Effect of different protein and energy levels on growth performance and body composition of red tilapia

A 8-weeks feeding trial was conducted to explain the most suitable levels of protein and energy for red tilapia fry reared in fresh water. Nine experimental diets of 25, 30 and 35% crude protein and within each level, three levels of metabolizable energy (ME) 240, 280 and 320 kcal/100 g diets were formulated. Red tilapia fry (0.77 g) fed the experimental diets at a daily rate of 20% (during the 1^st month) and then decreased to 10% (2^nd month) of the total biomass. The obtained results showed that, increasing dietary protein and energy levels significantly improved all growth parameters (body weight, body length, weight gain and specific growth rate) of red tilapia fry. Fish group fed the diet contained 35% crude protein and 320 Kcal ME/100 g showed the highest final body weight, body length, weight gain and specific growth rate while fish fed the diet contained 25% crude protein and 240 kcal ME/100 g showed the lowest growth parameters. It is also found that increasing protein or energy levels in red tilapia fry diets significantly increased feed intake (FI) and significantly improved feed conversion ratio (FCR) and protein efficiency ratio (PER). The best feed efficiency parameters (feed conversion ratio and protein efficiency ratio) were obtained for fish group fed the diet containing 35% crude protein and 320 kcal ME/100 g while the diet contained 25% crude protein and 320 kcal ME/100 g diet had the worst FCR. Increasing dietary protein and energy levels in red tilapia fry diets significantly decreased protein and increased fat contents of red tilapia bodies. Generally, based on the present results, the experimental diet containing 35% crude protein and 320 kcal ME/100 g considered the most suitable diet for red tilapia fry reared in fresh water.