From Angus Australia.
Selected as being genetically capable to resist diseases.
soooo less or no sick pulls, perhaps less to no vaccinations needed etc..
And this tech has been ongoing for awhile.
then link from there.
there is a list of genetic lines ( including USA cattle ) that have higher proven ImmuneDEX or better immune systems.
Finally a rating that means $$$$.
those calves that have never seen a needle and will never need to are worth $100 to $200 per head More Money.
Cows that throw disease resistant calves are worth say $400 to $500 per, More Money.