Sentence:  For cows , feed providing an intake of 0.1 milligram of Aureomycin per pound of body weight daily aids in the reduction of bacterial diarrhea , in the prevention of foot rot , and in the reduction of losses due to respiratory <WSD>infection</WSD> ( infectious rhinotracheitis - shipping fever complex ) . 
Meaning of the word marked with <WSD> tags:  the pathological state resulting from the invasion of the body by pathogenic microorganisms