Evaluation of the effect of Clustat probiotic (Bacillus subtilis) on some growth and hematological factor as well as intestine tissue of the rainbow trout (Oncorhynchus mykiss)

At present, the use of probiotics as goodalternative for antibiotics is greatlyincreasing in aquaculture industry. The  objectives  of  this  study  was  to  evaluate  the  effect  of  dietary  supplementation  of B. subtilis probiotic (KEMIN ®) on growth and hematological parameters and also the morphology of intestine of rain bow trout (Oncorhynchus mykiss).

In this study 135 fish with an average initial weight of 35.68 ± 2.5 g were fed diets supplemented with of probiotic after 50 days. Experimental treatments included control without probiotic (control group), 1 and 2% probiotic levels.Fish were randomly sampled at the end of experimental period. The blood was extracted from caudal vein of samples for measuringblood parameters (total red and white cells, hemoglobin, differential blood cell count).Intestinal morphology including height and width of villi, density and area of goblet cells were quantified for histological examination. Growth parameters was also determined. 

At the end of the feeding trial, fish fed with probiotic supplemented diets had significantly higher growth performance than control group (p < 0.05). In addition, fish fed with probiotic diets had significantly higher red blood cell, neutrophils and height of villi compared to the control group (p < 0.05). No significant difference of some hematological parameters (such as white blood cell, hematocrit, hemoglobin, neutrophils and monocyte) and intestinal morphology (width of villi, density and area of goblet cells) was observed in all groups (p> 0.05).

The results of this study showed that the oral administration of B. subtilis possessed the beneficial and positive effects on growth and hematological factors as well as intestine tissue of rain bow trout.