The first two generations were Hereford stud bulls and since then it has been Hereford/Angus bulls
The Australian Herefords are hardy and stay fertile a lot longer than other breeds, the Angus are good milkers and birthers with good meat quality that can handle the cold winters we get here, in my area the majority of the cattle are this mixture.
Angus are especially good for the fact that they only sexually mature after they are physically big enough enough to calve.
so immature pregnancy is extremely rare.
I'm also really interested in Park, like tipped park in particular, one of my neighbours has speckled park.
One of my cows jumped the fence to get to their bull a year ago but did not end up getting pregnant from the encounter.