Dynamics of Macrophages in Laying Hens during Second and Third Production Cycles after Zinc Induced Molting

Abstract

The influence of a non-feed removal molting program on certain parameters of cell mediated and humoral immune response of the laying birds during 2nd and 3rd production cycles were recorded. Birds at the end of their 1st production cycle were induced to molt through the supplementation of high dietary zinc oxide (3000mg/Kg) for their 2nd and 3rd production cycles. Macrophage engulfment (%) and engulfment/cell were significantly increased after the use of opsonized sheep red blood cells (SRBC) for co-incubation during 2nd production cycle. Lipopolysacchrides (LPS) greatly enhanced the production of nitric oxide, as compared to the SRBC stimulation during the 2nd production cycle. Zinc feeding strengthened the antibody response against Newcastle disease virus (NDV) and egg drop syndrome virus (EDS) at the peak of the 2nd and 3rd production cycles, but decreased at 5% production stages. NDV also provoked a better antibody response when compared to EDS. Zn concentration in plasma showed a positive correlation with an increase in egg production. Our results validate the strengthened immune response during the 2nd production cycle after zinc-induced molting.