This bizarre animal experiment could solve climate change
It could offer surprising benefits.
Can we toilet train cattle? Would we want to?
The answer to both of these questions is yes — and doing so could help us address water contamination and climate change issues. Cattle urine is high in nitrogen, and this contributes to a range of environmental problems.
When cows are kept mainly outdoors, as they are in New Zealand and Australia, the nitrogen from their urine breaks down in the soil, this produces two problematic substances: nitrate and nitrous oxide.
Nitrate from urine patches leaches into lakes, rivers, and aquifers (underground pools of water contained by rock), polluting the water and contributing to the excessive growth of weeds and algae.
Nitrous oxide is a long-lasting greenhouse gas that is 300 times more potent than carbon dioxide. It accounts for about 12 percent of New Zealand’s greenhouse gas emissions, and much of this comes from the agricultural sector.
When cows are kept mainly in barns, as in Europe and North America, another polluting gas — ammonia — is produced when the nitrogen from urine mixes with feces on the barn floor.
However, if some of the urine produced by cattle could be captured and treated, the nitrogen it contains could be diverted, and the environmental impacts reduced. But how might urine capture be achieved?
We worked on this problem with collaborators from Germany’s Federal Research Institute for Animal Health and Research Institute for Farm Animal Biology. Our research is published today in the journal Current Biology. It forms part of our colleague Neele Dirksen’s Ph.D. thesis.
Toilet training (but without the diapers)
In our research project, funded by the Volkswagen Foundation, we applied principles from behavioral psychology to train young cattle to urinate in a particular place — that is, to use the “toilet.”
Behavioral psychology tells us behavior is likely to be repeated if followed by a reward or “reinforcer.” That’s how we train a dog to come when called.
So if we want to encourage a particular behavior, such as urinating in a specific place, we should reinforce that behavior. For our project, we applied this idea in much the same way as for toilet training children, using a procedure called “backward chaining.”
First, the calves were confined to the toilet area, a latrine pen, and reinforced with a preferred treat when they urinated. This established the cell as an ideal place to urinate.
The calves were then placed in an alley outside the pen and again reinforced for entering the cell and urinating there. If urination began in the path, it was discouraged by a mildly unpleasant spray of water.
After optimizing the training, seven out of the eight calves we trained learned to urinate in the latrine pen — and they learned about as quickly as human children do.
The calves received only 15 days of training, and the majority learned the complete set of skills within 20 to 25 urinations, which is quicker than the toilet-training time for three- and four-year-old children.
This showed us two things that weren’t known before.
- Cattle can learn to attend to their urination reflex because they moved to the pen when ready to use it
- Cattle will learn to withhold urination until they’re in the right place if they’re rewarded for doing so.
Toilet training cattle: The next stages
Our research is a proof of concept. Cattle can be toilet trained and without much difficulty. But scaling up the method for practical application in agriculture involves two further challenges, which will focus on the next stage of our project.
First, we need a way to detect urination in the latrine pen and deliver reinforcement — without human intervention.
This is probably no more than a technical problem. An electronic sensor for urination wouldn’t be challenging to develop, and small amounts of attractive rewards could be provided in pen.
Apart from this, we’ll also need to determine the optimal location and number of latrine pens required. This is a particularly challenging issue in countries such as New Zealand, where cattle spend most of their time in open paddocks rather than barns.
Part of our future research will require understanding how far cattle are willing to walk to use a pen. And more needs to be done to understand how to best use this technique with animals in indoor and outdoor farming contexts.
We know that nitrogen from cattle urine contributes to both water pollution and climate change, and toilet training cattle can reduce these effects.
The more urine we can capture, the less we’ll need to reduce cattle numbers to meet emissions targets — and the less we’ll have to compromise on the availability of milk, butter, cheese, and meat from cattle.