Livestock: October 1999

The drought of 1998 forced many graziers to consider available water supplies. A water deficiency reduces animal performance, such as milk production, more quickly and severely than feed or mineral deficiency. Both quantity and quality of water are important.

Many old ponds that were shallow and full of sediment failed to supply good-quality water. The diminished water level provided an opportunity to clean ponds and create a more permanent and desirable water supply.

Shallow ponds are inadequate because water quality deteriorates faster, particularly if livestock are allowed to enter the ponds on a daily basis. The animals stir the sediment and defecate and urinate in the pond. A real danger exists in July and August if a pond exhibits a bloom of blue-green algae, which flourish in stagnant water where there has been runoff from animal waste; the algae can be toxic if ingested by wildlife, livestock or people.

Water availability is a critical issue for those who employ cell or intensive grazing. Water can be supplied by ponds, streams, wells, springs, and rural water-distribution systems.

If you are thinking about creating a better water source and distribution system, here are some pertinent issues. How much water does a cow drink? That quantity and her requirements can be unrelated. The amount varies seasonally because of the moisture content of the grass she is grazing, weather conditions, the distance she has to travel to get water, and other factors such as breed and body weight. At 50 degrees, a cow may consume about five to seven gallons per day, but the amount increases by 0.4 gallons per day for every one-degree increase in air temperature. At 95 degrees, the same cow will drink an average of twenty-four gallons per day. Cows with water available within 800 feet at all times drank fifteen percent more water daily than those that traveled over 800 feet to get water (Gerrish and Davis, 1999).

How often will a cow come to water? The same factors that influence how much she drinks also influence how often she will drink. According to Gerrish and Davis (1999), beef cows may travel to water three to five times per day. They travel less often but stay longer if they have to go a long distance.

How much water can a cow drink at one time? Normally she will drink about two gallons in a one to three-minute period and, again, the amount and duration increase if the animal travels far.

How much water should be supplied for a herd and where should the water be located relative to the size and shape of the pasture? It is best to supply water in each pasture and not force cattle to travel a great distance down a lane or over rough terrain to obtain it. A recent study by Gerrish and Davis (1999) revealed that if cattle had to travel over 700 to 900 feet to obtain water, they foraged quite inefficiently.

As an example, on a 160-acre pasture only 130 acres were used because of nonuniform grazing caused by distance from water. Gerrish and Davis quote another example of a study in Wyoming: on a 2,000-acre pasture, seventy-seven percent of the grazing occurred within 1,200 feet of the water source. More than sixty-five percent of the pasture was over 2,400 feet from water but supported only twelve percent of the annual grazing use.

A herd's daily demand for water can be calculated easily by multiplying the number of cattle by the amount of daily consumption, which is very important if a well or spring is supplying water. Water availability and trough space should allow the herd to drink within forty-five minutes, and if either is deficient, the first animals to drink will begin drifting back to pasture, causing the more timid animals to return also before they have had an opportunity to drink.

For trough-watering, about one and one-half to two feet of space per adult animal is needed. The total trough space for a herd can be calculated by multiplying two minutes times the herd size and dividing by forty-five minutes. Copious trough space is not necessary to water a sizeable herd, but the recharge rate must be sufficient to refill the tank as animals drink.

Hopefully these suggestions will be valuable and stress the importance of the availability and distribution of high-quality water for livestock.

Reference: Gerrish, J. and M. Davis. 1999.Water availability and distribution, p. 81-88. In: J. Gerrish and C. Roberts (eds.). Missouri Grazing Manual. University of Missouri Extension, Columbia.