When Wacker sells cattle into the feedlot, he’s agreed in advance to raise those cattle exactly as the feedlot wants them raised. He’s used the vaccines the feedlot prefers right down to the brand. He’s fed the animals and bred the animals to the buyer's specification. When he buys cattle from other ranchers, he expects the calves to be raised to the same specification. He pays more for those cattle when those specifications are met.
Source : https://billingsgazette.com/news/government-and-politics/montana-ranchers-divided-after-trump-abandons-plan-to-regulate-cattle/article_fc91eb89-0254-58c3-9505-575f1cef64b4.html