University of Auckland-affiliated researchers have successfully demonstrated that cows can be toilet trained. It’s no
joke. Lindsay Matthews and Douglas Elliffe’s research with German colleagues could help reduce water contamination and
greenhouse gas emissions.
Cow urine is high in nitrogen. As it breaks down in the soil, it results in two problematic substances – nitrate and
nitrous oxide. Nitrate from urine patches leaches into lakes, rivers and aquifers, where it pollutes water and
contributes to the excessive growth of weeds and algae. Nitrous oxide, a long-lived greenhouse gas 300 times more potent
than carbon dioxide, accounts for 12 percent of New Zealand’s greenhouse gas emissions – and much of it comes from the
If cows could be trained to urinate in a “toilet” at least some of the time, nitrogen could be captured and dealt with
before it pollutes water or turns into nitrous oxide gas. Matthews and Elliffe’s research detailing how has been
published in the prestigious journal Current Biology
* and will be profiled in an upcoming issue of Science.
“We’ve shown proof of concept that we can train cows and train them easily,” said Elliffe, a University of Auckland
professor of psychology. “Cattle urine is a major cause of our nitrogen problem. Any reduction in that would make a
“People’s reaction is, ‘crazy scientists,’ but actually, the building blocks are there,” said Matthews, a University of
Auckland honorary academic and director of an independent research company. “Cows have bigger urinations when they wake
up in the morning, which demonstrates they have the ability to withhold urination. There’s nothing in their
neurophysiology that radically differentiates them from animals, such as horses, monkeys and cats, that show latrine
Matthews has been around cows for a long time – he grew up on a dairy farm and did his PhD research on learning and
preference in cows. In 2007, during a radio interview about the environmental impact of cattle excretion, the host
suggested Matthews should toilet train them. It was a joke – but it got Matthews thinking.
In 2015, Matthews was working with Professor Lars Schrader at the Federal Research Institute for Animal Health
in Germany when Schrader suggested toilet training to deal with ammonia emissions, which result from contact between
faeces and urine. Previous international attempts to toilet train cows had seen little success, but Matthews thought
that with his deep expertise, he might be able to do better. He brought in Elliffe, who has complementary skills in
behavioural analysis, to help.
With their German colleagues, Matthews and Elliffe worked with 16 calves at a farm operated by the Research Institute for Farm Animal Biology
in Germany. First, they demonstrated that most calves could be trained to “hold it.” If they began to urinate in the
wrong place, the scientists would make their collars vibrate. While the vibration didn’t hurt them, most of the calves
soon learned to walk a short distance to a latrine pen.
Next, Matthews and Elliffe put the calves in the latrine pen, which was bright green to differentiate it from other
pens, and rewarded them with a favoured food treat if they urinated there.
“This is how some people train their children – they put them on the toilet, wait for them to pee, then reward them if
they do it,” said Matthews. “Turns out it works with calves too. In very short order, five or ten urinations for some
animals, they demonstrated they understood the connection between the desired behaviour and the reward by going to the
feeder as soon as they started urinating.”
The next progression was to increase the distance cows had to walk to the latrine. If “accidents” occurred in another
part of the barn, scientists would squirt a little cold water at them. Most of the calves soon learned the ultimate
“Very quickly, within 15 to 20 urinations on average, the cows would self-initiate entry to the toilet. This is very
exciting because it means they were paying attention to their bladder getting fuller,” said Matthews. “By the end,
three-quarters of the animals were doing three-quarters of their urinations in the toilet.”
The calves received only 15 days of training and the majority learned the full set of skills within 20 to 25 urinations,
which compares favourably to toilet-training time for three- and four-year-old children.
The next step for Matthews and Elliffe is to bring their research to the New Zealand context. In the Northern
Hemisphere, cows spend much of their time in barns. In New Zealand, they spend most of their time outdoors. This makes
toilet training more of a challenge. However, cows do gather for milking and receiving supplements, so it may be
possible for them to use a latrine at those times. Installing latrines outdoors may be another possibility. Even if
these changes result in a lower success rate, reducing urine patches would have significant environmental benefits.
“If we could collect 10 or 20 percent of urinations, it would be sufficient to reduce greenhouse gas emissions and
nitrate leaching significantly,” said Elliffe.
Another challenge will be to scale up so it’s economically feasible to train millions of animals. This could be
accomplished by using urination-detecting sensors and automatic reward systems. Trained cows could be transitioned into
not expecting a food reward after every urination, the researchers say.
With help from UniServices, Matthews and Elliffe have met with representatives of the New Zealand dairy industry, who
are interested in the research as a potential way of avoiding the herd reductions that may otherwise be necessary to
meet emissions targets.
A further application of the research may be to extract and reuse nutrients, such as nitrogen and phosphorus, from the
collected cow urine. At the University of Auckland and elsewhere, there are researchers in fields such as chemistry and
engineering working on closely related problems.
“This is new science, what we’ve done here, so there are many ways to push it,” said Matthews.
This work was supported by the Volkswagen Foundation.
*The link to the paper: Dirksen et al. 2021: “Learned control of urinary reflexes in cattle to help reduce greenhouse gas emissions
”, Current Biology, will be live when the embargo is lifted.
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