Your Reading List

Beware of “things” in dairy cow water

Dairy Corner with Peter Vitti

Questionable water quality is not usually life-threatening, but it can impact a healthy cow’s nutrition and compromise essential nutrients needed for good milk production.

A professor who once taught our nutrition class a long time ago (a long time ago) said the actual amount of water drunk by lactating dairy cows was important for milk production. However, she said it was the “things” that existed in their drinking water, which often limit their health and production during lactation. Even today, I remember part of this lecture and always check the volume and quality of water flowing into a dairy barn.

Initially, the actual amount of water required by dairy cows depends upon their age, health status, body size, and milk production; water consumption by most milk cows during a typical lactation cycle can be estimated with relative accuracy in two major ways: (1) provide four to five litres of water for every one kilo of dry matter feed consumed or (2) provide three to 3.5 litres of water for every litre of milk produced.

Dairy cows spend six to eight hours per day at the feed bunk, yet spend a nominal total of 20 to 30 minutes per day drinking water. Research field trials also demonstrate most dairy cows prefer to do the majority of their drinking, right after exiting the milking parlor. Cows have been shown to consume about 50 to 60 per cent of their daily water intake within an hour after each milking.

This means good design and placement of any water system should follow a cow’s natural drinking behaviour. For example in a free-stall barn, a water trough should be placed near the milking parlor exit and within 20 metres of the feed bunk or at the cross-alleys in the barn. It should also have a recovery fill-rate of about 30 to 40 litres per minute. Since most troughs are metal (plastic ones are becoming popular), each tank should be occasionally checked and guaranteed free of stray-voltage.

Water of questionable quality is usually non-life threatening. However, it can still have a negative effect upon other aspects of otherwise well-balanced dairy nutrition and management, namely; decreased feed digestion and lower uptake of essential nutrients geared for good milk production.

Real water situations

Here are some open-ended real-life situations where I found poor quality water caused overall poor health, reproduction and milk performance:

  • Several milk cows of a 300-cow dairy had a mild diarrhea that never seem to disappear, despite the lactation herd being fed a well-balanced diet. I did not think subclinical acidosis or other digestive upsets was the cause. All of the barn’s close-up cow group of 15 to 20 cows also had severe udder edema. A water test of total dissolved solids (TDS) revealed high saline (salt) levels.
  • A 70-cow milking herd drew its drinking water from untreated river water and experienced a high level of mastitis and other health issues. Although, it was occasionally treated with chlorine, this problem was repetitive and afflicted cows took a long time to recover. A water test showed high counts of environmental E.coli.
  • Iron is an acknowledged nutrient for bacteria and has been implicated in salmonella outbreaks. High iron also contributes to poor tasting water.
  • The absolutely worst situation I encountered concerning poor water quality issues was a 150-cow dairy producer that had barn water that smelled of rotten eggs. The water coming out the tap in the barn-sink had a literal black colour. The cows suffered from low milk production, poor reproduction and had several health problems. I believed that there was a mass of decaying matter in his well or the farmer might have had high-sulphate levels contaminating water or both problems.
  • I see in many barns where cows drop feed from their mouths and I have seen thick black sludge build up in their troughs or waterers. Algae growth is also a common sight even during winter. On one such visit, a producer started to routinely clean the algae from the cows’ exiting water troughs and noticed a slight milk increase afterwards.

Granted, the corrective action necessary to solve each one of these situations was different, yet I started each “road-to-recovery” by taking water-samples. I had most of the samples tested for Total Dissolved Solids (TDS), pH (acid-base test), mineral concentrations and bacteria contamination.

Once, these lab analyze were completed and I reviewed them, specific action was taken in each case, where “things” in the water were found. In the last situation, the water tests were not used, because the producer walked by the water though, noticed the scummy green water and scrubbed the tank clean.

About the author


Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7497 or by email at [email protected]



Stories from our other publications