What is meant by "over?"

[LocoPollo]

What is meant when people say x hen over y cockerel, or y cockerel over z hen? I know they are crossing/breeding, but what exactly does "over" mean?

 

[danischi24]

It means "bred to". So x rooster "bred to" y hen.

 

[LocoPollo]

Ok, thanks! That is simple enough!