effect of the probiotic, lactobacillus plantarum on growth performance and haematological indices of rainbow trout (oncorhynchus mykiss) immunized with bivalent streptococcosis / lactococcosis vaccine

The present study evaluated the effect of lactobacillus plantarum as a probiotic on the growth performance and haematological parameters of juvenile rainbow trout (oncorhynchus mykiss) weighing 29.6 plusmn;1.8 g immunized with streptococcus/lactococcus bivalent vaccine for 60 days at 16 plusmn;1.5 ordm;c. fish were randomly allocated to 4 equal groups: probiotic (g kg1 feed equal to 108 cells g1) supplemented diet group (group p), vaccinated fish fed with a normal diet (group v), vaccinated fish fed with probiotic (group p+v) and unvaccinated fish fed normal diet (group c). results showed that weight gain, final weight, condition factor and thermalunit growth coefficient were improved in p+v group compared with other groups but was significantly different from groups v and c (p<0.05). also, feed conversion ratio in the p+v group was lower than other trails (p<0.05). in addition, white blood cell count (wbc) in groups v and p+v were significantly higher than in both p and c groups (p<0.05). also, pcv was significantly increased (p<0.05) in both p and p+v groups compared to group v and the control group. no significant difference (p>0.05) was found in rbc, hb, mch, mchc and mcv levels among the different experimental groups. these data show that application of l. plantarum could be a benefit of vaccinated trout, enhancing fish growth and haematological parameters