الفهرس 
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Abstract
A total of two hundred fecal samples of young calves from the examined calves farms, isolated 190 (95%) C. perfringens. Out of 190 isolates 150 (78.9%) revealed toxigenic isolates and 40 (21.1%) were non toxigenic. 150 toxigenic isolates were typed C. perfringens type A. A total of 90 intestinal samples were taken from dead calves, 90 isolates were C. perfringens. Out of 85 (94.4%)of dead calves revealed toxigenic isolates while 5.5% were non toxigenic. from 85 positive samples of intestinal contents of dead calves 88.8% were alpha toxin, 3.3% beta toxin and 2.2% epsilon toxin from slaughter house we examined 10 intestinal samples from calves suspected to be suffer from haemorrhagic enteritis before slaughter. We found that all isolates were C. perfringens and about 40% from 10 of slaughtered calves were toxigenic, while 60% non toxigenic. Typing of fecal and intestinal isolates by dermonecrotic reaction and PCR, the main cause of enterotoxaemia in calves was alpha toxin which secreted by C. perfringens type A that resulted in sudden death of young calves. The obtained results revealed that immunoprophylaxis is a control measure of much importance for protection of young calves from sudden death caused of enterotoxaemia which lead to great economic losses not only from calf mortality but also from losses in future growth and production. In this work a toxoid vaccine prepared from highly toxigenic isolates that causing enterotoxaemia using two different adjuvants: montanide oil ISA 206 and aluminium hydroxide gel and vaccinating pregnant cattle to follow up maternal immunity in their newly born calves and determine the titer of antibodies by SNT and ELISA methods. Two groups of pregnant cattle were vaccinated. The immune response of vaccinated pregnant cattle to monovalent C. perfringens type A vaccine adjuvanted either with montanide oil ISA 206 or aluminium hydroxide gel was higher and the antibody titer was 30IU / ml in 1st group meanwhile the 2nd vaccinated group was 40 I.U./ml. Titer of antibodies in young calves borne to dams of 1st group reached to 20IU/ml in the 1st week then begin to decrease and reached to 15, 15, 10, 5,5,3,2,1,1 and 0.5IU/ml at 2, 3,4,5,6,7,8,9,10 and 11 weeks of age, while titer of antibodies in young calves that borne to dams of 2nd vaccinated groups also begin high 30IU/ml at first week then decreased and reached to 25, 15, 10,5,5,3,2,1,1and 0.5 at 2, 3,4,5,6,7,8,9,10 and 11 weeks of age. The vaccine achieved good maternal immunity in newly born calves reached to 11 weeks and this ensured the importance of maternal immunity to calves in this period which achieved by passive immunization of pregnant cattle.