While drought concerns in many milk production areas of the U.S. have been reduced, the long-term need to conserve water has not. Joseph Harner, biological and agricultural engineer at Kansas State University, discussed potential targets for dairy farm water conservation efforts during the 2017 Western Dairy Management Conference, Feb. 28 to March 2 in Reno, Nevada.
Numerous studies over the past two decades have attempted to estimate the volume of water used in the production of milk. Depending on the season, cows drink 28 to 32 gallons of water per day, with a water consumption-to-milk production ratio of about 2.8-to-1. When including water for all uses on the dairy, the ratio is closer to 4- or 5-to-1.
“With cow cooling and deck flushing, we’ve seen an increase in that ratio,” Harner said.
Harner identified 10 conservation practices to reduce water use and manage water use efficiency.
1) Repair water trough leaks and adjust floats
When it comes to water conservation, Harner urged dairy farmers to begin at the water trough.
“The first and easiest thing to do is look at water troughs and make float adjustments and look for leaks there,” Harner said. “At least 10 percent of all water troughs are going to have water waste due to improperly adjusted floats. While it might not look like a lot of water, 28 ounces per 10 seconds can result in 700,000 to 1.5 million gallons of water per year in excess water use.”
In larger dairies (3,000 cows and 64 water troughs), that adds up to the potential for 5 to 10 million gallons of excess water going into the manure lagoon.
A common winter strategy in colder climates is to set floats for continuous flow to prevent icing. Instead, install frost-free or insulated water troughs.
Reducing leaks and making float adjustments can provide another benefit: Water splashed or leaking from water troughs located in cow housing areas can be both an economic drain, as well as an udder and herd health concern.
2) Recycle plate cooler water for potable uses
To cool 1 pound of milk, plate coolers can use about 2 to 4 pounds of water, all of which can be recycled. To reduce water consumption, the plate cooler water should be recycled for activities requiring potable water, such as cow water troughs and parlor deck flushing. Many state milk sanitation codes allow for non-potable water to be used for flushing the holding pen, and some allow non-potable water to be used for flushing the parlor deck.
Make sure plate coolers are using water efficiently. An Ohio study reduced water flow rate through plate coolers by 50 percent, with no impact on milk cooling.
Harner warned that regulations regarding use of potable and non-potable water in specific segments of dairy operations vary by state. For example, some states allow the use of recycled water for cow cooling or flushing milking parlor decks.
3) Adjust feed line soakers and holding pen sprinkler nozzles
As the understanding of heat stress and its impact on cow health and productivity grows, cow-cooling systems are becoming even more widely implemented. Technology refinements and research into cooling cycles and water volumes are helping make water use more efficient.
Harner said 1 pound of water can evaporate about 1,000 British thermal units (Btus) of heat generated by the cow. Cows give off about 5,000 Btus of energy per hour, so 5 pounds of water applied efficiently on the cow will be all that is needed.
Current estimates recommend applying about 2 pounds of water per cycle to provide heat stress abatement without impacting milk production or dry matter intake.
“Even at 2 pounds, we’re only about 50 percent efficient in terms of water usage,” Harner said. “This volume of water can add up significantly over the course of a year.”
To improve efficiency, a simple test is to place a quart jar under a nozzle, catching the volume of water per cycle. Multiply that by the number of “on-times” per hour to estimate water use per hour. One quart of water will equal approximately 2 pounds of water. The on-time of a soaker nozzle should equal the amount of time to fill a quart jar.
Shortening the on-cycle time can often accomplish adequate cooling without negatively impacting heat abatement. With today’s nozzles, on-times can frequently be shortened to two to four minutes.
Another way to conserve water during cow cooling is to consider using both temperature and humidity when adjusting controllers. Research has shown using temperature and humidity indexes can result in 30 to 50 percent water savings.
Kansas State University research is also looking at individual nozzle control sensors, turning on nozzles only if a cow is within 4 feet. A challenge for the technology includes the need for economical, low-voltage solenoids. Another challenge that might arise, Harner said, is that cows fed in a post-and-rail system may back away from the water, impacting feeding behavior.
“We know cows prefer not to get wet at the feedline,” he said. “The best guess right now, if we can get the controller technology and maintain feed intake, we could get a 75 to 80 percent water reduction for heat abatement.”
The holding pen offers management challenges – and opportunities for water conservation. Depending on holding pen capacity and cow parlor flow, it might be beneficial to fill just a portion of the holding pen and turn off back sprinkler nozzles.
“There may be opportunities for significant water conservation by disconnecting nozzles in the back third of the holding pen,” Harner said. Other ideas might be to put switches on controllers to delay on-times, or limit on-times to the front portion of the holding pen.
4) Adjust milking center floor flush system and use cow deck washers
While there’s a wide variation in water volume based on flush or scrape systems, wash pens are a heavy user of water. Harner said a reasonable target for average water consumption is less than 40 gallons per cow per day. To reduce water usage, make sure cattle housing and lying areas are clean.
Depending on parlor type, most milk codes require fresh, potable water when flushing the parlor deck. Water can be recycled from the plate cooler to perform this task. Some dairies are using programmable logic controllers (PLC) to limit the valve open cycle and frequency of parlor deck flushing.
Dairies using more than 1 to 1.5 gallons per square foot of parlor deck should evaluate their protocols and determine if water usage can be reduced. Some dairies flush the parlor deck more frequently than necessary to eliminate water tank overflows due to excessive plate cooler water. Water conservation strategies should incorporate protocols to reduce flush frequency and transfer water to other applications.
If a dairy is trying to match plate cooler water to parlor deck flushing, target a ratio of 2-to-1 (two-thirds of plate cooler water for flushing the deck and the remaining one-third for filling water troughs).
5) Evaluate water trough cleaning protocols
Another water trough consideration includes protocols for cleaning. Some have capacities of 60 to 80 gallons, and cleaning may mean completely emptying the trough by tipping or pulling the drain plug daily or every other day. Using those practices, refilling the trough will account for about 15 percent of water use in a trough on a daily basis.
Adjusting the frequency of cleaning water troughs to every two or three days may be one way to reduce water consumption without reducing herd health. In between, use a skimmer to remove the “crud” from the tanks rather than tipping or pulling a drain plug.
Modern tanks are shallower and have less water capacity, resulting in less water waste while cleaning.
6) Use and control of water hoses in the parlor
Water is critical to meet sanitation requirements in milking centers. Monitoring hose usage and total time per day to wash down individual claws may reveal an opportunity to conserve water. Strategically locate hoses and install nozzles so no water flow is occurring when hoses are not in use.
7) Look for abnormalities in wash cycles
Monitor parlor wash cycles by metering water usage. Train employees to optimize water use by following proper cow, parlor and milking system cleaning protocols.
8) Reduce/eliminate infrastructure leaks
Many dairies have small “wet spots” in farmyards due to leaks at aboveground or underground pipe joints. Not only do these leaks waste water, they also create extra yard work to manage grass or weed growth in these areas.
9) Take advantage of ‘free’ water
Often overlooked, dairy cows get a portion of their daily water needs from the feed ration. Monitor ration dry matter and moisture content.
10) Plug evaporative cooling system leaks
Evaporative pad system (distribution and return pipe) leakage can be significant. Most leaks are related to improperly installed seals around joints and seams. Be sure to calibrate misters to both temperature and humidity to reduce excessive water reaching bedding areas and creating unintended cow health consequences.
Summary
While there are many variables related to climate, cropping practices and dairy management, opportunities for water conservation remain. Water conservation should be a priority among the entire farm team, including managers and employees.
“The bottom line is that there is a lot we can do to conserve water,” Harner said. While transferring the dairy to the next generation usually focuses on financial factors, a question is, “will there be enough water available?”
“Through conservation, we could reduce water usage at least 20 percent without impacting profitability of milk production. Everyone is looking for the big things, but in most cases, it is the small things,” Harner concluded.
Not only is water wasted, but if it’s purchased through a water district, it can substantially add to milk production costs. 
Harner’s presentation, “Water Conservation for the Next Gen Dairies,” can be downloaded here.
All Western Dairy Management Conference proceedings are available on its website.
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Dave Natzke
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PHOTO: Staff photo.
