Antibodies on this scale are not _produced_ by animals. The way these things work is an antibody that binds to a specific target will be _discovered_ by immunizing animals and then screening it's blood or lymph nodes for antibodies of interest. Once an antibody is found and commercialized, it is produced in large bioreactors of cell cultures engineered to produce large amounts of a particular protein (in this case the antibody).

Source: work as a software dev at a company developing antibody drugs