Effect of essential amino acids (methionine and lysine) and treated oil in fish diet on growth performance and feed utilization of Nile tilapia, Tilapia nilotica (L.)

Abstract

Abstract. Nile tilapia, Tilapia nilotica (L.), were fed eight isonitrogenous diets in two laboratory experiments at the Faculty of Agriculture (Saba Basha), Alexandria University, Alexandria, Egypt. The diets were: (A) mixture containing 28% protein from both animal protein (fish meal) and plant protein (soybean meal and cotton seed meal) as a source of protein; (B) mixture free of animal protein; (C) mixture B supplemented with essential amino acids (EAA) (methionine and lysine); (D and E) composed of diet C supplemented with 5% and 3·5% oil respectively; (F and G) composed of diet C supplemented with emulsified or saponified 3·5% oil respectively and (H) mixture composed of diet C plus non-extracted rice bran instead of wheat flour as a source of energy without adding oil. Growth performance (energy and protein retention and protein efficiency ratio) decreased with the animal protein free diet B. Supplementation of methionine and lysine to diet C improved growth performance and feed utilization as well as addition of oil and treated oil but 5% oil and 3·5% saponified oil increased mortality of the tingeriings by 46·27% and 20% respectively. Diet F gave the lowest mortality and the highest growth, energy and protein retention and protein efficiency ratio.