In the previous two articles of this series (see part 1 and part 2) we noted the importance of total daily water intake from drinking water plus rations. By weight, water is the most important nutrient in a milking cow’s ration, easily making up greater than 80% of the total combined consumption. The previous articles focused on the chemical and mineral composition of drinking water and the steps to be taken if your cows’ drinking water contains high levels of undesirable constituents. Hopefully those articles motivated you to have your farm’s water tested for the constituents most often leading to water quality issues [total dissolved solids (TDS), sulfate (SO₄), chloride, (Cl), iron (Fe), and nitrate-nitrogen (NO₃-N)] and to take action if any of these constituents are consistently above actionable levels.

A cow’s water intake is influenced by many factors including dry matter intake (DMI), milk production, sodium (Na) intake, and air temperature. This leads to wide variations in water requirements among milking cows. For example, at 60 ^oF a cow milking 40 lbs/day will eat an estimated 42 lbs/day of DM and drink about 10.1 gal/day less water than her herdmate producing 100 lbs milk/day and eating 60 lbs/day of DM. Both cows will increase their water consumption by about 3.5 gal/day when the temperature increases from 60 to 80 ^oF. These intake figures assume water quality is satisfactory and there are no other factors interfering with water consumption.

Even though your water quality may be fine, there could be other major water issues on your farm preventing your cows from satisfying their water needs. Thus, analyzing the chemical constituents your cow’s drinking water is only the first step to ensure “water nutrition” and water intake are satisfactory. Remember, cow drinking water should receive your attention in two regards: 1) water quality (“Is your water fit to drink based on its chemical and mineral composition?”); and, 2) water delivery (“Are you providing an ample supply of good quality, fresh, clean water to your cattle?”). Water delivery concerns such issues as numbers of waterers per group and waterer location, size, and cleanliness. The most common waterer problems on dairy farms are

• inadequate number of waterers,
• inadequate watering space,
• poorly designed watering spaces, and
• dirty waterers.

Parlor Area: If providing water in return alleys provide ~2.0 linear feet of watering space per cow (e.g., 40 feet of watering space for a double-20). Warm plate cooler water is a good source for this water because cows prefer to drink warm water. This is even true in warm weather and warm climates. Remember, milk is ~87% water and cows may drink as much as 50-60% of their total daily water intake immediately after milking if given the opportunity.

Waterers in Cow Housing Areas: Provide a minimum of two water sources per group and cows should not have to walk more than 50 feet to get a drink of water. Waterers should be located close to feed bunks and protected from direct sunlight. Direct sunlight promotes algae growth which decreases water palatability. It is crucial to provide adequate open space around waterers. This is particularly important for waterers located in cross-over alleys. Cross-over alleys should be at least 13.5 feet wide to allow adequate watering and walking space. There should be approximately 4 inches of linear waterer space per cow in every group. It is critical to provide adequate waterer space and locate waterers properly to keep boss cows from preventing other cows from obtaining adequate water.

Waterer Cleanliness: Waterer cleanliness is the final, but very important, critical link in water nutrition. How clean? Would you be willing to cup your hands and take a drink from it? If not, then clean it! Water trough cleaning should be a regular chore that receives high priority.