Effects of Some Herbal Plant Supplements on Growth Performance and the Immune Response in Nile Tilapia (Oreochromis Niloticus)

Abstract Using of natural plants as immunostimulant in fish is more useful than antibacterial drugs that cause adversely side effects for fish, environment and consumers. Therefore, the present study was to investigate the effects of dietary turmeric (Curcuma longa), rosemary (Rosmarinus officinalis) and thyme (Thymus vulgaris) as feed additives on growth performance, proximate composition and some immuno-hematological parameters on Nile tilapia. Four nitrogenous (31.43-31.56 % crude protein) and isocaloric (17.90-18.04 kJ/g) diets were formulated to contain 0% (control), 1% of turmeric, rosemary or thyme, respectively. The results reveled that, supplementation with medicinal herbs significantly increased (P<0.05) weight gain, specific growth rates and protein efficiency ratio (PER) compared to those in the control group. Moreover, the medicinal herb additives had insignificant effect on carcass composition and some biochemical composition. Hematocrit and leukocrit levels in the fish fed with turmeric, rosemary and thyme added diet were found to be significantly (P <0.05) higher than the control group. However, leukocyte level among the experimental groups was not significantly differed (P >0.05). In neutrophils of experimental fish groups, there were higher numbers of NBT (+) cells fixed on lamellas than those of the control group. So, based on the current findings together with the low cost and the immunostimulative effect of turmeric, rosemary and thyme it can be recommended to be used in fish feed to minimize the mortalities caused by some pathogens.