Effects of dietary protein on growth, food consumption and body composition of Nile tilapia (Oreochromis niloticus L.)

The effects of dietary protein (25, 35 & 45%) on food consumption, growth and body composition of Nile tilapia, Oreochromis niloticus L (mean weight 10.83±0.32g) were investigated. Individual food consumption rates were measured by X-radiography technique. The highest concentration of dietary protein (45%) enabled the fish to grow faster and more efficiently. The diet containing 45% protein appears to be more suitable for Nile tilapia compared to 35% and 25% protein levels (determined by observed rates of SGR, FC, GE, CVc and FCR). An increase in dietary protein level led to an overall improvement in wet weight gain as evidenced by better wet/gain and feed/gain ratios. Increasing dietary protein level from 25% to 45% had no significant effect on the whole-body composition (protein, lipid and ash) of Nile tilapia. The dominant fish in all three diets had better growth rates than subordinate fish. Results from the present study indicated that fast growing dominant fish consuming the most food are in fact the least efficient in terms of nutrient deposition. This may be as a result of the faster growing dominant fish consuming excess of nutrient and energy requirement for maximum lean growth (protein deposition) and there is an associated increase in protein deposition.