Paratuberculosis, also known as Johne\\\'s disease, is a chronic progressive infection affecting all groups of domestic and wild ruminants, including cattle, goats, camels, buffaloes, and deer. The disease is caused by an acid-fast bacterium called Mycobacterium avium subspecies paratuberculosis. The clinical form of the disease results in chronic diarrhea, weight loss, weakness, and ultimately death. The subclinical form also leads to progressive weight loss, reduced milk production, decreased carcass value, and premature culling. This study aimed to determine the prevalence and directly identify Mycobacterium avium subspecies paratuberculosis in colostrum of dairy cows in several industrial dairy farms in Mashhad using the Nested-PCR method. For this purpose, 100 colostrum samples were collected from four industrial dairy farms in Mashhad. DNA was extracted from the samples and subjected to Nested PCR using specific primers. Out of the 100 colostrum samples collected, 16 samples (16%) were found to be infected with Mycobacterium avium subspecies paratuberculosis, which was confirmed by PCR. The infected samples belonged to three of the studied dairy farms. The isolation of Mycobacterium paratuberculosis from the colostrum of dairy cows in the studied farms highlights the importance of colostrum in the epidemiology of Johne\\\'s disease and its role in transmitting the disease to susceptible newborn calves at risk.

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