5.4 The Mortality Rate Following the challenge infection using P. fluorescens the mortality rate was significantly lower in all S. platensis supplemented groups vs. the control throughout the experimental period. 5.5 The Relative Level of Protection (RLP) The results recorded in (Table 4) evoked significant protection in all S. platensis supplemented groups vs. the control. It worth mentioned that the mean value level is in-group 4 (group received 10 g/kg) is higher in all the tested parameters with significant difference.