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 infection ( infectious rhinotracheitis - shipping fever <WSD>complex</WSD> ) . 
Meaning of the word marked with <WSD> tags:  a conceptual whole made up of complicated and related parts