Effects of Pediococcus acidilacticias a Probioticon Hematology, Blood Parameters and Intestinal Histopathology of Rainbow Trout, Oncorhynchus mykiss

Inroduction & Objective: Nonpathogenic lactic acid bacteria have important role on intestinal microbial flora of animal host and they improve performance of fish by influencing gastrointestinal tract, reducing pH and improving immunity. An experiment was designed to study the physiological effects of Pediococcus acidilactici feeding on rainbow trout. Material and Methods: The ninety six rainbow trout with 60 g initial body weight were randomly assigned to six polyethylene tanks and fed by control or experimental diet which was contain 109 CFU.Kg1Pediococcus acidilacticifor 8 weeks feeding trials at three times daily feeding rate. The growth performance, final body weight, efficiency of carcass and liver, hematology and blood parameters and intestinal morphology of fish were evaluated at end of experiment. The body weight gain, feed conversion ratio, final body weight, condition factor, efficiency of carcass and liver weren’t affected by the dietary supplementation ofPediococcus acidilactici, as probiotic, .but significantly reduced mortality of fish (p<0.05).The number of white blood cells, percent of neutrophils and also width of intestinal villus increased by feedingPediococcus acidilactici. The supplementation ofPediococcus acidilactici to fish diets improved immunity and reduced mortality of grower rainbow trout.