On farms where cows relieve themselves as they graze, the accumulation and spread of cowpats and other waste can contaminate local soil and waterways. The alternative – confining cows in barns – does not only mean unhappier cows but also results in their urine and faeces combining to produce ammonia, an indirect greenhouse gas.

Although the ammonia produced in cow waste does not directly contribute to climate change, when it leaches into the soil, microbes convert it into nitrous oxide - the most significant greenhouse gas after methane and carbon dioxide. Agriculture is the largest source of ammonia emissions, with livestock farming making up over half of that contribution.

However, in uplifting bovine news this week, researchers have reported in Current Biology that cows can be toilet-trained. This enables waste to be collected and treated, thereby keeping barns clean, reducing air pollution and permitting the creation of more open, animal-friendly...