One of the most important reasons of the abortion and congenital malformation in newborn calves is BVDV infections considering the infection profusion at all over the world, it causes (leads to) many economic losses in cattle husbandry industry . The most important purposes of this research were to determine the rate of infection publicity and variant interference rate such as age, sex, health management and other environmental factors. In this research we tested 1357 serum samples Chahra Mahal were taken from different township of Caharmahal Bakhtiary province in Iran. All of those samples were tested in serum neutralization test (SN) by using the NADL strain of BVD virus. Infection rate in Shahrecord was 15.66%, in Brujen, it was 32.29%, in Farsan 27.88%, in Lordeghan 37.77% and in Ardel township was 14.98. The rate of whole province was 23.36%. Comparison between age groups showed that there was the lowest infection rate in 0-1 years old 12.5% and the cows had more than 8 years old had the most infection rate 47.36%. This means that increasing in age causes .the increase in rate of infection. There is the least infection rate (12.24%) in spring and the most infection rate (26.54%) in autumn. If the herds had veterinary inspection, this rate will be 16.19% and if they hadn’t, the rate were 29.57%. The infection rate in cows which had regular vaccination programme were 20.62%, and those didn’t have a regular vaccination programme were infected about 34.05% and the infection in males were 19.17% and in females 23.59%. On the other hand, infection rate about cows keeped with sheep together was 37.83% and cows separated from sheep have infection about 16.98%. The infection rate in cows which had abortion were 29.26% and those who had not abortion were 23.4 1%. Statistic analysis of these data shown that there was a significant difference between, increasing of age and keeping cows and sheep together and BVDV infection with there wasn’t any significant differenc between BVDV infection with veterinary inspection, vaccination, sex and health management.
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