effects of dietary administration of yarrow extract on growth performance and blood biochemical parameters of rainbow trout (oncorhynchus mykiss)

the present study was conducted to investigate the clinical effects and possible side effects of yarrow extract ( achillea millefolium l.) as feed additive on biochemical blood parameters and growth performance of rainbow trout ( oncorhynchus mykiss ). fishes were treated with 0 (control), 0.1, 0.5 and 1% of yarrow extract for 30 days. plasma alanine aminotransferase (alt), aspartate aminotransferase (ast), lactate dehydrogenase (ldh), alkaline phosphatase (alp), creatine kinase (ck), peroxidase activity, total complement and lysozyme activity, glucose, total protein, triglyceride and cholesterol were measured after 15 and 30 days of yarrow treatment. there were no significant changes in the lysozyme activity and glucose levels. total protein and globulin levels were significantly higher in the fish fed with diets enriched with 1% yarrow extract on day 30. triglyceride and cholesterol levels was significantly decreased in the fish fed with diets containing 0.5% and 1% yarrow extract on day 30 ( p <0.05). ldh, ck and peroxidase activities in the fish fed with diets having 1% yarrow extract were significantly decreased at the end of the experiment ( p <0.05). in contrast, a significant increase in ast, alp and total complement activity was observed in the fish fed with 1% yarrow extract diet, on day 15 ( p <0.05). the weight gain and specific growth rate increased and food conversion ratio decreased in in the fish fed 1% yarrow extract on day 30. condition factor in the fish fed with yarrow extract was significantly higher than control group on 30 day. in conclusion, on the basis of these results, oral administration of yarrow extract up to 0.5% have not side effect on blood biochemical and clinical parameters of fishes. however, oral administration of 1% of yarrow extract caused cytotoxicity and modifications in blood biochemical parameters of fish.