Water Wisdom

Often taken for granted, this essential nutrient has to be provided in sufficent volume at the right time.

The most important essential nutrient for your dairy herd is something many of us take for granted-water. When you consider water makes up 87 per cent of the volume of milk you produce, quenching your cows' thirst is a crucial part of optimizing milk production.

Dairy farmers sometimes focus on other nutrients they feed their herds while forgetting to consider the quantity and quality of water available. Yet water intake can be a potential limiting factor for milk production. I have seen farms where production increased substantially after they overhauled their water delivery systems.

Considerable research has been done to predict water intake of dairy cattle, and a few studies have addressed their drinking behaviour. Some recent research has looked at how often and when dairy cows drink, and describes the relationship between their behaviour and the amount of water ingested.

Various factors can affect water intake. These include milk production, ration dry matter, dry matter intake, sodium intake and ambient temperature. A typical dairy cow consumes an average 115 litres of water daily, and high-producing animals can lap up 160 litres. Good access to water and adequate flow rates are key to meeting these requirements for your herd.

Behaviour studies have shown cows spend less than 30 minutes a day drinking, most of that during daylight hours. They consume less than 25 per cent after 7 p.m.

Peak water consumption periods are linked to milking and feeding. Cows drink up to 60 per cent of their daily requirements in the hour following milking, making water availability critical at this time. Position water sources -with adequate flow rates -to provide sufficient water when demand peaks.

A cow can drink up to 16 litres of water per minute when she has access to a water trough. The system's flow rate should provide this amount at a minimum. Water bowls reduce the rate but they should still be able to deliver at least four litres per minute.

In free-stall barns, position water sources so cows have easy access to sufficient water after milking and feeding.

In tie-stall barns, just after milking and feeding, many cows drink at the same time. The last bowl on the line has to deliver as much water as the first. To achieve this goal, ensure the line has adequate delivery pressure and pipe size-the longer the line, the less the pressure and flow rate at the end. Similarly, the smaller the pipe diameter, the more pressure and flow will drop along its length.

Avoid any line restrictions, especially close to the pump, since they will impact the system downstream. The pump is the heart of the system. It should be chosen according to pressure and flow rate required, and inspected and serviced regularly.

Regularly check water pipes for clogging, especially if they are made from galvanized metal. Hard water or a high level of iron or manganese can prematurely clog a system.

A clogged system provides much less water per minute to cows and can be the sole reason for low milk production. For example, let's compare two pieces of one-inch-diameter pipe. One is clear of obstructions, and the other is clogged to the point only one-quarter of its original diameter remains. At equal pressures, the unclogged pipe will deliver 15 times more water per minute than the clogged one.

Also, cleaning water bowls and troughs regularly ensures deficient hygiene doesn't affect your herd's water consumption.

If water intake, feed intake and animal performance are sub-optimal, evaluate water quality by having a laboratory analysis done for factors affecting intake and herd performance. These include total dissolved solids, sulfur, sulfate, iron, manganese, nitrate, toxic compounds (heavy metals, pesticides) and harmful micro-organisms.

On most farms, water originates from your own well, making you responsible for water quality. Have your water analysed regularly, since quality could vary seasonally.

When in doubt about your water quality or the amount your herd receives, consult a specialist to get the full picture. After all, in terms of nutrient volumes ingested per day per cow, water tops the list.


V. Cardot, Y. Le Roux, and S. Jurjanz 2008. J. Dairy Sci. 91:2257-2264, Drinking Behavior of Lactating Dairy Cows and Prediction of Their Water Intake;

Beede, D. K. 2005. The most essential nutrient: Water. Pages 13-32 in Proc. 7th Western Dairy Management Conf, Reno, Nv. Kansas State Univ., Manhattan.

This article appeared in the September 2008 Ontario Milk Producer magazine.

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