Wellness Management in Beef Feeder Cattle: Changing Mental Models to Support Beneficial Emergent System Behaviors

Despite evidence-based "improvements" in animal health products and management, losses to bovine respiratory disease have increased with associated animal wastage, welfare concerns, and antimicrobial use; questioning the fitness of current disease-centric paradigms for improving critical outcomes in complex adaptive systems. Systems thinking is used to model a paradigm shift from mental models based on management of failure outcomes in a flawed pass/fail dichotomy to one of managing success outcomes on a continuum. In the proposed wellness paradigm, the notion of health as absence of disease is rejected and replaced with perspective of disease as symptomatic of systems insufficiently supporting wellness.

Protection against Mycoplasma bovis infection in calves following intranasal vaccination with modified-live Mannheimia haemolytica expressing Mycoplasma antigens

Novel live vaccine strains of Mannheimia haemolytica serotypes (St)1 and St6, expressing and secreting inactive yet immunogenic leukotoxin (leukotoxoid) fused to antigenic domains of Mycoplasma bovis Elongation Factor Tu (EFTu) and Heat shock protein (Hsp) 70 were constructed and tested for efficacy in cattle. Control calves were administered an intranasal mixture of M. haemolytica St1 and St6 mutants (ΔlktCAV4) expressing and secreting leukotoxoid while vaccinated calves were administered an intranasal mixture of like M. haemolytica St1 and St6 leukotoxoid mutants coupled to M. bovis antigens (EFTu-Hsp70-ΔlktCAV4). Both M. haemolytica strains were recovered from palatine tonsils up to 34 days post intranasal exposure. On day 35 all calves were exposed to bovine herpes virus-1, four days later lung challenged with virulent M. bovis, then euthanized up to 20 days post-challenge. Results showed all cattle produced systemic antibody responses against M. haemolytica. The vaccinates also produced systemic antibody responses to M. bovis antigen, and concurrent reductions in temperatures, middle ear infections, joint infection and lung lesions versus the control group. Notably, dramatically decreased lung loads of M. bovis were detected in the vaccinated cattle. These observations indicate that the attenuated M. haemolytica vaccine strains expressing Mycoplasma antigens can control M. bovis infection and disease symptoms in a controlled setting.

Effect of suckler cow vaccination against glycoprotein E (gE)-negative bovine herpesvirus type 1 (BoHV-1) on passive immunity and physiological response to subsequent bovine respiratory disease vaccination of their progeny

The study objectives were: 1) to characterise the development of immunocompetence in beef suckler calves from birth to three months of age, and 2) to trace glycoprotein E (gE)-negative bovine herpesvirus type 1 (BoHV-1) antibodies from dam to calf and subsequent vaccination against pneumonia. Thirty multiparous beef suckler, spring-calving cows, consisting of two genotypes were involved; Limousin × Friesian (LF) and Charolais × Limousin (CL). Cows were immunised against the inactivated antigen strain of BoHV-1 (gE- (IBR marker vaccine) at day − 84 and received a booster at day − 56 relative to the expected calving date (d 0). Calves were immunised at 14 and 42 days of age against PI-3 virus, BRSV and Mannheimia (Pasteurella) haemolytica serotype A1 using a commercial vaccine administered subcutaneously. Additionally, calves were immunised against BoHV-1 at 42 days of age, using 1 dose of a live commercial vaccine administered intranasally. Blood samples were collected from all calves (n = 30) via jugular venipuncture at birth, prior to colostrum feeding (0 h), at 12 h (h), 24 h, 72 h and 168 h after the initial feeding of colostrum, and at d 7, 14, 28, 42, 56 and 84 post birth. The mean ratio of gE negative antibodies circulating in the blood of LF and CL dams pre-partum scored negative to gE ab (S/N ≥ 0.70). Antibody levels of BoHV-1 (wild type (wt)) peaked at 12 h post-birth in calves and declined thereafter, as the maternal antibodies decayed. There was no difference in BoHV-1 and BRSV antibody levels in calves post vaccination.

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Greater decrease in cow serum IgG concentration in LF cows than CL cows pre-partum.

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Progeny of LF cows have a greater pre-weaning ADG than the progeny of CL cows.

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Maternally derived antibodies affects response to vaccination in suckled beef calves.

Evolving views on bovine respiratory disease: An appraisal of selected key pathogens - Part 1

Bovine respiratory disease (BRD) is one of the most commonly diagnosed causes of morbidity and mortality in cattle and interactions of factors associated with the animal, the pathogen and the environment are central to its pathogenesis. Emerging knowledge of a role for pathogens traditionally assumed to be minor players in the pathogenesis of BRD reflects an increasingly complex situation that will necessitate regular reappraisal of BRD pathogenesis and control. This review appraises the role of selected key pathogens implicated in BRD pathogenesis to assess how our understanding of their role has evolved in recent years.