Cows are walking machines. They transform materials (grass, hay, water, and feed) into finished products (milk, beef, leather, and so on). As any factory, cows produce waste. Solid waste is eliminated through the rear end of these ‘complex machines’, and it is used as fertilizer. The fermentation process in their four stomachs produces gas. These walking machines have two chimneys: one in the front end, and other in the rear end. Gaseous emissions through the front end chimney are called burps. Cows burp a lot. Every minute and half these burps release methane gas. Methane is dangerous to the planet because it contributes to the greenhouse effect. The world population is growing very fast. That means there are more people eating beef. Consequently, there is more cattle – more walking machines – producing more methane gas. This is the problem, but very few people want to change their eating habits. What about you?