What is the primary purpose of administering vaccines to animals?

The primary purpose of administering vaccines to animals is to stimulate an immune response. Vaccines work by introducing a harmless component of a pathogen, such as a weakened or inactivated form of the virus or bacteria, into the animal's body. This exposure helps the immune system recognize the pathogen and prepare to fight it off in the case of future exposure. By doing so, vaccines can help prevent serious diseases and infections, creating a stronger immune defense.

The other options do not accurately reflect the main role of vaccines. Treating existing infections would require medication therapies, not vaccination. The enhancement of growth and weight pertains to nutritional strategies rather than immunological approaches, while providing nutritional benefits relates more to dietary supplements and does not cover the preventive nature of vaccines. Therefore, stimulating an immune response is the correct and primary role of vaccination in animal health.