In ovo administration of the Marek's disease vaccine in conjunction with 25-hydroxyvitamin D3 and its subsequent effects on the performance and immunity-related characteristics of Ross 708 broiler hatchlings

Authors: FATEMI, S - Mississippi State University; MOUSSTAAID, A - Mississippi State University; WILLIAMS, C - Zoetis; DEINES, J - Zoetis; POUDEL, S - Mississippi State University; POUDEL, I - Mississippi State University; Collins Elliott, Katie; WALTERS, E - Mississippi State University; FORCIER, N - Mississippi State University; PEEBLES, E - Mississippi State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2023
Publication Date: 11/6/2023
Citation: Fatemi, S.A., Mousstaaid, A., Williams, C.J., Deines, J., Poudel, S., Poudel, I., Collins Elliott, K.E., Walters, E.R., Forcier, N., Peebles, E.D. 2023. In ovo administration of the Marek's disease vaccine in conjunction with 25-hydroxyvitamin D3 and its subsequent effects on the performance and immunity-related characteristics of Ross 708 broiler hatchlings. Poultry Science. 103(1), 103199. https://doi.org/10.1016/j.psj.2023.103199.
DOI: https://doi.org/10.1016/j.psj.2023.103199

Interpretive Summary: Previous research found promising results when 25-hydroxyvitamin D3 (25OHD3) was administered to broiler embryos prior to hatch through in ovo administration. This form of vitamin D administered in ovo helped reduce the inflammatory response and improved the intestinal health of broilers challenged with coccidiosis as well as increased the body weight gain and overall performance of broilers at processing age. The majority of broilers in the United States, however, are in ovo vaccinated for a tumor-causing viral disease called Marek's disease. In order to administer 25OHD3 to commercial broilers in ovo, this form of vitamin D would have to be injected along with the Marek's disease vaccine (MDV). Thus, this experiment sought to test the effects of combining previously tested dosages of 25-hydroxyvitamin D3 along with the Marek's vaccine when administered in ovo on hatchability and the newly hatched chick. The treatments included 1) noninjected (control); or a 50 µL solution volume of 2) MDV alone; or MDV combined with 3) 0.6 µg of 25OHD3; 4) 1.2 µg of 25OHD3; or 5) 2.4 µg of 25OHD3. The hatchability of the chicks were not affected by the various treatments and the hatched chicks were heaviest in the MDV + 1.2 or 2.4 µg of 25OHD3. In comparison to the noninjected treatment group, the expression of the genes for 1 a-hydroxylase and 24 hydroxylase was improved when MDV was combined with either 1.2 or 2.4 µg of 25OHD3. Lastly, expression of the genes linked to viral detection (TLR-3) and antibody production (INF-ß) was increased in the treatments that contained any level of 25OHD3. These results indicate that in comparison to the controls, the effects of MDV were observed to be greater on hatchling body weight and splenic gene expression when it was administered in combination with the 1.2 or 2.4 µg doses of 25OHD3. Research on the growth of the chicks post-hatch is needed, but these early at-hatch results also show promising results for the combination of Marek's disease vaccine and 25OHD3 for improving the health of broilers when administered in ovo.

Technical Abstract: The combined effects of the in ovo injection of commercial Marek's disease vaccine (MDV) and various levels of 25-hydroxyvitamin D3 (25OHD3) on the hatch variables, immunological measurements, and gene expression of Ross 708 hatchling broilers were investigated. A total of 5 in ovo injection treatments that were applied at 18 d of incubation (doi) included: 1) noninjected (control); or a 50 µL solution volume of 2) MDV alone; or MDV combined with 3) 0.6 µg of 25OHD3; 4) 1.2 µg of 25OHD3; or 5) 2.4 µg of 25OHD3. At hatch, hatchability of set and live embryonated eggs, hatchling body weight, hatch residue analysis, serum IgY and alpha-1 acid glycoprotein (AGP) concentrations, and the expression of genes related to immunity (INFa, INFß, INF', TLR-3, and TLR-21) and vitamin D3 activity (1 a-hydroxylase, 24 hydroxylase, and vitamin D receptor) were determined. No significant treatment differences were observed for hatchability of set and live embryonated eggs, or for serum IgY and AGP concentrations. However, hatchling body weight was higher when MDV was combined with either 1.2 or 2.4 µg of 25OHD3 than when MDV was provided alone or in combination with 0.6 µg of 25OHD3. Also, in comparison to the noninjected treatment group, the expression of the genes for 1 a-hydroxylase and 24 hydroxylase was improved when MDV was combined with either 1.2 or 2.4 µg of 25OHD3. Lastly, expression of the genes linked to viral detection (TLR-3) and antibody production (INF-ß) was increased in those treatments that contained any level of 25OHD3. These results indicate that in comparison to controls, the effects of MDV were observed to be greater on hatchling BW and splenic gene expression when it was administered in combination with the 1.2 or 2.4 µg doses of 25OHD3. Further research is needed to determine the posthatch effects of the administration of various levels of 25OHD3 in combination with MDV.