Associations between bovine coronavirus and bovine respiratory syncytial virus infections and animal performance in Swedish dairy herds

Abstract

To assess the economic impact of bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) infections, accurate estimates of their associated effects on animal performance are needed. This study aimed to quantify the variation in individual test-day milk yield and somatic cell count, risk of reproductive failure after first service of dairy cows, and risk of death of calves and heifers according to the BCV and BRSV status of the herd. Three types of status were defined for BCV and BRSV infections, based on 1) the dynamics over a 7-mo period of BCV- and BRSV-specific antibody levels in pooled milk of primiparous cows; 2) the possible occurrence of presumably BCV- and BRSV-related clinical outbreaks; and 3) the combination of both pieces of information. A total of 36,184 test days, 2,716 cows with a first service, and 4,104 calves and heifers in 65 Swedish herds were included in the analyses. Animal performance associated with BCV and BRSV infections was quantified using hierarchical mixed generalized and survival models, after adjustment for covariates known to influence the performance under study. A significant reduction in milk yield was observed for cows in presumably BRSV recently infected herds, as well as in herds having a presumably BRSV-related clinical outbreak (of 0.57 and 0.91 kg/d, respectively), compared with cows in presumably infection-free herds. There was also a significant increase in somatic cell count (of 12,000 cells/mL) for cows located in herds with a BRSV outbreak. The risk of failure after first service, as well as the risk of death in calf and heifer, was numerically higher in BRSV-infected herds, although this was not statistically significant. In contrast, BCV infection herd status, as defined in the present study, was not significantly associated with any production losses in animals from infected herds compared with those in infection-free herds.

Herd level estimation of probability of disease freedom applied on the Norwegian control program for bovine respiratory syncytial virus and bovine coronavirus

“…Transmission dynamics for BCV has not yet been investigated in Norway, although one study describes a regional outbreak of winter dysentery (Toftaker et al, 2017). Studies from Sweden have shown that recent BCV infection is common, indicating that the infection is easily transmitted (Beaudeau et al, 2010;Ohlson et al, 2013). Due to the constant risk of virus introduction, the assumption that a negative status is valid for a long time is questionable.…”

Bovine respiratory syncytial virus and bovine coronavirus antibodies in bulk tank milk – risk factors and spatial analysis

“…BRSV was the most commonly isolated agent in respiratory outbreaks in cattle herds in a recent Norwegian study (Klem et al, 2014a). BCoV is the cause of calf diarrhea, respiratory disease and winter dysentery (contagious diarrhea in adult cattle) (Boileau and Kapil, 2010) have shown significant effects of BCoV infection on production in terms of decreased milk yield and poor growth rate (Tråvén et al, 2001;Beaudeau et al, 2010b) which both result in economic loss.…”

Bovine respiratory syncytial virus infection enhances Pasteurella multocida adherence on respiratory epithelial cells

“…The genome is translated into 11 proteins by 10 mRNAs (Gershwin et al, 2005;Meyer et al, 2008). BRSV is the primary etiological agent of respiratory disease in calves aged up to 12 months (Gershwin et al, 2005); indeed, it is a major cause of respiratory disease in beef and dairy calves worldwide (Beaudeau et al, 2010;Klima et al, 2014). BRSV is capable of infecting feedlot cattle and cattle on dairy farms, resulting in clinical disease in the absence of bacteria (Larsen et al, 2001;Tjønehøj et al, 2003); however, initial infection by BRSV suppresses the bovine immune system and facilitates secondary infection of the lower respiratory tract by bacteria (Larsen et al, 2001;Gershwin et al, 2005).…”

“…BRSV is capable of infecting feedlot cattle and cattle on dairy farms, resulting in clinical disease in the absence of bacteria (Larsen et al, 2001;Tjønehøj et al, 2003); however, initial infection by BRSV suppresses the bovine immune system and facilitates secondary infection of the lower respiratory tract by bacteria (Larsen et al, 2001;Gershwin et al, 2005). Therefore, BRSV is considered to be a causative agent of bovine respiratory disease complex (BRDC), which results in economic losses to farmers because of the morbidity and mortality in cattle (Beaudeau et al, 2010;Klima et al, 2014).…”