The timing of calf vaccination can affect later performance.
Heather Smith Thomas
Angus Beef Bulletin Extra
A cow in a natural environment may not become exposed to very many disease-causing organisms, but many cattle are confined part of the year in corrals, small pens or pastures that have been contaminated by heavy cattle use — with more chance of disease spread. With vaccination and natural exposure to various pathogens, the cow develops many antibodies and strong immunity. During the last part of pregnancy she puts these antibodies into the colostrum she produces, so her calf can have instant immunity right after it suckles.