RED DEER – Water is a dairy cow’s most important nutrient.
Milk is 87 percent water and the cow’s body weight is 50-80 percent water, depending on age and life stage.
Cows may drink more than 80 litres per day depending on the season. That means lactating cows drink about four litres of water per kilogram of dry matter intake, or 2.6 litres of water per kg of milk produced. It is important to make sure they have easy access to troughs or water bowls.
“We do a poor job of building barns. We can’t emulate nature and we need to come up with a better design,” said Vern Osborne, dairy researcher at the University of Guelph in Ontario. He spoke at the Western Dairy Seminar in Red Deer March 9.
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Drinkers should be set at the height of the brisket. They should be easy to reach and not placed so one dominant cow guards the bowl and no others can get to it.
Osborne suggested farmers put a meter on the water source to measure consumption and times when cows drink. Maximum intake seems to be about an hour after milking with the remainder taken in after each feeding.
He has experimented with different ways to get cows to drink more.
Water that is at or near body temperature encourages them to drink 12 percent more.
Adding glucose to the water gives them extra energy and its presence appeared to reduce the amount of ammonia in the urine.
Sodium bicarbonate in the water seemed to depress rumen acidity when the cows drank more.
Fish oil in the water caused no difference in fluid intake but dry matter consumption went up.
Orange flavouring enticed the cows to drink more but Osborne suggested that might have been because cows like novelty.
Cows can obtain some valuable minerals in water. Adding nutrients in the same way as swine and poultry producers do is also a good way to deliver minerals.
Water quality should be tested twice a year because sometimes the presence of minerals like iron in the water can tie up other nutrients and they won’t be available to the cow.
There is a lack of research about minerals and vitamins in water, said Jim Linn, University of Minnesota dairy nutritionist.
He said cows’ intake depends on whether they are lactating, how much dry matter they eat, outside temperature and sodium content.
Western Canada has hard water. However, the high calcium and magnesium content is not believed to affect intake. Soft water is zero to 60 parts per million calcium and magnesium, moderate is 60-120 ppm and hard water is 121-180 ppm.
There is no strong evidence of problems caused by nitrates in water. During drought, feed containing high levels of nitrates, along with high nitrate content in the water, could lead to toxicity.
There is good evidence sulfates in water affect animal performance. Generally calves can handle water containing 500 ppm or less of sulfates. If mixing milk replacer, it is important to keep sulfate levels at less than 500 ppm. Cows can tolerate sulfate levels at less than 1,000 ppm.
There are different types of sulfates so it is important to find out whether it is iron, sodium or calcium sulfate. If water is hard, there is likely a high calcium sulfate content.
Iron in water could lead to oxidative stress, mastitis and reduced immune function. Dietary iron supplementation is not recommended in high iron water. Even if the water is high in salts, producers should offer free choice salts anyway.
When farmers were told to remove the salt, there were reports of cows licking urine pools.
