Sentence:  Increases rate of gain and improves feed efficiency , aids in the prevention or <WSD>treatment</WSD> ( depending on level fed ) of the early stages of shipping fever , prevents or treats bacterial diarrhea , and aids in reducing incidence of bloat and liver abscesses . 
Meaning of the word marked with <WSD> tags:  care provided to improve a situation (especially medical procedures or applications that are intended to relieve illness or injury)