Isolation of Bacterial causes of Respiratory Infections in Calves in Smallholder farms in and around Gonder Town, Ethiopia

Abstract Background: Bovine respiratory disease (BRD) is considered as the major cause of severe respiratory tract infections in calves. Pasteurellosis is a multifactorial respiratory disease, which mainly affect calves within four weeks of weaning. A cross-sectional study was conducted from October 2017 to April 2018 in and around Gondar town, Amhara Regional State, North West of Ethiopia. The aim of the study was to isolate Mannheimia and Pasteurella species from calves up to six months old, and to assess the associated risk factors with the occurrence of respiratory disease. Sex, age (< 16 weeks and > 16 weeks), body condition status (poor, medium, good), breed (local and cross breed), livelihood (mixed crop and urban), farming systems (semi intensive and intensive), herd size (small medium, and large), maternity pens (present or absent), and method of colostrum feedings (hand bucket and suckling) were the examined risk factors.Results: A total of 84 nasopharyngeal swab samples were collected from calves with any signs of illness related to pasteurellosis. The overall isolation rate of the respiratory pathogens was 64/84 (76.2%) (95% CI=65.7-84.8), with 46.4% of Mannheimia haemolytica and 28.8% Pasteurella multocida isolates. The distribution of pathogens was statistically higher (P< 0.001) in calves with respiratory problems (93.6%; 95% CI= 82.5-98.7) compared to those with no symptoms of respiratory illness (54.1%; 95% CI= 36.9-70.5). Among the examined risk factors age, sex, breed, farming system were found to be potential risk factors and significantly associated with Pasteurella infection of calves (p<0.05). The higher isolation rate of Mannheimia haemolytica indicated that it is the major cause of respiratory disease in the study area.Conclusion: The present finding revealed that pasteurellosis is one of the major diseases of calves in the study area in which M. haemolytica and P. multocida were found to be commonly involved in respiratory infections. Improved farm management including timely feeding of colostrum, appropriate hygiene of the calf house and training of farmers is recommended to prevent and control of respiratory diseases in the study area.