Influence of some feed additives on growth rates and physiological measurements of blue tilapia (Oreochromis aureus)

Influence of some feed additives on growth rates and physiological
measurements of blue tilapia (Oreochromis aureus)
Raky Fakhry Attalla
National Institute of Oceanography and Fisheries, Cairo.
E-mail: [email protected]
Abstract
An experiment was conducted to evaluate the effect of two different commercial feed additives on growth
performance, feed utilization and some blood parameters of Oreochromis aureus fingerlings. Seven treatments were
applied, two forms of Allium sativum (powder and oil extract), Thymus vulgaris (dried powder and oil extract), and their
combination (1:1) of each form, in addition to control group diet free from any additives. The experiment was completed
using fourteen glass aquaria (80×45×40 cm, each,). Each was stocked with 40 fingerlings with an average initial body
weight 2.8 ± 0.3 g. and body length 6.0 ± 0.3 cm. The experiment lasted for 10 weeks. Generally, growth performance,
feed conversion ratio, protein efficiency ratio, survival and apparent protein digestibility were improved for blue tilapia
(O. aureus) fed on diets with commercial feed additives compared to fish fed the control diet. In terms of blood
measurements, alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT)
activities in plasma decreased significantly (P<0.05) for fish fed all treated groups. Plasma total protein, albumin and globulins of fish fed on additives significantly increased (P<0.05) for those fed on additives, while blood glucose, triglycerides and cholesterol values were significantly decreased (P<0.05), as compared to the control group. These results revealed that feeding (O. aureus) with a mixture of thyme and garlic powders or oil extracts, can promote growth rate, decrease mortality rate and improve the physiological activities. Keywords: Blue tilapia, growth, blood measurements, feed additives, Garlic, Thymus.