve cow health and production by making sure they always have adequate access to clean, high quality water.

(Part of this article was published in American Assoc. of Bovine Practit. Newsletter, June, 2001.)