Mazandaran province is with an area of about 460,456 km², at the proximity of the Caspian Sea on the north and Alborz Mountain on the south (Fig. 1). The province enjoys a moderate, semitropical climate with an average temperature of 25℃ in summer and about 8℃ in winter. The province also enjoys a quasi-Mediterranean climate, and the annual rainfall averages 650 mm in the eastern part of Mazandaran province and more than 1,300 mm in the western part. For its abundant superficial water resources, it is favorable for agriculture and animal husbandry. A considerable area of this province is used for rice culture. Once the rice is harvested, many of the fields are used for raising sheep, cattle, and buffaloes. Permanent open pastures and forests are used independently by owners to feed their animals. Official estimates for the year 2002 listed 2,106,300 sheep, 232,700 goats, 7,500 buffaloes, 21,800 horses, and 886,800 cattle, the latter including 69.7% of the domestic race (a special breed typical of Mazandaran), 25.2% mixed breeds, and 5% Holstein (Iranian Veterinary Organization, unpublished data).

During the spring and summer of 2004-2005, the tick samples were collected from infested cattle that grazed in the eastern and western areas in Mazandaran province. After collection, tick samples were separately stored in 70% ethanol, labeled with the date and the name of the field until the species determination. Adult ticks were identified under a stereomicroscope, according to general identification keys (Hoogstraal, 1956; Walker et al., 2003; Estrada-Pena et al., 2004).

A total of 873 ticks were collected from the 86 heads of cattle. The tick fauna was composed of 7 species (Table 1). The most frequent and abundant tick species in western parts of Mazandaran province were Boophilus annulatus, Rhipicephalus bursa, and Haemaphysalis punctata, whereas in eastern parts were Hyalomma marginatum, Hyalomma anatolicum excavatum, and Ixodes ricinus (Table 2).

In the present study, the highest prevalence of B. annulatus was observed in the western area of Mazandaran province. This finding is in agreement with the observation made by Razavi and Seifi (2006). Also, Nabian et al. (2007) reported the highest prevalence of B. annulatus in Giluan province near regions to the western area of Mazandaran province. The variation in the prevalence of western and eastern areas may be due to climatic factors, since the western areas are more forest regions and the annual rainfall averages more than the eastern areas. The prevalence of R. bursa (16.8%) in the present study is along with the results of the study by Razavi and Seifi (2006). Contrary to our finding, Nabian et al. (2007) found only Rhipicephalus sanguineus with a high prevalence in the sheep of Mazandaran province. Mazlum (1971) showed that R. bursa is the dominant tick in the north areas of Iran and R. sanguineus in the south west of Iran. Three reasons may account for this discrepancy. First, cattle in contrast to sheep are an unsuitable host for R. sanguineus. Second, the origin of the collected ticks in sheep by Nabian et al. (2007) may be from neighboring province, such as Khorasan province with a high prevalence of R. sanguineus in sheep and goats (Razmi et al., 2002, 2003). Third, climatic changes that occurred after a long time may have resulted to modify the distribution and abundance of ticks and caused a heavy spread of tick species with strong adaptability, such as R. sanguineus.

Ixodes ricinus is one of the species found only in regions of Caspian Sea zone (Mazlum, 1971). The prevalence of I. ricinus was similar to the finding of Razvi and Seifi (2006) and was higher than the results of Nabian et al. (2007). So far, several Haemaphysalis species were collected from different hosts in Mazandaran province (Mazlum, 1971; Rahbahri et al., 2007), but we observed only H. punctata in cattle. In a recent study, the prevalence of this species was higher than other species in Caspian Sea zone (Rahbari et al., 2007). Among the 4 Hyalomma tick species found in this study, H. marginatum and H. anatolicum excavatum were those abundant in the eastern and western areas, respectively. Mazlum (1971) reported all of these Hyalomma species, excluding H. asiaticum, in Mazandaran province. It seems that H. asiaticum was observed for the first time in cattle of this area. Nabian et al. (2007) observed only H. anatolicum and H. deteritum with low prevalences in Mazandaran province. Two species of Dermacentor, i.e., D. marginatus and D. daghestanicus, were reported from this province in the last time (Mazlum, 1971). However, only one female tick was collected in the present study, and we could not identify the species. Based on the results, it is concluded that B. annulatus, R. bursa, and H. marginatum are dominant tick species in dairy cattle of Mazandaran province, and should be done more studies about the role of these species in transmission of blood parasites.