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Objective: 1-If Histophilus somni can be involved of mastitis in Holstein dairy cattle. 2- The frequency of
Histophilus somni and other bacteria isolated in mastitis
cases. Design: Cross-sectional. Animals: 116 Holstein dairy cattle.
Procedure: Cows were examined in 6 dairy cattle herds in
suburb of Mashhad, Iran. They were tested for clinical (No:
22; 18.64%) and sub clinical mastitis (No: 94; 81.04%) by using routine clinical methods and California Mastitis Test
(CMT). They were cultured in Brain Heart Infusion Yeast
agar at 37° C in 10% Co2 for Histophilus somni and other
bacteria infection. They were evaluated after 24-48 hours.
Statistical analysis: Chi- square and Fisher tests.
Results: Histophilus somni was isolated from only 2(1.73%)
clinical mastitis cows. Sub clinical mastitis cows were not infected by Histophilus somni. There were significant differences between clinical and sub clinical mastitis in
respected to mammary gland infection (P<0.05). The
infection rate in winter and spring seasons were 1 .73%(No:
58) and (1.73%), respectively. However, 8 bacteria were
isolated, too.
Conclusion: The infection rate of mastitis due to
Histophilus somni was very low (1.73%). It was cultured
difficulty. The real infection rate may be higher. It is
necessary to use more sensitive methods. J.Fac.Vet.Med.
Univ. Tehran. 60,2:137-141,2005.