Effect of beta-Carotene Supplementation on Plasma and Yolk IgY Levels Induced by NDV Vaccination in Japanese Quail

Abstract

Newly hatched Japanese quail (Coturnix coturnix japonica) chicks were fed diets containing different levels of retinoids (vitamin A) or beta-carotene. Group A received a commercial diet containing 10000 IU vitamin A per kilogram. The diets of Groups B, C, and D contained no vitamin A but were supplemented with 1-, 2.5-, and 5-fold retinol equivalents of beta-carotene. Each group contained 16 quails in a 1:1 sex ratio. At 8 weeks of age the quails were immunized orally with Newcastle disease virus (NDV) vaccine according to the manufacturer’s recommendations. Boosters were given three times at two-week intervals. Blood samples were taken at two-week intervals until 14 weeks of age. The anti-NDV IgY titre was determined by a locally developed direct enzyme-linked immunosorbent assay (ELISA). Groups A and B showed nearly the same antibody response. This indicates that the preformed vitamin A and the equivalent beta-carotene have the same immunomodulatory effect. Groups receiving higher doses of beta-carotene (Groups C and D) exhibited significantly higher plasma IgY levels compared to Groups A and B. The results indicate that elevated doses of beta-carotene have a slight effect on the adaptive immune response in Japanese quail.