Final answer:
The killed BVD/IBR vaccine is preferred over a modified live vaccine during pregnancy, in immunocompromised animals, and during calving season to ensure the safety and health of the animals.
Step-by-step explanation:
Reasons for Using a Killed BVD/IBR Vaccine Over a Modified Live Vaccine
There are certain circumstances where using a killed BVD/IBR vaccine is preferred over a modified live vaccine. The specific reasons for this include:
- Pregnancy: To avoid potential risks to the fetus, killed vaccines are safer as they do not contain live organisms that could replicate and cause infection.
- Immunocompromised Animals: Animals with weakened immune systems may not be able to handle the controlled infection induced by live vaccines, thus killed vaccines provide a safer alternative.
- Calving Season: Due to the potential stress and increased susceptibility to infections around calving, killed vaccines may be preferred to reduce risk of disease transmission.
All of the above reasons (a. Pregnancy, b. Immunocompromised animals, c. Calving season) are situations where killed vaccines should be used over live vaccines to ensure the safety and health of the animals involved.