Dietary Aloysia triphylla essential oil on growth performance and biochemical and haematological variables in Nile tilapia

Abstract

This study examined the growth, biochemical and haematological variables of Nile tilapia juveniles (Oreochromis niloticus) fed diets incorporated with essential oil from Aloysia triphylla (EOAT). Five diets were formulated; each containing increasing levels of EOAT (0.00 [control], 0.25, 0.50, 1.00 and 2.00 mL kg diet−1) for 45 days. Blood and intestinal samples of three fish per replicate (n = 4) were taken at the end of the experiment. Fish survival did not differ between treatments (p > .05). Positive linear effects of dietary EOAT supplementation on the final weight, weight gain and specific growth rate (R2 = 0.73) and haematocrit (R2 = 0.75) and erythrocytes (R2 = 0.85) levels in fish, were observed (p < .05). The addition of 2.00 mL EOAT kg diet−1 increased the intestinal lipase and alkaline protease activities, plasma alanine aminotransferase and albumin levels, the albumin to globulin ratio and lysozyme activity, and decreased the intestinal amylase activity, plasma glucose, triglycerides and globulin levels compared with the control group (p < .05). Thus, 2.00 mL EOAT kg diet−1 is recommended for use in feed, since it ensures Nile tilapia growth, intestinal lipase and alkaline protease activities, plasma lysozyme and albumin levels, and haematocrit and erythrocyte values.