Potty trained cows: From polluter to problem solver

 Potty training cattle sounds like a joke but it’s no laughing matter — because cow pee creates nitrous oxide (laughing gas), and lots of it. Cattle manure, mainly urine, excreted directly onto pasture or applied to fields contributes nearly 16 percent of human-induced nitrous oxide emissions. This equates to about 1.5 percent of anthropogenic global greenhouse gas (GHG) discharges. Surprised? Well, consider this — the global cattle population is about 1.5 billion and each animal urinates 15 to 30 liters a day. That’s about 10,000 Olympic-sized swimming pools of pee — every day.

Nitrous oxide is an especially potent GHG, with nearly 300 times the warming potential of carbon dioxide and lasts over 100 years in the atmosphere. No wonder cattle urine is a worrisome contributor to climate change. And the problems with pee don’t end there. At pasture, excess urinary nitrogen leaches from the soil into streams and underground water, degrading aquatic ecosystems and polluting drinking water. In barns and feedlots, urine can mix with feces on the floor to form ammonia. Ammonia causes acid rain, is converted to nitrous oxide, and causes respiratory diseases in humans and animals.

What if the urine could be collected at the source — in a cow toilet? Like children, cattle normally urinate and defecate without control, so potty training would be required. The only problem is, up until now, cows have not been very obliging in this respect. But my team of researchers from the University of Auckland in New Zealand, and the Federal Research Institute for Animal Health and the Research Institute for Farm Animal Biology in Germany have made a breakthrough. We were inspired by methods used for successfully potty-training children.

Each calf was placed in a very distinctively colored pen — the walls were made of green paneling, the floor was soft and green, and there was a green stripe on the one-way entrance door. The calves were given brief training sessions in which every pee was followed immediately by a highly palatable treat – molasses in one experiment and crushed barley grain in another. After five to 10 urinations, most of the calves would turn and face the reward dispenser whilst urinating — clearly displaying a causal link between peeing and payoffs.

So far so good, but the next step provided evidence of the ground-breaking development. We placed the calves in an alley outside the toilet, waited and watched. When showing signs of an impending urination (e.g., by wiggling their hind feet or back), some animals immediately walked up to the toilet, pushed through the door, urinated, collected their feed reward, then exited through a second door. A remarkable result — demonstrating mastery of a set of hitherto unknown learning and cognitive abilities. The animals were attending to internal sensations associated with bladder filling, voluntarily controlling the bladder reflex, self-initiating movement into the toilet and subsequent relaxation of the bladder sphincter, thereby allowing urination. Some calves made mistakes in the alley, which were “corrected” with a gentle spray of cold water. 

Researchers show that cows can be potty-trained. This “MooLoo” training reduces the impact of ammonia emissions released through cow waste by capturing it in a latrine. Read more in @CurrentBiology: https://t.co/Lek0IQn8tG @niebgnal pic.twitter.com/kkxdN505va

— Cell Press (@CellPressNews) September 13, 2021

Within a further 10 to 30 urinations most of the calves had learned the correct toileting sequences. Notably, some calves learned as quickly as the fastest toddlers. At the completion of training three-quarters of the calves were using the toilet consistently.

So, we have proven that cattle can be potty trained. What now? To reduce climate-damaging effects of cattle excreta, we would need to potty train millions of cattle so that their urine could be collected and used in a climate-friendly way. Automated training procedures need to be developed. The technology exists to achieve this e.g., by automatically coupling sensors detecting urination with food rewards when animals are in designated toileting areas. The requisite numbers and locations of “potties” within the farm environment also needs to be determined. Potty training will likely be easier for cattle kept in close confinement such as feedlots and barns.

Modelling has revealed that the capture of about 80 percent of cattle urine in toilets could potentially lead to a 56 percent reduction in ammonia emissions. A similar rate of success with nitrous oxide emissions would help countries with large cattle populations to reduce their GHG emissions footprint. Polluter turned problem solver!

Lindsay R. Matthews, Ph.D., is an animal behavioral scientist at the University of Auckland. He is the senior author of a recent study on potty training cattle in the journal Current Biology. Follow him on Twitter: @LindsayRMatthe1