A microencapsulated feed additive containing organic acids, thymol, and vanillin increases in vitro functional activity of peripheral blood leukocytes from broiler chicks

Authors: Swaggerty, Christina - Christi; He, Louis; Genovese, Kenneth - Ken; CALLAWAY, TODD - University Of Georgia; Kogut, Michael - Mike; PIVA, ANDREA - University Of Bologna; GRILLI, ESTER - University Of Bologna

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2020
Publication Date: 7/1/2020
Publication URL: https://handle.nal.usda.gov/10113/6915706
Citation: Swaggerty, C.L., He, L.H., Genovese, K.J., Callaway, T.R., Kogut, M.H., Piva, A., Grilli, E. 2020. A microencapsulated feed additive containing organic acids, thymol, and vanillin increases in vitro functional activity of peripheral blood leukocytes from broiler chicks. Poultry Science. 99(7):3428-3436. https://doi.org/10.1016/j.psj.2020.03.031.
DOI: https://doi.org/10.1016/j.psj.2020.03.031

Interpretive Summary: Young chicks can easily get sick the first week of their life because their immune system is not fully functional. Because of this, the chicks are susceptible to harmful bacteria (like Salmonella) that may make them sick, as well as people. The objective of this project was to try and boost the immune system of young chicks by supplementing their diet with a special feed additive. We wanted to know if the feed additive could make immune cells found floating in the chicken's bloodstream function better so they would mature more quickly and therefore protect the chick from getting sick. Day-old chicks were assigned to either a control diet (no supplement) or a diet supplemented with the feed additive. After 4 days, blood cells were collected from the chicks and their immune function was tested in the lab. We found that immune cells collected from the blood taken from the chicks given the feed additive responded better and were functionally stronger than the cells from birds on the control diet. In conclusion, four days of feeding chicks the supplemented diet was enough to boost their immune cells. Young chicks with a stronger immune system are less likely to get sick. A healthier chick will grow up to be a healthy bird that enters the food chain and therefore less likely to pass on bugs like Salmonella, thus, creating a safer food supply for the consumer.

Technical Abstract: During the first week post-hatch, young chicks are vulnerable to pathogens as the immune system is not fully developed. The objectives of this study were to determine if supplementing the starter diet with a microencapsulated feed additive containing citric and sorbic acids, thymol, and vanillin affects in vitro functional activity of peripheral blood leukocytes (PBL). Day-old chicks (n=800) were randomly assigned to either a control diet (0 g/metric ton [MT]) or a diet supplemented with 500 g/MT of the microencapsulated additive. At 4-d-of-age, peripheral blood was collected (100/group) and heterophils and monocytes isolated (n=4). Heterophils were assayed for the ability to undergo degranulation and production of an oxidative burst response, while nitric oxide production was measured in monocytes. Select cytokine and chemokine mRNA expression levels were also determined in both cell populations. Statistical analysis performed using Student's t-test comparing the supplemented diet to the control (P less than or equal to 0.05). Heterophils isolated from chicks fed the microencapsulated citric and sorbic acids, thymol, and vanillin had higher (P less than or equal to 0.05) levels of degranulation and oxidative burst responses than those isolated from chicks on the control diet. Heterophils from the supplemented chicks also had greater (P less than or equal to 0.05) expression of IL10, IL1ß, and CXCL8 mRNA than those from control-fed chicks. Similarly, nitric oxide production was significantly (P less than or equal to 0.05) higher in monocytes isolated from birds fed the supplement. The cytokine/chemokine profile in monocytes from the supplement-fed chicks showed a significant (P less than or equal to 0.05) drop in IL10 mRNA expression while IL1ß, IL4, and CXCL8 were unchanged. In conclusion, four days of supplementation with a microencapsulated blend made up of citric and sorbic acids, thymol, and vanillin, enhanced the in vitro PBL functions of degranulation, oxidative burst, and nitric oxide production compared to the control diet. Collectively, the data suggest feeding broiler chicks a diet supplemented with a microencapsulated blend of citric and sorbic acids, thymol, and vanillin may prime key immune cells, making them more functionally efficient and acts as an immune-modulator to boost the inefficient and undeveloped immune system of young chicks.