No burping or farting, please! So read a recent memo coming out of British chocolate-maker Cadbury – to its bovine employees. In an effort to reduce its contribution to global warming, the company has been looking at ways to reduce the amount of methane given off by its cows.

According to Cadbury, over 60% of its greenhouse gas emissions come from the milk used to make its chocolate — a glass and a half per bar, as it proudly states. Each dairy cow annually emits between 80 and 120 kg of methane (incidentally, mainly through burping and not farting) — which is equivalent to the carbon emissions given off by an average family car over a year. As if eating chocolate wasn’t guilt-inducing enough for some already.

So, the company is teaching its farmers to put their cows on a diet and has recently come out with a guide to low carbon farming. By modifying their diets, the hope is to reduce the amount of methane that is produced by micro-organisms in the cows’ stomachs.

Of course, it's not all about methane, which makes up only about a quarter of the average dairy farm's emissions. Cadbury has committed itself to a reduction of 50% in its overall carbon emissions by the year 2020, and says it's on track to achieve a 10% reduction by 2010. Going "low carbon" will mean farmers have to take a hard look at the overall energy efficiency of their processes and improve the way they use fertilizers. And let's not forget the practice of deforestation, labeled by some as the "hidden cause of global warming," which is used to make way for new pastures. More on that another time.