Abstract: [Objective]Clostridium perfringens can infect calves through various ways such as digestive tract and trauma,resulting in diarrhea and sudden death of calves.[Method]In this experiment, field investigation, pathological autopsy and smear staining microscopy of diseased tissues were used to diagnose the cases of calf death caused by suspected Clostridium perfringens infection,and then corresponding comprehensive prevention and control schemes were adopted.[Result]The field investigation showed that the incidence of the disease was 16.35 %（34 /208）,and the mortality rate was 11.76%（4/34）.Finally,30 calves without therapeutic value were eliminated. The results of smear and Wright 's staining microscopy of liver,intestinal contents,mesenteric lymph nodes and other tissues of dead cattle showed that the pathogenic bacteria were Gram-positive,rounded at both ends,with obvious capsule of coarse bacilli.[Conclusion]Based on the field investigation,medical history analysis and morphological observation of bacteria,it was determined that the infection of Clostridium perfringens was the cause of the death of calves. The main route of infection was the digestive tract transmission of feeding cow residues and unfermented wrapped silage.Through emergency immunization,stopping feeding contaminated forage and drinking water disinfection, the further spread of the disease was effectively controlled.

Key words: clostridium perfringens, large-scale pasture, prevention and control