ARTICLE 78 FEED & ADDITIVE MAGAZINE August 2024 vaccination and a dietary supplementation of GLA (V-GLA+), a vaccinated non-supplemented control group (V+GLA-) and a group that received both the vaccination and the GLA (V+GLA+). We first analyzed the serum of day 7-old birds for IBV-specific antibodies. In the V+GLA+ group, significantly higher anti-IBV titer values were found (Fig. 1). This finding is of utmost importance, as a higher number of antibodies against IBV at this early age is correlated with a higher protection level and lower mortality after IBV infection later in life (De Wit et al., 2010). ...AND THE CELLULAR IMMUNE RESPONSE In a later stage, at day 28, we collected spleens from birds from the different treatment groups to look at the splenocytes, mainly consisting of lymphocytes. Surprisingly, a lower amount of splenocytes was found in birds from the V+GLA+group. However, no differences were detected in the basal levels of cytokines secreted by T lymphocytes, nor in the levels of peripheral blood mononuclear cells. This suggests that the basal activity of splenocytes or the evasion of patrolling effector cells in the blood was not negatively affected. In a next step, we incubated the splenocytes for 24 hours with Concanavalin A or with an IBV peptide, to measure T cell reactivity to a general or specific stimulus, respectively. Using an ELISpot assay, we could detect more and larger IFNγ-reaction spots in the cells derived from the V+GLA+ group (Fig. 2), which means that the GLA product was able to increase the proportion and reactivity of cell subsets like T helper 1 cells (TH1) and cytotoxic T lymphocytes (CTL) in vaccinated birds. Activated CTL cells are crucial to clean up infected cells, while TH1 cells can increase the pathogen-destroying activity of macrophages. CONCLUSION In summary, the tested GLA represents a promising additive for promoting health in broilers. By stimulating the birds’ natural defense mechanisms, the product is expected to improve vaccination efficiency as well as to increase resilience against viral and other pathogenic challenges. As research continues to uncover the full potential of lauric acid-based products such as GLA, we can expect knowledge to increase on how poultry producers can optimally apply these compounds to achieve healthier, more resilient birds and more sustainable and efficient poultry production systems. Hence, FRA® C12 Dry is an important part of Adisseo's recent program, Secure Performance, in which we aim to enhance poultry resilience towards pathogens. day 7 V-GLA+ V-GLA+ : non vaccinated, GLA supplemented p < 0.05 V+GLAV+GLA- : vaccinated, non GLA supplemented V+GLA+ V+GLA+ : vaccinated, GLA supplemented 1.2 1 0.8 0.6 0.4 0.2 0 Specific anti-IBV/total lgY ratio (OD) Figure 1. Total specific anti-IBV titers reported individually on total IgY titers of broilers from the three experimental diets at day 7.
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