Urine is a bigger problem, at least in Europe, Matthews said. But he predicted they could train cows to poop in a certain place. Urine contains nitrogen, and when mixed with feces 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 8 gallons (30 liters) of urine a day, Matthews said. In 2019, nitrous oxide comprised 7% of all the U.S. greenhouse gases, according to the Environmental Protection Agency.
At the lab is 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.
There are a couple caveats to this experiment. 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.
Experiment.1 They gave diuretics to the cattle to get them to urinate more because they had limited time to run the experiments under ethics guidelines.
Experiment.2 They trained cows to use the MooLoo to urinate, not defecate.
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."
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.
