The main aim of this study was to investigate the relationship between residual feed intake and some hematological parameters in laying hens fed different level of Propolis. Residual feed intake is used as a trait to distinguish efficient and non-efficient laying chicken. A Phytohemagglutinin-P (PHA-P) assay and white blood cells differentiation were used to evaluating the immune response of the laying hens fed different propolis levels. The present result indicated that the laying hens fed different levels of Propolis had significantly hyper responder to PHA-P injection, higher lymphocytes count and lower heterophils count when compared with control-group. With respect to residual feed intake, it was generally noticed that the observed feed consumption values were somewhat closely to expect feed consumption values for hens fed diet containing 100 or 150 mg Propolis compared to remaining treatments. Also, the results revealed that the equations calculated for laying hens fed diet adding 100 or 150 mg Propolis had a better rate of determination (R2) compared to other fed 0 or 50 mg Propolis. In accordance to correlation coefficients, it could be noticed that the wattle swelling measured at 24, 48 and 72 h post PHA-P injection were significantly positive correlated with residual feed consumption in supplemental propolis at 100 mg. Similar trend was observed in 150 mg supplemental propolis laying at 72 h post PHA-P injection. With respect to white blood cells differentiation, the present results showed that significantly negative relationship between RFC and heterophils percentage in all treatment groups. Inversely, the relationship between RFC and lymphocytes percentage was significant and positive in all treatment groups. Finally, it could be concluded that the Propolis supplementation improve the immune status of laying hens via minimizing the residual feed intake.
A. Galal, A.M.H. Ahmed, W.A.H. Ali, M.H. El-Sanhoury and Hedia E. Ahmed, 2008. Residual Feed Intake and its Effect on Cell-Mediated Immunity in Laying Hens Given Different Propolis Levels. International Journal of Poultry Science, 7: 1105-1111.