Dairy cows need lots of water to produce milk

PHOTO: Matt Barton, UK Agricultural Communications Specialist

Milk is 87% water, and without sufficient water intake, cow’s milk yield will suffer.

Water is important for survival for most species. Dairy cows, in particular, require large quantities to produce milk. Therefore, it is important for dairy producers to provide plenty of water within a convenient location to keep their herd well hydrated.

“Cows need to consume between 30 and 50 gal. of water per day,” said Donna Amaral-Phillips, extension dairy specialist for the University of Kentucky College of Agriculture, Food & Environment. “That’s more than 415 lb. of water every day.”

That number may sound extremely high until one realizes that it takes up to 4.5 lb. of water to make just 1 lb. of milk and that cows produce an average of 70 lb., or 8 gal., of milk each day.

Dairy cows rely on saliva and other fluids to assist them in digesting feedstuffs. If they don’t get enough water, it starts a chain reaction in which digestion, feed intake and energy decrease.

“Managing water on a per-cow basis in a dairy herd can be quite difficult for any producer,” said Jeffrey Bewley, University of Kentucky associate extension professor. “For this reason, dairy producers have to make decisions that benefit the entire herd. That’s why we allow the cows ample access to water at the UK Dairy — so they can drink as much as they want.”

Dairy managers have to make sure cows have access to water in the barn at a centrally located trough. Ideally, the trough will be near a feed bunk so it’s easy for cows to drink after eating. Cows usually drink the most after eating and after being milked.

“It’s important for the water trough to have enough space for multiple cows to drink at the same time,” he said. “Three to five inches of water space per cow is usually adequate, and the height of the trough should be 2-3 ft. from the ground.”

One waterer per 20 cows will help ensure that cows stay hydrated. The waterers should hold at least 5 gal. at time, with a refill rate of at least 2.5 gal. per minute to keep fresh, clean water flowing. So, while it may be hard to monitor each cow’s water intake, providing enough fresh water and space for the entire herd usually gets the job done.