What is a training set?
Is the tenderness marker the same across breeds?
In total genetic interaction with total environment, is tenderness a trait that expresses itself more or less with life history environmental circumstances?
Things like drought, temperature, nutrition? even wind? Various forms of stress?
For the segment of the beef business that markets directly, or markets genetics to producers who market beef directly, tenderness is more important than marbling. Personally, I think meat (promoted grass fed) that hangs 3 weeks to acquire tenderness is missing the mark. We could learn a lot from the South Americans about tenderness, perhaps.