Urine contains nitrogen, and when mixed with faeces becomes ammonia, which is an environmental issue with acid rain and other problems, Matthews said. It can also taint the water with nitrates and create the airborne pollutant nitrous oxide, he said.
And cows do pee a lot. A single cow can produce about 30 litres of urine a day, Matthews said. In 2019, nitrous oxide comprised 7 per cent of all the US greenhouse gases, according to the Environmental Protection Agency.
"I am not surprised they can train calves to urinate in set locations, but I am surprised no one has demonstrated this before," said Duke University animal cognition scientist Brian Hare, who wasn't part of the research. "The critical question is can it and will it scale?"
If it could be done, toilet training animals makes it easier to manage waste products and reduce greenhouse gas emissions, said Donald Broom, a professor of animal welfare at the University of Cambridge in England.
At the lab in Dummerstorf, Germany, the researchers mimicked a toddler's training, putting the cows in the special pen, waiting until they urinated and then giving them a reward: a sweet liquid of mostly molasses. Cows do have a sweet tooth, Matthews said. If the cows urinated outside the MooLoo after the initial training, they got a squirt of cold water.
Then in two sets of experiments, the researchers let the Holstein cows roam about the indoor facility. When they had to urinate, 11 of them pushed into the pen, did their business, and got their sweet reward.
There are a couple of caveats to this experiment.
One, they gave diuretics to the cattle to get them to urinate more because they had limited time to run the experiments under ethics guidelines.
And number two, they didn't do number twos. They only trained cows to use the MooLoo to urinate, not defecate.
Urine is a bigger problem, at least in Europe, Matthews said. But he predicted they could train cows to poop in a certain place too.
While dogs, cats and horses can be toilet trained, they already show the desire to go in special places, but cows don't, Matthews said.
The biggest environmental problem for livestock, though, is the heat-trapping gas methane they emit in belches and flatulence, a significant source of global warming. The cows can't be trained not to belch or fart, Matthews said: "They would blow up."
- Associated Press