According to Gustavo Schuenemann, the success of a dairy farm’s replacement program comes down to calves’ first 60 days of life. Schuenemann is a dairy cattle Extension specialist and veterinarian at Ohio State.
If the quantitative goal is to at least double the calves’ body weight in 60 days, which is the case on many of the farms Schuenemann visits, much of that success relates to water consumption.
Why Does Water Matter?
Calves’ bodies are about 75% water, and water intake is crucial for all physiological processes and to help calves process feed. Schuenemann’s research finds that for the first 20 days of life calves will drink one to two quarts of water (in addition to water in their milk or milk replacer). As they start eating solid food, they will substantially increase their water intake.
Drinking water is an acquired behavior. Calves do not instinctively recognize water as drinkable. They learn by trial and error or observation. Early access to water helps them learn to drink sooner – especially important when a starter solid feed is introduced.
“The first three days of life are key for newborn calf survival; offer ad libitum [free choice] water from day one,” Schuenemann said.
His datasets indicate that from birth to weaning at 60 days, a calf needs about 28.6 lbs. of water for every 2.2 lbs. of weight gained. This is assuming a calf birth weight of 84 lbs. and weaning weight of 180 lbs. (96 lbs. of body weight gain).
If the goal is to at least double their body weight in the first 60 days of life, then it’s critical that the calves start eating solid feed. But according to Schuenemann, not all water is created equal. This can have an impact on water intake and solid food consumption, impacting average daily gain.
What is Osmolality?
Liquid solutions, like milk, water and blood, can be measured for a total number of dissolved substances called solutes – things like minerals or sugars. The process of measuring a liquid’s solutes is called osmolality, and the solutes are measured in osmoles per kilogram of solvent (mOsm/kg).
The osmolality of pure water is 0 because it contains no dissolved particles. For some context, cow’s milk has an osmolality of 300 mOsm/kg and saltwater an osmolality of 1,000 mOsm/kg.
On farms Schuenemann works with, he’s found that most water osmolality ranges from 1 to 50 mOsm/kg. This is because drinking water can contain dissolved minerals and other substances.
Some milk replacers have an osmolality closer to 400 – 450 mOsm/kg. When water with an osmolality of 50 mOsm/kg is mixed with this milk replacer, it can increase the osmolality of the fluid diet up to 500 mOsm/kg. This can increase osmotic pressure inside the gastrointestinal tract and damage the cell lining, resulting in diarrhea and dehydration. The result is less solid feed consumption and less average daily gain.
“We don’t want this because it triggers inflammation and triggers a process that is painful for the calf because they don’t want to eat and they don’t want to drink,” Schuenemann said.
Mixing electrolyte products into milk replacer can create an even higher osmolality.
“The higher the osmolality, the less margin of error you have. And at the farm level, it is very difficult to work when there is no margin of error,” Schuenemann said.
Farms with high water osmolality (as indicated by water mineral testing) may want to consider an alternative water source. Although Schuenemann noted that reverse osmosis has shown promising results in removing undesirable minerals and improving water intake in calves, the technology is still emerging and not yet widely accessible or adopted by farmers for on-farm water purification.
“If you reduce some of the mineral compositions in water, you substantially improve water intake and reduce osmolality,” he said.
Other Factors Associated with Water Intake
Sanitation of drinking water equipment is important, although again, Schuenemann understands that cleaning equipment is labor intensive and time-consuming. It can, however, make a big difference in how much water calves will drink.
Sanitizing waterers and feeding equipment reduces the bacterial counts, and Schuenemann’s studies indicate that calves will increase their water intake when they have access to bacteria-free water.
Tools, like a Hygenia® SystemSURE Plus, can be used on the farm to test cleanliness of drinking water and feeding equipment. For example, a bucket can be swabbed, and the sample is placed in a small handheld device which measures the amount of adenosine triphosphate (ATP) present. The process of ATP testing is based on bioluminescence, which involves the production of light by living organisms such as E. coli. A high ATP reading indicates that the bucket needs cleaning and sanitation.
Water temperature also has an impact on water intake. Calves prefer to drink water which is close to their body temperature.
In one on-farm experiment, Schuenemann found that by warming water from 46.5º to 64.4º, the calves consumed 50% more water.
Young calves cannot thermoregulate very well, and they are very sensitive to both cold and heat stress.
Heat stress can be alleviated by making sure calves have shade and proper ventilation. But even with well-designed calf facilities, heat stress can occur, which causes calves to drink more water. Heat stress can also change behavior – they may eat and drink less during the day and more at night.
“During the night they should have access to water because this is when they are more active,” Schuenemann said.
Similarly, extreme cold can impact calves’ water and feed consumption. A well-designed calf barn that is well-ventilated but still eliminates drafts is important for dairy farms in cold climates.
Behavioral research studies have shown that calves prefer open buckets for water rather than nipples because they drink water very quickly.
“It’s important to carefully design water access when setting up these facilities. Understanding calf behavior helps ensure we’re not unintentionally limiting their water intake,” Schuenemann said.
