Until he extends the circle of his compassion to all living things, man will not himself find peace.
Dr Albert Schweizer 

cruelty
The handling and slaughter of factory farmed animals causes immense suffering.

Treating other creatures as commodities fosters a culture of insensitivity. Most of us are uncomfortable at some level with exploiting other animals for food.

epidemics
Crowded animal sheds let diseases go lethal on a scale impossible in the wild and fast-tracks their crossover to humans. Epidemics are inevitable until this stops.

antibiotics
Factory farms breed antibiotic resistant disease organisms. Already many antibiotics have been rendered useless. There are few antibiotics left to deal with resistant strains.

pesticides
Pesticides and other chemicals accumulate in animal products as factory farm animals are forced up the food chain to consume fish, grains and corn. Hopefully they are no longer fed animal excreta.

starvation
A huge proportion of the world's fish and grain is diverted to animal feed for marginal financial gains leaving the world's poor short of food.

Cash crops forced on the poor by the IMF and World Bank through corrupt governments have destroyed their sustainable subsistence living. By subsidising western lifestyles the wealth of subsistence economies has transformed into poverty.

environment
Factory farming including aquaculture depletes and pollutes soil, ground-water, waterways and oceans.