Mixing inactivated oil-emulsion vaccines: Assessing feasibility and safety
Intensive poultry production requires frequent vaccination with various inactivated vaccines, primarily administered by injection. This practice presents operational challenges, including increased labor costs, handling stress for birds, and biosecurity risks. Traditional approaches, such as the production of multivalent vaccines or simultaneous administration at different injection sites, are constrained by technical complexity. While mixed inactivated vaccines have been evaluated in other livestock species, no prior studies have addressed their combined use in poultry.
The study published in The Journal of Applied Poultry Research aimed to assess the feasibility, safety, and immunogenicity of administering mixed inactivated vaccines in chickens by:
1. Evaluating the physicochemical stability of mixed vaccines,
2. Testing immune responses in SPF chickens,
3. Assessing immunization effectiveness under large-scale layer farm conditions.
Physicochemical Stability: The mixed vaccines maintained stable particle size distribution, showed no phase separation or microbial contamination, and exhibited endotoxin levels within acceptable ranges, even after seven days of storage.
SPF Chickens: No significant differences in antibody titers against Newcastle Disease and Avian Influenza (H9, H5, H7) were observed between chickens vaccinated with mixed vaccines and those vaccinated with individual formulations.
Field Trial in Layers: The mixed vaccination protocol reduced the number of required injections from nine to five without compromising antibody responses.
The researchers concluded that mixing inactivated oil-emulsion vaccines under controlled conditions does not compromise their physicochemical properties or immunogenicity. Combined immunization with mixed vaccines is effective, safe, and applicable in both experimental and field settings. This approach significantly reduces injection frequency, labor costs, and bird handling stress. However, it should be noted that the mixing was performed under laboratory conditions, specifically, heating in a water bath at 42°C, mixing in a sterile container with a magnetic stirrer at 1200 rpm for three minutes, followed by repackaging. The study's conclusions do not guarantee the applicability of this method to other vaccines or uncontrolled settings.
Nevertheless, this study provides a meaningful contribution to the understanding of the feasibility and implications of mixing inactivated vaccines for poultry vaccination programs.
