BACKGROUND: Diarrhea syndrome is associated with irrecoverable damages in the husbandry industry worldwide due to losses resulted from fatality, weight loss, growing weak calves and treatment costs. Hence, investigation of diarrhea causes in different areas is important to attempt management strategies to prevent and control it. OBJECTIVES: Present study was carried to investigate prevalence of some important entropathogens in diarrheic calves until three months old, in Shahrekord suburb husbandries. METHODS: Fecal samples were taken from 82 female calves in first day of diarrhea and were examined for isolation of salmonella, Escherichia coli, clostridium, cryptosporidium, and coccidia through common microbiological and parasitological methods. RESULTS: In general, prevalence of isolated organisms were: salmonella 36.6%, Escherichia coli 24.4%, clostridium 9.8%, cryptosporidium 9.8%, and coccidian 7.31%, and Escherichia coli K99 were isolated from four calves. The most prevalent pathogens were Escherichia coli and Salmonella. CONCLUSIONS: The calves are unavoidably exposed to infectious causes of diarrhea during their whole lifespan, because they acquire organisms from environment immediately after birth. Therefore, attempts at efficient management methods, hygienic principles and receiving enough colostrum, particularly in cold seasons, may be efficient in the control, prevention and decrease of diarrhea and its subsequent losses.

BACKGROUND: Salmonella are endemic on most large intensive dairy farms and salmonellosis is a common cause of neonatal morbidity and mortality. Disease and mortality usually reflect a variety of management events and environmental stressors that contribute to compromised host immunity and increased pathogen exposure. OBJECTIVES: In this study, PCR method was used to identify Salmonella Enteritidis, Infantis, Dublin and serovars isolated from diarrhea samples and aborted fetuses of Tehran and Alborz provinces dairy Farms. Further observation showed that the isolation of S. Enteritidis and S. Infantis is closely related to the consumption of contaminated poultry meat powder in diet of cows. METHODS: Forty-one Salmonella were isolated from diarrhea and aborted fetus samples in Tehran and Alborz provinces Farms and were confirmed by biochemical assays, then the isolates were identified by serological methods by polyvalent and monovalent Salmonella antisera. DNA of samples was extracted by Boiling method and was tested by PCR. Salmonella serovars were identified according to the presence of specificgenes for Salmonella Enteritidis, Infantis and Dublin.  RESULTS: All samples were tested by PCR were positive. 32 samples were identified as Salmonella Enteritidis (78/04 %), 4 samples were identified as Salmonella Infantis (9/77 %) and 5 samples were identified as Salmonella Dublin (12/19 %). CONCLUSIONS: According to the results, it seems that PCR can be used as a alternative method to the expensive and time consuming biochemical and serological methods for identifying Salmonella serovars. As Salmonella Enteritidis was usually isolated from poultry, isolation from cows may be due to has been used chicken meat powder in diet of the dairy farms.