A fella who bought a part of our cowherd 8 years ago has used Shaver bulls on them.  I believe Red Poll and Shorthorn are two of the breeds that make up the composite.   Would make sense as this fellow has many mottled colour calves that looked like Shorthorns (Off straightbred Hereford cows and a solid red Shaver bull).  He gets docked at the sale barn of course, but they are good growthy calves.

I should add that he sources his bulls from a Shaver Beefblend breeder in Brandon, MB.  Don't remember the name.  They have an ad occasionally in the Manitoba Co-operator and Western Producer.