Detection of fecal coronavirus antigen in diarrheic calves of high- and average-producing Holstein dairy cows


Abstract: From January to December 2009, 661 fecal samples from natural cases of diarrheic calves were taken by veterinary staff from the Department of Large Animal Internal Medicine of Shiraz Veterinary School and veterinary practitioners in Fars Province, Iran. The samples were taken from 267 diarrheic calves of high-producing dairy cows (HPDCs) and 394 diarrheic calves of average-producing Holstein dairy cows (APDCs). Fecal samples were collected and submitted for the laboratory diagnosis of coronavirus antigens. Herd selection was based on geographical location and density of cattle in the region. All herds had HPDC and APDC coronavirus-infected diarrheic calves in their population. The rate of coronavirus infection in diarrheic APDC calves in the northern region was highest when compared to other geographical locations. It was also found that diarrheic coronavirus-infected HPDC calves in the northern region of Fars Province were at much lower risk of diarrhea than APDC calves in the same region (P < 0.05). Diarrheic coronavirus-affected APDC Holstein calves of younger dams (>2 to 3 years) showed a higher rate of infection when compared to diarrheic HPDC coronavirus-infected calves in the same age group (P < 0.05). It was also found that the proportion of infected coronavirus diarrheic APDC calves decreased with the increased parity of their dams. There was no difference among the occurrence of coronavirus infection in diarrheic HPDC and APDC calves of different herd size groups.

Keywords: Coronavirus, diarrheic calves, dairy cows

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