Abstract
Simple SummaryIn bovines, infection of the respiratory tract is frequent. It may lead to severe disease and death, and often requires antimicrobial treatment. Antimicrobial treatment is known to be related to antimicrobial resistance, which poses a threat to public health; therefore, efforts to better understand the causes of airway infection must be undertaken. Many different pathogens may be responsible for disease onset, including viruses. The aim of this study was to describe the prevalence of respiratory viruses in Swiss veal calves and to identify risk factors for infection. In a convenience sample of 764 swabs, prevalence rates were determined for bovine respiratory syncytial virus (BRSV, 2.1%), bovine parainfluenza-3 virus (BPI3V, 3.3%), bovine coronavirus (BCoV, 53.5%), influenza D virus (IDV, 4.1%), and influenza C virus (ICV, 0%). Due to the high prevalence rate, risk factors were investigated for BCoV. Younger calves tested positive more frequently than older calves. Increasing group size was associated with increasing probability for occurrence of BCoV. To summarize, different viral pathogens circulate in veal calves.The prevention of bovine respiratory disease is important, as it may lead to impaired welfare, economic losses, and considerable antimicrobial use, which can be associated with antimicrobial resistance. The aim of this study was to describe the prevalence of respiratory viruses and to identify risk factors for their occurrence. A convenience sample of 764 deep nasopharyngeal swab samples from veal calves was screened by PCR for bovine respiratory syncytial virus (BRSV), bovine parainfluenza-3 virus (BPI3V), bovine coronavirus (BCoV), influenza D virus (IDV), and influenza C virus (ICV). The following prevalence rates were observed: BRSV, 2.1%; BPI3V, 3.3%; BCoV, 53.5%; IDV, 4.1%; ICV, 0%. Logistic mixed regression models were built for BCoV to explore associations with calf management and housing. Positive swab samples were more frequent in younger calves than older calves (>100 days; p < 0.001). The probability of detecting BCoV increased with increasing group size in young calves. Findings from this study suggested that young calves should be fattened in small groups to limit the risk of occurrence of BCoV, although an extended spectrum of risk factors for viral associated respiratory disorders such as nutritional aspects should be considered in future studies.
Highlights
Since the 1960s, bovine respiratory disease (BRD) has been a major challenge for the beef and dairy industry, in veal calf farming, as well as for veterinarians and researchers
Based on existent nasopharyngeal swabs used in previous projects, the principal aims of the present study were to describe the occurrence of viral pathogens with a potential involvement in BRD in the upper respiratory tract of veal calves in Switzerland (i.e., bovine respiratory syncytial virus (BRSV), bovine parainfluenza-3 virus (BPI3V), bovine coronavirus (BCoV), influenza C virus (ICV), and influenza D virus (IDV)), to perform a risk factor analysis to explore associations between the presence of these pathogens and factors related to calf management and housing, and to investigate co-infections of viruses and bacteria
This study focused on the investigation of the prevalence of viral pathogens in Swiss veal farms and risk factors involved in BRD, the population under study was limited in size and geographical extension
Summary
Since the 1960s, bovine respiratory disease (BRD) has been a major challenge for the beef and dairy industry, in veal calf farming, as well as for veterinarians and researchers. In veal and beef production, performance and profitability can be quantified, e.g., through weight loss or reduced average daily gain in the living animal, and through carcass traits after slaughter. BRD decreased average daily gain and had significant effects on hot carcass weight and marbling scores in feedlot cattle [9]. Assuming that weight loss leads to anorexia, depression, a febrile response, and inflammation, this results in concerns for animal welfare in addition to the economic aspects. These circumstances emphasize the need for a better understanding of the etiopathogenesis of BRD and improved disease control strategies
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