GROWTH PERFORMANCES, MUSCLE-GROWTH-RELATED GENE EXPRESSION AND HAEMATO-BIOCHEMICAL RESPONSES OF GIFT TILAPIA FED WITH DIETARY L-LYSINE SUPPLEMENTED DIETS

Gene expression studies provide a better understanding of genomic responses in fish nutrition researches. Biochemical and haematological parameters are a reflection of health and physiological responses that may be influenced by various nutrients in the feed. Lysine is an essential amino acid present in high proportion in fish muscle tissue, involved in growth and maintenance of fishes. The present research was conducted to determine the effects of dietary L-lysine supplementation on growth performances, muscle growth-related-gene expression, haematological and biochemical responses of GIFT tilapia.

An 8-week indoor feeding trial was conducted in 15 nos. of 1 X 1 X 1.5 m sized cages in triplicate, with GIFT tilapia weighing on an average of 10 g. Five corn-soy based isonitrogenous and isoenergetic diets were formulated to contain graded levels of lysine (% of dry diet) viz., T0 (1.45), T1 (1.6), T2 (1.75), T3 (1.9) and T4 (2.05). Each diet was randomly assigned to triplicate groups of 30 juvenile fish, which were fed three times daily (9:00, 13:00 and 17 h). Among the experimental diets T4, the diet containing lysine level of 2.05 % of dry diet yielded significantly (p<0.05), higher mean body weight gain (48.43 g) followed by T3 (45.7 g), T0 (43.47 g), T2 (34.64 g) and T1 (31.13 g). The best results in terms of feed conversion ratio (1.13), specific growth rate (1.74), feed efficiency ratio (0.87), average daily growth (1.07), specific growth rate (1.74), haematological, biochemical parameters and muscle-growth-related gene expressions were observed in T4. The results demonstrated that the dietary lysine requirement in corn-soy based diet for GIFT tilapia would be 2.05 % of dry diet for better growth performances.