The milk industry
A cow, as any female mammal, only produces milk after parturition. Then, the calf is taken from his mother - the males to be used in the meat industry and the females in the milk industry. The separation between the calf and his mother is a tough experience to the nursing calf. And the mother may also express its agony through crying and mooing.
Through "cultivation", the farmers increased the daily amount of milk being pumped out from the cow to more than thirty liters, while only a few decades ago the daily amount was no more than eight liters. The cow's body wasn't adjusted to the changes and as a result the cows suffer from injuries and disabilities. The enormous strain to the udders causes blood vessels to rupture. When the tendons that hold the udders loosen - the udders fall, the nipples get infected and inflammations and edemas rapidly develop. "Redundant" nipples may exacerbate these infections; therefore they are cut off using sharp scissors, without painkillers.
Even though the life expectancy of the cow is more than twenty years, cows in modern farm are slaughtered at the age of three to six. Many cows collapse from exhaustion before reaching the slaughterhouse, so they are pulled with a metal chain or carried with a fork lift, which leads to injuries, strains and fractures.