From off the page of https://www.foodandwaterwatch.org/problems/factory-farming-food-safety explains the problem of factory farming. “Factory farms pollute the environment and our drinking water, ravage rural communities, and harm the welfare of animals—while increasing corporate control over our food. Factory farmingis an unsustainable method of raising food animals that concentrates large numbers of animals into confined spaces.” 
“Eggs From Caged Hens. Battery cages are small wire cageswhere about 95 percent of laying hens spend their entire lives; each hen is given about 67-76 square inches of space (a standard sheet of paper measures 94 square inches).” https://www.google.com/amp/s/m.huffpost.com/us/entry/2458525/amp