Bovine Coronavirus (BoCV) Infection in Calves with Diarrhoea and Their Dams

Abstract

Background: Bovine coronavirus (BoCV) is common with high seroprevalence in dairy cattle. It is reported in many countries. Also, BoCV causes diarrhea in dairy calves. The transmission of BoCV is the fecal-oral/aerosol-nasal routes. Feces from clinical cases or clinically normal dairy cattle are source of infection, also contamination of feed and water. The purpose of the current study was to investigate BoCV infection in diarrheic calves (age and sex) and their dams (age). For this reason, the serological and virological methods were used. Haematological parameters of the calves and their dams were compared using the statistical methods.Materials, Methods & Results: In this study, following clinical examination of 3500 cattle and their calves from 25 number of dairy farms 184 calves with diarrhoea and their dams (183) (≥2 - ≤6 age) were sampled for BoCV presence by enzyme linked immunosorbent assay (ELISA). Additionally, all blood samples were examined by hematological methods. 172 (93.99%) cows and 172 (93.99%) calves were found antibodies (Ab) positive (+). The high levels of Ab for BoCV were detected as 36.05 % in dams 6 years and older ages. In the calves, Ab to BoCV were found at the highest level (25.26%) in the female calves ≥5 - ≤6 months ages. BoCV antigen (Ag) was detected in only faecal sample of a (0.54%) calf. When the haematological parameters were compared between BoCV Ab (+) and BoCV Ab negative (-) dams, only white blood cell (WBC) values were found statistically significant (P < 0.05). When the haematological parameters were compared between BoCV Ab (+)/Ag (-) and BoCV Ab (-)/Ag (-) calves, WBC (P < 0.05), lymphocyte (P < 0.01) and granulocyte (P < 0.01) values were found statistically important. When the haematological parameters were compared between BoCV Ab (+)/Ag (+) and BoCV Ab (-)/Ag (-) calves, both lymphocyte and granulocyte values were statistically important (P < 0.01).Discussion: BoCV infection has found worldwide among cattle of all ages. The disease results in major economic losses in dairy herds that result from treatment costs and calf deaths. One hundred seventy two out of 183 mothers whose blood sampling was done were detected as seropositive. Many researchers found similar results in dairy cattle. It was detected the highest seropositivity in cattle more than six years old. One hundred seventy two blood samples out of 184 calves were detected seropositive. Also, the highest seropositivity was detected among of > 5 and < 6 months of age. BoCV Ag (+) presence was detected in only one faecal sample of one calf out of 184. Researchers were found same or higher BoCV Ag(+) rates in faeces of diarrheic calves. In the study lymphocyte counts of seropositive cows and in Ab(+)/Ag(+) calves determined decrease. However, the counts in seropositive calves were increased. Leukocytes levels were also high in seropositive calves. Haematocrit values were decreased in seropositive cows, calves and in Ab(+)/Ag(-) calves. BoCV infections were detected at low level in diarrheic calves. But, BoCV seropositive mature and diarrheic calves were found at high levels. Haematological application methods could be used to be supportive with the serological and virological methods. All farm managements should be maintained with strict hygiene practices. Milking bottle, calf pens or hutches need to be sanitized. The calves must be prevent contamination from faeces and urine of other calves. The protective vaccination must be applied all animals.