Risk factors associated with exposure to bovine respiratory disease pathogens during the peri-weaning period in dairy bull calves

Abstract

BackgroundBovine respiratory disease (BRD) remains among the leading causes of death of cattle internationally. The objective of this study was to identify risk factors associated with exposure to BRD pathogens during the peri-weaning period (day (d)-14 to d 14 relative to weaning at 0) in dairy bull calves using serological responses to these pathogens as surrogate markers of exposure.Clinically normal Holstein-Friesian and Jersey breed bull calves (n = 72) were group housed in 4 pens using a factorial design with calves of different breeds and planes of nutrition in each pen. Intrinsic, management and clinical data were collected during the pre-weaning (d − 56 to d − 14) period. Calves were gradually weaned over 14 days (d − 14 to d 0). Serological analysis for antibodies against key BRD pathogens (BRSV, BPI3V, BHV-1, BHV-4, BCoV, BVDV and H. somni) was undertaken at d − 14 and d 14. Linear regression models (for BVDV, BPI3V, BHV-1, BHV-4, BCoV and H. somni) and a single mixed effect random variable model (for BRSV) were used to identify risk factors for changes in antibody levels to these pathogens.ResultsBRSV was the only pathogen which demonstrated clustering by pen. Jersey calves experienced significantly lower changes in BVDV S/P than Holstein-Friesian calves. Animals with a high maximum respiratory score (≥8) recorded significant increases in H. somni S/P during the peri-weaning period when compared to those with respiratory scores of ≤3.Haptoglobin levels of between 1.32 and 1.60 mg/ml at d − 14 were significantly associated with decreases in BHV-1 S/N during the peri-weaning period. Higher BVDV S/P ratios at d − 14 were significantly correlated with increased changes in serological responses to BHV-4 over the peri-weaning period.ConclusionsHaptoglobin may have potential as a predictor of exposure to BHV-1. BRSV would appear to play a more significant role at the ‘group’ rather than ‘individual animal’ level. The significant associations between the pre-weaning levels of antibodies to certain BRD pathogens and changes in the levels of antibodies to the various pathogens during the peri-weaning period may reflect a cohort of possibly genetically linked ‘better responders’ among the study population.

Microbial diversity involved in the etiology of a bovine respiratory disease outbreak in a dairy calf rearing unit

“…P. multocida, M. bovis, and H. somni were detected in single or in mixed infections with other BRD pathogens. These results need to be considered with caution, as P. multocida and M. haemolytica are eventually listed as a primary agent of BRD, being more often considered opportunistic pathogens, and contributing to the increase of clinical signs in outbreaks [5,15]. Our study differs from another study that evaluated bacteria present in the lower respiratory tract of healthy and diseased calves with BRD in Brazil, in which Enterobacteriaceae were the predominant bacteria in BALF samples [21].…”

“…Bovine respiratory disease (BRD) in calves represents an important cause of economic losses for the dairy industry worldwide due to costs associated with reduced weight gain, farm labor, treatment, prophylaxis, and high morbidity and mortality rates [1][2][3][4]. Bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine alphaherpesvirus 1 (BoHV-1), bovine coronavirus (BCoV), and bovine parainfluenza virus 3 (BPIV-3) are the main viral pathogens infecting the bovine respiratory system [5][6][7]. Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis are the major bacteria involved in secondary infection of the respiratory tract and are associated with pneumonia in young dairy calves [6,8,9].…”

ATAC-Seq identifies regions of open chromatin in the bronchial lymph nodes of dairy calves experimentally challenged with bovine respiratory syncytial virus

“…In Ireland, the mortality rate for dairy calves between 0 and 6 months of age is 5.4% [ 2 ], while the pre-weaning dairy calf mortality rate in the US is 7.8% [ 3 ]. Bovine respiratory disease (BRD) accounts for the largest proportion of dairy calf mortality between 2 and 6 months of age [ 4 ]. The global prevalence of BRD in dairy calves varies greatly between studies, and ranges from 3.5 to 40% [ 5 – 10 ].…”

Pathogen-specific risk factors in acute outbreaks of respiratory disease in calves

“…Also, Mycoplasma bovis is increasingly recognized as a primary pathogen, although this remains controversial in the scientific community (Calcutt et al, 2018). Despite the importance of BRD, most available studies on pathogen identification in live animals are limited in number of herds and pathogens studied (Autio et al, 2007;Pardon et al, 2011;Murray et al, 2018). Also, most of them involve intensive systems such as feedlots or veal calves, which are confronted with respiratory disease year round at a predictable moment in the production cycle (Pardon et al, 2011;Timsit et al, 2017).…”