Ineffective vaccines, declining employment in the agricultural sector and increasing awareness of antimicrobial resistance has led policymakers to shift the focus onto the development of superior, more efficacious vaccines as a major contribution in reducing the pressure to intensify on the farming sector. Although many vaccines against BRD are currently available on the UK market, they have limitations. Only a few of the vaccines have been registered as suitable for use in pregnant or lactating cows and all require refrigeration. Additionally, all come with a strong recommendation for a booster to advance immunity and none have been tested for maternal antibody interference. Only eleven of the vaccines registered for use in the UK are multivalent and only four have been tested and deemed suitable for use alongside other veterinary treatments, frequently with those of the same manufacturer. However, multiple pathogens are considered threats during the neonatal stage and so it is impractical and ineffectual to have monovalent or incompatible medicines. Vaccination against BRD presents many challenges.
|More neutral pH and lower levels of enzymatic activity than digestive tract
|Prime neonatal calf in the presence of MDA
|Induction of systemic and mucosal immunity
|User-friendly (potential use in herds/developing world/remote farms)
|Rapid clearance of low affinity antigens
|Potential antigen loss during inoculation (impact on cost)
|Lack of compatible adjuvants for mucosal vaccines